Baptista V, Zheng Z L, Coleman F H, Rogers R C, Travagli R A
Department of Neuroscience, Pennington Biomedical Research Center, Louisiana State University System, Baton Rouge, 70808, USA.
Brain Res. 2005 Aug 9;1052(2):139-46. doi: 10.1016/j.brainres.2005.05.073.
Esophageal sensory afferent inputs terminate principally in the central subnucleus of the tractus solitarius (cNTS). Neurons of the cNTS comprise two major neurochemical subpopulations. One contains neurons that are nitric oxide synthase (NOS) immunoreactive (-IR) while the other comprises neurons that are tyrosine hydroxylase (TH)-IR. We have shown recently that TH-IR neurons are involved in esophageal-distention induced gastric relaxation. We used whole cell patch clamp techniques in rat brainstem slices combined with immunohistochemical and morphological reconstructions to characterize cNTS neurons. Postrecording reconstruction of cNTS neurons revealed two morphological neuronal subtypes; one group of cells (41 out of 131 neurons, i.e., 31%) had a multipolar soma, while the other group (87 out of 131 neurons, i.e., 66%) had a bipolar soma. Of the 43 cells in which we conducted a neurochemical examination, 15 displayed TH-IR (9 with bipolar morphology, 6 with multipolar morphology) while the remaining 28 neurons did not display TH-IR (18 with bipolar morphology, 10 with multipolar morphology). Even though the range of electrophysiological properties varied significantly, morphological or neurochemical distinctions did not reveal characteristics peculiar to the subgroups. Spontaneous excitatory postsynaptic currents (sEPSC) recorded in cNTS neurons had a frequency of 1.5 +/- 0.15 events s(-1) and an amplitude of 27 +/- 1.2 pA (Vh = -50 mV) and were abolished by pretreatment with 30 muM AP-5 and 10 muM CNQX, indicating the involvement of both NMDA and non-NMDA receptors. Some cNTS neurons also received a GABAergic input that was abolished by perfusion with 30-50 muM bicuculline. In conclusion, our data show that despite the heterogeneity of morphological and neurochemical membrane properties, the electrophysiological characteristics of cNTS neurons are not a distinguishing feature.
食管感觉传入神经主要终止于孤束核的中央亚核（cNTS）。cNTS的神经元包括两个主要的神经化学亚群。一个亚群包含一氧化氮合酶（NOS）免疫反应阳性（-IR）的神经元，而另一个亚群则由酪氨酸羟化酶（TH）-IR神经元组成。我们最近发现，TH-IR神经元参与食管扩张诱导的胃舒张。我们运用全细胞膜片钳技术，结合免疫组织化学和形态学重建方法，对大鼠脑干切片中的cNTS神经元进行了特性研究。对cNTS神经元记录后的重建显示出两种形态学神经元亚型；一组细胞（131个神经元中的41个，即31%）具有多极胞体，而另一组（131个神经元中的87个，即66%）具有双极胞体。在我们进行神经化学检查的43个细胞中，15个显示TH-IR（9个具有双极形态，6个具有多极形态），其余28个神经元未显示TH-IR（18个具有双极形态，10个具有多极形态）。尽管电生理特性范围差异显著，但形态学或神经化学差异并未揭示各亚群特有的特征。在cNTS神经元中记录到的自发性兴奋性突触后电流（sEPSC）频率为1.5±0.15次事件/秒（s(-1)），幅度为27±1.2皮安（pA）（钳制电压Vh = -50毫伏），并且在用30微摩尔AP-5和10微摩尔CNQX预处理后被消除，这表明NMDA和非NMDA受体均参与其中。一些cNTS神经元还接受GABA能输入，在用30 - 50微摩尔荷包牡丹碱灌注后被消除。总之，我们的数据表明，尽管形态学和神经化学膜特性存在异质性，但cNTS神经元的电生理特性并非其区别特征。
