Zhang X, Renehan W E, Fogel R
Division of Gastroenterology, Henry Ford Hospital, Detroit, Michigan 48202, USA.
Am J Physiol. 1998 Feb;274(2):G331-41. doi: 10.1152/ajpgi.1998.274.2.G331.
Perfusing the duodenum with acid solutions dramatically reduces gastric motility and acid secretion. We propose that the presence of acid in the proximal small intestine initiates a vagovagal reflex that excites inhibitory neurons in the nucleus of the solitary tract (NST) and reduces the activity of the neurons in the dorsal motor nucleus of the vagus nerve (DMNV). However, results from several investigations suggest that the relevant circuit may not be as simple as we had believed. The present study was designed to address this dilemma by employing intracellular and extracellular recording and intracellular labeling techniques to provide direct information on the activity of neurons in the NST and DMNV during and after intestinal exposure to acid solutions. The results obtained prove that NST and DMNV neurons respond to HCl in the duodenum. In some instances, these neurons were very stimulus specific, although the majority of the cells in our sample (47% of NST neurons and 86% of DMNV neurons) also responded to distension of the stomach and/or duodenum. It is important to note, however, that many of the more broadly responsive neurons in the dorsal vagal complex were able to distinguish between mechanical and chemical stimulation of the gastrointestinal (GI) tract. Most of the NST neurons that responded to duodenal perfusion with HCl were excited by this stimulus. Conversely, activity of most of the DMNV neurons decreased after the onset of the HCl stimulus. These findings verify the existence of a vagovagal reflex pathway initiated by duodenal perfusion with acid. Presumably, this reflex would decrease gastric motility and acid secretion, reducing the amount of acid that enters the duodenum and ultimately protecting the intestinal mucosa.
用酸性溶液灌注十二指肠可显著降低胃动力和胃酸分泌。我们提出，近端小肠中酸的存在会引发迷走-迷走反射，该反射会刺激孤束核（NST）中的抑制性神经元，并降低迷走神经背运动核（DMNV）中神经元的活性。然而，多项研究结果表明，相关回路可能不像我们认为的那么简单。本研究旨在通过采用细胞内和细胞外记录以及细胞内标记技术来解决这一困境，以提供关于小肠暴露于酸性溶液期间及之后NST和DMNV中神经元活性的直接信息。所获得的结果证明，NST和DMNV神经元对十二指肠中的盐酸有反应。在某些情况下，这些神经元对刺激具有高度特异性，尽管我们样本中的大多数细胞（47%的NST神经元和86%的DMNV神经元）也对胃和/或十二指肠的扩张有反应。然而，重要的是要注意，迷走神经背侧复合体中许多反应更广泛的神经元能够区分胃肠道的机械刺激和化学刺激。大多数对十二指肠灌注盐酸有反应的NST神经元受到这种刺激的兴奋。相反，大多数DMNV神经元的活性在盐酸刺激开始后降低。这些发现证实了由十二指肠灌注酸引发的迷走-迷走反射通路的存在。据推测，这种反射会降低胃动力和胃酸分泌，减少进入十二指肠的酸量，并最终保护肠黏膜。
