Departamento de Farmacología y Fisiología, Facultad de Veterinaria, Universidad de Zaragoza, Miguel Servet, 177, 50013 Zaragoza, Spain.
Vet J. 2012 Jun;192(3):352-8. doi: 10.1016/j.tvjl.2011.09.003. Epub 2011 Oct 12.
The objectives of this study were to evaluate the role of nitric oxide (NO) synthase isoforms (nNOS, eNOS, and iNOS) in the regulation of the migrating motor complex (MMC) in sheep using electromyography and their expression in the gastrointestinal (GI) tract by Western blot (WB) and immunohistochemistry. Intravenous administration of L-NAME or the nNOS inhibitor 7-nitroindazole (7-NI) decreased the MMC interval. Myoelectric activity of intestinal phase II was increased, whereas antral activity was reduced. These effects were blocked by L-arginine. Inhibitors of either iNOS (aminoguanidine and S-methylisothiourea) or eNOS (L-NIO) were ineffective. The NO donor sodium nitroprusside decreased GI myoelectric activity, inhibited the MMC pattern, and prevented the effects induced by L-NAME and 7-NI in the intestine. Intracerebroventricular administration of these agents did not modify GI motility. In the rumen, abomasal antrum, duodenum, and jejunum, WB showed three bands at about 155, 145, and 135kDa corresponding to nNOS, and a 140-kDa band (eNOS); however iNOS was not detected. Positive nNOS immunostaining was observed in neurons of the myenteric and submucous plexus of all GI tissues, while eNOS was found in the endothelial cells, ruminal and intestinal epithelium, as well as in some enteric neurons and in endocrine-like cells of the duodenal Brunner's glands. In contrast, only weak iNOS immunoreactivity was found in ruminal epithelium. Taken together, our results suggest that NO, synthesized at a peripheral level by nNOS, is tonically inhibiting the MMC pattern and intestinal motility in sheep.
本研究旨在评估一氧化氮（NO）合酶同工酶（nNOS、eNOS 和 iNOS）在调节绵羊移行性运动复合波（MMC）中的作用，采用肌电图检测，并通过 Western blot（WB）和免疫组织化学检测其在胃肠道（GI）中的表达。静脉注射 L-NAME 或 nNOS 抑制剂 7-硝基吲唑（7-NI）可缩短 MMC 间期。肠相 II 的肌电活动增加，而胃窦活动减少。这些作用可被 L-精氨酸阻断。iNOS 抑制剂（氨基胍和 S-甲基异硫脲）或 eNOS 抑制剂（L-NIO）均无效。NO 供体硝普钠可降低 GI 肌电活动，抑制 MMC 模式，并防止 L-NAME 和 7-NI 在肠道中引起的作用。这些药物的脑室内给药不会改变 GI 运动。在瘤胃、网胃前胃、十二指肠和空肠中，WB 显示约 155、145 和 135kDa 的三个条带，对应于 nNOS，以及 140kDa 的条带（eNOS）；然而，未检测到 iNOS。nNOS 免疫染色阳性见于所有 GI 组织的肌间和黏膜下神经丛神经元，而 eNOS 见于内皮细胞、瘤胃和肠上皮，以及一些肠神经元和十二指肠 Brunner 腺的内分泌样细胞。相比之下，仅在瘤胃上皮中发现微弱的 iNOS 免疫反应性。综上所述，我们的结果表明，NO 由外周水平的 nNOS 合成，对绵羊的 MMC 模式和肠道运动具有紧张性抑制作用。
