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Regulation of Peristaltic Reflex by Nitric Oxide

一氧化氮调节蠕动反射

基本信息

批准号：
06671279
负责人：
MIZUTANI Masatoshi
金额：
$ 1.34万
依托单位：
Okayama Prefectural University Junior College
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

It had been demonstrated that, in the canine small intestine in vivo, polarized enteric reflexes that cause a contraction on the oral side of the stimulus and a relaxation on the anal side (an ascending contraction and a descending relaxation in the peristaltic reflex) were initiated by mechanical or chemical stimulation of the mucosa. Recently, we have found that 5-HT3 receptors play an important role in the peristaltic reflex in the canine jejunum. In the present study, we investigated the involvement of nitric oxide in the peristaltic reflex mediated by 5-HT3 receptors in dogs anesthetized with urethane and alpha-chloralose. A neurally decentralized jejunal loop was partitioned into two segments with respect to blood supply. Drugs were infused intra-arterially into each segment and mechanical responses in the oral and anal segments were monitored.Each ascending contraction induced by administration of 2-methyl-serotonin (an agonist of 5-HT3 receptors), 5-methoxytryptamine (an agonis … More t of 5-HT4 receptors), and acetylcholine to the anal segment, and by stroking the mucosa in the anal segment was augmented by treating the oral or anal segment with NG-nitro-L-arginine (L-NNA, an inhibitor of nitric oxide synthase). Effects of these augmentation were restored by L-arginine but not D-arginine. The descending relaxations induced by administration of 2-methyl-serotonin to the oral segment and by stroking the mucosa in the oral segment were reduced by treating the anal segment with L-NNA.The inhibitory effects of L-NNA was restored by L-arginine. L-NNA did not affect the spontaneous contractions.These results suggest firstly that nitric oxide is released from the enteric neurons when peristaltic reflexes are activated, secondly that nitoric oxide plays a role as a transmitter of final neurons in the reflex pathway for the descending relaxation, and finally that nitric oxide partially inhibits a cholinergic transmission in the ascending pathway activated by chemical and mechanical stimulation, thus nitric oxide regulates the magnitude of the ascending contraction. Less

已证实，在活体犬的小肠中，引起刺激口侧收缩和肛侧松弛(蠕动反射中的上行收缩和下行松弛)的两极化肠道反射是由机械或化学刺激引起的。最近，我们发现5-HT3受体在犬空肠蠕动反射中起重要作用。在本研究中，我们研究了一氧化氮在乌拉坦和α-氯醛糖麻醉犬的5-HT3受体介导的蠕动反射中的作用。神经分散的空肠环根据血液供应被分成两段。将药物注入每个节段，监测口腔和肛门节段的机械反应。每次由2-甲基-5-羟色胺(5-羟色胺受体激动剂)、5-甲氧基色胺(…激动剂)引起的上行收缩5-羟色胺受体(5-HT4受体)和乙酰胆碱对肛门段的刺激作用增强，而用一氧化氮合酶抑制剂L处理口腔或肛门段时，可增强肛门段的刺激作用。这些增强作用可被L-精氨酸恢复，但不能被D-精氨酸恢复。用L-精氨酸处理肛门段可减轻口段给予2-甲基-5-羟色胺和抚触口段黏膜所引起的下行松弛作用，L-精氨酸可恢复L-NNA的抑制作用。这些结果提示，当蠕动反射被激活时，肠神经元会释放一氧化氮；其次，一氧化氮在下行松弛反射通路中作为终末神经元的递质；最后，一氧化氮部分抑制了化学和机械刺激激活的上行通路中的胆碱能传递，从而调节了上行收缩的幅度。较少