Kalu D N, Hardin R R, Cockerham R, Yu B P, Norling B K, Egan J W
Mech Ageing Dev. 1984 Jul;26(1):103-12. doi: 10.1016/0047-6374(84)90169-6.
Studies were carried out on male F344 rats to examine the influence of aging and life-prolonging food restriction on bone and circulating parathyroid hormone levels. In ad libitum fed animals, the weight, density and calcium content of the femur increased with age and achieved their peak levels by 12 months of age. These levels remained stable until about 24 months and by 27 months of age the ad libitum fed animals had lost appreciable amounts of bone. The maturation of the femurs of the animals maintained on 60% of the ad libitum food intake was delayed and their bones were lighter, less dense and contained less calcium than bones from ad libitum fed rats of corresponding ages. But at 6, 12 and 24 months of age, the femur strength to body weight ratios were very highly significantly greater (P less than 0.0001) for the restricted animals compared to the ad libitum fed controls. Circulating immunoreactive parathyroid hormone increased progressively with aging in the animals fed ad libitum and the animals that experienced bone loss at advanced age also had the highest level of the hormone. In contrast, in the food restricted animals aging was not associated with a marked increase in serum parathyroid hormone or with senile bone loss. The data are discussed in relation to the mechanism of the observed changes.
对雄性F344大鼠进行了研究，以考察衰老和延长寿命的食物限制对骨骼及循环甲状旁腺激素水平的影响。在自由采食的动物中，股骨的重量、密度和钙含量随年龄增加，在12月龄时达到峰值水平。这些水平在约24个月前保持稳定，到27月龄时，自由采食的动物已损失了相当数量的骨质。食物摄入量维持在自由采食量60%的动物，其股骨成熟延迟，与相应年龄自由采食大鼠的骨骼相比，它们的骨骼更轻、密度更低且钙含量更少。但在6、12和24月龄时，与自由采食的对照动物相比，限食动物的股骨强度与体重之比非常显著地更高（P<0.0001）。在自由采食的动物中，循环免疫反应性甲状旁腺激素随衰老而逐渐增加，在老龄出现骨质流失的动物中该激素水平也最高。相反，在限食动物中，衰老与血清甲状旁腺激素的显著增加或老年性骨质流失无关。针对所观察到的变化机制对这些数据进行了讨论。
