Developmental of the brainstem NTS function studied by optical imaging and living stain methods

采用快速电压敏感染料NK2761吸收染料进行多位点光学记录，研究迷走神经通路中功能性突触网络的发育组织。在鸡胚胎第7天（E7）和大鼠胚胎第15天（E15），迷走神经刺激引起的谷氨酸能兴奋性突触后电位（EPSPs）首次在孤束核（NTS）检测到，此时突触前和突触后神经元形态分化不完全。当去除细胞外Mg^<2+>时，鸡胚E6和大鼠胚E14处均有小epsp被激活。这些结果表明，n -甲基- d -天冬氨酸（NMDA）受体介导的突触功能在谷氨酸能EPSP表达前一天潜伏产生。与舌咽神经相关的功能性突触似乎与迷走神经同时产生，但其空间分布与迷走神经不同。我们进一步研究了从NTS到更高中枢的第二突触通路的发展，发现当初级传入事件与NTS神经元形成功能性突触时，NTS的神经元回路已经产生。

Multiple-site optical recording with a fast voltage-sensitive dye, absorption dye NK2761, was used to study the developmental organization of functional synaptic networks in the vagal pathway. Glutamatergic excitatory postsynaptic potentials (EPSPs) evoked by vagus nerve stimulation was first detected from the nucleus of the tractus solitarius (NTS) at embryonic day 7 (E7) in chick embryos and E15 in rat embryos, when morphological differentiation of pre- and postsynaptic neurons is incomplete. When extracellular Mg^<2+> removed, small EPSPs were elicited at E6 in chick embryos and E14 in rat embryos. These results suggest that synaptic function mediated by N-methyl-D-aspartate (NMDA) receptors is latently generated one day before the expression of glutamatergic EPSP. Functional synapses related to the glossophyaryngeal nerve appear to be generated at the same time as the vagus nerve, but their spatial distribution was different from that of the vagus nerve. We further investigated the development of second synaptic pathways from the NTS to higher centers, and found that neuronal circuits from the NTS are already generated when the primary afferents form functional synapses with NTS neurons.