We recently reported that insulin can partially protect the knee joint against osteoarthritis (OA) development in a rat model of type 1 diabetes mellitus (T1DM). However, the combined protective effect of insulin and swim exercise against OA development secondary to diabetes has not been investigated before. Therefore, we hypothesized that swim exercise can augment the protection of the knee joint in diabetic rats treated with insulin. T1DM was induced in Sprague Dawley rats and treated with insulin and/ or swim exercise. Tissues harvested from the articular cartilage of the knee joint were examined by light microscopy, and blood samples were assayed for biomarkers of oxidative stress and inflammation. Treatment of diabetic rats with insulin and swim exercise substantially protected the articular cartilage and significantly (p<0.0001) inhibited the inflammatory biomarkers, tumor necrosis factor-alpha (TNF- α) and interleukin-6 (IL-6), and the oxidative stress biomarker, malondialdehyde (MDA) measured as thiobarbituric acid reactive substances (TBARS) comparable to control. Whereas, a lesser effective protection was observed by insulin or swim exercise alone. Thus, we demonstrate a substantial protection against OA development in rats treated with combined insulin and swim exercise possibly due to a complete inhibition of biomarkers of inflammation and oxidative stress.
KEY WORDS: Diabetes; Knee joint; Osteoarthritis; Swim exercise; Rat model.