长期递增负荷运动对雌性大鼠胫骨上段骨组织形态计量学的影响

摘要

Objective This study was to investigate the effects of long-term training with progressively increasing load on the bone metabolism of female rats. Methods 3-month-old female rats with regular estrous cycle were randomly divided into 8 groups, and the rats in the 8 groups underwent 2-, 4-, 6-, 8-, 9-, 11-, 13-, and 15-week treadmill training with progressively increasing load, re-spectively. Corresponding control groups and basic control group were also recruited. All rats were injected with tetracycline (25 mg/kg) on the 14th and 13th day, and calcein (5 mg/kg) on the 4th and 3rd day before they were sacrificed. The bone sections of right proximal tibia without decalcification were prepared for histomorphometric analysis. Results During the 15-week training: ? The bone mineral density of the rats increased initially and then gradually decreased to its minimun by the end of 15 weeks: ? The percent trabecular bone area (%Tb.Ar) , number of trabecular bone (Tb.N) and thickness of trabecular bone (Tb.Th) decreased significantly, and resolving power of trabecular bone (Tb.Sp) increased significantly. (3) parameters of bone formation and bone resorption, including %L.Pm, MAR, BFR/BS, BFR/BV, Oc.N, and Oc.Pm% showed an increase tendency following an initial drop, and bottomed out eventially on the 1 lth week. Conclusions 15-week training with progressively increasing load seriously affects the BMD and bone histomorphometry of female rats. Overload training significantly aggravates bone formation, especially bone resorption, and finally decreases BMD of female rats.%目的:探讨长期递增负荷运动对骨代谢影响的可能机制.方法:将动情周期规律的3月龄雌性大鼠随机分为8组,分组进行2、4、6、8、9、11、13、15周的递增负荷运动,并设立同期对照组和基础对照组.在造模过程中监控体重、体成分、阴道脱落细胞、血生化及骨密度等指标的变化.所有大鼠被处死前13、14天皮下注射盐酸四环素25 mg/kg各1次,于处死前3、4天注射钙黄绿素5 mg/kg各1次,两次荧光标记间隔10天.实验结束后,取大鼠右侧胫骨上段制成不脱钙骨切片,测定骨组织形态计量学指标.结果:①持续15周的递增负荷跑台运动中,大鼠全身骨密度(BMD)先上升后下降,至15周运动结束降至最低点.②大鼠胫骨上段骨组织形态计量学静态参数表现为骨小梁面积百分数(％Tb.Ar)、骨小梁厚度(Tb.Th)先轻微上升后下降,呈近似倒“V”形变化,峰值出现在T11组；骨小梁数量(Tb.N)随运动负荷增加逐渐降低；骨小梁分离度(Tb.Sp)前期持平,T11组～T15组明显增加.③动态参数和细胞参数表现为骨形成参数(标记周长百分数％L.Pm、矿化沉积率、骨面积水平骨形成率BFR/BS、骨体积水平骨形成率BFR/BV、单位骨小梁面积成骨细胞数Ob.N和成骨细胞周长百分数Ob.Pm％)和骨吸收参数(单位骨小梁面积破骨细胞数Oc.N和破骨细胞周长百分数Oc.Pm％)呈先下降后上升的“V”形变化,T11组达最低点.结论:持续15周递增负荷跑台运动对大鼠骨组织形态计量学参数及BMD有明显影响,过量负荷运动均明显加剧骨吸收和骨形成,但骨吸收大于骨形成,骨量降低,骨代谢呈高转换状态.