安氟醚对海马CA1区锥体神经元的自发性微小抑制性突触后电流的调控

为探讨吸入性麻醉剂安氟醚对海马CA1区锥体神经元的γ-氨基丁酸(GABA)能自发性微小抑制性突触后电流(mIP-SCs)的调控作用,本研究采用酶消化和机械分离的单细胞模型,应用制霉菌素穿孔膜片钳技术,记录安氟醚对海马CA1区锥体神经元的GABA能突触后电流的影响。结果显示:(1)安氟醚可使GABA的浓度-效应曲线平行左移,但不影响GABA引起的最大反应;(2)安氟醚能够可逆性地增大GABA能自发性mIPSCs的发放频率而不影响其幅度;(3)在无钙细胞外液条件下,仍能观察到安氟醚对GABA能自发性mIPSCs发放频率的增强作用;膜通透性胞内钙库Ca2+的螯合剂BAPTA-AM可抑制安氟醚的增强作用。以上结果提示在海马CA1区安氟醚可能通过释放胞内钙库内的Ca2+使神经终末内Ca2+浓度升高而增加GABA的释放,从而达到中枢抑制作用。

The effects of enflurane on GABAergic inhibitory postsynaptic currents of the hippocampal CA1 pyramidal neurons in the rat

To investigate the effects of enflurane on the γ-aminobutyric acid-ergic(GABAergic)spantaneous miniature inhibitory postsynaptic currents(mIPSCs)in acutely enzyme-treatment and mechanical dissociated single rat hippocampus CA1 pyramidal neurons,nystatin-perforated patch recording technique was used in the present study under voltage-clamp conditions.The results showed:(1)Enflurane shifted the GABA concentration-response curve to the left in a parallel fashion without changing the maximum response;(2)Enflurane reversibly increased the frequency of the mIPSCs without affecting the mean amplitude;(3)The increase in the frequency of mIPSCs in the presence of the enflurane was also observed in Ca2+-free external solution.Membrane permeable and selective chelator of intracellular Ca2+ stores,BAPTA-AM,prohibited the facilitatory effect of enflurane on the spontaneous mIPSCs frequency.The present results suggested that enflurane may increase the Ca2+ concentration in the GABAergic presynaptic nerve terminals on the hippocampal CA1 pyramidal neurons by enhancing the release of Ca2+ from intracellular Ca2+stores.