ISSN:
1432-0827
Schlagwort(e):
1,25(OH)2D3
;
Vitamin D metabolities
;
Parathyroid hormone
;
PTH secretion regulation
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
,
Medizin
,
Physik
Notizen:
Summary The effect of vitamin D metabolites on parathyroid hormone secretion was studied using rat parathyroid gland cultured in basal medium Eagle containing 5% serum obtained from thyroparathyroidectomized rat, 1 mM magnesium, and calcium concentration varying from 0.75–2.25 mM, and radioimmunoassay for rat parathyroid hormone (rPTH). 1,25 dihydroxycholecalciferol (1,25(OH)2D3), 5×10−10−2.5×10−8M, consistently decreased rPTH secretion in dose-related manner; the effect reached steady state after 24 hin vitro addition of 1,25(OH)2D3 and was also observed at different medium calcium concentrations (0.75, 1.25, 1.75 mM). Comparison of dose-responses for inhibitory activity of some vitamin D metabolites on rPTH secretion showed: 1,25(OH)2D3=1,24,25(OH)3D3〉1α OHD3〉25 OHD3. Cholecalciferol (10−5M), 24,25-dihydroxycholecalciferol (10−8−10−6M) and 25,26-dihydroxycholecalciferol (5×10−9−5×10−7M) did not inhibit rPTH secretion. Analysis of structural activity relation of vitamin D metabolites studied indicated that 1α or pseudo-1α hydroxylated metabolites or analogs were active in inhibiting rPTH secretion, while, non-1α hydroxylated metabolites were without or were weakly inhibitory only at very high concentrations. This study provides further evidence for a direct role of 1,25(OH)2D3 on a negative feedback loop for regulation of parathyroid gland function.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF02405350
