Traynor P, Dryden W F, Smith P A
Department of Pharmacology, University of Alberta, Edmonton, Canada.
Can J Physiol Pharmacol. 1992 Jun;70(6):826-34. doi: 10.1139/y92-111.
These experiments tested the hypothesis that the normal electrophysiological properties of mature bullfrog sympathetic ganglion (BFSG) neurones are maintained by the retrograde supply of nerve growth factor-like molecules from peripheral target tissues. Maintenance of these cells in explant culture in the absence of nerve growth factor (NGF) for up to 30 days produced electrophysiological changes that resemble those previously shown to accompany axotomy in vivo. These included (i) an increase in action potential (ap) duration (spike width), (ii) a decrease in the amplitude of the afterhyperpolarization (ahp), which follows the ap, and (iii) a rapidly developing decrease in ahp duration. When murine NGF (2.5 s; 50 ng/mL) was included in the culture medium there was less attenuation of ahp amplitude. Inclusion of affinity-isolated sheep IgG antibodies (0.5 micrograms/mL; raised against murine 2.5 s NGF) in the culture medium promoted a greater reduction in ahp amplitude than was seen in the "control" explants that were maintained in the absence of NGF. By contrast, the decrease in ahp duration that occurred in control explants was neither attenuated by exposure to NGF nor was it enhanced by NGF antibodies. Also, the increase in spike width that was seen in control explants was enhanced both by murine NGF and by NGF antibodies. Although some of the data support the hypothesis that factor(s) with some similarity to NGF may be synthesized by BFSG in vitro, loss of the retrograde transport of such factors does not explain all aspects of the electrophysiological response to target deprivation and (or) axotomy.
成熟牛蛙交感神经节（BFSG）神经元的正常电生理特性是由外周靶组织逆行供应的神经生长因子样分子维持的。在无神经生长因子（NGF）的情况下，将这些细胞进行外植体培养长达30天，会产生电生理变化，这些变化类似于先前在体内切断轴突时所显示的变化。这些变化包括：（i）动作电位（ap）持续时间（峰宽）增加；（ii）跟随ap的超极化后电位（ahp）幅度减小；（iii）ahp持续时间迅速缩短。当培养基中加入鼠源NGF（2.5 s；50 ng/mL）时，ahp幅度的衰减较小。在培养基中加入亲和纯化的羊IgG抗体（0.5微克/毫升；针对鼠源2.5 s NGF制备），与在无NGF条件下培养的“对照”外植体相比，ahp幅度的降低更为显著。相比之下，对照外植体中出现的ahp持续时间缩短，既没有因暴露于NGF而减弱，也没有因NGF抗体而增强。此外，对照外植体中出现的峰宽增加，在加入鼠源NGF和NGF抗体后均增强。虽然一些数据支持这样的假说，即与NGF有某些相似性的因子可能在体外由BFSG合成，但此类因子逆行运输的丧失并不能解释对靶剥夺和（或）轴突切断的电生理反应的所有方面。
