Physiology & behavior
-
Physiology & behavior · Mar 2008
The orexigenic effect of melanin-concentrating hormone (MCH) is influenced by sex and stage of the estrous cycle.
Recently, it was shown that the orexigenic effect of melanin-concentrating hormone (MCH) is attenuated by estradiol treatment in ovariectomized (OVX) rats. This suggests that female rats may be less responsive than male rats to the behavioral effects of MCH. To investigate this hypothesis, the effects of lateral ventricular infusions of MCH on food intake, water intake, meal patterns, and running wheel activity were examined in male and female rats. ⋯ To examine the influence of endogenous estradiol, food intake was monitored following MCH treatment in ovarian-intact, cycling rats. As predicted by our findings in OVX rats, the orexigenic effect of MCH was attenuated in estrous rats, relative to diestrous rats. We conclude that the female rat's reduced sensitivity to the orexigenic effect of MCH may contribute to sex- and estrous cycle-related differences in food intake.