模拟失重条件下蛋白质/钾摄入比与骨代谢标志物的相关性研究

THE CORRELATION BETWEEN DIETARY PROTEIN/POTASSIUM RATIO AND BONE METABOLISM MARKERS UNDER SIMULATED WEIGHTLESS CONDITIONS IN RATS

目的探索蛋白质/钾摄入比(TPro/K)对失重性骨丢失的防护作用。方法54只雄性SD大鼠随机分为空白对照组,尾吊对照组,尾A组(TPro/K=30),尾B组(TPro/K=40),尾C组(TPro/K=50),尾D组(TPro/K=60),每组9只,空白对照组和尾吊对照组喂养正常饲料,其余组分别喂养固定比例的特制饲料。喂养5w后,Micro-CT检测骨密度和微结构,ELISA法检测血清骨代谢指标,分析TPro/K与骨代谢的相关性。结果5 w处理后,与空白对照组相比,尾吊处理显著影响SD大鼠体重(P<0.05),与尾吊处理组比较,蛋白质/钾摄入组体重无显著差异。各组大鼠进食量无统计学差异。与尾吊对照组相比,随着膳食蛋白质/钾的摄入比增加,SD大鼠骨密度(BMD)、血清骨形成标志物骨钙素(BGP)和骨特异性碱性磷酸酶(BAP)以及超氧化物歧化酶(SOD)水平呈先增大后下降的趋势,在蛋白质/钾的摄入比为40时,即尾B组处理达到最高(P<0.05)。与此相反的是,骨皮质骨骨小梁的空隙和大鼠抗酒石酸酸性磷酸酶(TRAP)呈现先减小后增大的趋势,同样在尾B组处理时达到最高。多项式拟合分析显示蛋白质/钾摄入比与BAP和SOD含量有相关性,与BGP和TRAP水平无相关性。结论蛋白质/钾摄入比与模拟失重状态下SD大鼠骨代谢标志物具有相关性,合理调整膳食中蛋白质/钾比例可缓解尾吊大鼠发生骨丢失.

Objective To explore the correlation between protein/potassium intake ratio(TPro/K)and bone loss under simulated weightlessness.Methods Fifty four male SD rats were randomly divided into control group,tail-suspended control group,tail-suspended group A(TPro/K=30),tail-suspended group B(TPro/K=40),tail-suspended group C(TPro/K=50)and tail-suspended group D(TPro/K=60),with 9 rats in each group.Control group and tail-suspended control group were fed a normal diet.The other groups were fed diets with different protein/potassium rations.After 5 weeks of feeding,Bone mineral density and microstructure were detected by Micro-CT.Serum bone metabolism indexes were detected by ELISA,and the correlation between the ratio of TPro/K and bone metabolism markers was analyzed.Results After 5 weeks of treatment,body weight decreased significantly in the tail-suspended control group compared with the control group(P<0.05).There was no significant difference in food intake among groups.Compared with the tail-suspended control group,bone mineral density(BMD),serum bone formation marker osteocalcin(BGP),bone specific alkaline phosphatase(BAP)and superoxide dismutase(SOD)increased firstly and then decreased with increasing ratio of dietary protein/potassium.In contrast,the interspaces of trabecular bone and tartrate-resistant acid phosphatase(TRAP)decreased firstly and then increased with the highest in the tail-suspended group B.The results of polynomial fitting analysis showed that the ratio of protein/potassium in the diet was correlated with the levels of BAP and SOD,but not with BGP and TRAP.Conclusion Dietary ratio of protein/potassium was correlated with biomarkers of bone metabolism in rats under simulated weightlessness.Reasonable adjustment of dietary protein/potassium ratio may alleviate bone loss in tail hanging rats.