The influence of dietary fat level on the relative reinforcing potency of intragastric (IG) corn oil and sucrose was tested with flavor preference conditioning. Rats were given ad libitum access to a low-fat chow (LF; 12% fat kcal) or a high-fat chow (HF; 48% fat kcal) maintenance diet. They were given four 22-h/day one-bottle training sessions each with CS+F, CS+C, and CS- flavors paired with IG 7.1% oil emulsion, 16% sucrose solution and water, respectively. During training the LF and HF rats consumed equal amounts of CS+F and CS- and less of the CS+C. Overall, the training nutrient intakes of the LF group averaged 18% protein/55% carbohydrate/27% fat, whereas the HF group averaged 12/37/51%. In two-bottle choice tests the groups showed equally strong preference for the CS+F over the CS- (82-86%). They also preferred the CS+C over the CS-, but the LF rats had a stronger preference (93%) than did the HF rats (77%). The CS+C was preferred to the CS+F; the LF group’s 72% preference did not differ significantly from HF group’s 60% CS+C preference. The results extend prior work showing IG fat is less reinforcing than IG carbohydrate. Relative to the LF diet, the primary effect of HF diet was attenuation of carbohydrate-based flavor preference, perhaps due to greater satiation effects by carbohydrates when they comprise less of the overall diet. Supported by DK031135.

Serotonin inhibits, while a₂-adrenergic, gabaergic or opioidergic activation of the lateral parabrachial nucleus (LPBN) facilitates sodium intake. In the present study we investigated possible interactions between these mechanisms in the LPBN on water and 1.8% NaCl intake induced by sc furosemide (10 mg/kg) + captopril (5 mg/kg). Male Holtzman rats (n=6–9) with cannulas implanted bilaterally in the LPBN were used. Injections of the serotonergic 5HT_2A/2C receptor agonist DOI (5 µg) inhibited 1.8% NaCl (0.6±0.1, vs. veh.: 3.7±0.8 ml/2 h) and water intake, while the a₂-adrenergic agonist moxonidine (0.5 nmol) increased 1.8% NaCl intake (30.5±5.4 ml/2 h) and water intake. Similar to moxonidine alone, 1.8% NaCl intake (26.5±6.4 ml/2 h) and water intake increased if moxonidine was injected after DOI into the LPBN. The opioidergic antagonist naloxone (40 µg) or the GABA _A receptor antagonist bicuculline (5 nmol) partially reduced the effects of moxonidine on 1.8% NaCl intake (23.7±8.0, and 27.0±6.0, respectively, vs. moxonidine: 40.2±9 ml/2 h). The results suggest that the increase of water and NaCl intake by a₂-adrenergic receptor activation in the LPBN is probably due to an inhibition of LPBN serotonergic inhibitory mechanisms, and is also partially dependent on gabaergic and opioidergic mechanisms in this area. Supported by: FAPESP, CAPES, CNPq.

The pontine parabrachial nucleus is a hindbrain nucleus that is ideally situated to contribute to feeding behavior. Receptors for hypothalamic feeding-related peptides have been identified in the lateral PBN (lPBN), including neuropeptide Y (NPY) Y1 and melanocortin-4 (MC4R) receptors. We evaluated whether direct lPBN injections of Y1 and MC3/4R ligands (NPY and SHU9119) affected the consumption of water and sucrose solutions, using a sensitive microstructural analysis of licking. Rats with bilateral cannulas aimed at the lPBN were offered water, 0.1M or 1M sucrose solutions. Rats were injected with either vehicle or NPY (100 pM/side in 0.4ul), or the MC4 antagonist SHU9119 (30 pM/side), 15 min prior to testing. These doses are below feeding-effective threshold doses for 4V infusions of these compounds. NPY had no effect on intake or numerous measures of licking microstructure, for any solution tested. SHU9119 significantly increased 4h intake of 1M sucrose with more variable increases for 0.1M sucrose. Microstructure analysis indicated effects that varied by concentration. SHU9119 increased meal frequency for 0.1M sucrose but not 1M sucrose, while average meal size for 1.0M sucrose was increased by SHU9119 but reduced for 0.1M sucrose. For both solutions, however, SHU9119 nearly doubled the mean ingestion rate and it significantly reduced the mean pause time. There was no effect on the mean burst size or initial lick rate, suggesting no change in gustatory evaluation. No significant effects were observed for water. Overall, results suggest that lPBN SHU9119 enhanced intake by producing a more temporally dense consumption pattern within meals, consistent with a diminution of inhibitory postingestive feedback. In addition, SHU9119 appeared to enhance appetitive processes by initiating more meals for solutions that were less caloric. Supported by NIH DC07389.

Withdrawal from chronic d-amphetamine (AMPH), a putative animal model of anhedonia and depression, has been shown to reduce reward function, including operant and consummatory responses for 4% sucrose. However, a using microstructural analysis of licking for 4% sucrose, we found that AMPH withdrawal failed to alter measures associated with gustatory evaluation. To further explore the anhedonia hypothesis, we evaluated licking for sucrose in brief access tests before, during, and following AMPH treatment. Rats received a series of either 12 escalating AMPH doses (1-10 mg/kg, i.p.; n = 10) or isotonic saline (n = 6) injections over 4 days. Licking for an array of 7 sucrose solutions (in M, 0, 0.015, 0.031, 0.062, 0.125, 0.25, and 0.5), presented randomly 4 times daily (20s trials), was recorded starting 2 days before the start of AMPH/saline administration and ending 5 days after AMPH/saline withdrawal. Both AMPH and saline groups expressed sigmoidal concentration-licking functions, with no between-group differences in licking on baseline days (ps > 0.23). Relative to saline, three days of AMPH treatment increased licking for 0.015 M, 0.031 M, and 0.0625 M sucrose, producing a left-shift in the concentration-licking curve. No significant decline in sucrose licking was observed after AMPH withdrawal. These results suggest that AMPH enhanced gustatory evaluation, but that the processes mediating AMPH withdrawal-induced behavioral suppressions are unrelated to the hedonic evaluation of palatable taste stimuli.

Body image dissatisfaction and low self-esteem are central factors in developing eating disorders. Experimentally-induced dieting failures lead to decreases in self-esteem, which may make subsequent restraint efforts more difficult. To the extent that this is a cognitively mediated process, an introspective review on one’s attempts at dieting (and failures) could decrease self-esteem and increase body image dissatisfaction. To evaluate this hypothesis, 64 college women first reported their perceived body size and completed a measure of self-esteem. Two weeks later, they completed measures assessing food and weight-related issues (restraint, disinhibition, hunger, body image dissatisfaction, drive for thinness, and dieting history/success). Immediately afterwards, they again reported their perceived body size and self-esteem. Self-esteem was decreased by making dieting history salient (p=0.06). Women also reported slightly larger body sizes after being queried of their dieting history (mean increase = 3%), but the difference was not statistically significant. Changes in perceived body size, however, were significantly associated with changes in self-esteem, as indicated by repeated-measures ANCOVA (p < 0.05). Additionally, change in self-esteem was negatively correlated with change in perceived body size (p < .05). Further analysis revealed that the number of diets women reported was associated with larger perceptions of body image over time (â = .375, p = .057), and the incongruence between women's actual-ideal weights co-varied with the number of dieting attempts (â = 0.46, p = .02). Finally, self-esteem change significantly predicted body image change, (â = -0.26, p = 0.02.). The results suggest that thinking of diet history and eating introduces subtle negative challenges to self-esteem that may thwart efforts at dietary restraint, or contribute to other eating-disorder relevant cognitive processes. Supported by Amherst College.

Agouti-related protein (AgRP), an endogenous melanocortin receptor inverse agonist, stimulates feeding. Exogenous application promotes ingestion over an extended multi-day period. In the current study, several methods were employed to determine the effects of lateral (LV) or third ventricle (3V) injections of AgRP on appetitive and consummatory measures of feeding behavior. In Exp.1, rats were injected with AgRP (1nM/3ul) or vehicle into either 3V or LV, 2h prior to 30min enclosure in one side of a conditioned place preference test chamber, over 3 consecutive days. On day 4, rats were tested for 30 min place preference. In Exp.2, rats received LV injection of AgRP/vehicle 2h prior to 4h scheduled access to a lick spout containing 0.05M sucrose. The time of each lick was recorded. In Exp.1, rats receiving LV but not 3V AgRP injections exhibited a significant preference for the sided associated with AgRP (p<0.001). AgRP, LV or 3V, also significantly increased chow intake over training days (p<0.05). In Exp.2, LV AgRP significantly increased 4h sucrose intake by ~40% (p<0.05). This effect was entirely mediated by a comparable increase in meal frequency (p<0.05). There was no effect of AgRP on any measures of intra-meal microstructure, including average meal size, meal duration, ingestion rate, initial lick rate, or burst size or number. These results are consistent with the finding that AgRP enhances foraging more than feeding in the hamster, while they contrast the effects of hindbrain melanocortin antagonist injections in rat, which were limited to meal size rather than frequency. Together, the results suggest multiple sites of AgRP action on separate aspects of feeding. Supported by NIH DK 59836 and DC 07389.

Melanin-concentrating hormone (MCH) and neuropeptide-Y (NPY) are orexigenic peptides found in hypothalamic neurons that project throughout the forebrain and hindbrain. The effects of fourth ventricle (4V) infusions of MCH (5 ug) and NPY (5 ug) on licking for water, 4 mM saccharin and sucrose (0.1 M and 1.0 M) solutions were compared to identify the contributions of each peptide to hindbrain-stimulated feeding. NPY increased meal size only for the sucrose solutions, suggesting that caloric feedback is pertinent to the orexigenic effect; MCH infusions under identical testing conditions failed to produce increases for any tastant. In contrast to the effects previously reported after forebrain ICV NPY infusions, 4V NPY failed to increase either meal frequency for any taste solutions or ingestion rate in early phases of the sucrose meals. Overall, 4V NPY responses were limited to intrameal behavioral processes, whereas previously-reported forebrain NPY stimulation elicits both consummatory and appetitive responses. A second dose-response experiment again showed no effect of MCH for doses up to 6nM, supporting the conclusion that MCH-induced orexigenic responses require forebrain stimulation. The dissociation between MCH and NPY effects observed for 4V injections is consistent with reports that forebrain ICV injections of MCH and NPY produced nearly dichotomous effects on the pattern of licking microstructure, and collectively, the results indicate that the two peptides have separate sites of action in the brain.

Bariatric surgery is the most effective treatment for achieving long term weight loss in clinically severe obese patients. This study examines changes in hunger, fullness and appetite hormones in relation to a fixed meal in patients pre and 5 months post RYGBS. There were 10 severely obese, otherwise healthy premenopausal women, BMI = 45.3 ± 6.8 SD, % body fat (BODPOD) = 53.6 ± 6.0, age = 35 ± 9.3. Ratings of hunger and fullness immediately preceded blood draws at 0, 15, 30, 60 min in relation to a fixed complete liquid meal of Glytrol, 250 ml, 1kcal/ml, consumed at 0-10 min. The meal was presented at 2 pm following an overnight 18-hour fast. Results revealed a decline in hunger prior to the meal (p = .013) and an increase (p = .009) in area under the curve (AUC) for fullness from pre to post 5 months. However, fasting ghrelin and AUC for ghrelin did not change from pre to post 5 months. AUC for PYY (p= .009) and GLP-1 (p=.004) increased from pre to 5 months post surgery. However the change in hunger did not correlate with the change in fasting ghrelin and the change in fullness AUC did not correlate with the changes in AUC for GLP-1 or PYY. Moreover, the reduction in stomach capacity itself would not be able to help explain the reduction in premeal hunger post surgery. Thus other biological mechanisms to explain the changes in hunger and fullness post RYGBS should be explored. Supported by NIH DK 61519 and MO1 RROO64529.

Obesity is currently at epidemic rates in the United States, and this includes a large percentage of women of child-bearing age. It is clear that maternal obesity significantly increases the rates of birth defects, maternal complications, fetal loss, and the incidence of large for gestational age (LGA) infants. Equally intriguing is the emerging relationship between maternal obesity and the predisposition of children born of these pregnancies having an increased risk for overweight and obesity as adults. Elucidation of the possible mechanisms by which the intrauterine environment transmits these signals and impacts fetal development is necessary. To investigate these parameters, we have examined changes in expression levels for hypothalamic POMC and NPY in 3-week old offspring from dams on a high fat diet during pregnancy. Compared to controls, these mice show significant changes in POMC levels. No differences were found in NPY expression. As the offspring from high fat diet dams weighed significantly more at this age, alterations in POMC expression may support epigenetic regulation resulting from a high nutritional state during development. We have begun examination of changes in DNA methylation of specific genes related to maternal dietary status. Results from our proposed work will provide significant insight into the underlying causes of the potential long-term risk for development of overweight or obesity associated with an obese intrauterine environment.

Hormonal variation affects bitter taste; bitterness varies with the menstrual cycle, rises in early pregnancy and falls after menopause. Less is known about hormonal effects on sweet taste, but we observed that sweetness varies more among pre-menopausal women than among men, which suggests variation with the menstrual cycle (SSIB, 1997). Here we expand that observation to sweet taste and food/beverage hedonics across the lifespan. Attendees at lectures (N=4212, ages 18-90) rated the sweetness of a piece of candy and the bitterness of 6-n-propylthiouracil (PROP) using the general Labeled Magnitude Scale (gLMS); variability was assessed from the regression of sweetness on bitterness, thereby accounting for effects of taster status. Although the sweetness of the candy did not change with age, sweetness ratings were more variable for women of child-bearing age than for same-aged men. Attendees also rated their liking for 26 foods and beverages (including sugar) on a hedonic version of the gLMS that assesses liking for foods in the context of all hedonic experience. Liking for sugar (and for sweets in general) declined with age, with women showing more rapid decline. However, ratings for high-fat foods rose with age for both sexes. The maximum, minimum and average hedonic ratings from each age cohort provide an estimate of how food palatability changes over time. The maximum rating did not change with age, but the minimum and average ratings rose. This generalized increase in food liking may contribute to the increase in body mass observed with advancing age. (DC 00283)

To model the restriction and re-feeding exhibited by bulimics, two groups of adult male Sprague Dawley rats were exposed to repeated cycles of three days of no restriction, caloric restriction (33% of the daily Kcal of “no restriction” days), and re-feeding 2h into the dark period. Conditions were similar between the two groups, except that on the re-feeding days the BINGE group received chow and a 2h access to sweetened fat (90% Crisco and 10% sucrose blend), whereas the CONTROL group received only chow. In the first experiment in which the restriction/re-feeding cycles were repeated for 3 wks, two subgroups from each group were sacrificed immediately BEFORE or AFTER the scheduled re-feeding. Regional forebrain tissue homengates were subjected to HPLC/EC for monoamine detection. The BEFORE-BINGE group (n=2) had lower hypothalamic dopamine levels than the BEFORE-CONTROLS (n=3, p<0.05), whereas the AFTER- BINGE group (n=3) had lower prefrontal cortical dopamine levels than the AFTER-CONTROLS (n=3, p<0.05). In another experiment in which the restriction/re-feeding cycles were repeated for 5 wks, both groups were sacrificed 90 min following the re-feeding of a “clamped” amount of sweetened fat and chow. The BINGE group (n=6) had more c-Fos immunopositive cells in the caudal and intermediate regions of the nucleus of the solitary tract than the CONTROLS (n=6; p<0.05, for both regions). These results suggest that a history of calorie restriction followed by access to a sweet/fatty food leads to forebrain and hindbrain alterations that may be involved in perpetuating binge-like eating. Supported by DK070707 and MH015330.

The dorsal vagal complex in the caudal medulla is considered an important integrative area in the distributed neural network controlling food intake with melanocortin receptor-4 (MC4R) signaling playing a crucial role. Here, we used patch-clamp whole cell recording from NTS neurons to investigate the effects of MC4R ligands that have previously been shown to powerfully modulate meal structure and total food intake. Thirty-nine percent (25/64) of NTS neurons responded to perfusion with MTII or alpha-MSH, 28% with an increase and 11% with a decrease in the frequency of spontaneous EPSPs, without affecting their amplitude. MTII-induced effects in the frequency of EPSPs were unaffected by TTX, but all effects were abolished by the MC3/4R antagonist SCHU9119. To test whether the mediating MC4-receptors are located on vagal afferent terminals, we also recorded NTS neurons from rats that had undergone vagal afferent rhizotomies 4 days before slice preparation. Only 1 out of 10 neurons from such rats responded with an increase in the frequency of spontaneous EPSCs following MTII. Together with earlier observations, these results suggest that alpha-MSH released from hypothalamic and local POMC neurons acts on presynaptic MC4-receptors on vagal afferent terminals to predominantly increase glutamate transmission to NTS neurons, but that in a minority of cases the effect can also be inhibitory. Such a mechanism is consistent with the notion that descending melanocortinergic projections from leptin-sensitive areas in the basomedial hypothalamus can suppress food intake by changing the capacity of vagal hindbrain mechanisms of satiation. Supported by NIDDK 47348.

Our previous work suggests that the caudal brainstem mechanisms of food satiation may involve signaling through the mitogen-activated protein kinase ERK1/2 cascade in a population of nucleus of the solitary tract (NTS) neurons. Peripheral administration of CCK and fourth ventricular injection of the stable MC4-receptor agonist MTII led to rapid phosphorylation of ERK 1/2 in specific neurons, and CCK as well as MTII-induced suppression of food intake in fasted rats was significantly attenuated by fourth ventricular administration of U0126, a blocker of ERK-phosphorylation. Here, we tested the ability of U0126 to attenuate the satiating effects of oxytocin and bombesin/GRP two other natural ligands that may suppress food intake in the dorsal vagal complex through their hypothalamus-NTS projections. Both, oxytocin (2ìg in 4V) and bombesin (25ng in 4V) suppressed food intake similarly in vehicle and U0126-pretreated rats (30 min intake oxytocin: -2.1 and -2.9 g; bombesin: -2.05 and -2.9g, respectively; all decreases significant, p<0.01). These results demonstrate that unlike CCK and MC4-receptor activation by MTII, oxytocin and bombesin suppress meal size and food intake in the caudal medulla by a mechanism that does not depend on ERK-signaling. Together with our earlier observations on descending melanocortinergic projections from the arcuate nucleus, the results further suggest that descending systems use different local mechanisms in the NTS for the integration of vagus-mediated and descending modulatory signals in the control of satiation and satiety. Supported by NIDDK 47348.

Otsuka Long-Evans Tokushima Fatty (OLETF) rats lacking CCK1 receptors are hyperphagic and obese. We have demonstrated that neuropeptide Y (NPY) gene expression is elevated in the dorsomedial hypothalamus (DMH) of OLETF rats and have suggested that the absence of CCK1 receptors leads to this overexpression of DMH NPY as a major contributor to the hyperphagia and obesity. To assess this hypothesis, we generated a vector of adeno-associated virus-mediated RNA interference with a short hairpin RNA for knocking down NPY gene expression and delivered this recombinant vector into the DMH bilaterally in 4-week-old OLETF rats. We found that knockdown of NPY gene expression in the DMH significantly decreased food intake and body weight of OLETF rats. Glucose tolerance test revealed that OLETF rats had an increase in blood glucose levels and became glucose intolerance with a delayed glucose clearance following a gavage administration of glucose as compared to lean LETO controls. Knockdown of NPY gene expression in the DMH ameliorated such alterations of OLETF rats. At sacrifice, knockdown of NPY gene expression in the DMH significantly reduced epididymal, subcutaneous and brown fat mass of OLETF rats. Together, these data demonstrated an etiological role for NPY gene overexpression in the DMH in the hyperphagia and obesity of OLETF rats. (Supported by DK057609 and DK074269. OLETF and LETO rats were a generous gift of Otsuka Pharmaceutical, Japan.)

High-fat (HF) feeding and obesity lead to progressive reductions in insulin sensitivity and type 2 diabetes mellitus. The cytokine TNF-a has been shown to contribute to this pathology in overweight HF-fed mice. Here we examined whether genetic deficiency of TNF-a protects against the development of insulin resistance independent of HF-feeding or obesity. Eight-wk old TNF-a KO and wild type (WT) mice were fed chow (CH) or HF (60% energy from fat) diet. One and 4 wk later plasma glucose and insulin levels were measured after 12-h fasts and 3-h re-feeding. Plasma leptin and resistin levels and body adiposity were measured after 4 wk. KO mice ate more CH, but not more HF diet, than WT mice. BW and adiposity increased more in HF than CH mice, and TNF-a deficiency had no effect on either, despite the CH intake difference. Fasting glucose was lower after 1 wk in KO HF than WT HF mice. Fasting insulin was lower in KO CH than WT CH mice. Fed glucose tended to be increased in KO mice in all tests, but was significantly so only in 4-wk CH. Fed insulin was markedly lower in KO mice in all tests. Fasting leptin and resistin were increased by HF, with no genotype effect. Fed leptin (CH and HF) and resistin (HF) were reduced in KO mice. These data suggest that TNF-a deficiency improves insulin sensitivity even in the absence of HF-feeding or obesity, and that the mechanism may involve reduced circulating leptin.

After exposure to a novel food an association is thought to form between its sensory characteristics and its post-ingestive action. When the food is energy dense, its sensory properties can come to signal this fact and meal size is moderated accordingly. In humans, evidence for this ‘learned satiety’ is equivocal. However, previous studies have focused on measures of ad lib. food consumption. Outside the laboratory we tend to make decisions about portion size and so energy intake is determined before a meal begins. Therefore, we reasoned that learning might be more likely to be expressed in expectations about the satiating quality of food (i.e., whether it is expected to be ‘filling’). Female participants (N = 58) sampled a novel dessert and then provided a measure of their expectations relative to two very familiar foods. Half of the participants then consumed a low-energy dessert (228 Kcal). The other half consumed a high-energy dessert (552 Kcal). Both desserts were matched for their sensory properties. The next day expectations were assessed again and the participants were offered ad lib. access to an intermediate energy-dense dessert. Although both groups consumed a similar amount of this dessert, ‘learned expected satiety’ was clearly evident - participants in the high-energy condition increased their expectations about the satiating quality of the dessert whereas those in the low-energy condition did not. This is the first evidence for learning of this kind and it challenges claims that humans are insensitive to covert manipulations to the energy density of food.

Brain-derived neurotrophic factor (BDNF) has been implicated in the etiology of human eating disorders, specifically obesity and anorexia, with mature-onset obesity being induced by hyperphagia. Endocrine abnormalities often interact with hypothalamic pathways to induce alterations in food intake and/or body weight. Therefore, we sought to investigate whether thyroid hormone could modulate hypothalamic BDNF gene expression in vivo. First, we injected chicken embryos on embryonic day (e) 18 and e19 with 0.1 ml of 10^-9 M T₃, 0.075g/mL methimazole (a thyroid hormone synthesis inhibitor) or a similar volume of water and then collected the hypothalami on e20. Decreased BDNF and thyrotropin releasing hormone (TRH) mRNA levels were observed in the T₃ relative to methimazole-treated hypothalami using quantitative real-time PCR (qPCR) measurements (P<.05; n=6). Next, we determined whether T₃ inhibited BDNF expression in juvenile chickens surgically implanted at 29 days of age with osmotic minipumps that delivered 192 µg T₃/kg/day (n=5) or 50% DMSO/50% propylene glycol as vehicle control (VC) (n=4). After three days of treatment, exogenous T₃ suppressed hypothalamic BDNF and TRH gene expression relative to VC animals (P<.05). Collectively, these findings suggest that T₃ alters hypothalamic BDNF expression in vivo, which could influence the neural circuitry controlling the anorexic or obese phenotype. Hyperthyroidism decreases BDNF expression, which could lead to hyperphagia to support increased metabolism. This interaction is a potential homeostatic mechanism that links hypothalamic energy regulation with food intake and body weight.

Program ENERGY is a science/health-inquiry learning enrichment classroom program (body science, health, nutrition) designed to prevent obesity and type 2 diabetes. Effectiveness of Program ENERGY-Cortez (PE-C) for 2nd & 3rd graders and their parents in a rural, low-income (54% free or reduced school lunch), high Native American and Hispanic population in Southwestern CO was determined. The principals and classroom educators approved the program after reviewing its objectives and methods. PE-C was delivered by an experienced graduate student and volunteers recruited from the community. Volunteers included both high school and nursing students. In kind donations were provided by several small local businesses, providing materials for teaching aids, rewards and snacks. The intervention school students received the Program ENERGY curriculum including 16 bi-weekly classroom lessons (topic introduction, a hands-on inquiry science activity, and a healthy snack). A comparison school did not receive the program. Effectiveness was evaluated by pre/post assessments (beginning and end of school year). Results of pre- and post- tests show statistically significant improvements in the intervention school compared to the comparison school: health and science knowledge, attitudes (e.g. healthy food selection), behaviors (increased body acceptance), and increased interest in science/health-related careers. These improvements were similar to those observed in the initial implementation in Fort Collins, CO. PE-C is an effective elementary school/family-based intervention with high rates of enrollment/retention, positive evaluations by children/educators that produced significant positive outcomes in health/science knowledge, attitudes, behaviors and increased interest in science and health-related careers.

Program ENERGY's goal is to reduce obesity/type 2 diabetes in suburban/rural elementary school children and families by teaching/reinforcing body science, energy balance and healthy behavior choices. Subjects were 2-6 grade children and their families and the approach is an integrated science/math/health enrichment. Children discover, explore, inquire and learn the basis of healthy behaviors in a challenging, scientific setting, with the support of scientists/health professionals/students. Knowledge is brought home and shared with their families. A 32-week program of classroom and gym activities was conducted in second and third grade classes in two consecutive school years. Beginning and end of the school year assessments including knowledge and attitudes about food and physical activity, anthropomorphic and behavioral assessments were conducted. Results of pre- and post- tests for year 1 show statistically significant improvements in the intervention school compared to the control school: health and science knowledge, attitudes (e.g. healthy food selection), behaviors (e.g. increased steps, increased body acceptance), and increased interest in science/health-related careers. Improvements were maintained during the second year. The 2-yr intervention had high rates of enrollment and retention, positive evaluations by children and educators, produced significant positive outcomes in health/science knowledge, attitudes (healthy food selection), behaviors (e.g., increased steps, increased body acceptance), and increased interest in science and health-related careers. Program ENERGY is an effective elementary school/family-based intervention with high rates of enrollment/retention, positive evaluations by children/educators that produced significant positive outcomes in health/ science knowledge, attitudes, behaviors and increased interest in science and health-related careers.

Program ENERGY's goal is to reduce obesity/type 2 diabetes in suburban/rural elementary school children and families by teaching/reinforcing body science, energy balance and healthy behavior choices. An extension of PE focusing on brain and nervous system science and good decision making was delivered to 6th grade children at Tavelli Elementary School in Ft. Collins, CO. Children discover, explore, inquire and learn the basis of healthy behaviors in a challenging, scientific setting, with the support of scientists/health professionals/students. Knowledge is brought home and shared with their families. An 8-week program of classroom and outdoors activities was conducted. Beginning and end of intervention assessments including knowledge and attitudes about brain and nervous system science were conducted. Results of pre- and post- tests show statistically significant improvements in the intervention school: health and science knowledge (brain science), attitudes (mental illness), behaviors (sensory physiology, increased body acceptance), and increased interest in science/health-related careers. The intervention had high rates of enrollment and retention, positive evaluations by children and educators, produced significant positive outcomes in health/science knowledge, attitudes, behaviors and increased interest in science and health-related careers. Thus, this extension of Program ENERGY into the areas of brain and nervous system science and behavior was effective and could be replicated in other schools.

Mastication contributes to satiety by multiple mechanisms, one of which may entail release of compounds like lipids that elicit release of gut peptides. In this study, almonds were chosen due to their satiating property and evidence that the bioaccessibility of their lipid is largely dependent on mechanical fracture of their cell walls. Healthy adults participated in this three-arm, cross-over design study. For each test day, they reported to the laboratory after an overnight fast, underwent a baseline blood draw, and completed an appetite questionnaire. In random order, they chewed 11, 5g portions of almonds either 10, 25 or 40 times before swallowing. Further blood draws were taken and appetite was reassessed at specified times for 4 hours. Over the following 4 days, participants consumed all meals in the laboratory. All feces were collected during this controlled feeding period and appetite sensations were recorded each waking hour. Glucose and insulin concentrations did not differ by chewing treatment. Analysis of fecal samples showed that with fewer chews, more energy was lost in the feces. This suggests decreased lipid bioavailability. There were no significant differences in fullness or hunger ratings over the 4 hours post-almond consumption between chewing treatments. Future analysis will examine cholecystokinin (CCK), glucogon-like-peptide-1 (GLP-1), ghrelin, and leptin to explore the implications of differences in lipid bioavailability.

11b-hydroxysteroid dehydrogenase-1 (11b-HSD-1) plays a critical role in the regulation of intracellular glucocorticoids. 11b-HSD-1 is highly expressed in adipose and liver. Increased message and/or activity of 11b-HSD-1 are characteristics of both human and animal models of obesity. Hexose-6-phosphate dehydrogenase (H6PDH) is colocalized with 11b-HSD-1 and plays a critical role in determining the directionality and activity of 11b-HSD-1. The purpose of this study was to investigate the effects of sucrose solution access on body weight, body composition, and message of 11b-HSD-1 and H6PDH in omental adipose and liver of adult male Sprague-Dawley rats. Rats were assigned to one of three groups (n=8/group): 1) control (ad libitum access to chow and water only), 2) ad libitum access to either a 16% sucrose solution (S16) or 3) a 32% sucrose solution (S32) in addition to ad libitum diet and water. Results: The S32 group consumed significantly more calories per day than the S16 and the control groups, yet there was no significant difference in mean body weight among groups. Mean percentages of body fat were not different in the S16 and S32 groups, but were significantly higher than controls. Plasma insulin positively correlated with percentage of body fat. Hepatic 11b-HSD-1 message was suppressed by 41.2% and 47.3% in the S16 and S32 groups, respectively, while H6PDH message increased by about 2-fold in both sucrose-fed groups. In omental fat, 11b-HSD-1 message increased by nearly 17- and 20-fold, and H6PDH message increased by approximately 4.5- and 2-fold in the S16 and S32 groups, respectively. Sucrose access and 11b-hydroxysteroid dehydrogenase-1 message in liver and adipose tissue in rats

We have been testing the hypothesis that estrogen signaling through specific estrogen receptors contributes to the regulation of energy homeostasis and behavior. Mice lacking estrogen receptor alpha (ERa) have previously been reported to have an obese phenotype and attenuated locomotor activity. We have extended these findings to show that estrogen signaling through hypothalamic ERa contributes to the regulation of food intake, body weight, and energy expenditure. To better understand the hypothalamic contribution of estrogen signaling, we first characterized some behavioral aspects of the whole-body ERa knockout mouse, and found that they had decreased homecage locomotor activity and voluntary wheel running activity, increased body weight, and changes in fat distribution to favor development of the metabolic syndrome. They were also resistant to the effects of leptin to regulate food intake and body weight. Recently, we have obtained ERa floxed mice and have bred them with nestin-CRE mice to develop mice lacking estrogen receptors in neurons. We have begun characterization of these mice through multiple metabolic and behavioral tests to test the hypothesis that estrogen signaling through neuronal ERa significantly contributes to the phenotype seen in total body ERa knockout mice. Finally, in addition to nuclear receptors, the actions of estrogen may be mediated through GPR30, a membrane/intracellular receptor. Here we report on metabolic and behavioral phenotyping assays of GPR30 knockout mice, designed to delineate whether the observed phenotype is mediated through genomic effects or by rapid signaling through membrane receptors.

The conditioned place preference (CPP) paradigm is a well established method for studying reward and reinforcement mechanisms. However, most parametric CPP studies have concentrated on effects of drugs of abuse. With the growing concern for an obesity epidemic, it is important to consider the potential implications involving the role of reward and reinforcement associated with caloric intake. In these studies, we investigated the roles of macronutrients and metabolic status in the acquisition and expression of place preference. We used a two-chamber conditioning apparatus to pair food reward with a specific chamber with either white or black walls. First, C57BL/6 mice were conditioned under ad-libitum or caloric restriction using either carbohydrate or high-fat diet (HFD) reinforcers of equal calorie content. We then assessed CPP under both caloric restriction and ad-libitum feeding conditions. Results of these experiments suggest that caloric restriction enhanced the acquisition of CPP relative to ad-libitum feeding, regardless of macronutrient used as a reinforcer. Additionally, expression of CPP for HFD but not carbohydrates was maintained following 24 hour ad-libitum access to chow.

It has been suggested that there is an association between increased consumption of high fructose corn syrup and the recent increase in the incidence of obesity. Leptin, an adipose tissue-derived cytokine, inhibits food intake and increases energy expenditure in rodents by crossing the blood brain barrier and activating leptin receptors in the forebrain. Banks et al (2004) reported that elevated triglyceride levels inhibit leptin transport and a high fructose diet increases post-prandial triglycerides. Therefore, we tested whether consumption of a high fructose diet (HFruc: 60% kcal fructose) would induce leptin resistance in Sprague Dawley rats. Post-prandial serum triglycerides were increased by 75% in rats fed HFruc diet for three weeks compared with rats fed a fructose-free diet (LFruc). The HFruc and LFruc rats were infused intraperitoneally with either PBS or 60 ìg leptin/day for two weeks. Leptin reduced the body fat content LFruc rats by 25% but had no effect in HFruc rats, even though they were less fat than LFruc rats (3% vs. 5% carcass weight). In a second experiment rats fed HFruc or LFruc diets for 4 weeks were injected i.p. with increasing doses of leptin (0, 0.5, 1.0 or 2.5 mg/kg). All doses of leptin inhibited 2-hour food intake of LFruc rats but had no effect on intake of HFruc rats. Thus, consumption of a HFruc diet induces leptin resistance, possibly because elevated levels of circulating triglycerides inhibit leptin transport across the blood brain barrier. Supported by grant R01DK53903 awarded to RBSH.

Previously published results from our laboratory indicate that injection of NMDA receptor antagonists into the dorsal hindbrain increase food intake and suggest that capsaicin-resistant (myelinated) vagal afferents terminals that express NMDA-type glutamate receptors participate in control of meal size. NMDA receptors are heteromeric ion channels incorporating distinct subunits, including NR1, NR2A, NR2B, NR2C and NR2D. The NMDA channel’s electrical and signaling properties are determined by its NR2 subunit phenotype. In the present study we tested the hypothesis that myelinated vagal afferent neurons express different NMDAR NR2 subunits than non-myelinated neurons. Six-week-old male Sprague-Dawley rats received intraperitoneal injections of capsaicin or vehicle. Nodose ganglia were processed for with primary antibodies against the capsaicin receptor (VR1), and NR1, NR2B, NR2C, or NR2D NMDAR subunits. In vehicle-treated rats, at least 60% of all nodose vagal afferents were immunopositive for VR-1 and capsaicin treatment reduced VR1 immunoreactivity to 10%. Furthermore, capsaicin reduced the number of NMDA NR1 and NR2B subunit expressing neurons by at least 50%, while resulting in no detectable loss of NMDA NR2C or NR2D immunopositive neurons. Our results indicate that NMDA NR2C and NR2D subunit immunoreactivity in the nodose ganglia is limited to capsaicin resistant myelinated vagal afferents. Taken collectively with previous behavioral findings, we hypothesize that NMDA NR2C and/or NR2D expressing vagal afferents may mediate increased food intake evoked by injection of NMDA antagonists into the hindbrain and may contribute to the control of meal size. Supported by NIH Grants DK52849 and NS20561 and Poncin Scholarship 2006.

Despite the increased consumption of fast food, >80% of all food eaten occurs at home. In addition, hungry humans and fasted hamsters hoard more food than there non-hungry counterparts. Given the increasing prevalence of obesity, understanding the mechanisms underlying appetitive ingestive behaviors (foraging, food hoarding) may provide a new target for intervention beyond that more well-studied consummatory ingestive behavior (food intake). Neuropeptide Y (NPY) and agouti-related protein (AgRP) are two neuropeptides that play a role in both phases of ingestion in a variety of species. Central injections of either peptide increase food intake in laboratory rats and food hoarding in Siberian hamsters. The likely source of NPY and AgRP subserving these responses endogenously is NPY/AgRP synthesizing arcuate (Arc) neurons. Because fasting increases Arc NPY and AgRP synthesis in rats and Siberian hamsters and because fasting increases food hoarding in hamsters, we tested whether destruction of NPY/AgRP-producing Arc neurons by neonatal treatment with MSG blocks fasting-induced increases in food hoarding in adult Siberian hamsters. Surprisingly, food hoarding in MSG-treated animals was increased 100% more than controls with refeeding after a 56h fast, with the greatest increase occurring during the first hour postfast. The underlying cause of this increase could be MSG-induced increased NPY receptors shown to occur in MSG-treated rats that also have an exaggerated NPY-induced increased food intake. These data suggest a similar increase in NPY receptors with MSG treatment in Siberian hamsters. This work was funded by NIH R01 DK 78358.

Social stress is an environmental factor affecting mood and motivation in humans and animals. The visual burrow system (VBS) is behavioral method for monitoring stress associated with social stratification in rodents. The current study tested the hypothesis that animals rendered subordinate after VBS exposure would display decreased motivation for food reward. In particular, we predicted that subordinate animals would exhibit attenuated operant responding for mixed nutrient reinforcers relative to dominate animals. Thirty-two male Long-Evans rats and sixteen female rats divided into eight separate groups (n=4 males & n=2 females/group) were exposed to the VBS for seven consecutive days to allow the formation of a dominance hierarchy. At the conclusion of burrow exposure each animals bodyweight, and plasma corticosterone were measured. Consistent with previous data, subordinate animals lost a significant amount of body weight and displayed elevated basal corticosterone relative to dominant and control animals confirming previous studies. Subordinate and dominate animals consumed equal amounts of Boost in the homecage. However, when required to bar press for the Boost, subordinate animals displayed decreased responding relative to dominant animals. This effect was observed across a range of reinforcement schedules and persisted up to two months following VBS exposure. These data confirm previous findings and are consistent with the hypothesis that social stress affects food motivation for mixed nutrient reinforcers. They also suggest that social stress may regulate different aspects of ingestive behavior, and that the affects of VBS exposure on food motivation could be permanent. Support DK4806110, DK6659603, and NIH1001690.

Anticancer chemotherapies, such as cisplatin, induce nausea, vomiting and anorexia. Cisplatin acts on vagal afferents of the gut to produce emesis but little is known about how this drug and other chemotherapies generate anorexia and nausea. Electrophysiological data from our laboratory indicate activation of vagal afferents of the common hepatic branch (CHB) by cisplatin. The goal of this study was to assess the effect of CHB lesion on anorexia and pica produced by cisplatin in the rat. We also examined the effects of the dopamine-D2 agonist apomorphine, which induces emesis via a central mechanism. Although rats lack a vomiting response, they ingest kaolin clay (a pica response) when made sick by toxins, and this behavior can be blocked by anti-emetic drugs. Our results show that cisplatin-induced pica was markedly reduced in CHB-vagotomized animals. Similarly, suppression of daily food intake and body weight following cisplatin treatment was also blunted by CHB ablation. CHB lesion had no effect on apomorphine-induced pica. The results indicate that the CHB, which innervates primarily the upper duodenum, plays an important role in cisplatin-induced malaise. These data also suggest that pica has sensory pathways similar to emetic systems in other species since a vagal lesion inhibited cisplatin-induced pica but had no effect on apomorphine-induced pica. In summary, this investigation is important because it helps to define neural systems involved in malaise, which can significantly impact feeding behavior in patients with chronic disease, such as cancer and AIDS, who receive potent drug treatments. Supported by NIH-DK065709 and NIH-DC000014.

Damage to the CeA reduces 0.3 M NaCl intake that follows 36 hours of water deprivation and partial volume rehydration with water for 2 hours (WD-PR protocol). In the present work we investigated the effect of CeA damage (CeAX) on central neuronal c-fos expression at the end of the WD-PR. Adult Sprague-Dawley rats (n=6), either hydrated or at the end of a WD-PR, were anesthetized and had their brains removed for immunohistochemistry specific for c-fos protein. The groups were devided into sham lesion, bilateral CeA lesion (CeAXb), unilateral CeA lesion (CeAXu) and misplaced bilateral lesion (CeAXm). The c-fos expression (number of positive cells/10–² mm²) averaged for medial parabrachial nucleus (MPBN) and parvocellular portion of the hypothalamic paraventricular nucleus (PVNp) was enhanced in CeAXb (24±3) and CeAXu (18±2, n=3) WD-PR groups compared to shams (7±2) or hydrated CeAXb (3±1). Damage to the CeA did not change c-fos expression in the lamina terminalis or lateral parabrachial nucleus. No alterations occured in CeAXm. The enhanced neuronal activation in PVNp and MPBN might relate to reduced sodium appetite in animals with damage to the CeA. Support: CNPq, FAPESP, Joint UFSCar/UNESP Graduate Program in Physiological Sciences.

The protein source may be a determinant of the satiating efficacy of protein. We investigated the effects of whey protein (WP), pea protein hydrolysate (PPH), a combination of WP+PPH, and control (milk protein, MP) on appetite ratings, postprandial changes in hunger/satiety hormones and energy intake (EI). 39 subjects (BMI: 27.6 ± 1.7 kg/m²; age 42.3 ± 13.8 years) participated in the study which had a randomized, crossover design and consisted of 2 parts (experiment 1 and 2). In experiment 1, appetite profile was measured and blood samples were taken. In experiment 2, appetite profile and EI were measured. Some indications of lower hunger (experiment 1), desire to eat (experiment 2) and thirst (experiment 1 and 2) were shown after consumption of PPH compared to MP or WP+PPH (p<0.05). A longer intermeal interval and a higher satiety index were suggested after consumption of PPH. Both PPH and WP lead to greater satiety (experiment 2) and fullness (experiment 2) compared to MP and WP+PPH (p<0.05). For WP, a positive correlation between insulin and both CCK and GLP-1 was observed (p<0.05). However, both CCK and GLP-1 were increased by MP (p<0.05) and PYY and ghrelin were stimulated by WP+PPH (p<0.05). No effect on EI was seen. In conclusion, there was modest evidence with respect to satiety by PPH consumption. Different exogenous biopeptides produced differences in release of endogenous peptides that had inconsistent relationships with satiety. Therefore, evidence derived from a supposed biomarker for satiety does not guarantee the highest satiety.

The objective of this study was to confirm the satiety/energy intake effect of a novel fat emulsion (Olibra®) versus placebo in the short term in different age and weight groups. 41 subjects (group 1: BMI: 22.0 ± 1.6 kg/m²; age 23.7 ± 2.8 years; group 2: BMI: 27.7 ± 1.6 kg/m²; age 43.6 ± 4.9 years) participated in a randomized, double-blind, placebo-controlled, crossover study. An energy intake and satiety test (with questionnaires) took place on 2 occasions, with placebo or test yoghurt as breakfast. In group 1, consumption of test yoghurt reduced hunger and desire to eat during the morning (AUC, p<0.05), increased fullness 3h after consumption (p<0.05) and increased the intermeal interval (3.7 ± 1.2h in test group compared to 2.9 ± 1.0h in placebo group, p<0.05). Furthermore, the test yoghurt reduced desire to eat (1h and 3h after yoghurt, p<0.05) and prospective food consumption (1h after yoghurt, p<0.05) in the total group. No effect on energy intake was seen. In conclusion, the Olibra® emulsion exerted a suppressive effect on appetite ratings in the short-term. These effects were most expressed in normal-weight women aged 18 to 30 years. Furthermore, it may be necessary to assess energy intake at a timepoint before hunger scores returned to baseline.

Nutritional intake contributes to the development of human disease mainly by influencing the development of obesity-related conditions such as diabetes and cardiovascular disease. Orosensory variation strongly affects ingestive behavior and nutrient intake, while genetic variation in taste receptors (TRs) strongly affects taste sensitivity and food preference. Moreover, the expression of TRs in the gastrointestinal tract suggests that they may be involved in the nutrient-dependent regulation of metabolism. Therefore, we hypothesized that genetic variation in TRs may impact the development of obesity-related disease. To investigate these possibilities, we genotyped > 60 haplotype-tagging single nucleotide polymorphisms (SNPs) within 2 kb of all TAS1R and TAS2R genes in DNA samples from the Amish Family Diabetes Study. We identified candidate SNPs from the dbSNP and HapMap databases, and prioritized those with a minor allele frequency of ≥ 0.2 in the CEU cohort (Utah residents with ancestry from northern and western Europe). We then evaluated the effects of genotype on 39 obesity-related traits (with adjustments for age, sex, and BMI). Several SNPs were significantly associated with obesity-related traits, including diabetes, glucose and insulin levels during oral glucose tolerance tests, weight, and eating behaviors. We conclude that common variation in taste receptor genes may influence food preference, metabolism and/or risk factors associated with obesity. Support: NIDCD, NHLBI, NIDDK, UMSOM.

Cannabinoid agonist is reported to increase intake of highly palatable foods when injected into the fourth cerebroventricle (Physiol. Behav. 80: 611, 2004). One possible mechanism for enhanced intake by cannabinoid agonists is attenuation of visceral signals from the gut. Our initial attempts to address this question have focused on induction of cFos by intraperitoneal cholecystokinin (CCK). It is well recognized the CCK induces cFos immunoreactivity in neurons of the caudal nucleus of the solitary tract (NTS) and area postrema (AP). We hypothesized that cannabinoid agonist will attenuate CCK-induced cFos in the hindbrain. We found that CCK induced a significant increase in cFos-immunoreactive neurons in the NTS and AP. The number of cFos-immunoreactive neurons was decreased significantly by prior application of the cannabinoid agonist CP55940. This reduction in cFos-immunoreactive neurons by CP 55940 was blocked by the CB1 receptor antagonist SR141716. Moreover, treatment with cannabinoid antagonist alone does not appear to significantly elevate cFos in the NTS. These observations suggest that cannabinoids may work in the NTS to blunt inhibitory signals from the gut resulting in elevated food intake. (Supported by Dept. of Physiol. & Pharm., Univ. of Georgia)

Protein is widely considered to be more satiating than carbohydrate. However, it is unclear whether this rule applies equally to drinks as solid foods. Discrepancies in the literature may indicate a critical level of protein (PRO) is required in drinks, to obtain differences in appetite between CHO and PRO. In this repeated measures, cross-over design study, 28 lean male volunteers (18-35 yrs) ate a standard breakfast in the laboratory and 210 minutes later consumed one of four preloads 30 minutes prior to an ad. libitum pasta meal. Three of the preloads were isocaloric (~278kcal) mixed composition dairy fruit drinks (300g) of low (12.5% energy PRO/87% energy CHO), medium (25% energy PRO/75% energy CHO) and high (50% energy PRO/50% energy CHO) protein content. The control drink was a low energy (78kcal) alternative (12.3% energy PRO/84.3% energy CHO). ANOVA linear contrasts indicated a dose response effect of preload protein level on intake (g) at the ad. libitum meal, (F(1,24) =16.15, p<0.001). Subsequent intake in each condition was: control (637.5g±39.7), low (596.9g±40.5), medium (546.9g±34.7), and high protein (533.6g±42.3). Participants did not compensate fully at lunch for the additional energy in the test drinks, however in the high PRO condition alone, total energy intake was not significantly different from the control condition. There were no differences in ratings of hunger and fullness across conditions. Our findings support the view that increasing the protein composition of beverages could be of interest to prevent short-term positive energy balance.

The effects of fatty acids on gastrointestinal function and energy intake vary with their chain length. In rats, lauric acid, a fatty acid with 12 carbon atoms (“C12”) suppressed energy intake more than oleic acid, a fatty acid with 18 carbon atoms (“C18”), on a calorie-for-calorie basis. We hypothesised that, at equicaloric loads, C12 would inhibit antral pressure waves (PWs), stimulate pyloric pressure waves (IPPWs) and suppress appetite and energy intake more than C18. 10 healthy males were studied on three separate occasions. Pressure waves and appetite perceptions were measured during 60-min intraduodenal infusions of i) C12, ii) C18 or iii) control (saline) (all pH8.4, 0.4 kcal/min for C12 and C18). Energy intake was quantified at a cold buffet-style meal immediately following the infusions. Both C12 and C18 suppressed antral PWs and stimulated IPPWs compared with control (P<0.05), with no difference between C12 and C18. There were no significant changes in appetite perceptions, and nausea was not experienced. Energy intake tended to be less following C12 (5052±362 kJ) when compared with control (5486±454 kJ) and C18 (5504±345 kJ) (P=0.09), and the suppression of energy intake (expressed as % suppression from control) by C12 (7.9 %) was greater than the suppression by C18 (-0.3 %; P=0.05). In conclusion, while C12 and C18 have comparable effects on gastrointestinal motility, C12 suppresses energy intake more than C18. Whether any differences in gut hormone secretion account for the difference in energy intake between the two fatty acids warrants investigation.

Gastric emptying and intragastric distribution of a meal, and gastrointestinal hormones, including cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1), play an important role in appetite regulation. Healthy, lean, young males have widely been used in studies evaluating energy intake. It has, however, been reported that there is marked inter-individual variability in energy intake in this group. Whether there is significant intra-individual variation in acute energy intake after a nutrient preload, and, if so, this relates to changes in gastric emptying and gastrointestinal hormone release, is unclear. We hypothesised that appetite/energy intake after a nutrient preload would be reproducible and associated with reproducible patterns of gastric emptying and gastrointestinal hormone release. 15 healthy males consumed a glucose preload (50g glucose in 300ml water; 195kcal) on 3 separate occasions. Gastric emptying and intragastric meal distribution (measured by 3D ultrasound), plasma CCK and GLP-1 and appetite perceptions were evaluated over 90 minutes, after which energy intake from a cold, buffet-style meal was quantified. Energy intake (kJ) and amount eaten (g) showed excellent agreement between visits (intraclass correlation coefficient, r_i >0.8), while for macronutrient distribution, reproducibility was moderate to good (0.54< r_i <0.77). Furthermore, patterns of gastric emptying, intragastric meal distribution and appetite perceptions did not differ (all P<0.05), and areas under the plasma CCK and GLP-1 curves also showed excellent agreement (r_i >0.8), between days. Therefore, in healthy males, patterns of gastric emptying and gastrointestinal hormone secretion are highly reproducible, when measured repeatedly on separate occasions, and associated with reproducible energy intakes.

CCK suppresses appetite and modulates gastrointestinal motility, however, the relationship between these parameters remains unclear. Furthermore, the effects of CCK on appetite may be due to nausea caused by supraphysiological CCK concentrations. We hypothesised that CCK would have dose-dependent effects on pyloric motility and appetite, in the absence of nausea. Healthy males (23±1 years; BMI 23±0.5 kg/m²) were studied on 4 occasions in double-blind, randomised fashion. Appetite and pyloric pressures were measured during 120-min intravenous infusions of (i) saline (control), or CCK-8 at (ii) 0.33 (‘CCK0.33’), (iii) 0.66 (‘CCK0.66’) or (iv) 2 (‘CCK2’) ng/kg/min. At 90 min energy intake at a buffet meal was quantified. There was an effect of treatment on scores for desire-to-eat (P<0.05). All CCK infusions decreased desire-to-eat when compared with control (P<0.05), and their effects were dose-related (R=0.7, P=0.05). No infusion induced nausea. There was a treatment-by-time interaction for the number of isolated pyloric pressure waves (IPPWs) (P=0.001). All CCK infusions increased IPPWs when compared with control; CCK0.66 and CCK2 between 0-90 min (P<0.01), and CCK0.33 between 0-45 min (P<0.05). Mean energy intake was less following both CCK0.66 (3630±550 kJ) and CCK2 (3319±359 kJ) when compared with control (3974±491 kJ). There was an inverse relationship between desire-to-eat and IPPWs (R=-0.7, P<0.05), and a trend for a positive relationship between desire-to-eat and energy intake (R=0.53, P=0.09). In conclusion (i) intravenous CCK has dose-related effects on pyloric motility and appetite, in the absence of nausea, and (ii) the stimulation of IPPWs may be a determinant of appetite suppression.

The effects of fat on gastric emptying, gastrointestinal hormone release and energy intake are dependent on the digestion of fat to free fatty acids (FFAs). There is limited information about the comparative effects of FFAs and triglycerides (TGs) on these factors. In animals, oleic acid inhibits energy intake more potently than an isocaloric infusion of its TG, triolein. 9 healthy males (23±2 years, BMI 22±1 kg/m²) were studied on three occasions to evaluate the effects of (i) 40 g of oleic acid (“FFA”) (1830 kJ), (ii) 40 g of macadamia oil (“TG”) (1856 kJ) (both 600 ml oil-in-water emulsions stabilised with 4 % milk protein and labelled with 15 MBq ¹²³I ), or (iii) 600 ml 4 % milk protein (“control”, 352 kJ), administered intragastrically, on gastric emptying, plasma CCK and PYY, appetite and energy intake. Gastric emptying of FFA was much slower than of TG (P<0.05), with greater retention of FFA, than TG, in the proximal stomach (P<0.001). Hunger was less (P<0.05), and fullness greater (P<0.05), following FFA administration, when compared with both control and TG. Plasma concentrations of both CCK and PYY were greater after FFA than after TG or control (P<0.05). Energy intake was less after FFA, when compared with TG (control: 4754±610 kJ, TG: 5463±662 kJ, FFA: 4199±410 kJ*; *P<0.05 vs TG). Conclusion: Free fatty acids empty from the stomach more slowly, but stimulate CCK and PYY release and suppress appetite and energy intake much more potently, than triglycerides.

Tendency to binge eat is a known risk factor for weight gain and obesity. The present study examined hedonic and homeostatic processes of appetite regulation in normal weight women with a range of binge eating scores. 35 subjects (24.1±1.0years, BMI: 21.9±0.5kg/m2) completed the Binge Eating Scale (BES), Three-Factor Eating Questionnaire (TFEQ), Food Craving Scale (FCS) and attended two test-meal sessions comprising a fixed preload followed by an ad-libitum buffet. Energy intake, food selection, subjective sensations of appetite and hedonic response were measured. Novel procedures to measure food liking, wanting and preference (Finlayson et al. 2007) were employed. BES scores correlated with BMI (p<0.05), TFEQ-disinhibition (p<0.01) and hunger (p<0.01), and FCS items relating to impaired ability to resist cravings (p<0.05) and loss of control over eating (p<0.05). On comparison of low (<7; N=12) and high (>10; N=12) tertile scores on the BES, higher scores were associated with differences in sensory perception, greater preference for high-fat sweet foods (p<0.05), stronger sensations of hunger post preload (p<0.01), and increased ad libitum intake of high-fat sweet foods (p<0.01). Higher scores were linked to enhanced explicit wanting for food which persisted after consumption of the preloads (p<0.01). No differences in implicit wanting were found. Within a group of young women with normal BMI, BES scores had the capacity to differentiate high and low BMI plus a range of appetite responses related to motivation to eat, food preference and tendency to overconsume. BES scores could be a useful predictor of weight gain and later obesity. MRC(CASE)#G78/8223 in conjunction with NRC, Lausanne; and INAP-G, Paris.

Considering the psychological mechanisms that influence eating, we assume that both implicit and explicit processes will operate. This distinction informs the liking vs wanting issue of food reward. The present study investigated the effect of meal-induced satiation on implicit and explicit processes of liking (L) and wanting (W) by developing a computer-based procedure to measure L and W in hungry and satiated states. Explicit measures were derived from analogue ratings whilst the implicit W measure was derived from RT in a forced-choice procedure, which also identified food preferences. 70 subjects (21.8±0.9years, BMI: 22.2±0.5kg/m2) completed the computer-task before and immediately following consumption of a savoury test meal. Satiation caused explicit ratings of L and W to decrease in all food categories (p<0.01); but with a more marked decrease for savoury foods compared with sweet foods (p<0.01). Implicit W was increased for sweet categories (p<0.01), but not for savoury. Implicit and explicit measures of L&W independently correlated with preference for sweet foods. This study provides support that implicit and explicit processes of food reward can be simultaneously measured and dissociated using a test meal. Adjustments in hunger were linked to changes in explicit L&W in a manner consistent with sensory specific satiety, while a relationship between hunger and implicit W was absent. We suggest that implicit W is not systematically downregulated by the physiological consequences of food consumption in the same way as hunger and therefore may be largely independent of homeostatic processes influencing intake. MRC(CASE)#G78/8223 in conjunction with NRC, Lausanne.

We recently reported that caloric restriction was associated with a selective shortening of dendrites in the VMH. In the present study, we tested the hypothesis that exposure to a high-fat diet, which causes weight gain in a subset of rats, also would be associated with modifications in dendritic morphology. Adult male rats were provided with a 15% fat diet (n=9) or a 45% fat diet (n=9) for 17 days. There was substantial variability in the 17-day weight gain in the group of animals given the HFD. Therefore, this group was subdivided. All animals that were within one standard deviation of the average weight gain of the low-fat control group were considered “non-responders” (n=4). The animals whose weight gain was beyond that range were considered “responders” (n=5). The HFD-responders consumed more kcal per day and gained more weight than either the control animals or the HFD-non-responders (both p<0.03). In addition, leptin levels were approximately 75% higher in the HFD-responders compared with the LFD control group (p<0.04). Brains from these animals were processed for Golgi impregnation. Dendrites were classified as longest primary, short primary, or secondary. Although this analysis is still ongoing, preliminary evidence (n=3 per group) suggests that the long primary dendrites are shortened in the HFD-responders. Thus, dendrite morphology in the VMH may not be monotonically correlated with leptin levels or energy balance. This research was supported by DK52018.