Salih M A, Herbert D C, Kalu D N
Department of Physiology, University of Texas Health Science Center, San Antonio, Texas 78284-7756.
Mech Ageing Dev. 1993 Aug 1;70(1-2):1-21. doi: 10.1016/0047-6374(93)90055-v.
Male F344 rats fed ad libitum or maintained on 60% of the ad libitum food intake were sacrificed at 6, 12, 18 and 24 months of age. The thyroids were removed for the analysis of the C-cell hormones, calcitonin, calcitonin gene-related peptide (CGRP) and somatostatin. In the animals fed ad libitum, the peptide content of all three hormones and their mRNA pools increased significantly with age. The increases were markedly suppressed by food restriction. Similarly, the rate of mRNA synthesis of the hormones increased with age and was attenuated by food restriction. Calcitonin and CGRP containing cells increased in number with age in the ad libitum fed animals. In the food restricted animals the numbers of calcitonin positive cells were consistently but not significantly lower than those of ad libitum fed animals at similar ages. In the case of CGRP containing cells, their numbers were significantly lower in the food restricted than in the ad libitum fed animals from 18 months of age. Our findings indicate that aging and food restriction modulate the levels of the thyroidal C-cell hormones at the levels of cell proliferation and possibly gene transcription.
随意进食或按随意进食量的60%进食的雄性F344大鼠，在6、12、18和24月龄时被处死。取出甲状腺用于分析C细胞激素、降钙素、降钙素基因相关肽（CGRP）和生长抑素。在随意进食的动物中，所有三种激素的肽含量及其mRNA库均随年龄显著增加。食物限制显著抑制了这种增加。同样，激素的mRNA合成速率随年龄增加，而食物限制使其减弱。在随意进食的动物中，含降钙素和CGRP的细胞数量随年龄增加。在食物限制的动物中，降钙素阳性细胞的数量在各年龄段始终低于随意进食动物，但差异不显著。就含CGRP的细胞而言，从18月龄起，食物限制动物中的细胞数量显著低于随意进食动物。我们的研究结果表明，衰老和食物限制在细胞增殖水平以及可能的基因转录水平上调节甲状腺C细胞激素的水平。
