Discovery of an "Obesity Gene"

A strain of very fat mice has revealed what may be an important secret about human obesity. Over the past 50 years, experiments indicated that these mice were probably homozygous for a defective gene. In late 1994, a team from Rockefeller University discovered this "ob" gene and found a very similar gene in humans (Nature 1994 Dec 1; 372:425). An explosion of research ensued.

The following picture has emerged. In response to a rise in insulin levels from feeding, the normal ob gene makes a protein called leptin in fat cells. Blood-borne leptin reaches the hypothalamus, which responds by suppressing appetite, increasing energy expenditure, and decreasing insulin levels. Through this negative feedback loop, the act of eating stimulates the ces…