| Summary: | 碩士 === 國立中正大學 === 心理學所 === 98 === It has been well established that the vagal and sympathetic nerves innervate the gastrointestinal tract. During the earliest and pre-symptomatic stage of the Parkinson''s disease (PD), α-synuclein-positive Lewy bodies and Lewy neurites first occur in the autonomic pathways in the gastrointestinal (GI) tract. As proposed in Braak’s infection model of the PD, the putative pathogen is first absorbed from the mucosa of the GI tract and infects α-synuclein-positive neurons in the intrinsic enteric nervous system; then, the vagal preganglionic fibers spread the pathogen to the central nervous system. To examine the interaction of the vagal and sympathetic motor fibers innervating the GI tract and mesenteric arteries, we traced the vagal efferents by injecting Dextran–Texas Red into the dorsal motor nucleus of the vagus and labeled the sympathetic posganglionic fibers with tyrosine hydroxylase immunohistochemistry. The vagal and sympathetic fibers innervating in the superior mesenteric artery (SMA) and the muscle wall of forestomach, duodenum, jejunum, and ileum were examined with the laser scanning confocal microscope. Different innervation types of the vagal and sympathetic efferents were found in the forestomach and small intestine. In the forestomach, vagal efferents had dense-tangle, dense-ring, simple-ring, and string type of endings; the sympathetic fibers had dense-tangle and string types. In the duodenum, vagal efferents had simple-ring, spray-ring, string, and fork type of endings; sympathetic had ring, string, and fork types. In the jejunum, vagal efferents had string and simple-ring type of endings; sympathetics had only string type. In the ileum, vagal efferents had simple-ring, string, and string-dot type of endings; sympathetic had fork, string, and string-dot types. Almost all of the autonomic fibers run together and the swollen varicosities of the fibers may indicate chemical interaction in the myenteric plexuses (MP). Vagal and sympathetic efferents are enclosed within the same nerve bundles and run in parallel with the SMA and their small branches. Vagal efferents have varicosities in apposition with the
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sympathetic fibers. The in-apposition innervation patterns of the vagal and the sympathetic efferents found in the nerve bundle, in addition to the MP, may offer an extra way of PD infection.
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