Effect of Diabetes Mellitus on the Structure of Skeletal Muscle in Adult Male Albino Rats and the Protective Role of Chromium: Histological and Immunohistochemical Study

Introduction: Diabetes may induce many physiological and biochemical changes in skeletal muscle fibers. These were supposed to be caused by hypoinsulineamia and hyperglyceamia. Chromium is trace element its effect on the body is related to carbohydrate and fat metabolism. Chromium improved the metabolism of skeletal muscle especially in athletes. Aim of the Work: We evaluate the histological and immunohistochemical changes induced by diabetes in the skeletal muscle and the protective role of chromium. Material and Methods: Twenty five adult Sprague-Dawlery male albino rats were used. The rats were divided into two main groups; the control group (10 rats) and the diabetic group (15 rats). The control group was divided in 2 subgroups 5 animals each. Subgroup la served as a control group while subgroup lb was formed of animals that received oral chromium. Group II in which diabetes was induced using streptozotocin (STZ) was divided into 3 subgroups 5 animals each. Subgroup Ha formed of diabetic rats. Subgroup lib formed of diabetic rats that received insulin. Group lie formed of diabetic rats that received insulin and chromium. The duration of experiment was 2 months. At the end of experiment, gastrocnemius muscles were dissected out and prepared for H and E stain, electron microscopic study and immunohistochemistry for CD34 of endothelial cells of capillaries. Results: Skeletal muscle of group Ha showed disruption and discontinuity. Mononuclear cellular infiltrate was detected among skeletal muscle fibers. Ultrathin sections showed damaged myofibrils, swollen irregular mitochondria and absent T tubules within the muscle fibers. Microvasculature of skeletal muscle was decreased as demonstrated by immunostaining for CD34. Group lib showed improvement of skeletal muscle fibers and their microvasculature but not complete as that of the control. In group lie, there was complete improvement of the skeletal muscle fibers and microvasculature among the muscle fibers. Significant decrease in thickness of muscle fibers in diabetic rats and insulin treated subgroup lib could be measured. Intake of chromium was found to improve these changes in subgroup He. Significant increase in blood glucose was detected in subgroup Ha and was controlled in subgroups lib and lie. Conclusion: Diabetes produced marked structural changes in skeletal muscle but these changes could be prevented by intake of chromium in addition to the insulin.