Leptin and reproduction.

Fertility in mammals requires adequate nutrition and a certain reserve of metabolic fuel (Van Der Spuy, 1985). Individuals experiencing wasting diseases (e.g. insulin-dependent diabetes), severe dietary restriction (e.g. anorexics), or who are high-performance athletes (e.g. marathon runners or ballet dancers) may have severely impaired reproductive systems (De Souza & Metzger, 1991; Stewart, 1992; Griffen et al. 1994). The effect of nutritional status on reproduction is postulated to reflect the action of unknown metabolic signal(s) that are recognized by the brain and serve as indices of metabolic state (Kennedy & Mitra, 1963). Leptin has been postulated to be either the, or one such, signal. Thus, if metabolic reserves are low or the system is stressed, reproduction will be inhibited (Barash et al. 1996; Chehab et al. 1996).