Leptin and the regulation of food intake and the neuroendocrine axis in sheep.

1. Leptin is secreted by fat and acts on the brain. 2. Central infusion of leptin reduces food intake but does not alter endocrine secretions in normally fed sheep. 3. Leptin treatment can correct for altered hormonal secretion in fasted animals. 4. Alterations in bodyweight (leptin status) affect the expression of a number of genes in the hypothalamus that are involved in the regulation of food intake and neuroendocrine function. 5. Leptin receptors are found in both the hypothalamus and pituitary and direct action of leptin can be demonstrated on the somatotrophs in the pituitary.