A Role for Leptin in Sexual Maturation and Puberty?

Abstract

Leptin, the ob gene product, is involved in the regulation of body weight in rodents, primates and humans. It provides a molecular basis for the lipostatic 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 control of body fat stores by coordinated regulation of feeding behaviour, metabolic rate, autonomic nervous system regulation and body energy balance. Apart from the function of leptin in the central nervous system on the regulation of energy balance, it may well be one of the hormonal factors that signal to the brain the body’s readiness for sexual maturation and reproduction. During late pregnancy and at birth when maternal fat stores have been developed, 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 leptin could signal the expansion of fat stores in order to prepare the expectant mother for the energy requirements of full-term gestation, labour and lactation. Leptin serum concentrations change during pubertal development in rodents, primates and humans. In girls, leptin serum concentrations increase dramatically as pubertal development proceeds. The pubertal rise in leptin levels parallels the increase in body fat mass. In contrast, leptin levels increase shortly before and during the early stages of puberty in boys and decline thereafter. Testosterone has been found to suppress leptin synthesis by adipocytes both in vivo and in vitro. The decline of leptin levels in late puberty in boys accompanies increased androgen production during that time and most likely reflects suppression of leptin by testosterone and a decrease in fat mass and relative increase in muscle mass during late puberty in males. This overview focuses on those topics of leptin research which are of particular interest in reproductive and adolescent medicine.

Testosterone substitution of hypogonadal men prevents the age-dependent increases in body mass index, body fat and leptin seen in healthy ageing men: results of a cross-sectional study

“…Leptin may be the main mediator of the influence of sex hormones on adipocytes: testosterone has been found to suppress leptin synthesis by adipocytes both in vivo and in vitro (24). In healthy normal men, suppression of endogenous testosterone production with gonadotrophin-releasing hormone (GnRH) agonists (25) or GnRH antagonists (26) results in an increase of leptin serum levels and, vice versa, testosterone administration to normal healthy men results in reduced leptin serum levels (25).…”

Leptin and adiponectin in the female life course

“…Leptin, the product of the OB gene located at 7q31.3, provides a molecular basis for the lipostatic theory of the regulation of energy balance (4). It has become clear that leptin also plays an important role in reproduction, both during pregnancy and early neonatal life (4).…”

Metabolic decompensation in children with type 1 diabetes mellitus associated with increased serum levels of the soluble leptin receptor

“…Biological effects of leptin include the suppression of food intake and the increase of energy expenditure, and consequently, the regulation of body weight (2)(3)(4)(5). Several studies have suggested that leptin also influences sexual progression through puberty (6)(7)(8). Impaired growth and pubertal delay have been observed in children with diabetes (9)(10)(11).…”