Leptin in chicken. In poultry, whole-body energy homeostasis control is economically essential, since poultry selection for growth is associated with an increased body fat storage. In mammals, leptin is involved in the regulation of food intake and body energy expenditure. In chicken, this hormone may play a similar role. In chicken, the leptin gene is expressed not only by adipose tissue but especially by the liver. Hepatic expression of leptin in the chicken is most likely associated with the almost exclusive role played by this organ in lipogenesis. As in mammals, chicken leptin level reflects body fat store and the expression of this hormone may be regulated by the nutritional status of the animal and composition of its diet. Acting probably on a receptor located in the hypothalamus, leptin inhibits food intake of chicken. Modulated by several factors also involved in the regulation of food intake and energy expenditure in the chicken, leptin effects,seem to be similar in chicken and mammalian species.