Effects of food deprivation on induction of neural progestin receptors by estradiol in female syrian hamsters. Du, Yue, George N. Wade, and Jeffrey D. Blaustein. Neuroscience and Behavior Program and Department of Psychology, Box 37710, University of Massachusetts, Amherst, Massachusetts 01003 -7710,
APStracts 2:0322R, 1995.
Food deprivation, as well as treatment with metabolic inhibitors, suppresses steroid hormone-induced estrous behavior in ovariectomized (OVX) Syrian hamsters. Previous work indicates that 48 h of food deprivation decreases the number of detectable estrogen-receptor immunoreactive (ERIR) cells in the ventromedial hypothalamus (VMH) and the area just lateral to it (VLH), increases the number of ERIR cells in the medial preoptic area (MPO), and has no effect on the number of ERIR cells in the nucleus of the solitary tract in OVX hamsters. The present study examined the effects of food deprivation on neural progestin receptor binding using an in vitro binding assay and on progestin receptor immunoreactivity (PRIR) in estradiol -primed, OVX hamsters. Parallel behavior tests for sexual behavior were also performed in both experiments. OVX hamsters received 2.5 [mu]g estradiol benzoate (EB) and were fed ad libitum or food deprived at the same time. Forty-eight h later, animals were killed in preparation for the immunocytochemistry or progestin receptor assay. Binding assays indicated that 48 h food deprivation decreased progestin receptor levels in the preoptic area and had no effect in the mediobasal hypothalamus, an area which includes the VMH and the arcuate nucleus (ARH). Immunocytochemical analysis confirmed these findings. Food deprivation caused a decrease in sexual receptivity and in the number of detectable PRIR cells in the MPO and medial amygdala but had no effect on the number of detectable PRIR cells in the VMH/VLH, the ARH, or the anteroventral periventricular nucleus. These results suggest that food deprivation modulates progestin receptor binding and PRIR in a site-specific manner. In addition, the effects of food deprivation on neural ERIR and PRIR are significantly different. 

Received 12 September 1995; accepted in final form 8 November
1995.
APS Manuscript Number R564-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 8 December 95