结合雌激素对去势大鼠骨折愈合生物力学指标的影响

Effects of premarin on bone biomechanic indexes in fracture healing of ovariectomized rats

目的探讨结合雌激素(倍美力)对去势大鼠骨折愈合及骨痂生物力学指标的影响。方法采用54只6月龄雌性大鼠,分为倍美力组、伪手术组和去势组。倍美力组和去势组大鼠均切除两侧卵巢,切除后第8周,各组大鼠均实施右侧股骨骨折,同时倍美力组按0.065mg/(kg·d)给予倍美力药物灌胃。3组均在实施骨折后第2、4、6、8周随机处死大鼠,取其右侧股骨行X射线照片观察骨痂变化,测定软骨痂及骨折断端骨痂吸光度、骨痂Ⅰ型胶原阳性表达积分吸光度及骨折后第8周右股骨的生物力学指标。结果 X线片显示,倍美力组和伪手术组骨痂密度在骨折后各时期均高于去势组;倍美力组在骨折后第8周的软骨痂吸光度和骨折断端骨痂吸光度均低于去势组,组间比较差异有统计学意义(P<0.05),而与伪手术组比较差异无统计学意义(P>0.05);去势组的骨痂Ⅰ型胶原阳性表达积分在骨折后各时期均低于倍美力组与伪手术组,组间比较差异有统计学意义(P<0.05),而倍美力组与伪手术组的表达比较差异无统计学意义(P>0.05);倍美力组的破坏强度、弯曲弹性模量、刚度系数均优于去势组,组间比较差异有统计学意义(P<0.05),而与伪手术组比较差异无统计学意义(P>0.05)。结论结合雌激素可使骨痂中Ⅰ型胶原合成增多,使骨的柔韧性增加、硬度增加,最终改善骨的生物力学性能。

Objective To explore the effects of conjugated estrogen hormones（premarin）on the bone biomechanic indexes and fracture healing of the ovariectomized rats.Methods 54 female rats,aged 6-month-old,were divided into 3groups：premarin group,sham operation group（SHAM group）and ovariectomized group（OVX group）.Rats in the premarin group and the OVX group were ovariectomized.The right femur was broken by operation at 8weeks after ovarrectomization.Premarin[0.065 mg/（kg·d）]was given immediately through intragastric administration after establishment of osteporotic fracture model in the premarin group.Rats in the 3groups were randomly killed at the end of postoperative 2,4,6,8weeks respectively.The right femur was examined for observing the change of bone callus by X-rays;the absorbance determination of cartilage callus and bone callus in the end of femural fracture were performed;the integral absorbance detection of positive expression of typeⅠ bone collagen and the detection of biomechanical indexes of right femur at 8weeks after fracture were performed.Results The X-ray examination showed that the bone callus density in various periods after fracture in the premarin group and the SHAM group were significantly higher than that in the OVX group.The absorbance of cartilage callus and bone callus of the end of fracture at8 weeks after fracture in the premarin group were lower than that in the OVX group with statistical difference（P〈0.05）,but without statistical differences compared with that in the SHAM group（P〈0.05）.The integral absorbance of positive expression of typeⅠ bone collagen in vanous periods in the OVX group was significantly lower than that in the premarin group and the SHAM group（P〈0.05）,while there were no statistical differences in the expression between the premarin group and the SHAM group（P〉0.05）.The destructive intension,elastic modulus and stiffness coefficient of right femur in the premarin group were better than those in the OVX group with statistical differences（P〈0.05）,while without statistical differences compared with the SHAM group（P〉0.05）.Conclusion Premarin may increase the synthesis of typeⅠ collagen,and the flexibility and hardness of bones,finally improve the biomechanics properties.