Food deprivation inhibits estrous behavior in hormone-treated Syrian hamsters despite elevated estradiol levels.
Estradiol and progesterone (P) induce female mammalian reproductive behaviors, which are, in turn, sensitive to food availability. When ovariectomized, steroid-primed hamsters are food deprived for 48 h, estrous behavior is suppressed. While this suppression of estrous behavior may be due to alterations in neural steroid receptor levels, it is also possible that decreased levels of circulating estradiol could be involved in mediating this suppression. Ovariectomized Syrian hamsters given varying doses of estradiol benzoate (EB) and P were tested to determine whether increasing doses of sex steroids would overcome the suppressive effects of food deprivation on estrous behavior. As expected, lordosis duration decreased in food-deprived animals. Increasing the levels of EB, but not P, increased lordosis duration in the food-deprived animals so that animals who were given 20 microg of EB had lordosis durations significantly longer than food-deprived hamsters that received 1.5 microg and 2.5 microg EB. Following an injection of 2.5 microg of EB, food-deprived hamsters actually had higher circulating levels of estradiol than ad libitum-fed animals. Therefore, increasing circulating levels of estradiol can increase lordosis durations in fasted animals; however, the suppression of estrous behavior occurs despite increased circulating estradiol levels in ovariectomized, steroid-treated animals. The most parsimonious explanation for this phenomenon is a deprivation-induced reduction in neural responsiveness to estradiol.
Jones
Juli E
JE
Center for Neuroendocrine Studies, University of Massachusetts, Amherst 01003-7720, USA. jones@cns.umass.edu
Pick
Rebecca R
RR
Wade
George N
GN
D000818:Animals; D006224:Cricetinae; D004958:Estradiol / Q000031:analogs & derivatives* / Q000097:blood* / Q000494:pharmacology; D030762:Estrous Cycle / Q000502:physiology*; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D008647:Mesocricetus; D011187:Posture; D011374:Progesterone / Q000494:pharmacology; D012726:Sexual Behavior, Animal / Q000502:physiology*
C074283:estradiol 3-benzoate; D011374:Progesterone; D004958:Estradiol