Leptin

Leptin is the product of the obese (ob/ob) gene, homozygous mutations in which causes extreme obesity and associated phenotypes. Leptin is a circulating hormone produced by adipose cells, and the signaling form of the receptor, the product of the diabetes (db/db) gene, is expressed in hypothalamic neurons that are critical for the regulation of energy balance and glucose homeostasis. Unfortunately, after extensive basic and clinical research, it appears that neither leptin treatment or sensitization to leptin are generally effective to treat obesity. Instead the function of leptin is probably to signal nutritional deficit to produce appropriate neuroendocrine responses.