Leptin is a metabolic signal to the reproductive system.

TLDR

Leptin, a hormone produced by adipocytes, is implicated in regulating food intake and metabolism. The study tested whether leptin conveys metabolic signals to the reproductive system by evaluating its effects in leptin‑deficient ob/ob mice. Leptin or vehicle was injected intraperitoneally twice daily for 14 days into pair‑fed ob/ob mice, after which blood was collected and the animals were euthanized. Leptin treatment raised LH, ovarian and uterine weights, and improved ovarian/uterine histology in females, and increased FSH, testicular and seminal vesicle weights, epithelial height, and sperm counts in males, showing that leptin stimulates the reproductive endocrine system in both sexes of ob/ob mice and may act as a permissive signal in normal animals.

Abstract

Leptin, a newly-discovered hormonal product of the obese (ob) gene, is expressed by adipocytes and thought to play a role in the regulation of food intake and metabolism. We tested the hypothesis that leptin signals metabolic information to the reproductive system by examining its effects on the reproductive system of ob/ob mice, which have a congenital deficiency in leptin and are infertile. We treated pair-fed males and females with leptin (50 microg twice daily, ip) or vehicle (n=10/group) for 14 days, after which the animals were bled and killed. Leptin-treated females had significantly elevated serum levels of LH, increased ovarian and uterine weights, and stimulated aspects of ovarian and uterine histology compared to controls. Leptin-treated males had significantly elevated serum levels of FSH, increased testicular and seminal vesicle weights, greater seminal vesicle epithelial cell height, and elevated sperm counts compared to controls. These results demonstrate that leptin stimulates the reproductive endocrine system in both sexes of ob/ob mice and suggest that leptin may serve as a permissive signal to the reproductive system of normal animals.