LEPTIN IS A METABOLIC SIGNAL TO THE REPRODUCTIVE-SYSTEM

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 si gnals metabolic information to the reproductive system by examining it s effects on the reproductive system of ob/ob mice, which have a conge nital deficiency in leptin and are infertile. We treated pair-fed male s and females with leptin (50 mu g twice daily, ip) or vehicle (n=10/g roup) for 14 days, after which the animals were bled and killed. Lepti n-treated females had significantly elevated serum levels of LH, incre ased ovarian and uterine weights, and stimulated aspects of ovarian an d uterine histology compared to controls. Leptin-treated males had sig nificantly elevated serum levels of FSH, increased testicular and semi nal vesicle weights, greater seminal vesicle epithelial cell height, a nd elevated sperm counts compared to controls. These results demonstra te that leptin stimulates the reproductive endocrine system in both se xes of ob/ob mice and suggest that leptin may serve as a permissive si gnal to the reproductive system of normal animals.