TY - JOUR
T1 - Rat calcium-sensing receptor is regulated by vitamin D but not by calcium
AU - Brown, A. J.
AU - Zhong, M.
AU - Finch, J.
AU - Ritter, C.
AU - McCracken, R.
AU - Morrissey, J.
AU - Slatopolsky, E.
PY - 1996
Y1 - 1996
N2 - Parathyroid hormone (PTH) secretion is regulated by extracellular calcium acting through a cell surface calcium receptor (CaR). We have examined the potential regulation of the CaR in the parathyroid glands (PTG) and kidney by calcium and 1,25-dihydroxyvitamin D3 [1,25-(OH2D3]. Rats fed vitamin D-deficient ( -D) diets containing 0.02, 0.4, or 2.0% Ca had a wide range of serum ionized Ca (2.5-5.2 mg/dl) and PTH (22-590 pg/ml) concentrations. PTG CaR mRNA did not vary significantly with ionized calcium or PTH, indicating that hypocalcemia and hyperparathyroidism may not alter CaR expression. However, PTG CaR mRNAwas 40% lower in the -D rats than in age-matched rats fed a vitamin D-replete (+D) diet (P < 0.002). Repletion of -D rats with 1,25-(OH)2D3 produced a dose-dependent increase in PTG CaR mRNA. Treatment of +D rats with 100 ng of 1,25-(OH)2D3 increased CaR mRNA by 33% (P < 0.05) and 54% (P < 0.002) in the PTG and by 89% (P < 0.02) and 91% (P < 0.02) in the kidney in two independent experiments. PTG CaR peaked at 16 h (150% of control, P 0.05) after 1,25-(OH)2D3 administration but returned to normal by 24 h. This upregulation of CaR expression by 1,25-(OH)2D3 may be involved in the suppressive effects of vitamin D compounds on PTH secretion.
AB - Parathyroid hormone (PTH) secretion is regulated by extracellular calcium acting through a cell surface calcium receptor (CaR). We have examined the potential regulation of the CaR in the parathyroid glands (PTG) and kidney by calcium and 1,25-dihydroxyvitamin D3 [1,25-(OH2D3]. Rats fed vitamin D-deficient ( -D) diets containing 0.02, 0.4, or 2.0% Ca had a wide range of serum ionized Ca (2.5-5.2 mg/dl) and PTH (22-590 pg/ml) concentrations. PTG CaR mRNA did not vary significantly with ionized calcium or PTH, indicating that hypocalcemia and hyperparathyroidism may not alter CaR expression. However, PTG CaR mRNAwas 40% lower in the -D rats than in age-matched rats fed a vitamin D-replete (+D) diet (P < 0.002). Repletion of -D rats with 1,25-(OH)2D3 produced a dose-dependent increase in PTG CaR mRNA. Treatment of +D rats with 100 ng of 1,25-(OH)2D3 increased CaR mRNA by 33% (P < 0.05) and 54% (P < 0.002) in the PTG and by 89% (P < 0.02) and 91% (P < 0.02) in the kidney in two independent experiments. PTG CaR peaked at 16 h (150% of control, P 0.05) after 1,25-(OH)2D3 administration but returned to normal by 24 h. This upregulation of CaR expression by 1,25-(OH)2D3 may be involved in the suppressive effects of vitamin D compounds on PTH secretion.
KW - Calcitriol therapy
KW - Calcium set point
KW - Hyperparathyroidism
KW - Vitamin D deficiency
UR - http://www.scopus.com/inward/record.url?scp=0029916843&partnerID=8YFLogxK
U2 - 10.1152/ajprenal.1996.270.3.f454
DO - 10.1152/ajprenal.1996.270.3.f454
M3 - Article
C2 - 8780248
AN - SCOPUS:0029916843
SN - 0002-9513
VL - 270
SP - F454-F460
JO - American Journal of Physiology
JF - American Journal of Physiology
IS - 3 PART 2
ER -