20 years of leptin: what we know and what the future holds

This special issue of Journal of Endocrinology celebrates the 20th anniversary of the discovery of leptin, a hormone produced by adipose tissue, which provides critical signals to the organism regarding the status of its energy stores. The discovery of leptin not only revolutionised our understanding of endocrine physiology but has also resulted in a registered medicinal product which is already improving the health of patients with serious metabolic diseases. In this issue, we have gathered together a group of essays by some of the world leaders in leptin research, including an overview by Dr Jeffrey Friedman who, in his seminal article in December 1994, described the adipocyte-derived hormone, the lack of which was responsible for the severe obesity in ob/ob mice and suggested that it should be named leptin.