Effects of hypoxia and vibration training on bone metabolism and insulin sensitivity in type 2 diabetic osteoporosis rats / 中国组织工程研究

ABSTRACT

BACKGROUND: Hypoxia program to alleviate type 2 diabetes insulin resistance has been recommended, but this program is still questioned because of the risk of osteoporosis caused by hypoxia in patients with diabetes. OBJECTIVE: To investigate the effect of vibration training on bone mineral density, bone structural mechanics, bone metabolism and insulin sensitivity in type 2 diabetic osteoporosis rats under hypoxia environment. METHODS: Ninety clean Sprague-Dawley rats were randomly divided into two groups, and subjected to high-fat diet (n=60), or normal diet (n=30), for 8 weeks. High-fat rats were given the injection of streptozotocin to establish the rat model of type 2 diabetic osteoporosis. The control rats were subdivided into normoxia control and hypoxia control groups; the model rats were subdivided into hypoxia modeling group, hypoxia modeling vibration group, normoxia modeling group, normoxia modeling vibration group. Hypoxia and vibration program was performed by hypoxia tank and vibration platform (PowerPlate?) for 12 weeks. Glucose metabolism, insulin sensitivity, bone metabolism and bone mineral density and modeling were detected at 4 weeks after modeling and 12 weeks after vibration training. RESULTS AND CONCLUSION: At 12 weeks after intervention, the fast insulin level, fast blood glucose, and homeostasis model assessment of insulin resistance in the hypoxia modeling vibration group were significantly superior to those in the hypoxia modeling, normoxia modeling, and normoxia modeling vibration groups (P < 0.05). The bone mineral density, maximum stress, maximum load, breaking load and elastic modulus in the normoxia modeling vibration and hypoxia modeling vibration groups were significantly lower than those in the normoxia control and hypoxia control groups (P < 0.05). After vibration training, all indexes were significantly increased (P < 0.05). These results suggest that hypoxic environment can promote the insulin sensitivity, improve glucose and lipid metabolism in type 2 diabetic rats, but can lead to a decrease in bone mineral density and increase bone resorption. Vibration training not only can significantly enhance the insulin sensitivity, but also can avoid the decreased bone mineral density, bone metabolism disorder, and biomechanical properties induced by hypoxia.