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目的观察甲基苯丙胺(Meth)对瞬时外向钾电流的影响及原因。方法将怀孕18 d SD大鼠胎鼠海马神经元分为对照组和Meth处理组,利用全细胞膜片钳方法记录外向瞬时钾电流变化;采用原位末端转移酶标记技术(TUNEL)观察Meth引起的细胞损伤作用;利用逆转录聚合酶链反应(RT-PCR)方法观察瞬时外向电流成分中Kv1.4、4.1、4.2和4.3表达,并通过western-blot方法观察Kv4.2蛋白表达。结果与对照组[(87.4±12.5)pA/pF]比较,Meth能引起瞬时外向钾电流增大[(120.1±19.6)pA/pF](P<0.01),与对照组(1.00±0.18)比较,Meth处理组凋亡率为对照组的(7.11±0.95)倍(P<0.01),钾通道抑制剂4-氨基吡啶(4-AP)明显抑制神经元凋亡(P<0.01);Kv4.2可能是外向电流成分中主要贡献者,Meth能上调Kv4.2通道蛋白表达;与Kv4.2上调密切相关的Kchip2/3、Kchip4、CaMK2蛋白表达增高。结论 Meth引起的瞬时钾电流增大可能通过Kv4.2上调来实现,但其机制仍需进一步探讨。
Objective To investigate the effect of Meth on transient outward potassium current and its causes. Methods The hippocampal neurons of 18-day-old SD rats were divided into two groups: control group and meth treatment group. Whole-cell patch-clamp method was used to record the outward potassium current changes. Meth was detected by TUNEL Cell injury. The expression of Kv1.4, 4.1, 4.2 and 4.3 in transient outward current was observed by reverse transcription-polymerase chain reaction (RT-PCR). The expression of Kv4.2 protein was observed by western-blot. Results Meth increased the transient outward potassium current ([(120.1 ± 19.6) pA / pF] (P <0.01) compared with that of the control group [(87.4 ± 12.5) pA / pF] The apoptotic rate of Meth group was (7.11 ± 0.95) times that of the control group (P <0.01), and 4-aminopyridine (4-AP) inhibited neuronal apoptosis significantly (P <0.01). 2 may be the main contributor to the outward current component. Meth can up-regulate the protein expression of Kv4.2 channel, and increase the expression of Kchip2 / 3, Kchip4 and CaMK2 in Kv4.2. Conclusion The increase of transient potassium current induced by Meth may be achieved through the up-regulation of Kv4.2, but its mechanism still needs to be further explored.