Champion S, Mauchamp J
Mol Pharmacol. 1982 Jan;21(1):66-72.
A muscarinic cholinergic effect on thyrotropin-stimulated cyclic AMP accumulation in cultured porcine thyroid cells is characterized. The muscarinic agonists carbachol, acetylcholine, oxotremorine, and pilocarpine decreased the acute cyclic AMP response to stimulation with thyrotropin (20 mU/ml). A 50% decrease was obtained in the presence of 0.1 mM carbachol. Maximal effects were observed when cells were cultured in the presence of thyrotropin (100 microU/ml) or prostaglandin E2 (1 microM), whereas cells cultured in basal medium or in the presence of dibutyryl cyclic AMP showed a low response to carbachol. Evidence is reported suggesting that carbachol acutely decreases cyclic AMP synthesis. The properties of the muscarinic receptors present in thyroid cells were defined by using the binding of the muscarinic antagonist [3H]quinuclidinyl benzilate to cell homogenates. Scatchard plots revealed a single population of binding sites with a KD of 0.3 nM. The numbers of binding sites per cell after 4 days in culture were 880 in control cells, 4335 in thyrotropin (100 microU/ml)-treated cells, 5600 in prostaglandin (1 microM)-treated cells, and 1420 in dibutyryl cyclic AMP-treated cells. Therefore the sensitivity to carbachol appeared to be related to the number of antagonist binding sites and to be independent of the sensitivity of the cells to acute thyrotropin stimulation.
研究了毒蕈碱型胆碱能对培养的猪甲状腺细胞中促甲状腺激素刺激的环磷酸腺苷（cAMP）积累的影响。毒蕈碱激动剂卡巴胆碱、乙酰胆碱、氧化震颤素和毛果芸香碱降低了对促甲状腺激素（20 mU/ml）刺激的急性cAMP反应。在存在0.1 mM卡巴胆碱的情况下，反应降低了50%。当细胞在促甲状腺激素（100 μU/ml）或前列腺素E2（1 μM）存在下培养时观察到最大效应，而在基础培养基中或在二丁酰环磷酸腺苷存在下培养的细胞对卡巴胆碱的反应较低。有证据表明卡巴胆碱可急性降低cAMP合成。通过使用毒蕈碱拮抗剂[3H]喹核醇基苯甲酸酯与细胞匀浆的结合来确定甲状腺细胞中存在的毒蕈碱受体的特性。Scatchard图显示出单一的结合位点群体，解离常数（KD）为0.3 nM。培养4天后，对照细胞中每细胞的结合位点数为880个，促甲状腺激素（100 μU/ml）处理的细胞中为4335个，前列腺素（1 μM）处理的细胞中为5600个，二丁酰环磷酸腺苷处理的细胞中为1420个。因此，对卡巴胆碱的敏感性似乎与拮抗剂结合位点的数量有关，且与细胞对急性促甲状腺激素刺激的敏感性无关。
