Estradiol-dependent decreases in emotional binge-like eating are associated with decreased brain pERK expression in ovariectomized rats.

Bulimia nervosa, binge eating disorder and emotional eating occur more commonly in females than in males. To investigate the influence of the ovarian cycle and estradiol (E2) on binge eating, we used an animal model in which binge-like eating is evoked in female rats by three cycles of food restriction followed by “frustration” stress (15 min exposure to the sight and odor of a palatable food). We sought to determine whether binge-like eating behavior varies across the estrus cycle or is influenced by E2 in ovariectomized (OVX) rats, and whether these differences are associated with differences in the neuronal activation pattern using extracellular signal-regulated kinase (ERK) phosphorylation as a marker in the basolateral (BLA) and the central (CeA) amygdala, paraventricular nucleus of hypothalamus (PVN) and arcuate nucleus (ARC). Food restricted and stressed non-estrus rats showed binge-like eating behavior and an increase in ERK phosphorylation in ARC, PVN and in the CeA, but not in BLA, in comparison to the control not restricted and not stressed rats. The binge-like eating response and ERK phosphorylation were not present in restricted and stressed rats in estrus, and in OVX-E2 rats. Stress and food restriction elicited binge-like eating behavior both in non-estrus as well as in OVX rats not treated with E2. These results are consistent with reports in women with bulimia nervosa, and they extend our previous findings and increase the validity of our model that can be used in translational studies of the mechanism of binge eating behavior.