Gender differences in ghrelin response to chronic immobilization stress in rats: possible role of estrogen.

Ghrelin is a peptidergic hormone known to be one of the main hormones involved in the regulation of energy balance. Here we evaluated ghrelin response to stress in rats after ovariectomy and during estradiol benzoate (EB) therapy and compared results of males and females, to know whether ghrelin is involved in disordered eating behaviors in response to stress, and for understanding differences between males and females in food intake and weight gain especially during stress. 96 adult rats were classified into; male, female, ovariectomized (Ovx), Ovx with EB. Half animals of each group were exposed to immobilization stress 20 min/day for 21 days. We found that chronic stress significantly augments serum ghrelin levels in both males and females, which is correlated with an increase in food intake and body weight. Females displayed significant higher ghrelin than males especially in response to stress, ovariectomy suppresses serum ghrelin in both unstressed and stressed females which is rescued by replacement with EB. EB replacement augments ghrelin response to stress in Ovx female, and reduces food intake and body weight. In conclusion, there is a clear sex difference in ghrelin secretion in response to stress caused by EB, since it amplifies ghrelin response to stress in females.