Kouvelas E D, Dichter M A, Greene L A
Brain Res. 1978 Oct 6;154(1):83-93. doi: 10.1016/0006-8993(78)91053-3.
Studies were carried out on the development and physiological role of receptors for alpha-bungarotoxin (alphaBT) on chick embryo sympathetic neurons maintained in dissociated cell culture. Neurons from embryos of 13 days incubation (E13) developed alphaBT receptors in vitro with a time course and to a maximum level per cell similar to that previously observed for such neurons in vivo. In vitro receptor development by E11 and E8 neurons was also present, but (in comparison with E13 neurons) reached somewhat lower maximal levels. Receptor development in vitro was not affected by exclusion of non-neuronal cells from the cultures. In the present and in previous studies, binding of alphaBT to chick sympathetic neurons was blocked by a variety of ligands of nicotinic acetylcholine receptors. However, saturating concentrations of toxin were found here to be ineffective in blocking either (a) release of [3H]norepinephrine from the cultured neurons elicited via nicotinic stimulation of acetylcholine receptors or (b) depolarizing responses of the cultured neurons elicited by iontophoretically applied acetylcholine and nicotine. Kinetic studies further revealed that, while the idssociation of alphaBT from the cultured neurons is considerably enhanced in the presence of a cholinergic ligand (100 micrometer nicotine), the rate of this dissociation (t1/2 congruent to 30 min) appears to be too slow to account for the inability of the toxin to block nicotinic responses. Such findings show that chick embryo sympathetic neurons can develop receptors for alphaBT both in vivo and in vitro, but that the toxin does not block activation of their nicotinic acetylcholine receptors. The physiologic nature of specific binding sites for alphaBT on such neurons is thus presently unclear.
对在解离细胞培养中维持的鸡胚交感神经元上α-银环蛇毒素（αBT）受体的发育及其生理作用进行了研究。孵化13天（E13）胚胎的神经元在体外发育出αBT受体，其时间进程和每个细胞的最大水平与先前在体内观察到的此类神经元相似。E11和E8神经元在体外也有受体发育，但（与E13神经元相比）达到的最大水平略低。从培养物中排除非神经元细胞并不影响体外受体的发育。在本研究和先前的研究中，αBT与鸡交感神经元的结合被多种烟碱型乙酰胆碱受体配体所阻断。然而，在此发现饱和浓度的毒素在阻断以下两种情况时均无效：（a）通过烟碱型刺激乙酰胆碱受体从培养神经元中释放[3H]去甲肾上腺素，或（b）离子电渗法应用乙酰胆碱和尼古丁引起的培养神经元的去极化反应。动力学研究进一步表明，虽然在胆碱能配体（100微摩尔尼古丁）存在下，αBT从培养神经元上的解离明显增强，但这种解离速率（t1/2约为30分钟）似乎太慢，无法解释毒素无法阻断烟碱型反应的原因。这些发现表明，鸡胚交感神经元在体内和体外均可发育出αBT受体，但该毒素并不阻断其烟碱型乙酰胆碱受体的激活。因此，目前尚不清楚此类神经元上αBT特异性结合位点的生理性质。
