Bornstein J C, Hendriks R, Furness J B, Trussell D C
Centre for Neuroscience, Flinders University, Bedford Park, Australia.
J Comp Neurol. 1991 Dec 15;314(3):437-51. doi: 10.1002/cne.903140303.
The projections and terminal ramifications of electrophysiologically characterized myenteric neurons of the guinea pig small intestine were studied after intracellular injection of the marker substance biocytin. Myenteric neurons were impaled with microelectrodes containing 4% biocytin in 2 M KCl (pH 7.4) and characterized electrophysiologically as either AH-neurons or S-neurons. AH-neurons were neurons in which action potentials were followed by prolonged after-hyperpolarizations (lasting greater than 4 seconds). S-neurons were neurons in which such hyperpolarizations were not seen. Electrical stimulation of internodal strands evoked prominent fast excitatory synaptic potentials in S-neurons, but not in AH-neurons. Biocytin was injected electrophoretically into the impaled AH-neurons by passage of hyperpolarizing current (0.6-0.8 nA for 5-15 minutes) through the recording electrode. The preparation was then fixed in Zamboni's fixative, dehydrated, and exposed to avidin coupled to horseradish peroxidase which allowed the injected biocytin to be visualised via a diaminobenzidine reaction. In many cases, the injected biocytin appeared to fill all the processes of injected AH-neurons that ramified within the myenteric plexus. The filled processes included axons running up to 4 mm within the plexus and profuse varicose terminals ramifying within both the ganglion containing the injected cell body and nearby ganglia. Most (90%) cell bodies of the injected AH-neurons had the morphology of Dogiel type II neurons; large, mostly smooth cell bodies with few short processes and several long processes. The other 10% of the AH-neurons had similar cell bodies and long processes but also had prominent short filamentous processes. This population was termed dendritic AH-neurons. The projections and terminals of 28 AH/Dogiel type II neurons and 7 dendritic AH-neurons were analysed in detail. Both types of neurons project circumferentially to provide terminals to nearby ganglia, but the AH/Dogiel type II neurons also provide terminals to their own ganglia while the dendritic AH-neurons typically do not. Although many of the injected AH-neurons had projections orally or anally along the intestine no evidence for a preferential direction of projection was obtained. Analysis of the areas and distributions of the terminal fields of the AH/Dogiel type II neurons suggests that each may contact several other myenteric neurons and that each myenteric neuron may receive input from about ten AH/Dogiel type II neurons.
在对豚鼠小肠肌间神经丛中经电生理特性鉴定的神经元进行细胞内注射标记物生物胞素后，研究了其投射和终末分支情况。用含有4%生物胞素的2M氯化钾（pH 7.4）的微电极刺入肌间神经丛神经元，并通过电生理特性将其鉴定为AH神经元或S神经元。AH神经元是指动作电位后跟随有长时间超极化（持续时间大于4秒）的神经元。S神经元是指未观察到这种超极化的神经元。对节间束进行电刺激时，S神经元会诱发明显的快速兴奋性突触电位，而AH神经元则不会。通过将超极化电流（0.6 - 0.8 nA，持续5 - 15分钟）通过记录电极，将生物胞素电泳注入被刺入的AH神经元。然后将标本固定在赞博尼固定液中，脱水，并暴露于与辣根过氧化物酶偶联的抗生物素蛋白，通过二氨基联苯胺反应使注入的生物胞素可视化。在许多情况下，注入的生物胞素似乎充满了肌间神经丛内分支的被注入AH神经元的所有突起。充满的突起包括在神经丛内延伸达4毫米的轴突以及在含有被注入细胞体和附近神经节的神经节内分支丰富的曲张终末。大多数（90%）被注入的AH神经元的细胞体具有多吉尔II型神经元的形态；细胞体大，大多光滑，有少数短突起和几个长突起。另外10%的AH神经元具有相似的细胞体和长突起，但也有明显的短丝状突起。这群神经元被称为树突状AH神经元。详细分析了28个AH/多吉尔II型神经元和7个树突状AH神经元的投射和终末。这两种类型的神经元都沿圆周方向投射，为附近的神经节提供终末，但AH/多吉尔II型神经元也为其自身的神经节提供终末，而树突状AH神经元通常不这样做。尽管许多被注入的AH神经元沿肠道有向口腔或向肛门的投射，但未获得投射优先方向的证据。对AH/多吉尔II型神经元终末场的面积和分布分析表明，每个神经元可能与其他几个肌间神经丛神经元接触，并且每个肌间神经丛神经元可能从大约十个AH/多吉尔II型神经元接收输入。
