Hormone boosts resistance to obesity

Beating obesity—Dr. Catherine Kotz, whose lab work at the Minneapolis VA involves specially bred obesity-prone rats, is part of a research team exploring the links between weight gain and the brain hormone "orexin." (Photo by Don Olson)

In a recent review article, researchers with VA and the University of Minnesota explained what they have learned so far about an obesity-fighting hormone called orexin. The hormone helps regulate what the scientists call "spontaneous physical activity," or SPA. The work on orexin and SPA is part of ongoing research by the team on brain mechanisms that trigger weight gain and weight loss. Unlike higher-intensity formal exercise, SPA is the simple moving around and unconscious fidgeting that people do throughout the day. The researchers have found that orexin increases SPA and in turn can reduce the likelihood of weight gain. In lab experiments, for example, rats fed a high-fat diet were less prone to gain weight when they received brain injections of orexin. The scientists say learning how to safely alter orexin levels—or otherwise affect the brain's SPA pathways—is "an attractive target for obesity prevention and therapy." (Annals of the New York Academy of Science, July 17, 2012)