Cellular, molecular and physiological aspects of leptin: Potential application in animal production

Abstract

This review encompasses the biochemistry and physiology of the newly discovered adipose hormone, leptin. Leptin appears to fulfill the role of the long sought after "lipostat", which functions to regulate energy intake in relation to body stores in the form of fat. Leptin is a 16 000 Dalton polypeptide which interacts with specific receptors in the hypothalamus to regulate food intake and body fat stores. Leptin receptors exist in several forms, which can be divided into those with small cytoplasmic domains and one with a single long cytoplasmic tail. The latter is thought to mediate most of leptin's effects, acting through the JAK-STAT signal transduction pathway. Several reports have shown direct effects of leptin on tissues with the short form of the leptin receptor. Specific effects of leptin on appetite, energy metabolism and reproduction are reviewed. Leptin may prove to be most useful to animal producers as a stimulant of the reproductive system or as a molecular marker to genetically select livestock for improved reproductive capacities or carcass characteristics, while leptin antagonists may improve metabolic rate and body composition. Key words: Leptin, obese protein, leptin receptor, review, livestock production