雌激素对运动防治骨质疏松效果的影响

目的 探讨雌激素对运动防治骨质疏松效果的影响.方法 48只5个月龄SD雌性大鼠随机分为假手术组(Sham组)、假手术加运动组(Sham+run组)、单纯去卵巢组(Ovx组)、去卵巢加运动组(Ovx+run组)、去卵巢加运动加1/4雌激素组(Ovx+run+e1组)和去卵巢加运动加雌激素组(Ovx+run+e2组).其中Ovx+run+e1组和Ovx+run+e2组于术后1周开始皮下注射不同剂量的己烯雌酚,Ovx+run+e1组剂量为0.025mg/kg,1次/4d;Ovx+run+e2组为0.025mg/kg,1次/d,持续12周.Sham+run组、Ovx+run组、Ovx+run+e1组、Ovx+run+e2组于术后1周开始采用大鼠专用跑笼进行运动训练12周.术后13周行股骨远端骨密度和生物力学测量,并对胫骨近端进行骨组织计量学测量.结果 (1)Ovx组股骨远端骨密度值最低(0.10±0.01)g/cm2],与其他各组相比差异有统计学意义(均P＜0.05);Ovx+run+e2组与Sham+run组骨密度值相当分别为(0.14±0.02)g/cm2和(0.13±0.02)r/cm2],均显著高于其他各组(均P＜0.05);Sham组、Ovx+run组和Ovx+run+e1组之间骨密度值差异无统计学意义(0.11±0.01)g/cm2比(0.12±0.01)g/cm2比(0.12±0.01)g/cm2,均P＞0.05].(2)Sham组骨小梁的厚度、骨小梁面积百分比和骨小梁数量与Ovx+run+e2组、Sham+run组差异无统计学意义,且均高于Ovx+run+e1组、Ovx+run组和Ovx组(均P＜0.05);而骨小梁分离度在Sham组、Ovx+run+e2组和Sham+run组之间差异也无统计学意义,但低于Ovx+run+e1组、Ovx+run组和Ovx组(均P＜0.05).骨小梁面积百分比和骨小梁数量:Ovx组＜Ovx+run组＜Ovx+run+e1组(均P＜0.05);骨小梁分离度:Ovx组＞Ovx+run组＞Ovx+run+e1组(均P＜0.05);骨小梁厚度在3组间差异无统计学意义.(3)Ovx组极限剪切载荷、剪切强度极限、最大剪应变、剪切弹性模量明显低于其他各组(均P＜0.05).Ovx+run+e2组的极限剪切载荷、剪切强度极限、最大剪应变与Sham+run组相当,均高于其他各组(均P＜0.05);剪切弹性模量则与Sham+run组、Ovx+run组相当,均高于Sham组、Ovx组、Ovx+run+e1组(均P＜0.05).Sham组、Ovx+run+e1组与Ovx+run组极限剪切载荷、剪切强度极限、最大剪应变之间差异均无统计学意义.Sham组剪切弹性模量小于Ovx+run组(P＜0.05),但Sham组与Ovx+run+e1组、Ovx+run+e1组与Ovx+run组之间差异无统计学意义.结论 雌激素水平对运动防治骨质疏松的效果有显著影响.雌激素充足,对运动防治骨质疏松效果起协同作用;雌激素不足,则对运动防治骨质疏松效果无协同作用.

Effects of estrogen on outcomes of exercise therapy for osteoporosis

Objective To study the effects of estrogen on outcomes of exercise therapy for osteoporosis. Methods Forty-eight 5-month-old female SD rats were randomly divided into following groups:sham operated rats (Sham group), sham operated rats on exercise therapy (Sham+run group), ovariectomy rats (Ovx group), Ovx rats on exercise therapy (Ovx+run), and Ovx rats on exercise therapy and 1/4-dose (Ovx+run+e1 group) or full-dose (Ovx+run+e2 group) estrogen. For the last two groups, subcutaneous injection of diethylstilbestrol was started one week after oophorectomy at a dose of 0.025 mg/kg once every 4 days (Ovx+run+e1 group) or once daily (Ovx+run+e2 group) and lasted for 12 weeks. Exercise therapy,designed as in-cage running, was also started one week after operation in the Sham+run, Ovx+run, Ovx+run+e1 and Ovx+run+e2 groups and lasted for 12 weeks. On week 13, bone mineral density (BMD) and bone biomechanical parameters of distal femur and bone histomorphometry of proximal tibia were measured.Results (1)Ovx group had the lowest B MD (0.10 ± 0.01 ) g/cm2] compared statistically with the other groups (all P＜0.05). Ovx+run+e2 (0.14±0.02) g/cm2] and Sham+run (0.13±0.02) g/cm2] groups had BMD that was comparable to each other but significantly higher than the other groups (all P＜0.05). No statistical difference in BMD could be found among Sham (0.11 ±0.01) g/cm2], Ovx+run (0.12±0.01)g/cm2] and Ovx+run+e1 (0.12±0.01 ) g/cm2] groups (all P＞0.05). (2)The trabecular thickness, percentage area of trabeculae and trabecular bone mass in Sham group were comparable to those in Ovx+run+e2 and Sham+run groups but were higher than those in Ovx+run+el, Ovx+run and Ovx groups (all P＜0.05). Sham,Ovx+run+e2 and Sham+run groups had trabecular separation that was comparable among each other but less than those in Ovx+run+e1, Ovx+run and Ovx groups (all P＜0.05). The percentage area of trabeculae and the trabecular bone mass increased while trabecular separation decreased in order of groups by Ovx, Ovx+run,and Ovx+run+e1 (all P＜0.05), while the trabecular thickness did not differ among the three groups. (3)The maximum shearing force, maximum shearing stress, maximum shearing strain and shearing elasticity modulus in Ovx group were remarkably lower than those in other groups (all P＜0.05 ). Ovx+run+e2 group had maximum shearing force, maximum shearing stress and maximum shearing strain that were comparaile to Sham + run group but greater than those in other groups (all P＜0.05) , and shearing elasticity modulus comparable to Sham+run and Ovx+run groups but greater than those in Sham, Ovx and Ovx+run+el groups (all P＜0.05). No statistical differences in maximum shearing force, maximum shearing stress and maximum shearing strain were found among Sham, Ovx+run+e1 and Ovx+run groups. The shearing elasticity modulus in Sham group was lower than that in Ovx+run group (P＜0.05) but was not significantly different between Sham and Ovx+run+e1 group and between Ovx+run+e1 and Ovx+run group. Conclusions Estrogen levels may have a strong impact on outcomes of exercise therapy for osteoporosis. Adequate estrogen supplement can be synergistic to the outcomes of exercise therapy for osteoporosis. But inadequate estrogen supplement can not be synergistic.