自然衰老大鼠不同部位骨组织形态、骨密度及骨代谢指标的变化

Changes in bone morphology,bone mineral density and bone metabolism in different parts of natural aging rats

背景:大鼠是四足啮齿动物,其骨骼负重方面与直立行走的人类并不相同,且大鼠最大寿限内出现骨稳态破坏的时程变化与人也是不一致的。目的:分析不同大鼠自然衰老过程中骨代谢的变化。方法:将SD大鼠分为雌性组与雄性组,各40只。其中雌性组随机分为雌性7,10,15,20月龄组,各10只;雄性组随机分为雄性7,10,15,20月龄组,各10只。实验于2016年6月经厦门大学附属福州第二医院动物实验伦理委员会批准,批准号20160012。结果与结论:①雌性及雄性SD大鼠在7-10月龄时腰椎、股骨头及胫骨上段骨小梁排列规则,形成均匀致密网状;雌性SD大鼠在15-20月龄骨小梁纤细,间距增宽,排列散乱稀疏,可见多处中断;雄性SD大鼠在15月龄骨小梁稍细小,间距增宽,排列仍较整齐,20月龄骨小梁出现部分中断。②雌性及雄性SD大鼠各部位骨小梁面积百分比在10月龄起随月龄增加而下降,在20月龄达到最低值。骨密度结果也呈现相同趋势。③雌性及雄性SD大鼠骨碱性磷酸酶水平随着月龄增加逐渐降低。雌性SD大鼠1型胶原羧基末端肽水平随着月龄增加逐渐升高,雄性SD大鼠1型胶原羧基末端肽水平自10月龄起随着月龄增加逐渐降低。④提示SD大鼠骨骼7月龄处于生长平衡,10月龄开始衰退,15月龄衰退加速,20月龄完全衰退;其中雌性SD大鼠在15-20月龄骨代谢处于高转换状态,雄性SD大鼠在15-20月龄骨代谢处于低转换状态。

BACKGROUND:Rats are a kind of quadruped rodents,with the bone weight being different from that of humans who walk upright,and the time course of bone homeostasis damage within the maximum life span of rats is also inconsistent with that of humans.OBJECTIVE:To explore the changes in bone metabolism in different rats during natural aging.METHODS:A total of 80 Sprague-Dawley(SD)rats(male and female half)were randomly assigned into 7-,10-,15-,20-month groups according to their sex(n=10 per group).The study protocol was approved by the Animal Ethics Committee of Fuzhou Second Hospital Affiliated to Xiamen University with an approval No.20160012 in June 2016.RESULTS AND CONCLUSION:The bone trabeculae of female and male SD rats at 7 to 10 months of age arranged regularly and formed a uniform dense network.The bone trabeculae of female SD rats at 15 to 20 months of age were fine,the spacing was widened,the arrangement was scattered and sparse,and there were many discontinuities.The bone trabeculae of male SD rats at 15 months of age were slightly smaller,the spacing was widened,and the arrangement was still orderly,and the bone trabeculae of male SD rats at 20 months of age were partially interrupted.The percentage of bone trabecular area in all parts of female and male SD rats began to decrease at 10 months of age,and reached the lowest value at 20 months of age.The bone mineral density also showed the same trend.The bone alkaline phosphatase level of female and male SD rats decreased gradually with the increase of month age.The level of type 1 collagen carboxy terminal peptide in female SD rats increased gradually with the increase of month age,while that of male SD rats began to decrease gradually at 10 months of age with the increase of month age.To conclude,the skeletal bone of rats experiences four stages at 7,10,15,and 20 months old:bone growth balance,beginning to decline,rapidly decline,and completely decline,respectively.Female SD rats at 15-20 months of age are in a high-transition state of bone metabolism.Male SD rats at 15-20 months of age are in a low-transition state.