The Research Of Ovariectomized SD Rats' Change Of Bone Microstructure And Pain Threshold

Objective: To discuss the change of tibia's microstructure,the biomechanics properties,the change of the mechanical pain and the thermal pain threshold,the concentration of estrogen in the group of OVX and SHAM,and then do the correlation analysis among them.So we can understand the osteoporotic pain and osteoporosis deeper.Methods: 32 SD female rats which are 6 month old were randomly divided into ovariectomy group(OVX group)and control group(SHAM group),each group including 16 rats.Preoperation two groups were weighed,and mechanical pain threshold and thermal pain threshold were measured for 5 consecutive days respectively.11 weeks after operation the two groups were weighed,mechanical pain threshold and thermal pain threshold were measured 5 consecutive days,then these rats were put to death.We measured two groups of the wet weight uterine,saved the blood serum specimens and bilateral tibia specimens which used for the measurement of bone microstructure,biomechanics,and determination of the concentration of estrogen.And to do bivariate correlation analysis among bone microstructure parameters,biomechanics,pain threshold and estrogen level.Results: The OVX group of bone volume fraction,number of bone trabecular and the trabecular connection density,maximum load,maxium stress,elasticity modulus,serum estrogen concentrations were lower than in the SHAM group(P < 0.05),trabecular space are increased in the OVX group(P < 0.05),and the trabecular thickness has no statistical difference with the SHAM group.Preoperative two groups in body weight,mechanical pain threshold,has no statistical difference between thermal pain threshold.The mechanical pain threshold in OVX group is lower than in the SHAM group 11 weeks later(P < 0.05),body weight increased(P < 0.05),wet weight of uterus decreased,and no significant statistical differences between thermal pain threshold.Conclusions: With ovariectomy rats oestrogen levels decrease,bone microstructure degeneration gradually,biomechanical performance degradation,mechanical pain threshold is reduced,and there are correlations among them.