Sept. 29 (HealthDay News) -- The appetite-regulating hormone leptin may contribute to osteoarthritis in obese people, according to a new study that suggests that skeletal wear and tear caused by excess weight isn't the only cause of the painful and debilitating condition.

Duke University researchers found that extremely obese mice didn't develop osteoarthritis if their bodies didn't have leptin. In fact, joints in obese mice without leptin appeared healthier than those in normal mice.

The study appears in the Sept. 29 issue of the journal Arthritis & Rheumatism.

This is the first time that leptin has been identified as a "metabolic link" between obesity and altered cartilage metabolism in joints, according to a university news release.

"Although there was some earlier evidence that leptin might be involved in the arthritis disease process, we didn't think that there would be no arthritis at all" in the obese mice without leptin, said Farshid Guilak, director of orthopedic research in the Duke Department of Surgery, in the news release.

Leptin influences many osteoarthritis-related factors, such as body weight, inflammation and bone metabolism.

"With obesity and osteoarthritis, there are good similarities between humans and mice," Guilak said. "If we can find a pathway that links a high-fat diet with arthritis, then we can try to identify and block the inflammatory mediators that are linked with the dietary fat."

SOURCE: Duke University, news release, Sept. 29, 2009