Stress-Coping Strategy and Mom’s Stress Levels During Pregnancy May Determine Anorexia Susceptibility in Rats
July 7, 2015, Denver, CO - Johns Hopkins researchers have found that offspring born to mother rats stressed during pregnancy lost weight faster and failed to turn on appropriate brain hunger signals in response to exercise and food restriction, compared to offspring from non-stressed mothers. The research reveals a specific combination of stress, personality, and environmental factors that may contribute to anorexic behaviors. The findings will be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the society for research into all aspects of eating and drinking behavior.
“This research brings us a step closer toward understanding anorexia vulnerability and provides insight into the development of potential individualized treatment for this eating disorder,” says lead author Gretha Boersma, Ph.D., a postdoctoral fellow at Johns Hopkins Medicine.
The researchers mildly stressed pregnant rats by introducing environmental disturbances. Then, they mimicked the physiological characteristics and some psychological consequences of anorexia nervosa in the offspring by limiting eating time and giving access to a running wheel. That combination leads to severe weight loss, hyperactivity, and voluntary refusal to eat in the presence of food, resembling symptoms of anorexia. The key discovery was revealed when the research team determined the individual offspring’s stress-coping style. Rodents and humans typically deal with stress in two distinct coping styles: Proactive individuals actively confront stressors, while passive individuals try to avoid dealing with them. When confronted with an annoying object in the home environment, a proactive rat will bury it while a passive rat will freeze or try to move away from it. The passive-coping, prenatally stressed offspring showed the strongest resemblance to anorexia nervosa. They lost weight faster than their proactive littermates or passive rats from mothers that weren’t stressed.
To explore why the passive-coping rats from stressed mothers lost weight faster, the researchers analyzed the levels of hunger signals in the hypothalamus, the region of the brain that controls hunger and thirst. In normal rats, the chemical signals called agouti-related peptide (Agrp) and orexin increase during food restriction to promote appetite. But the passive-coping rats did not show increases in Agrp and orexin levels, suggesting these rats lose weight because the hunger signals aren’t turned up when they should be.
“The results of this study suggest that we may be able to identify a subgroup of patients, those with a passive stress-coping style and a history of stress during early development, who might be highly vulnerable to anorexia when they start dieting,” says Boersma.“ Identifying ways to control the Agrp and orexin hunger signals may be a treatment option for patients with this specific history”.
Research: Rats vulnerable to weight loss during activity-based anorexia lack increased expression of Agrp and Orexin in response to starvation.
Lead Author: Gretha J. Boersma, Department of Psychiatry and Behavioral Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD, USA.
Co-Authors: Nu-Chu Liang, Jennifer D. Albertz, Laura A. Moody, Shivani Aryal, Timothy H. Moran, Kellie L. Tamashiro.
Contact: Gretha Boersma, 410-955-2996, firstname.lastname@example.org
Study finds that high fat diet changes gut microbe populations and the brain’s ability to recognize fullness
July 7, 2015, Denver, CO - Have you ever wondered why eating one good-tasting French fry may lead you to eat the whole batch and leave you wanting more? According to a new study with rats, that high-fat indulgence literally changes the populations of bacteria residing inside the gut and also alters the signaling to the brain. The result? The brain no longer senses signals for fullness, which can cause overeating—a leading cause of obesity.
The findings from this study conducted by researchers at the University of Georgia, Washington State University and Binghamton University, are to be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior, the society for research into all aspects of eating and drinking behavior.
“When we switch the rats to a high fat diet, it reorganizes brain circuits,” explained Krzysztof Czaja, DVM, PhD, a principal investigator on the study who is an associate professor of neuroanatomy at the University of Georgia College of Veterinary Medicine. “The brain is changed by eating unbalanced foods. It induces inflammation in the brain regions responsible for feeding behavior. Those reorganized circuits and inflammation may alter satiety signaling.”
So what happens to the microbiota in the intestines after a switch to a high fat diet? Dr. Czaja likens the phenomenon to how a sudden significant shift in temperature might impact the people who live in the affected area: Some people will be fine. Others will become ill.
“In the regular physiological state, many different strains of bacteria live in a balanced environment in the intestinal tract,” said Dr. Czaja. “They don’t overpopulate. There are little shifts, but in general this population is quite stable. When we start feeding the rats a different diet, there is an immediate effect. Suddenly, different nutrients are changing the microenvironment in the gut and some bacteria begin to overpopulate. Some sensitive bacteria begin to die and some populations may even vanish. So, introducing a significant change in the gut microenvironment triggers a cascade of events that leads to this population switch.”
These changes can cause inflammation that damages the nerve cells that carry signals from the gut to the brain, resulting in gut-brain miscommunication. It is not yet known whether this change is permanent or reversible, but Dr. Czaja and his colleagues plan to address this question in the future.
When it comes to diet and how it impacts health, Dr. Czaja says we should “think systemically.” “All of the components and receptors in our body are interconnected and should work in harmony. There is not a single receptor responsible for huge physiological outcomes.”
Throughout most of history until just a few decades ago, our bodies were accustomed to whole foods derived from natural sources, rather than artificial and highly processed foods. The research provides new insight into how balance in the intestinal microbiota and gut-brain communication—which was well-adjusted over millennia – might be disturbed by the introduction of modified foods high in fat and sugar. Disrupting that balance leads to the confused brain and inappropriate satiety feedback that can result in obesity.
This research was supported by the National Institute on Deafness and Other Communication Disorders, grant number 1R01DC013904.
Research: Diet-induced obesity is associated with a change in the intestinal microbiota, activation of microglia, and reorganization of the nucleus of the solitary tract
Lead Author: Krzysztof Czaja, Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia, Athens, GA
- E. Cooper, Department of Integrative Physiology & Neuroscience, Washington State University, Pullman, WA
- C. Vaughn, Department of Integrative Physiology & Neuroscience, Washington State University, Pullman, WA
- P. M. Di Lorenzo, Department of Psychology, Binghamton University, Binghamton, NY
- J.H. Peters, Department of Integrative Physiology & Neuroscience, Washington State University, Pullman, WA
- J.L. O’Loughlin, School of Molecular Biosciences, Washington State University, Pullman, WA E. M. Cooper, Department of Integrative Physiology & Neuroscience, Washington State University, Pullman, WA
- M. E. Konkel, School of Molecular Biosciences, Washington State University, Pullman, WA
Kids’ brain responses to food depend on their body composition
July 7, 2015, Denver, CO – Research using brain imaging technology has revealed a brain response pattern in children that might represent a step along the path to childhood obesity. The study, conducted by Nicole Fearnbach, a graduate student in Penn State University’s Department of Nutritional Sciences, scanned children’s brain activity while they viewed pictures of high- and low-calorie foods, and found that both lean body mass and body fat are linked to how kids’ brains respond to food. Their research is to be presented here this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior.
The researchers focused on a brain region called the subtrantia nigra, involved in reward, learning, and motor control, which responds to food stimuli. Fearnbach and her colleagues discovered the neural activation in this brain area differed in children of different weight groups. Children with greater lean body weight had more powerful brain response in the substantia nigra when looking at high-calorie foods compared to children with lower lean body weight. The study also found that children with higher body fat had lower activity in this same brain area when they saw pictures of healthier, low-calorie foods like fruits, vegetables, and grilled chicken.
“We think that kids with more lean body weight might have a greater reward response to higher calorie foods, in part because they have greater energy needs compared to children with less lean body weight. Lean body weight largely determines how many calories we burn each day through our resting metabolic rate. Bigger kids burn more calories, and our results show that their brains respond differently to foods,” explained Fearnbach.
“Interestingly, we also found that children with more body fat had a reduced brain response to lower calorie foods, which tend to be the healthier options,” Fearnbach added. “It might be that kids with higher body fat find those healthier foods to be less rewarding. But we don’t know yet whether having more body fat is a cause or a consequence of these brain responses.”
The results of this study suggest that children’s body composition may influence how their brains respond to food, but it likely depends on whether these foods are high or low in calories. Future research studies are needed to determine how these findings relate to children’s food intake or their body weight over time.
The study, conducted through Penn State’s Department of Nutritional Sciences and Social, Life, and Engineering Sciences Imaging Center, involved 38 children ages 7 to 10 and their parents. Each family participated in five total laboratory visits. Children’s body composition was measured to get lean body weight and body fat. Children also completed a functional magnetic resonance imaging (fMRI) scan where they looked at pictures of foods that differed in energy content. Foods were either high or low in energy density, which is equal to the number of calories per unit of food weight. The researchers then determined each child’s brain response to these different food categories, and looked at how it was influenced by their body composition.
Fearnbach worked with coauthors Laural English, Dr. Stephen Wilson, Dr. Jennifer Savage-Williams, and Dr. Barbara Rolls, under the supervision of Dr. Kathleen Keller, Assistant Professor of Nutritional Sciences and Food Science.
For more information:
Neural response to images of food varying in energy density is associated with body composition in
Children. SN FEARNBACH, LK ENGLISH, SJ WILSON, JS SAVAGE, BJ ROLLS, KL KELLER
S. Nicole Fearnbach , Doctoral Student
Department of Nutritional Sciences, The Pennsylvania State University
(609) 954 3068
Mother’s diet affects offspring alcohol and nicotine use in lab animal studyJuly 7, 2015, Denver, CO - Researchers at The Rockefeller University have found in a study with rats that a mother’s consumption of a fat-rich diet during pregnancy increases her offspring’s risk of a combined alcohol and nicotine abuse in adolescence. The study performed by Olga Karatayev in the Neurobiology Laboratory of Dr. Sarah Leibowitz at Rockefeller provides insight into early life factors that contribute to substance abuse. The results are to be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior.
Clinical studies have demonstrated that alcohol and nicotine abuse tend to be linked. Excessive drinking is commonly associated with greater smoking. The question is, what may be contributing to this co-abuse of alcohol and nicotine that has become more evident in recent years?
Whereas most animal studies of such co-abuse combine oral consumption of alcohol with intravenous self-administration of nicotine, Karatayev and Leibowitz developed a new approach that involves training the rats to press a lever to receive small infusions through an intravenous (IV) tube of either alcohol or nicotine alone, or of both in combination. With this method, rats begin avidly working for the drug, with the confounding factors from alcohol’s bitter taste being eliminated.
The investigators revealed that maternal consumption of a high-fat diet caused the offspring to treat the nicotine as more rewarding, especially when it was combined with alcohol, compared to offspring of mothers eating a low-fat diet. When a test required the young rats to work progressively harder at lever pressing, the fat-exposed rats kept working to obtain the next dose after the control rats gave up. Maternal consumption of fat also caused the rats to take significantly larger amounts of the alcohol plus nicotine mixture than of nicotine alone, an effect not evident in the low-fat control condition. This demonstrates for the first time that exposure to a fat-rich diet in utero causes in the offspring a greater vulnerability to the excessive co-use of alcohol and nicotine during adolescence.
Recent studies from the Rockefeller laboratory have led Karatayev and Leibowitz to propose how changes to specific brain systems during development link maternal fat consumption to adolescents’ alcohol and nicotine abuse. A class of chemical signals called neuropeptides, which ordinarily act in the hypothalamus region of the brain to promote food intake, appear to promote drug-seeking as well. They find that the neuropeptides that are stimulated by fat intake in adult animals are similarly responsive in the embryo. Prenatal fat exposure increases the growth of more neurons in these specific brain areas, leading to a long-lasting increase in levels and activity of the chemical messengers during adolescence that are likely to increase the risk for drug abuse.
For more information:
Research: Nicotine and ethanol co-use in Long-Evans rats: Stimulatory effects of perinatal exposure to a fat-rich diet.
Authors: O Karatayev, O Lukatskaya, S-H Moon, W-R Guo, D Chen, D Algava, S Abedi and S F Leibowitz
Affiliation: Rockefeller University, NY, NY, United States
Published in: Alcohol, 2015, 49(5): 479-89.
Dr. Sarah Leibowitz
(212) 327-8378; Sarah.Leibowitz@rockefeller.edu
Heightened ability to imagine odors linked to higher body weight
July 7, 2015, Denver, CO - Researchers at The John B. Pierce Laboratory and the Yale School of Medicine have revealed that the ability to vividly imagine the smell of popcorn, freshly baked cookies and even non-food odors is greater in obese adults. Their research is to be presented this week at the Annual Meeting of the Society for the Study of Ingestive Behavior (SSIB), the foremost society for research into all aspects of eating and drinking behavior.
All of us can imagine the view of a favorite spot or sing a song to ourselves. Not so with imagining odors. People vary greatly in their ability to imagine the smell of freshly baked bread or the sweet aroma of a bouquet of roses. This raises the possibility that differences in the ability to image odors, especially food odors, might promote food cravings. The researchers based their study on Kavanagh’s Elaborated Intrusion Theory of Desire, which proposes that creating vivid mental images stimulates and maintains food cravings triggered by the thought, smell and sight of food. Although previous research demonstrates that food cravings occur more often in obese individuals, the role of odor imagery ability in this link had not been examined. If individuals with higher body weights report a heightened ability to imagine odors, this may intensify the food craving experience through the creation of more vivid images of flavors and aromas
In the study, participants completed a series of questionnaires that asked them to imagine both visual and odor cues and then to subsequently rate the vividness of these cues. The researchers found that individuals with a higher body mass index (BMI) reported greater ability to vividly imagine food and non-food odors.
“These findings highlight the need for a more individualistic approach in identifying factors that may increase risk for weight gain,” said Dr. Barkha Patel, study lead author and Postdoctoral Fellow. They also call for “future work to assess imagery ability directly rather than relying upon self-report measures,” said Dr. Dana Small, senior author and a Professor of Psychiatry at the Yale School of Medicine and Deputy Director at the John B. Pierce Laboratory.
For more information:
Greater Perceived Ability to Form Vivid Mental Images in Individuals with High Compared to Low BMI. BP Patel, K Aschenbrenner, D Shamah, DM Small.
Dana M Small
Tel: 203-562-9901 x272