INFLUENCE OF THE OVARIAN CYCLE AND ESTRADIOL ON BINGE EATING EVOKED IN FEMALE RATS BY FOOD RESTRICTION AND FRUSTRATION STRESS

Eating disorders show marked gender differences (Klump 2013 PsychMed 2008;38:174957) and epidemiologic studies suggest that bingeeating episodes are more common in females than in males. To further investigate the mechanisms underlying this sex difference, we used an animal model described by Cifani (2009 Psychopharm 204:113–125). We aimed to determine whether bingeeating behavior varies across estrus cycle and is influenced by estradiol (E2) in ovariectomized (OVX) rats. We quantified the activation of extracellular signal regulated kinase (ERK) signaling pathway in OVX rats treated with E2 or oil. Restricted and stressed rats in estrus and OVX rats treated with E2 did not show bingeeating in comparison to the control nonrestricted and nonstressed rats.The lack of binge eating behavior in estrous rats was accompanied by significant decrease in ERK phosphorylation in arcuate nucleus, paraventricular nucleus of hypothalamus and in central amygdala but not in basolateral amygdala in comparison to nonestrous rats and to nonrestricted/ nonstressed animals. Our findings show that bingeeating does not occur during estrous phase. Because this was recapitulated in OVX rats treated with E2, suggests that the inhibitory effect of E2 on eating is partly responsible for lack of bingeing.These results are consistent with reports in women with bulimia nervosa and increase the validity of our model that can be used in translational studies of the mechanism of binge eating behavior.