副甲状腺ホルモン受容体遺伝子発現に対する低カルシウム食飼育の影響

概要

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Parathyroid hormone (PTH) acts on bone and kidney by binding to PTH/PTH-related protein receptor (PTH1R) and regulate calcium (Ca) and phosphorous (P) homeostasis. This experiment was undertaken to investigate the effect of Ca and vitamin D restriction (-Ca-D) diet on PTH1R mRNA expression in the major PTH target tissues such as bone and kidney. Rats fed -Ca-D diet showed significant decrease in serum Ca and P on day 14 and day 7, respectively. Serum PTH and 1, 25 dihydroxyvitamin D_3[1,25(OH)_2D_3] markedly increased on day 14 and day 1, respectively. Renal VitaminD-1 a-hydroxylase activities increased slightly during day 1-7 and markedly during day 14-35. PTH1R mRNA abundance determined by Northern blot analysis did not change in bone and kidney, when rats were fed -Ca-D diet for up to 14 days. These results suggest that down-regulation of PTH1R in PTH target tissues is due to degradation, internalization and desensitization of the receptor protein without transcriptional attenuation.
奥羽大学の論文
2003-06-30