AGING AND DIETARY MODULATION OF RAT SKELETON AND PARATHYROID-HORMONE
AGING AND DIETARY MODULATION OF RAT SKELETON AND PARATHYROID-HORMONE
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DOI：
10.1210/endo-115-4-1239
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发表时间：
1984-01-01
期刊：
影响因子：
4.8
通讯作者：
YU, BP
中科院分区：
文献类型：
--
作者：
KALU, DN;HARDIN, RH;YU, BP
本研究以SPF F344雄性大鼠为实验对象，评价无营养的限食增龄对大鼠骨骼和循环甲状旁腺激素的影响。6周龄F344大鼠分为5组。1组大鼠随机饲喂蛋白质含量为21%的日粮。2组大鼠从6周龄起按1组大鼠平均摄食量的60%饲喂，终生饲养。第3组大鼠在6月龄前按随机摄取量的60%饲喂，6月龄后转为随机摄取量。第4组的大鼠在6岁前进行即食喂养，然后将即食食物的摄取量改为60%。第5组大鼠被随意喂食蛋白质含量仅为12.6%的饲料，以便这些动物每天摄入与第2组大鼠相同数量的蛋白质。1组动物的骨长、骨重、骨密度和钙含量随着年龄的增长而迅速增加，并在约0岁时趋于平稳。12岁以上。在这些动物身上没有骨质流失的证据，直到大约。24个月大的时候，但到了27个月大的时候，这些动物已经失去了相当数量的骨头。动物的循环免疫反应性PTH水平随着年龄的增长而增加，在27月龄时明显升高。3组和5组大鼠的骨骼和血清PTH水平与年龄相关的变化与1组动物相似，但5组大鼠的血清PTH没有出现终末性升高。限制进食时间最长的第2组和第4组动物的骨骼生长和成熟速度减慢，但动物没有出现老年性骨质流失或循环甲状旁腺激素的明显终末增加。限制食物摄入的有益效果并不是由于限制蛋白质摄入或仅在快速生长期间限制食物摄入而产生的。
Studies were carried out on SPF F344 male rats to evaluate the effects of aging and life-prolonging food restriction, without malnutrition, on rat skeleton and circulating PTH. Six week old F344 rats were divided into 5 groups. Group 1 rats was fed ad lib a diet that contained 21% protein. Group 2 rats were fed 60% of the mean food intake of group 1 rats from 6 wk of age for the rest of their lives. Group 3 rats were fed 60% of the ad lib food intake until 6 mo. of age and then switched to ad lib feeding. Group 4 rats were fed ad lib until 6 mo.of age, and then switched to 60% of the ad lib food intake. Group 5 rats were fed ad lib a diet that contained only 12.6% protein so that these animals ingested the same amount of protein per day as the group 2 rats. In group 1 animals, bone length, weight, density, and Ca content increased rapidly with age and plateaued at .apprx. 12 mo. of age. There was no evidence of bone loss in these animals until .apprx. 24 mo. of age, but by 27 mo., the animals had lost appreciable amounts of bone. The circulating immunoreactive PTH levels of the animals increased with advancing age, with a marked rise at 27 mo. The age-related changes in bone and serum PTH levels of rats in groups 3 and 5 were similar to those of group 1 animals, except that a terminal increase in serum PTH did not occur in group 5 rats. In the group 2 and 4 animals which were food restricted for the longest period, bone growth and maturation was slowed down, but the animals did not experience senile bone loss or marked terminal increase in circulating PTH. The salutary effects of food restriction were not due specifically to the restriction of protein intake or to restricting food intake only during the period of rapid growth.