過去研究發現在老鼠的胃腸道裡具有多種神經化學物質(例如VIP、NPY、CGRP等，這些神經化學物質作用類似神經傳遞物質，或神經調節因子，能調節老鼠胃腸道之活動。一氧化氮是現今神經傳遞物質中被許多研究學者所熱衷探討之對象。於胃腸道，一氧化氮是一種很常見之抑制性神經傳遞物質，可抑制環走肌之活動。因此本研究探討天竺鼠食道肌層內，一氧化氮合成酉每與其它神經傳遞物質(GA、VIP、CGRP、NPY、SP)，在食道上、中、下三段中的表現及分佈情形，以及一氧化氮合成酉每與各神經傳遞物質是否有共存現象。另外，食道之神經支配也一併探討之。 研究結果顯示這些神經傳遞物質主要表現在食道肌層神經元，但是VIP、CGRP在黏膜下層的表現較肌層為明顯，這可能與黏膜層之分泌和促使血管擴張有關。不論興奮性之神經傳遞物質(如GAL、SP)或抑制性之神經傳遞物質(如NO、VIP)，在食道下段的分佈皆較食道中、上段為密集，可能與迷走神經共同參與食道之神經支配，與控制食道體蠕動與下食道括約肌活動有關。本研究並運用雙重染色法，發現食道肌層內，NOS能與抑制性之神經傳遞物質如VIP、CGRP共存於同一神經元中。 依據本研究結果，推論天竺鼠之食道肌層是由交感神經、副交感神經及肌層神經元共同支配，而肌層神經元在下食道括約肌中表現最為密集，應有助於較厚肌肉層的神經支配，以共同控制食道括約肌的活動。; Previous studies have shown that there are several kinds of neuroche-micals, such as vasoactive intestinal polypeptide (VIP), neuropeptide Y (NPY), present in the gastrointestinal tract of rat. The actions of these neurochemicals similar to the action of neurotransmitter, or neuromodulator, or neurotrophic factors. They can modulate the activity of the gastrointes-tinal tract. In the last few years, nitrergic neurons have been shown to be a major population in the enteric nervous system, and they are supposed to be interneurons as well as an inhibitory motor neurons to the circular smooth muscle of the gastrointestinal tract. Nitric oxide (NO), released by these nitrergic neurons, acts as an inhibitory neurotransmitter to the intestinal smooth muscle, also it acts as a neuromodulator to certain autonomic functions. Because the enteric nervous system of the guinea pig has been used as a model system for the analysis of enteric neural circuits, therefore the aims of the present study are to elucidate the presence and distribution of nitrer-gic neurons or nerve fibers within the esophagus of the guinea pig. The co-localization of other neurotransmitters, such as VIP, CGRP, NPY, or others with nitric oxide synthase (NOS) will also be examined with double labelling using immunocytochemistry. The efferent fibers to the esophagus will also be examined.
