骨质疏松动物骨组织及血清柠檬酸含量变化的研究

The changes of citric acid levels in bone tissue and serum of osteoporotic animals

目的探讨骨质疏松动物骨及血清柠檬酸的变化,为研究柠檬酸对骨结构/功能的影响提供依据。方法构建激素缺失/药物诱导或年龄增长相关的大小鼠骨质疏松模型,收集骨组织,micro CT测量骨密度。对骨组织切片进行免疫组化、TRAP染色、HE染色等,确定模型构建是否成功。并对骨质疏松动物的骨组织及血浆柠檬酸进行检测。结果去卵巢三个月后,小鼠子宫萎缩、体重增加、骨密度降低,发生明显骨质疏松。与对照组相比,其每克骨组织中柠檬酸水平显著降低。维甲酸诱导14 d后,大鼠骨密度明显下降,发生骨量丢失,其每克骨组织中柠檬酸含量相比对照组显著减少。20月龄自然衰老组小鼠骨密度显著降低,每克老年鼠骨组织中柠檬酸水平明显低于年轻小鼠。发生骨质疏松的大/小鼠,其血浆中柠檬酸水平显著低于各自对照组。结论通过构建不同的骨质疏松模型首次阐明了骨组织与血清柠檬酸水平与骨量丢失相关疾病骨质疏松的关系,血清柠檬酸水平可能是预测骨量丢失相关疾病如增龄性或绝经后骨质疏松的一个标志分子,为早期诊断和预防提供依据。骨中柠檬酸代谢的阐明为骨代谢提供了新的观点。

Objective To investigate the changes of citric acid level in bone and serum of osteoporotic animals,and to provide evidence for the investigation the effect of citric acid on bone structure/function.Methods Different osteoporotic mouse/rat models were constructed by surgery or drug,and bone mineral density(BMD)was detected by micro CT.Bone sections were subjected to immunohistochemistry staining,TRAP staining and H&E staining to confirm osteoporosis.Then the changes in citric acid levels in osteoporotic bone tissue and serum were analyzed.Results Three month after OVX,the mice showed obvious osteoporosis,suggested by a marked atrophy of the uterus,increased body weight and decreased BMD.Compared with sham group,citric acid content in bone tissues of OVX mice was significantly reduced.After 14 days treatment by retinoic acid(RA),bone loss occurred in rats,and citric acid content per gram of bone tissue from RA-treated rats markedly reduced.Aged mice(20 months old)showed a significantly reduction in BMD,and citric acid content in bone tissue of aged mice was significantly lower than adult mice.Serum citric acid levels in osteoporotic mice/rats were significantly reduced compared with controls.Conclusion These findings establish a novel relationship between citric acid content and osteoporosis,suggesting a critical role of bone citric acid in the maintenance of the citric acid balance in the circulation.Serum citric acid level may thus represent a novel marker for osteoporosis.