Obesity alone does not cause knee osteoarthritis

September 29th, 2009 - 5:11 pm ICT by ANI  

Washington, Sep 29 (ANI): In a study on mice, Duke University researchers have found that obesity alone cannot lead to osteoarthritis, a progressive musculoskeletal disorder that is characterized by loss of joint cartilage.

The researchers studied leptin-deficient mice to determine the role of obesity in developing knee osteoarthritis (OA).

In their opinion, obesity caused by a leptin deficiency would result in a higher incidence of knee OA.

Mice with a disruption of leptin signalling showed a 3-fold increase in body mass and 10-fold increase in body fat, but surprisingly did not display effects of knee OA.

The researchers compared leptin-deficient and leptin receptor-deficient female mice with wild-type mice to further understand the role this deficiency may play in increasing risk of knee OA.

At 10-12 months of age, mice were measured for body fat content and blood samples were taken to determine the level of inflammation in the animals.

Knee joints were analysed to determine bone thickness and to look for degenerative changes in the lateral femur, lateral tibia, medial femur, and medial tibia.

Though higher levels of leptin are present in obese individuals, they apparently have a resistance to the effects of the hormone where the body does not receive the signal it is full after eating.

According to Dr. Farshid Guilak and colleagues, the leptin-deficient mice showed a 10-fold increase in adiposity (body fat) but not a higher incidence of OA compared with wild-type mice.

“It was surprising that knee OA was not present given the severity of obesity in the leptin-impaired mice,” said Guilak.

The study implies that leptin could be directly involved in OA because without that hormone, obesity did not influence the occurrence of OA in the mice.

Mice with loss of leptin function also had reduced bone thickness beneath the cartilage and increased tissue volume at the end of the tibia, suggesting that obesity, other obesity-dependent factors, or the absence of leptin signalling independently diminishes bone structure.

The findings of the study have been published in Arthritis and Rheumatism. (ANI)

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