Calcitriol decreases calcitonin secretion from a human medullary carcinoma cell line via specific receptor action.
Since calcitonin stimulates calcitriol production we examined whether a feedback regulatory mechanism exists between these hormones. First, the calcitriol receptor was localized immunocytochemically in cultured TT cells originating from a human thyroid medullary (C-cell) carcinoma. The receptor was demonstrated by light and electron microscopy in cell nuclei and in small amounts in the cytosol. Receptor levels increased when the cells were cultured at physiological (120-240 pmol/l) or somewhat higher concentrations (1200-2400 pmol/l) of calcitriol. In parallel, the same doses of calcitriol markedly inhibited secretion of calcitonin into the medium. These results indicate a feedback loop between calcitriol and calcitonin.
Zabel
M
M
Department of Histology, Medical Academy, Poznan, Poland.
Dietel
M
M
D064026:Calbindins; D002116:Calcitonin / Q000378:metabolism*; D015740:Calcitonin Gene-Related Peptide / Q000096:biosynthesis; D002117:Calcitriol / Q000494:pharmacology*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008854:Microscopy, Electron; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid / Q000096:biosynthesis; D064030:S100 Calcium Binding Protein G / Q000096:biosynthesis; D013964:Thyroid Neoplasms / Q000378:metabolism*
D064026:Calbindins; D018167:Receptors, Calcitriol; D011987:Receptors, Steroid; D064030:S100 Calcium Binding Protein G; D002116:Calcitonin; D002117:Calcitriol; D015740:Calcitonin Gene-Related Peptide