Insulin mimic found in fat

A newly discovered metabolic factor produced predominantly by visceral fat mimics the effects of insulin, according to a report published in this week's Science. The factor, called visfatin, lowered insulin levels in vivo and in vitro and activated the insulin receptor, although in a manner different from that of insulin.

In recent decades, it has become apparent that adipose tissue is not a mere repository of triglycerides, but an extensive endocrine organ that secrets numerous adipocytokines—hormones with key roles in regulating metabolism. "Visfatin should shed new light on the mechanism of insulin resistance and metabolic syndrome [a collection of disorders that includes high insulin and cholesterol levels, and excess body weight] and should help develop a new therapy," senior author Iichiro Shimomura of Osaka University told The Scientist in an email.

Mitchell Lazar of the University of Pennsylvania, who was not involved in the study, was pleased with the "new ...