A role for leptin in sexual maturation and puberty?

Leptin, the ob gene product, is involved in the regulation of body weight i n rodents, primates and humans. It provides a molecular basis for the lipos tatic theory of the regulation of energy balance. White adipose tissue and placenta are the main sites of leptin synthesis. There is also evidence of ob gene expression in brown fat. Leptin seems to play a key role in the con trol of body fat stores by coordinated regulation of feeding behaviour, met abolic rate, autonomic nervous system regulation and body energy balance. A part from the function of leptin in the central nervous system on the regul ation of energy balance, it may well be one of the hormonal factors that si gnal to the brain the body's readiness for sexual maturation and reproducti on. During late pregnancy and at birth when maternal fat stores have been d eveloped, leptin levels are high. During these developmental stages leptin could be a messenger molecule signalling the adequacy of the fat stores for reproduction and maintenance of pregnancy. At later stages of gestation le ptin could signal the expansion of fat stores in order to prepare the expec tant mother for the energy requirements of fullterm gestation, labour and l actation. Leptin serum concentrations change during pubertal development in rodents, primates and humans. In girls, leptin serum concentrations increa se dramatically as pubertal development proceeds. The pubertal rise in lept in levels parallels the increase in body fat mass. In contrast, leptin leve ls increase shortly before and during the early stages of puberty in boys a nd decline thereafter. Testosterone has been found to suppress leptin synth esis by adipocytes both in vivo and in vitro. The decline of leptin levels in late puberty in boys accompanies increased androgen production during th at time and most likely reflects suppression of leptin by testosterone and a decrease in fat mass and relative increase in muscle mass during late pub erty in males. This overview focuses on those topics of leptin research whi ch are of particular interest in reproductive and adolescent medicine. Copy right (C) 1999 S. Karger AG, Basel.