Underfeeding, reproduction and central nervous system : role of leptin

Abstract

Relationships between fat tissue and reproduction have been described in a very large number of experiments, but the way by which animals are able to perceive their body fat content was not known until recently. Identified a few years ago by using molecular techniques, leptin is a protein hormone mainly synthetized and secreted by the adipose tissue. Leptin acts on numerous tissues by stimulating specific long or short receptors. In rodents, leptin is involved in the central regulation of feed intake, energy balance, thermoregulation, reproductive activity as well as in the regulation of angiogenesis and wound healing. To regulate LHRH neuronal activity, leptin acts on long form receptors of the hypothalamus. Its action on LHRH neuron would not be direct, but more probably via an action on other neuromediators (NPY, POMC, 5HT, Galanine). Leptin receptors are also found in the pituitary, gonads and placenta. In ruminants, leptin and leptin receptors have only recently been identified and cloned, but their roles remain to be determined.