■癫痫样活动是一组神经元过度兴奋的最惊人的结果,这些神经元可以在不同的大脑区域发生,然后扩散到其他部位。后来发现,这些节律在体外具有细胞相关性,称为阵发性去极化偏移(PDS)。在13-15DIV神经元神经胶质细胞培养中,抑制GABA(A)受体会引起碎屑PDS形式的动作电位爆发和细胞内Ca2浓度([Ca2]i)的振荡。我们证明了表达钙通透性AMPA受体(CP-AMPAR)的GABA能神经元以及Kv7型钾通道在培养的癫痫样活动中调节海马谷氨酸能神经元的兴奋性。
■使用电流钳模式下的全细胞膜片钳和钙成像显微镜的组合同时记录膜电位和[Ca2]i水平。为了鉴定GABA能细胞培养物,在进行重要的[Ca2]i成像后,将其固定并用抗谷氨酸脱羧酶GAD65/67和神经元特异性烯醇化酶(NSE)的抗体染色。
■表明CP-AMPAR参与PDS簇的调节,[Ca2]i脉冲伴随着它们。GABA能神经元的CP-AMPAR的激活被认为会导致GABA的释放,激活其他GABA能中间神经元的GABA(B)受体。假定这些GABA(B)受体的激活导致Gi蛋白的β-γ亚基的释放,激活钾通道,导致这些中间神经元的超极化和抑制。后者导致谷氨酸能神经元的去抑制,这些中间神经元的目标。反过来,CP-AMPAR拮抗剂,NASPM,有相反的效果。在全细胞配置中通过膜片钳方法测量GABA能神经元的膜电位表明,NASPM抑制簇和单个PDS中的超极化。据信Kv7型钾通道参与癫痫样活动期间超极化的控制。Kv7通道的阻断剂,XE991模拟了CP-AMPAR拮抗剂对PDS簇的作用。两种药物都增加了PDS簇的持续时间。反过来,Kv7活化剂,瑞替加宾,减少PDS簇和Ca2+脉冲的持续时间。此外,瑞替加滨在PDS簇的末端导致深度极化。Kv7通道被认为参与了PDS的形成,由于通道阻滞剂降低了PDS中的超极化率几乎三倍。因此,表达CP-AMPAR的GABA能神经元,通过调节其他GABA能神经元的突触后钾通道的活性来调节神经支配的谷氨酸能神经元的膜电位。
UNASSIGNED: Epileptiform activity is the most striking result of hyperexcitation of a group of neurons that can occur in different brain regions and then spread to other sites. Later it was shown that these rhythms have a cellular correlate in vitro called paroxysmal depolarization shift (PDS). In 13-15 DIV neuron-glial cell culture, inhibition of the GABA(A) receptors induces bursts of action potential in the form of clasters PDS and oscillations of intracellular Ca2+ concentration ([Ca2+]i). We demonstrate that GABAergic neurons expressing calcium-permeable AMPA receptors (CP-AMPARs) as well as
Kv7-type potassium channels regulate hippocampal glutamatergic neurons\' excitability during epileptiform activity in culture.
UNASSIGNED: A combination of whole-cell patch-clamp in current clamp mode and calcium imaging microscopy was used to simultaneously register membrane potential and [Ca2+]i level. To identify GABAergic cell cultures were fixed and stained with antibodies against glutamate decarboxylase GAD 65/67 and neuron-specific enolase (NSE) after vital [Ca2+]i imaging.
UNASSIGNED: It was shown that CP-AMPARs are involved in the regulation of the PDS clusters and [Ca2+]i pulses accompanied them. Activation of CP-AMPARs of GABAergic neurons is thought to cause the release of GABA, which activates the GABA(B) receptors of other GABAergic interneurons. It is assumed that activation of these GABA(B) receptors leads to the release of beta-gamma subunits of Gi protein, which activate potassium channels, resulting in hyperpolarization and inhibition of these interneurons. The latter causes disinhibition of glutamatergic neurons, the targets of these interneurons. In turn, the CP-AMPAR antagonist, NASPM, has the opposite effect. Measurement of membrane potential in GABAergic neurons by the patch-clamp method in whole-cell configuration demonstrated that NASPM suppresses hyperpolarization in clusters and individual PDSs. It is believed that
Kv7-type potassium channels are involved in the control of hyperpolarization during epileptiform activity. The blocker of
Kv7 channels, XE 991, mimicked the effect of the CP-AMPARs antagonist on PDS clusters. Both drugs increased the duration of the PDS cluster. In turn, the
Kv7 activator, retigabine, decreased the duration of the PDS cluster and Ca2+ pulse. In addition, retigabine led to deep posthyperpolarization at the end of the PDS cluster. The
Kv7 channel is believed to be involved in the formation of PDS, as the channel blocker reduced the rate of hyperpolarization in the PDS almost three times. Thus, GABAergic neurons expressing CP-AMPARs, regulate the membrane potential of innervated glutamatergic neurons by modulating the activity of postsynaptic potassium channels of other GABAergic neurons.