Optical studies of nicotinic acetylcholine receptor subtypes in the guinea-pig enteric nervous system
Optical studies of nicotinic acetylcholine receptor subtypes in the guinea-pig enteric nervous system
复制标题
DOI：
10.1242/jeb.01732
复制
发表时间：
2005-08-01
影响因子：
2.8
通讯作者：
Salzberg, BM
中科院分区：
文献类型：
--
作者：
Obaid, AL;Nelson, ME;Salzberg, BM
烟碱在肠神经系统（ENS）中的传递是广泛的，但单个烟碱乙酰胆碱受体（nAChR）亚型在其神经丛的功能连接中的作用一直是难以捉摸的。使用单克隆抗体（单克隆抗体）对神经元α 3-，α 4-，α 3/α 5-，β 2-，β 4-和α 7-亚基，结合放射免疫分析和免疫细胞化学，我们证明，豚鼠肠神经节含有所有这些nAChR-亚基的α 4除外，因此，不同于哺乳动物的大脑。然而，仅此信息不足以确定肠网络内所鉴定的nAChR亚型的功能作用，以及最终确定其对胃肠道生理学的具体贡献。我们已经使用电压敏感染料和高速CCD相机，结合特定的拮抗剂，以各种nAChR，阐明一些不同的贡献的个别亚型的肠道网络的行为。豚鼠的粘膜下神经丛有一个特别的优点，那就是它实际上是二维的，可以用单细胞分辨率光学记录所有神经元的电活动。在该神经丛中，α 3 β 2-、α 3 β 4-和/或α 7-nAChR的阻断总是导致突触反应的幅度降低。然而，由相邻神经节的电刺激诱发的快速兴奋性突触后电位（epsps）的幅度因细胞而异，反映了已经使用mAb观察到的亚基的差异表达，以及激活的突触输入的强度。同时，我们观察到，粘膜下神经元有大量的美加明（Mee）-不敏感（非烟碱）的组件，他们的快速epsps，这可能指向嘌呤能或多巴胺能快速epsps在这个系统中的存在。另一方面，在肌间神经丛中，拮抗剂诱导的诱发突触反应的变化取决于刺激电极相对于所研究的神经节的位置。一系列的活动模式，以下个别亚型的顺序药理学消除表明，nAChR可能能够调节兴奋性和抑制性途径的活动，在中枢神经系统中所描述的类似的方式。
Nicotinic transmission in the enteric nervous system (ENS) is extensive, but the role of individual nicotinic acetylcholine receptor (nAChR) subtypes in the functional connectivity of its plexuses has been elusive. Using monoclonal antibodies (mAbs) against neuronal alpha 3-, alpha 4-, alpha 3/alpha 5-, beta 2-, beta 4- and alpha 7-subunits, combined with radioimmunoassays and immunocytochemistry, we demonstrate that guinea-pig enteric ganglia contain all of these nAChR-subunits with the exception of alpha 4, and so, differ from mammalian brain. This information alone, however, is insufficient to establish the functional role of the identified nAChR-subtypes within the enteric networks and, ultimately, their specific contributions to gastrointestinal physiology. We have used voltage-sensitive dyes and a high-speed CCD camera, in conjunction with specific antagonists to various nAChRs, to elucidate some of the distinct contributions of the individual subtypes to the behaviour of enteric networks. In the guinea-pig, the submucous plexus has the extraordinary advantage that it is virtually two-dimensional, permitting optical recording, with single cell resolution, of the electrical activity of all of its neurones. In this plexus, the block of alpha 3 beta 2-, alpha 3 beta 4- and/or alpha 7-nAChRs always results in a decrease in the magnitude of the synaptic response. However, the magnitude of the fast excitatory post-synaptic potentials (epsps) evoked by electrical stimulation of a neighbouring ganglion varies from cell to cell, reflecting the differential expression of subunits already observed using mAbs, as well as the strengths of the activated synaptic inputs. At the same time, we observe that submucous neurones have a substantial mecamylamine (Mee)-insensitive (nonnicotinic) component to their fast epsps, which may point to the presence of purinergic or serotonergic fast epsps in this system. In the myenteric plexus, on the other hand, the antagonist-induced changes in the evoked synaptic response vary depending upon the location of the stimulating electrode with respect to the ganglion under study. The range of activity patterns that follows sequential pharmacological elimination of individual subtypes suggests that nAChRs may be capable of regulating the activity of both excitatory and inhibitory pathways, in a manner similar to that described in the central nervous system.