ROLE(S) OF THE VENTROMEDIAL NUCLEI IN HPA AXIS FUNCTION

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The purpose of these experiments is to understand how the ventromedial nuclei (VMN) direct neural and hormonal metabolic signals that may play a role in the development of clinical hypertension, obesity, and diabetes. Recent work from our lab has shown that the regulation of hypothalamic- pituitary-adrenal (HPA) axis function is embedded in a larger hypothalamic system regulates energy balance. The VMN of the hypothalamus are integral to feeding behavior, body weight, adrenocortical activity, and insulin secretion. We propose to study the integrative role VMN have on the HPA axis, feeding, and insulin secretion; we will test the hypothesis that inputs to the VMN from limbic and visceral inputs are involved. First, we will survey VMN's contribution to corticosteroid feedback on HPA function. Second, we will measure the degree to which circadian rhythms in HPA activity, and the effects of fasting on these rhythms, are mediated by VMN- driven input to the hypothalamic paraventricular nuclei (PVN) which contain the neuroendocrine motor output to the HPA axis. Finally, we will try to determine if the mineralocorticoid-receptor directed corticosterone feedback observed in rats with VMN lesions is mediated by inputs to VMN from cell groups in the ventral amygdalo-hippocampal area and whether VMN activity on food intake and HPA axis activity is regulated by cholecystokinin from the lateral parabrachial nuclei.