Effect of L-carnitine on diabetes-induced changes of skeletal muscles in rats.

Background: Patients with diabetes mellitus (DM) are at risk of experiencing chronic complications such as retinopathy, nephropathy and myopathy. We aimed to evaluate the effects of L-carnitine on type II DM (T2DM)-induced biochemical, contractile and pathological changes in skeletal muscles of rats.

Methods: Thirty-two male Sprague Dawley rats were divided into the control, control+L-carnitine, T2DM and T2DM+L-carnitine groups. Plasma levels of glucose, insulin, malondialdehyde and antioxidants such as reduced glutathione, catalase and superoxide dismutase, haemoglobin A1c (HbA1c), insulin sensitivity index (ISI) as well as the contractile properties of the gastrocnemius muscle were measured. Also, histopathological studies and immunohistochemical examination of the gastrocnemius muscle using the MuRF1 (muscle RING-finger protein-1) marker were performed.

Results: In diabetic rats, malondialdehyde, glucose, insulin, HbA1c and MuRF1 were increased, whereas ISI and antioxidants were decreased and the contractile properties deteriorated. L-carnitine decreased malondialdehyde, glucose, insulin, HbA1c and MuRF1 and increased ISI and antioxidants. Also, L-carnitine improves the contractile properties in diabetic rats. Histopathological studies confirm our data.

Conclusions: We conclude that L-carnitine exhibits protective effects on skeletal muscles of T2DM rats through its hypoglycemic and antioxidant actions as well as its inhibitory effect on protein degradation.