Nakamura K, Takahashi T, Taniuchi M, Hsu C X, Owyang C
Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan 48109, USA.
J Clin Invest. 1998 Apr 1;101(7):1479-89. doi: 10.1172/JCI627.
The mechanism that regulates the synthesis of nitric oxide synthase (NOS), a key enzyme responsible for NO production in the myenteric plexus, remains unknown. We investigated the roles of the vagal nerve and nicotinic synapses in the mediation of NOS synthesis in the gastric myenteric plexus in rats. Truncal vagotomy and administration of hexamethonium significantly reduced nonadrenergic, noncholinergic relaxation, the catalytic activity of NOS, the number of NOS-immunoreactive cells, and the density of NOS-immunoreactive bands and NOS mRNA bands obtained from gastric tissue. These results suggest that NOS expression in the gastric myenteric plexus is controlled by the vagal nerve and nicotinic synapses. We also investigated if stimulation of the nicotinic receptor increases neuronal NOS (nNOS) expression in cultured gastric myenteric ganglia. Incubation of cultured gastric myenteric ganglia with the nicotinic receptor agonist, 1,1-dimethyl-4-phenylpiperizinium (DMPP, 10(-10)-10(-7) M), for 24 h significantly increased the number of nNOS-immunoreactive cells and the density of immunoreactive nNOS bands and nNOS mRNA bands. nNOS mRNA expression stimulated by DMPP was antagonized by a protein kinase C antagonist, a phospholipase C inhibitor, and an intracellular Ca2+ chelator. We concluded that activation of the nicotinic receptor stimulates a Ca2+-dependent protein kinase C pathway, which in turn, upregulates nNOS mRNA expression and nNOS synthesis in the gastric myenteric plexus.
调节一氧化氮合酶（NOS）合成的机制尚不清楚，一氧化氮合酶是肠肌丛中负责产生NO的关键酶。我们研究了迷走神经和烟碱能突触在大鼠胃肌间神经丛中NOS合成介导中的作用。切断迷走神经干并给予六甲铵可显著降低非肾上腺素能、非胆碱能舒张、NOS的催化活性、NOS免疫反应性细胞的数量以及从胃组织获得的NOS免疫反应性条带和NOS mRNA条带的密度。这些结果表明，胃肌间神经丛中NOS的表达受迷走神经和烟碱能突触的控制。我们还研究了烟碱受体的刺激是否会增加培养的胃肌间神经节中神经元型一氧化氮合酶（nNOS）的表达。用烟碱受体激动剂1,1-二甲基-4-苯基哌嗪鎓（DMPP，10(-10)-10(-7)M）孵育培养的胃肌间神经节24小时，可显著增加nNOS免疫反应性细胞的数量以及免疫反应性nNOS条带和nNOS mRNA条带的密度。DMPP刺激的nNOS mRNA表达被蛋白激酶C拮抗剂、磷脂酶C抑制剂和细胞内Ca2+螯合剂所拮抗。我们得出结论，烟碱受体的激活刺激了一条Ca2+依赖的蛋白激酶C途径，进而上调胃肌间神经丛中nNOS mRNA的表达和nNOS的合成。
