Subramony P, Dryer S E
Program in Neuroscience, Florida State University, Tallahassee, FL 32306-4075, USA.
Proc Natl Acad Sci U S A. 1997 May 27;94(11):5934-8. doi: 10.1073/pnas.94.11.5934.
The developmental expression of macroscopic Ca2+-activated K+ currents (IK[Ca]) in chicken ciliary ganglion (CG) neurons is dependent in part on trophic factors released from preganglionic nerve terminals. Neuregulins are expressed in the preganglionic neurons that innervate the chicken CG and are therefore plausible candidates for this activity. Application of 1 nM beta1-neuregulin peptide for 12 hr evokes a large (7- to 10-fold) increase in IK[Ca] in embryonic day 9 CG neurons, even in the presence of a translational inhibitor. A similar posttranslational effect is produced by high concentrations (10 nM) of epidermal growth factor and type alpha transforming growth factor but not by 10 nM alpha2-neuregulin peptide or by neurotrophins at 40 ng.ml-1. beta1-neuregulin treatment for 12 hr also confers Ca2+ sensitivity onto large-conductance (285 pS) K+ channels observed in inside-out patches. beta-Neuregulins have no effect on voltage-activated Ca2+ currents of CG neurons. These data support the hypothesis that beta-neuregulins mediate the trophic effects of preganglionic nerve terminals on the electrophysiological differentiation of developing CG neurons.
鸡睫状神经节（CG）神经元中宏观钙激活钾电流（IK[Ca]）的发育性表达部分依赖于节前神经末梢释放的营养因子。神经调节蛋白在支配鸡睫状神经节的节前神经元中表达，因此是这种活性的合理候选者。应用1 nMβ1-神经调节蛋白肽12小时可使胚胎第9天CG神经元中的IK[Ca]大幅增加（7至10倍），即使存在翻译抑制剂也是如此。高浓度（10 nM）的表皮生长因子和α型转化生长因子可产生类似的翻译后效应，但10 nMα2-神经调节蛋白肽或40 ng.ml-1的神经营养因子则不会。β1-神经调节蛋白处理12小时也能使在膜外翻片中观察到的大电导（285 pS）钾通道具有钙敏感性。β-神经调节蛋白对CG神经元的电压激活钙电流没有影响。这些数据支持了β-神经调节蛋白介导节前神经末梢对发育中的CG神经元电生理分化的营养作用这一假说。
