Excitatory synaptic currents in lumbosacral parasympathetic preganglionic neurons evoked by stimulation of the dorsal commissure.
Excitatory synaptic currents in lumbosacral parasympathetic preganglionic neurons evoked by stimulation of the dorsal commissure.
复制标题
DOI：
10.1152/jn.00180.2002
复制
发表时间：
2003
影响因子：
2.5
通讯作者：
A. Miura;M. Kawatani;W. D. de Groat
中科院分区：
文献类型：
--
作者：
A. Miura;M. Kawatani;W. D. de Groat
应用全细胞膜片钳技术研究了新生大鼠脊髓片背连合（DCM）至L（6）-S（1）副交感节前神经元（PGN）的兴奋通路。通过将荧光染料注射到腹腔内的逆行轴突运输来鉴定PGN。在存在荷包牡丹碱甲碘（10 μ M）和士的宁（1 μ M）的情况下，通过刺激DCM在PGN中诱发兴奋性突触后电流（EPSC），以阻断抑制性通路。电刺激DCM诱发两种类型的内向电流。在大多数PGN（n = 66）中，电流（平均振幅，47.9 +/- 4.7 pA）发生在较短且相对恒定的潜伏期（3.8 +/- 0.1 ms），并可能代表单突触EPSC（1型）。然而，在其他神经元（n = 20），一个不同类型的EPSC（2型），由一个快速的单突触组件，随后由一个长期的内向电流叠加快速瞬变，推测代表兴奋性输入介导的多突触通路。将1型EPSC解剖成两个部分。快速成分被6-氰基-7-硝基喹喔啉-2，3-二酮（CNQX，5 μ M）阻断，缓慢衰减的成分被2-氨基-5-磷酸戊酸（APV，50 μ M）阻断。1型EPSC的快成分具有线性电流-电压关系，并且在-7.6 +/-1.3 mV的膜电位下反转（n = 5）。2型EPSC的快组分也被5 μ M CNQX阻断，其余的慢组分被50 μ M APV阻断。当在50 μ M APV存在下刺激DCM时，1型EPSC中的达峰时间和衰减时间常数分别为1.9 +/- 0.2和4.1 +/- 0.8 ms。在存在5 μ M CNQX的情况下，对NMDA受体介导的EPSC成分的检查揭示了具有负斜率电导区域（从-20到-80 mV）的电流-电压关系，该区域在无Mg（2+）的外部溶液中被消除。该组分的达峰时间和衰减时间常数分别为14.2 +/- 2.0和91.0 +/- 12.4 ms。1型EPSC在一些PGN中以全或无的方式响应，并且可能代表单一的突触响应;而2型EPSC总是表现出分级的刺激强度-响应关系。观察到EPSC的成对脉冲易化（50 ms刺激间隔; 141 +/- 5.6%增加，n = 8）。这些结果表明，PGN接受单突触和多突触的神经元和/或轴突通路在DCM的兴奋性输入。
Excitatory pathways from the dorsal commissure (DCM) to L(6)-S(1) parasympathetic preganglionic neurons (PGN) were examined using whole-cell patch-clamp recording techniques in spinal cord slices from neonatal rats. PGN were identified by retrograde axonal transport of a fluorescent dye injected into the intraperitoneal space. Excitatory postsynaptic currents (EPSCs) were evoked in PGN by stimulation of DCM in the presence of bicuculline methiodide (10 microM) and strychnine (1 microM) to block inhibitory pathways. Electrical stimulation of DCM evoked two types of inward currents. In the majority of PGN (n = 66), currents (mean amplitude, 47.9 +/- 4.7 pA) occurred at a short and relatively constant latency (3.8 +/- 0.1 ms) and presumably represent monosynaptic EPSCs (Type 1). However, in other neurons (n = 20), a different type of EPSC (Type 2) was noted, consisting of a fast monosynaptic component followed by a prolonged inward current with superimposed fast transients presumably representing excitatory inputs mediated by polysynaptic pathways. Type 1 EPSCs were pharmacologically dissected into two components. A fast component was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5 microM) and a slowly decaying component was blocked by 2-amino-5-phosphonovalerate (APV, 50 microM). The fast component of Type 1 EPSCs had a linear current-voltage relationship and reversed at a membrane potential of -7.6 +/- 1.3 mV (n = 5). The fast component of Type 2 EPSCs was also blocked by 5 microM CNQX and the remaining slower component was blocked by 50 microM APV. When the DCM was stimulated in the presence of 50 microM APV, the time to peak and decay time constant in Type 1 EPSCs were 1.9 +/- 0.2 and 4.1 +/- 0.8 ms, respectively. Examination of the NMDA receptor-mediated component of the EPSCs in the presence of 5 microM CNQX revealed a current-voltage relationship that had a region of negative slope conductance (from -20 to -80 mV), which was abolished in Mg(2+)-free external solution. The time to peak and decay time constant of this component were 14.2 +/- 2.0 and 91.0 +/- 12.4 ms, respectively. Type 1 EPSCs in some PGN responded in an all-or-none manner and presumably represented unitary synaptic responses; whereas Type 2 EPSCs always exhibited a graded stimulus intensity-response relationship. Paired-pulse facilitation (50-ms interstimulus intervals; 141 +/- 5.6% increase, n = 8) of EPSCs was observed. These results indicate that PGN receive monosynaptic and polysynaptic glutamatergic excitatory inputs from neurons and/or axonal pathways in the DCM.