A signal transmitting metabolic information from peripheral tissue to the human brain has long been looked for. Since the recent discovery of leptin, the product of the obesity (ob) gene, and its receptor, a rapidly growing body of research has begun to elucidate the role of leptin in body composition and reproduction. In prepubertal girls and boys, leptin concentrations increase slowly with age and body fat mass. In boys, this increase is interrupted in early puberty, when testosterone and lean body mass increase. In girls, leptin along with body fat mass continue to increase during puberty. The therapeutic response to leptin in a child with leptin deficiency confirms the importance of leptin in the regulation of appetite and body weight in humans. The first long-term results of leptin treatment indicate that adequate serum leptin concentrations are required for normal pubertal development. Whether leptin is a primary signal in the onset of human puberty or acts in a permissive way as one of several metabolic factors remains to be studied.
From the Sexual Health Clinic, Family Federation of Finland and Department of Ob & Gyn, Helsinki University, Helsinki, Finland.
Correspondence to Dan Apter, The Sexual Health Clinic, Family Federation of Finland, P.O. Box 849, 00101 Helsinki, Finland; e-mail: email@example.com.