Effects of insulin on diabetic bone histomorphometric and biomechanical abilities in streptozotocin-treated rats
LIN Huagang1, WANG Bo1, ZHANG Jun1, and JIA Hongwei2
1.Department of Orthopedics, the Second Hospital of Beijing Municipal Corps of Chinese People’s Armed Police Forces, Beijing 100037,China; 2.Department of Endocrinology,Tianjin Medical University General Hospital,Tianjin 300052,China
Abstract:Objective To study the effect of insulin on bone mass and the condition of bone turnover and bone biomechanical properties in STZ-induced diabetic rats. Methods Of 45 male SD rats studied, 30 were made diabetic by intravenous injection of streptozocin(50 mg/kg) on day -7. Thirty diabetic rats were randomly divided into 2 groups as group DM and control group. DM group were injected subcutaneously with insulin (6 U/kg/d) regularly.After their sacrifice on the day 56, blood was sampled and serum was separated for the measurement of Ca, P, ALPand OC. The left tibia was dissected for bone histomorphometry analysis. Right femur and lumbar vertebrae(L1-L4) were reserved for BMD test. The left femor was separated for three-point bending test,while the fifth lumbar vertibra was prepared for compression test to reflect the biomechanical properties of bone.Results A low-turnover osteopenia was evidenced in diabetic rats by decreased BMD in both femur and lumbar vertebrae, reduced serum OC level, decreased urine NTx/Cr ratio, decreased trabecular volume[TBV/TTV(12.06±2.48) vs (24.12±1.84)%, P<0.01]and bone formation rate[(0.44±0.11) vs (0.78±0.14)μm/d, P<0.01] by bone dynamic study. All these abnormalities except urine NTx/Cr ratio were partly or completely normalized by insulin treatment. The bone densities in vertebrae and femur of diabetic rats significantly decreased(P<0.01). Maximal load, elastic load, bending energy, maximal stress in three-point bending test were conducted,compared with normal control rats. These abnormalities could be partially corrected by insulin teatment(P<0.01).In addition,the fifth lumbar vertibrae of diabetic rats were obviously decreased(P<0.01), and maximal load,elastic load,energy absorbability and elastic modulus during compressing test. By insulin treatment, these indices partially reversed to the normal control level(P<0.01). Conclusion A low-turnover osteopenia is evidenced in STZ-induced diabetic rats with impaired bone biomechanical abilities.All these abnormalities of bone can be partially corrected by the injection of insulin. It shows that insulin can stimulate bone formation dramatically while not influence osteoclastic activity in diabetic rats.
林华刚,王博,张军,贾红蔚. 胰岛素对链脲佐菌素诱导的糖尿病大鼠 骨转换和骨力学性能的影响[J]. 武警医学, 2015, 26(10): 1010-1014.
LIN Huagang, WANG Bo, ZHANG Jun, and JIA Hongwei. Effects of insulin on diabetic bone histomorphometric and biomechanical abilities in streptozotocin-treated rats. Med. J. Chin. Peop. Armed Poli. Forc., 2015, 26(10): 1010-1014.
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