Effect Of Calcitriol On Bone Mechanical Structure In Diabetic Rats

Objective:Diabetic osteoporosis is an important complication of diabetes mellitus in the skeletal system.The pathogenesis of diabetes is lack of insulin,hyperglycemia,metabolic disorders of calcium and phosphorus,and chronic complications of diabetes.However,its exact mechanism remains unclear.The study found that diabetic rats significantly decreased vitamin D₃,resulting in abnormal calcium and phosphorus metabolism,which may be one of important pathogenesis of diabetic osteoporosis.Calcitriol,1,25-?OH?₂-Vit D₃,is one of the important active metabolites of vitamin D₃.The study found that calcitriol can increase bone marrow 1,25-?OH?₂-Vit D₃ concentration,which can directly act on osteoblasts and osteoclasts in bone tissue and treat osteoporosis.In this experiment,the effect of calcitriol on the mechanical structure of femur in diabetic rats was explored by means of bone histomorphometry and bone biomechanics to provide experimental basis for the clinical application of calcitriol.Methods:Fifty clean male Sprague-Dawley rats were randomly divided into model group?n=34?and normal control group?n=16?,fed adaptively for one week and fasted for overnight.The model group received an intraperitoneal injection of 30 mg/kg doses of STZ citric acid solutiona,and the control group was given the same dose of citrate buffer.72 hours later,blood was drawn from the tail vein and the changes of blood glucose level are monitored with a glucometer.If 33.3mmol/L?fasting blood glucose?11.1mmol/L,the rat is considered as a successful model.Thirty-two adult SD rats were randomly divided into 4 groups:diabetic group??DM??,diabetic group??DM??,calcitriol group??VD??and calcitriol group??VD??,with8 rats in each group.Administration of 1?g/kg calcitriol?1?g/ml peanut oil?to the VD group was given daily,while rats in the NC group and DM group were given the same amount of peanut oil.After 6 weeks?group??and9 weeks?group??,blood was drawn through right ventricular puncture to determine 1,25-?OH?2-Vit D3 concentration.The distal 1/3 of the left femur was stained by HE staining.The morphological changes of the bone were observed and bone histomorphometry quantitative analysis was tested.Biomechanical testing was performed on right femurs.Results:1 Compared with NC group in the same period,biomechanical properties was significantly lower in DM group,as well as the static parameters?percent trabecular area,trabecular thickness,trabecular number???<0.05?,while trabecular separation was significantly increased??<0.05?.2 With administration for 6 weeks,the rats in VD group showed significantlyincreaseinmaximumload?132.47±11.00?,break load?115.37±7.64?,trabecular number?3.562±0.374?and percent trabecular area?26.531±3.388?%,while trabecular thickness was significantly decreased,compared with DM group??<0.05?.3 After treated for 9 weeks,VD group also displayed significantly change in biomechanical properties?elastic load and rigid coefficient?and static parameters,with compared to DM group??<0.05?.Conclusions:Compared with normal rats,the femur of diabetic rats showed obvious changes of microstructure degeneration,and biomechanical properties decreased significantly.Calcitriol on rats with diabetes caused by osteoporosis have a good therapeutic effect,as it can improve the biomechanical properties and trabecular bone microstructure of rats'femur,and increase the stability of the structure of bone mechanics,thereby inhibiting the occurrence and development of osteoporosis on diabetic rats.