Nichols K, Staines W, Wu J Y, Krantis A
Department of Physiology, University of Ottawa, Canada.
J Auton Nerv Syst. 1995 Jan 3;50(3):253-62. doi: 10.1016/0165-1838(94)00096-3.
In the enteric nervous system, gamma-aminobutyric acid (GABA) is a transmitter of interneurons which are proposed to innervate excitatory and inhibitory motor neurons. Nitric oxide (NO) is a putative transmitter of enteric inhibitory motor nerves targeted by GABA. In addition, NO is synthesized by a variety of enteric nerves throughout the gut wall indicative of its potential to be a transmitter of other nerve types, including interneurons. We sought to determine if some populations of nitrergic neurons are interneurons in human infant colon. As enteric neural GABA is exclusive to interneurons, colocalization with NO synthase-related NADPH diaphorase was examined. GABA-transaminase (GABA-T) immunohistochemistry was used to identify GABAergic neurons and a histochemical protocol was used as a marker of neuronal NO synthase-related NADPH diaphorase activity in enteric layers. GABA-T immunoreactive neurons were seen in the ganglionated nerve networks of the myenteric and submucosal layers. GABA-T immunoreactive fibres were also present in the longitudinal and circular muscle layers. A subpopulation of GABA-T immunoreactive neurons within both the myenteric and submucosal ganglia express NO synthase-related activity. This colocalization extends further to a subpopulation of fibers within the muscle layers. These findings strongly suggest that in addition to its role in inhibitory motor neurons, NO may also be a transmitter of enteric interneurons.
在肠神经系统中，γ-氨基丁酸（GABA）是中间神经元的一种递质，这些中间神经元被认为可支配兴奋性和抑制性运动神经元。一氧化氮（NO）是GABA作用的肠抑制性运动神经的一种假定递质。此外，NO由贯穿肠壁的多种肠神经合成，这表明它有可能是包括中间神经元在内的其他神经类型的递质。我们试图确定在人类婴儿结肠中，某些含氮能神经元群体是否为中间神经元。由于肠神经GABA仅存在于中间神经元中，因此研究了其与一氧化氮合酶相关的还原型辅酶II黄递酶的共定位情况。采用GABA转氨酶（GABA-T）免疫组织化学方法鉴定GABA能神经元，并使用一种组织化学方法作为肠层中神经元型一氧化氮合酶相关还原型辅酶II黄递酶活性的标志物。在肌间和黏膜下层的神经节网络中可见GABA-T免疫反应性神经元。在纵行和环行肌层中也存在GABA-T免疫反应性纤维。肌间和黏膜下神经节内的一部分GABA-T免疫反应性神经元表达一氧化氮合酶相关活性。这种共定位进一步延伸至肌层内的一部分纤维。这些发现有力地表明，除了在抑制性运动神经元中的作用外，NO也可能是肠中间神经元的一种递质。
