Shao Mei, Hirsch June C, Giaume Christian, Peusner Kenna D
Department of Anatomy and Cell Biology and Neuroscience Program, George Washington University Medical Center, Washington DC 20037, USA.
J Neurophysiol. 2003 Aug;90(2):1182-92. doi: 10.1152/jn.00076.2003.
The principal cells of the chick tangential nucleus are vestibular nucleus neurons participating in the vestibular reflexes. In 16-day embryos, the application of glutamate receptor antagonists abolished the postsynaptic responses generated on vestibular-nerve stimulation, but spontaneous synaptic activity was largely unaffected. Here, spontaneous synaptic activity was characterized in principal cells from brain slices at E16 using whole cell voltage-clamp recordings. With KCl electrodes, the frequency of spontaneous inward currents was 3.1 Hz at -60 mV, and the reversal potential was +4 mV. Cs-gluconate pipette solution allowed the discrimination of glycine/GABA(A) versus glutamate receptor-mediated events according to their different reversal potentials. The ratio for spontaneous excitatory to inhibitory events was about 1:4. Seventy-four percent of the outward events were GABA(A), whereas 26% were glycine receptor-mediated events. Both pre- and postsynaptic GABA(B) receptor effects were shown, with presynaptic GABA(B) receptors inhibiting 40% of spontaneous excitatory postsynaptic currents (sEPSCs) and 53% of spontaneous inhibitory postsynaptic currents (sIPSCs). With TTX, the frequency decreased approximately 50% for EPSCs and 23% for IPSCs. These data indicate that the spontaneous synaptic activity recorded in the principal cells at E16 is primarily inhibitory, action potential-independent, and based on the activation of GABA(A) receptors that can be modulated by presynaptic GABA(B) receptors.
鸡切线核的主要细胞是参与前庭反射的前庭核神经元。在16日龄胚胎中，应用谷氨酸受体拮抗剂可消除前庭神经刺激产生的突触后反应，但自发突触活动基本不受影响。在此，使用全细胞电压钳记录对E16脑片主要细胞中的自发突触活动进行了表征。使用氯化钾电极时，在-60 mV下自发内向电流的频率为3.1 Hz，反转电位为+4 mV。铯葡萄糖酸盐移液管溶液可根据甘氨酸/GABA(A)与谷氨酸受体介导事件的不同反转电位对其进行区分。自发兴奋性与抑制性事件的比例约为1:4。74%的外向事件是由GABA(A)介导的，而26%是由甘氨酸受体介导的事件。研究显示了突触前和突触后GABA(B)受体的作用，突触前GABA(B)受体抑制了40%的自发兴奋性突触后电流（sEPSCs）和53%的自发抑制性突触后电流（sIPSCs）。使用河豚毒素（TTX）时，EPSCs的频率下降约50%，IPSCs的频率下降23%。这些数据表明，在E16主要细胞中记录到的自发突触活动主要是抑制性的、与动作电位无关，并且基于可被突触前GABA(B)受体调节的GABA(A)受体的激活。
