SPLTRAK Abstract Submission
Stress hormone responses to combined sodium deficiency and restraint in female rats are affected by estrogen
Department of Pharmacology and Physiology, Oklahoma State University Center for Health Sciences, Tulsa, OK, United States
   Stress is associated with challenges (stressors) that produce a deviation from homeostasis. Activation of the hypothalamic-pituitary-adrenal axis and the subsequent increase in glucocorticoids such as corticosterone (CORT) are integral in responses to stressors and contribute to restoring homeostasis. Animal studies of stress responses typically are conducted in males, even though stress disorders are more common in females. Moreover, stress often is studied in rats using acute restraint, a psychogenic stressor; however, physiological challenges, such as prolonged sodium (Na+) imbalance also are stressors, and the combination of physiological and psychogenic stressors alters CORT responses in male rats. At present, it is unknown whether estrogen affects interactions between psychogenic and physiologic stressors. Thus, this study examined CORT in ovariectomized female rats with (n=25) or without (n=26) estrogen in response to the combination of prolonged dietary Na+ deficiency (10 days) and acute (15 min) restraint. As expected, plasma CORT was increased by acute restraint, and the response was augmented by estrogen treatment.  Na+ deficiency alone had no effect on CORT levels in either group, but when acute restraint occurred after 10 days of dietary Na+ deficiency, the CORT response was blunted in estrogen-treated rats. These results suggest that estrogen alters glucocorticoid responses to a combination of prolonged physiologic and acute psychogenic stressors, which may influence the ability to restore homeostasis.