Dopamine effects on identified rat vagal motoneurons.
Dopamine effects on identified rat vagal motoneurons.
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DOI：
10.1152/ajpgi.00527.2006
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发表时间：
2007-04
期刊：
影响因子：
--
通讯作者：
Zhongling Zheng;R. Travagli
中科院分区：
文献类型：
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作者：
Zhongling Zheng;R. Travagli
A2区儿茶酚胺能神经元在脑干迷走神经环路中起着重要作用。然而，目前尚不清楚这些神经元是去甲肾上腺素能还是肾上腺素能，即显示酪氨酸羟基酶(TH)和多巴胺-β-羟基酶(DbetaH)免疫反应(-IR)或多巴胺(即TH-而不是DbetaH-IR)。我们的目的是研究A2区的神经元亚群是否是多巴胺能的，如果是的话，研究多巴胺(DA)对胃投射迷走神经元膜的影响。我们观察到，虽然大多数A2神经元既有TH-IR，也有DbetaH-IR，但有一小部分孤束核神经元只有TH-IR，提示DA本身可能在这些回路中起作用。脑干薄片的全细胞记录显示，71%的投射胃运动神经元对DA(1-300微米)有兴奋(28%)或抑制(43%)的反应，其余29%的神经元无反应。SK 38393可模拟DA引起的去极化，而SCH 23390可阻断DA引起的去极化。相反，溴化麦角隐亭可模拟DA的抑制作用，并可被L741626预先阻断。当在同一神经元上进行测试时，DA和NE的作用并不总是相似的。事实上，在DA引起膜去极化的神经元中，77%的神经元被去甲肾上腺素抑制，而75%的对DA不敏感的神经元被去甲肾上腺素抑制。我们的数据提示，DA通过D_1和D_2样受体调节胃投射运动神经元的膜特性，DA在脑干迷走神经环路中可能与去甲肾上腺素起不同的作用。
Catecholaminergic neurons of the A2 area play a prominent role in brain stem vagal circuits. It is not clear, however, whether these neurons are noradrenergic or adrenergic, i.e., display tyrosine hydroxylase (TH) and dopamine-beta-hydroxylase (DbetaH) immunoreactivity (-IR) or dopaminergic (i.e., TH- but not DbetaH-IR). Our aims were to investigate whether a subpopulation of neurons in the A2 area was dopaminergic and, if so, to investigate the effects of dopamine (DA) on the membrane of gastric-projecting vagal motoneurons. We observed that although the majority of A2 neurons were both TH- and DbetaH-IR, a small percentage of nucleus tractus solitarius neurons were TH-IR only, suggesting that DA itself may play role in these circuits. Whole cell recordings from thin brain stem slices showed that 71% of identified gastric-projecting motoneurons responded to DA (1-300 microM) with either an excitation (28%) or an inhibition (43%) of the membrane; the remaining 29% of the neurons were unresponsive. The DA-induced depolarization was mimicked by SK 38393 and prevented by pretreatment with SCH 23390. Conversely, the DA-induced inhibition was mimicked by bromoergocryptine and prevented by pretreatment with L741626. When tested on the same neuron, the effects of DA and NE were not always similar. In fact, in neurons in which DA induced a membrane depolarization, 77% were inhibited by NE, whereas 75% of neurons unresponsive to DA were inhibited by NE. Our data suggest that DA modulates the membrane properties of gastric-projecting motoneurons via D1- and D2-like receptors, and DA may play different roles than norepinephrine in brain stem vagal circuits.