Willing A E, Berthoud H R
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge 70808, USA.
Am J Physiol. 1997 Jan;272(1 Pt 2):R59-67. doi: 10.1152/ajpregu.1997.272.1.R59.
Functionally specific vagal afferents were stimulated by gastric balloon distension in unanesthetized rats, followed by double c-fos/dopamine beta-hydroxylase (DBH) immunocytochemistry, to identify second-order neurons in the dorsal vagal complex. Continuous and repeated phasic distension with similar volumes produced similar numbers and patterns of c-fos expression, with most of the activated neurons in the medial and commissural nucleus of the solitary tract (NTS) and dorsal motor nucleus (DMNX). Larger distension activated significantly more neurons in all responsive areas but there was no differential effect. In most NTS subnuclei and the DMNX, a small (3-5%) proportion of gastric distension-activated neurons was DBH-immunoreactive (DBH-IR), and this proportion did not significantly change with type of distension. With continuous and repeated small distensions, 10-12% and, with the large distension, 22-30% of all DBH-IR neurons expressed c-fos. The results suggest a large degree of convergence between rapidly adapting mucosal receptors and slowly adapting tension receptors, but not between low- and high-threshold tension receptors, and a relatively minor role of catecholaminergic second-order neurons in the dissemination of distension signals in the brain.
在未麻醉的大鼠中，通过胃气囊扩张刺激功能特异性迷走传入神经，随后进行双c-fos/多巴胺β-羟化酶（DBH）免疫细胞化学，以识别迷走背侧复合体中的二级神经元。用相似体积进行连续和重复的阶段性扩张产生相似数量和模式的c-fos表达，大多数激活的神经元位于孤束核（NTS）的内侧和连合核以及迷走神经背核（DMNX）。更大的扩张在所有反应区域激活了明显更多的神经元，但没有差异效应。在大多数NTS亚核和DMNX中，一小部分（3-5%）胃扩张激活的神经元是DBH免疫反应性的（DBH-IR），并且这一比例不会因扩张类型而显著改变。对于连续和重复的小扩张，所有DBH-IR神经元中有10-12%表达c-fos，对于大扩张，则有22-30%表达c-fos。结果表明，快速适应的黏膜受体和缓慢适应的张力受体之间存在很大程度的汇聚，但低阈值和高阈值张力受体之间不存在汇聚，并且儿茶酚胺能二级神经元在大脑中扩张信号传播中的作用相对较小。
