Magliola L, Anast C S, Forte L R
Department of Pharmacology, University of Missouri School of Medicine, Columbia 65211.
Bone Miner. 1986 Dec;1(6):495-505.
Evidence to date has failed to show a consistent effect of vitamin D metabolites on PTH secretion. This study was undertaken to assess the possible direct, acute effects of vitamin D metabolites on PTH secretion in vitro. Ethanol has been used in several published studies as the vehicle for vitamin D metabolites. We found that 0.2-1.0% ethanol inhibited PTH release from dispersed bovine parathyroid cells (PTC). Our experiments with vitamin D metabolites used ethanol as a vehicle at a concentration less than 0.1%. When compared to ethanol treatment, 10-100 nM 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), 25 and 100 nM 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) and 100 nM 1,24,25-trihydroxyvitamin D3 (1,24,25(OH)3D3) had no effect on PTH release from PTC incubated for up to 4 h. A combination of 1,25(OH)2D3 and 24,25(OH)2D3 (each 25 or 100 nM) was without effect. Also, 100 nM 1,25(OH)2D3 had no effect on PTH release from either bovine parathyroid gland slices or from parathyroid glands from either vitamin D-replete (+D) or vitamin D-deficient (-D) rats incubated for up to 4 h. The i.v. injection of 1 microgram 1.25(OH)2D3 into -D rats had no effect on either serum PTH or calcium (Ca), either 0.5 or 1.0 h after treatment. Parathyroid glands from -D rats incubated with 0.75 mM Ca secreted more PTH than glands of similar weight from rats given 25 micrograms vitamin D3 3 days earlier, suggesting that vitamin D or a metabolite of vitamin D may modulate the sensitivity of the parathyroid gland to medium Ca. In summary, we found no evidence for a direct, acute effect of vitamin D metabolites on PTH secretion under diverse experimental conditions.
迄今的证据未能表明维生素D代谢产物对甲状旁腺激素（PTH）分泌具有一致的作用。本研究旨在评估维生素D代谢产物在体外对PTH分泌可能产生的直接、急性作用。在一些已发表的研究中，乙醇被用作维生素D代谢产物的溶剂。我们发现0.2 - 1.0%的乙醇会抑制分散的牛甲状旁腺细胞（PTC）释放PTH。我们在使用维生素D代谢产物的实验中，乙醇作为溶剂的浓度低于0.1%。与乙醇处理相比，10 - 100 nM的1,25 - 二羟基维生素D3（1,25(OH)2D3）、25和100 nM的24,25 - 二羟基维生素D3（24,25(OH)2D3）以及100 nM的1,24,25 - 三羟基维生素D3（1,24,25(OH)3D3）对孵育长达4小时的PTC释放PTH均无影响。1,25(OH)2D3和24,25(OH)2D3（各25或100 nM）的组合也无作用。此外，100 nM的1,25(OH)2D3对牛甲状旁腺切片或来自维生素D充足（+D）或维生素D缺乏（-D）大鼠的甲状旁腺在孵育长达4小时后释放PTH均无影响。给 -D大鼠静脉注射1微克1,25(OH)2D3，在处理后0.5或1.0小时，对血清PTH或钙（Ca）均无影响。与3天前给予25微克维生素D3的大鼠中相似重量的甲状旁腺相比，用0.75 mM钙孵育的 -D大鼠的甲状旁腺分泌更多的PTH，这表明维生素D或维生素D的一种代谢产物可能调节甲状旁腺对培养基中钙的敏感性。总之，在多种实验条件下，我们未发现维生素D代谢产物对PTH分泌有直接、急性作用的证据。
