Increased level of calcitonin mRNA after 1,25-dihydroxyvitamin D3 injection in the rat.
Vitamin D metabolites are able to change plasma calcitonin (CT) levels, but nothing is known about a possible effect at the CT gene level. Here we have investigated the acute effects of 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3) on the CT biosynthetic activity of thyroid glands from adult rats. Plasma CT levels were significantly increased (X2) 1 and 2 h after 1,25-(OH)2D3 injection in the face of unchanged plasma calcium values. The thyroidal CT content also was unchanged. A 2-fold increase in CT mRNA level measured by dot-blot hybridization occurred 1 and 2 h after 1,25-(OH)2D3 administration. Expression of CT gene products was examined in the rabbit reticulocyte lysate cell-free translation assay. After polyacrylamide gel electrophoresis, specific immunoprecipitates were autoradiographed and quantified by integration. A single precursor of Mr approximately equal to 15 000 could be specifically immunoprecipitated with CT antisera. A 3-4-fold rise in translatable CT mRNA activity was observed 1 and 2 h after 1,25-(OH)2D3 injection. Thus, parallel changes in CT mRNA level, CT mRNA activity and plasma CT levels were observed in adult female rats after administration of 1,25-(OH)2D3. These findings demonstrate for the first time that 1,25-(OH)2D3 enhanced CT gene expression in the face of unchanged plasma calcium levels.
D000818:Animals; D002116:Calcitonin / Q000235:genetics*; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000097:blood; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D013961:Thyroid Gland / Q000502:physiology; D013997:Time Factors
D012333:RNA, Messenger; D002116:Calcitonin; D002117:Calcitriol; D002118:Calcium