The Effect of Estrogen Hormone on Leptin Receptor in Small Intestine of Ovariectomized Rats

Abstract

Objective: Leptin, a 16 kDa hormone encoded by the obese (Ob) gene, is known for its role in regulating food intake, body composition, and energy expenditure. Leptin receptor expression has been demonstrated in several tissues, including the small intestine. Weight gain may occur in humans after menopause or in animals following ovariectomy. Estrogen affects leptin and leptin receptor expressions. In this study, we aimed to contribute to the etiology of obesity by investigating the effects of E2 on leptin receptors in the small intestines of ovariectomized rats as a model of postmenopausal conditions. Materials and Methods: Bilateral ovariectomy was performed on 6-month-old Sprague-Dawley female rats. Ovariectomized rats (Ovx) were injected with 0.2 ml of sesame oil/rat/day or E2 (25 µg/rat/day) and euthanized at the 18th, 90th, or 162nd hours. Duodenum, jejunum, and ileum samples were fixed and embedded in paraffin using standard methods. The expression of leptin receptors were detected in the small intestine through immunohistochemistry. Results: Leptin receptor expression was found in the villi and crypt epithelium of the small intestine and in Brunner’s gland of the duodenum. E2 administration increased the leptin receptor expressions on the epithelium of villi and crypt in the duodenum and jejunum at the 90th hour (p<0.05); ileum at the 18th hour (p<0.05); and also on the epithelium of villi in the duodenum at the 162nd hour (p<0.05). Conclusion: Our results indicate that E2 may upregulate the expression of leptin receptors in the small intestine, where glucose and other nutrients are absorbed after food intake and digestion, depending on the timing.