Hormonal regulation of leptin expression in broiler chickens

Leptin, the polypeptide hormone encoded by the obese gene, is secreted by a dipose tissue and has been shown to induce satiety and increase energy expe nditure in mammals. In this study, we confirmed the presence of a leptin ho molog in liver and adipose tissues of broiler chickens. Leptin expression w as also detected in chicken embryonic Liver and yolk sac. The effects of ho rmone treatment on leptin expression in chickens were also investigated. Le ptin expression in the liver is increased by insulin and dexamethasone and decreased by glucagon and estrogen. There was no induction of leptin expres sion in adipose tissue by any treatment, whereas only estrogen decreased ad ipose expression. The differential effect on liver and adipose tissue sugge sts that adipocytes in chickens may be expressing leptin at a maximal rate or that its mechanism of expression regulation differs from liver. The loca lization of leptin expression and tissue-specific effects of hormone treatm ents on leptin expression observed in chickens may indicate a relationship between leptin and avian lipid metabolism.