Sex differences in the acute effect of an estrogen metabolite on binge eating in rats

Women are more likely to suffer from binge‐related disorders, even though estradiol decreases food intake. 2‐hydroxyestradiol (2OHE2), an estrogen metabolite, may account for the contradiction, due to possible interference with DA signaling. We hypothesized that 2OHE2 would enhance bingeing in a rat model. Two cohorts (1 male, 1 female) of 34 non‐food‐deprived rats were separated into daily control (D) (optional source of dietary fat for 20 min daily) or bingeing (INT) groups (optional fat for 20 min on Mon, Wed, Fri). During the 5‐wk binge induction period, shortening intakes escalated significantly faster in females than in males, such that males consumed significantly less fat/kg body mass than did females. This result is consistent with the idea that biological differences contribute to sex differences in bingeing. Rats were then injected with 2OHE2 (0, 1, 3, or 10 ìg/kg ip, in a Latin Square) immediately prior to fat access. Fat intake was significantly stimulated by 2OHE2 only in the male binge group (p<0.01), resulting in intakes comparable to female intakes after vehicle. Since endogenous levels of 2OHE2 are lower in males than in females, injections in males likely mimicked levels normally seen in females. Thus, 2OHE2 appears to exacerbate binge size, suggesting a novel biological mechanism for sex differences in the risk of eating disorders. Supported by MH67943 (RLWC).