Suppression and recovery of estrous behavior in Syrian hamsters after changes in metabolic fuel availability

A reduction in the availability of oxidizable metabolic fuels inhibits repr oduction. Forty-eight hours of metabolic fuel deprivation inhibits estrous behavior in ovariectomized, steroid-treated Syrian hamsters, but little is known about the time course of this inhibition. Likewise, refeeding reverse s deprivation-induced suppression, but the rate of recovery has not been ex amined. In two experiments we determined 1) the rate at which estrous behav ior declines in hamsters treated with metabolic inhibitors and 2) how rapid ly sexual receptivity is restored when hamsters are refed after a 48-h fast . We also measured circulating levels of leptin and insulin in an attempt t o determine their relationship to the inhibition and restoration of estrous behavior. More than 24 h of metabolic inhibitor administration were requir ed to inhibit lordosis, whereas only 6 h of refeeding were sufficient to re store the display of sexual receptivity to normal levels. Neither plasma in sulin nor leptin levels paralleled the changes in estrous behavior. We conc luded that 1) suppression of estrous behavior occurs more slowly than recov ery after a fast and 2) changes in circulating leptin and insulin probably do not have a critical role in these behavioral changes.