钙在促甲状腺激素诱导对环磷酸腺苷刺激产生不应性中的作用。

The role of calcium in the induction of refractoriness to cyclic AMP stimulation by TSH.

作者信息

Chayoth R, Arem R, Yoshimura Y, Field J B

出版信息

Metabolism. 1985 Dec;34(12):1128-32. doi: 10.1016/0026-0495(85)90158-1.

Abstract

An initial exposure of beef thyroid slices to 25 mU/mL thyroid-stimulating hormone (TSH) for two hours induces a diminished stimulation of cyclic adenosine monophosphate (AMP) production upon subsequent readdition of TSH but does not modify the effect of prostaglandin E1 (PGE1). Incubation of thyroid slices in calcium-free buffer with or without 2 mmol/L ethylene glycol bis (beta-aminoethyl ether)--N,N' = tetracetic acid (EGTA) prevented desensitization induced by TSH and PGE1, to the subsequent stimulation by TSH and PGE1, respectively, despite the presence of calcium in subsequent incubations. TSH-induced desensitization was not modified by increasing the calcium concentration up to 50 mmol/L in the initial incubation. However, the stimulatory effect of TSH upon cyclic AMP levels was decreased as the calcium concentration in the first incubation was increased. In the presence of at least 1 mmol/L calcium, an initial incubation of thyroid slices with 20 mumol/L ionophore A-23187 decreased the stimulation of cyclic AMP by 25 mU/mL TSH added to the slices for the first time during a subsequent incubation. Under these conditions, A-23187 had no effect on PGE1 stimulation of cyclic AMP. These results indicate that calcium may play a role in the TSH-induced, but not PGE1, desensitization of cyclic AMP formation.

摘要

将牛肉甲状腺切片初始暴露于25 mU/mL促甲状腺激素（TSH）两小时后，在随后再次添加TSH时，环磷酸腺苷（AMP）生成的刺激作用减弱，但不改变前列腺素E1（PGE1）的作用。将甲状腺切片在无钙缓冲液中孵育，无论有无2 mmol/L乙二醇双（β-氨基乙基醚）-N,N'-四乙酸（EGTA），均可分别防止TSH和PGE1诱导的对后续TSH和PGE1刺激的脱敏作用，尽管后续孵育中有钙存在。在初始孵育中将钙浓度提高至50 mmol/L，并未改变TSH诱导的脱敏作用。然而，随着第一次孵育中钙浓度的增加，TSH对环AMP水平的刺激作用降低。在至少1 mmol/L钙存在的情况下，甲状腺切片先用20 μmol/L离子载体A-23187进行初始孵育，会降低在随后孵育中首次添加到切片中的25 mU/mL TSH对环AMP的刺激作用。在这些条件下，A-23187对PGE1刺激环AMP没有影响。这些结果表明，钙可能在TSH诱导的环AMP形成脱敏中起作用，但在PGE1诱导的脱敏中不起作用。