Unitary excitatory synaptic currents in preganglionic neurons mediated by two distinct groups of interneurons in neonatal rat sacral parasympathetic nucleus
Unitary excitatory synaptic currents in preganglionic neurons mediated by two distinct groups of interneurons in neonatal rat sacral parasympathetic nucleus
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DOI：
10.1152/jn.1996.76.1.215
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发表时间：
1996-07-01
影响因子：
2.5
通讯作者：
deGroat, WC
中科院分区：
文献类型：
--
作者：
Araki, I;deGroat, WC
1. 采用全细胞膜片钳记录技术，对新生大鼠腰骶脊髓切片制备过程中副交感神经节前神经元（PGNs）的兴奋性突触后电流（EPSCs）进行了研究。邻近中间神经元的细胞外刺激可引起突触反应2。骶副交感神经核（SPN）内侧的中间神经元刺激分别在58%和11%的副交感神经核中引发EPSCs或抑制性突触后电流。刺激SPN背侧的中间神经元可在70%的pgns中诱发EPSCs。EPSCs发生在短潜伏期（2.1 ms），通常以全或无的方式被激发，表明它们是单突触的，由单个中间神经元（即单一的）介导。EPSCs由非n-甲基- d -天冬氨酸（non-NMDA）和NMDA受体介导。单次刺激引起的单一兴奋性突触后电位不能诱发PGNs的动作电位，但单次中间神经元的重复刺激（bb0 ~ 20hz）可诱发PGNs的放电。2-氨基-5-磷酸戊酸钠是一种NMDA受体拮抗剂，可减少高频神经元间脉冲诱导的PGNs突触去极化。背侧中间神经元介导的EPSCs的振幅（36.3 +/- 15.7 pA，平均+/- SD）小于内侧中间神经元介导的EPSCs （88.4 +/- 45.7 pA）。在PGNs中观察到EPSCs的配对脉冲促进（147.2 +/- 26.2%）。背侧神经通路的易化程度（174.6 +/- 10.3%）高于内侧神经通路（120.9 +/- 3.6%）。在每个神经元间通路中，易化程度与单一epsc的大小无关。结果表明，PGNs接受来自SPN背侧和内侧两个不同中间神经元群的单突触谷氨酸能兴奋输入。这两个中间神经元群可能在节前向盆腔器官流出的调节中具有不同的功能。
1. Excitatory postsynaptic currents (EPSCs) in parasympathetic preganglionic neurons (PGNs) were examined by the use of the whole cell patch-clamp recording technique in slice preparations of the neonatal rat lumbosacral spinal cord. Synaptic responses were evoked in PGNs by extracellular stimulation of a neighboring interneuron.2. Stimulation of interneurons medial to the sacral parasympathetic nucleus (SPN) elicited EPSCs or inhibitory postsynaptic currents in 58 and 11%, respectively, of PGNs. Stimulation of interneurons dorsal to the SPN evoked EPSCs in 70% of PGNs.3. EPSCs occurred at short latency (2.1 ms) and were usually elicited in an all-or-none manner, indicating that they were monosynaptic and mediated by a single interneuron (i.e., unitary).4. EPSCs were mediated by both non-N-methyl-D-aspartate (non-NMDA) and NMDA receptors.5. Unitary excitatory postsynaptic potentials evoked by single stimuli did not induce action potentials in PGNs, but repetitive stimulation (>20 Hz) of the single interneurons could evoke firing of PGNs. 2-Amino-5-phosphonovalerate, an NMDA receptor antagonist, reduced the synaptic depolarization induced in PGNs by high-frequency interneuronal impulses.6. EPSCs mediated by dorsal interneurons were smaller in amplitude (36.3 +/- 15.7 pA, mean +/- SD) than EPSCs mediated by medial interneurons (88.4 +/- 45.7 pA).7. Paired-pulse facilitation of EPSCs was observed in PGNs (147.2 +/- 26.2%). The degree of facilitation was higher in dorsal (174.6 +/- 10.3%) than in medial interneuronal pathways (120.9 +/- 3.6%). Within each of interneuronal pathways the degree of facilitation was independent of the magnitude of the unitary EPSC.8. The results show that PGNs receive monosynaptic glutamatergic excitatory inputs from two distinct populations of interneurons in the dorsal and medial regions of the SPN. These two populations of interneurons are likely to have different functions in the regulation of the preganglionic outflow to the pelvic organs.