Effects of mechanical stress on bone metabolism and life span in stroke-prone spontaneously hypertensive rats

研究跳跃运动对易卒中型自发性高血压大鼠（SHRSP）钙代谢和寿命的影响。据报道，SHRSP在生长过程中发生高血压，并死于脑卒中，同时存在钙代谢异常。认为钙代谢异常是其血管病变的重要因素之一。另一方面，在我之前的研究中，大鼠的跳跃运动有效地获得了局部骨骼中的钙积累。因此，我认为跳跃运动影响了SHRSP的全身钙代谢。首先，我研究了跳跃运动对SHRSP寿命的影响。虽然我尝试了两次，但我没有发现运动组和久坐组的寿命有显著性差异。其次，我研究了跳跃运动对SHRSP钙代谢的影响。跳跃运动能增加SHRSP大鼠下肢骨量，与正常大鼠相似。然而，跳跃运动并没有影响血清钙和甲状旁腺激素，虽然它显着降低血清磷在SHRSP。这些结果表明，跳跃运动并没有改变全身钙代谢。第三，研究了跳跃运动对SHRSP和正常大鼠血清骨细胞相关细胞因子和蛋白水平的影响。我没有发现在运动SHRSP或正常大鼠的骨桥蛋白，sRANKL，基质Gla蛋白和骨保护素的显着变化。我还测量了脂质代谢，但也没有发现跳跃运动的显着影响。总之，跳跃运动虽然能增加SHRSP局部骨量，但不改变其全身钙代谢。也不影响SHRSP的寿命。

I investigated the effects of jump exercise on calcium metabolism and life span in stroke-prone spontaneously hypertensive rats(SHRSP). It was reported SHRSP became hypertension as they grew and was died by cerebral apoplexy, and they also had abnormal calcium metabolism. It was assumed that the abnormal calcium metabolism was one of important factors of their vascular disease. On the other hand, in my previous study, jump exercise in rats effectively gained calcium accumulation in regional bones. Thus, I assumed that jump exercise influenced whole body calcium metabolism in SHRSP.Firstly, I investigated the effect of jump exercise on life span in SHRSP. Although I tried twice, I did not find significant difference in life span between exercised and sedentary group.Secondly, I investigated the effect of jump exercise on calcium metabolism in SHRSP. Jump exercise increased bone mass of lower limb in SHRSP like in normal rats. However, jump exercise did not affect serum calcium and parathyroid hormone although it significantly decreased serum phosphate in SHRSP. These results suggested that jump exercise did not alter whole body calcium metabolism.Thirdly, I investigated the effect of jump exercise on serum cytokine or protein level associated with osteocyte in SHRSP or normal rats. I did not find significant changes in osteopontin, sRANKL, matrix Gla protein and osteoprotegerin in exercised SHRSP or normal rats. I also measured lipid metabolism but also did not find the significant influences of jump exercise. In conclusion, jump exercise in SHRSP did not change whole body calcium metabolism although it increase local bone mass. It also did not influence life span in SHRSP.