Differential effects of noradrenaline on evoked, spontaneous and miniature IPSCs in rat cerebellar stellate cells
Differential effects of noradrenaline on evoked, spontaneous and miniature IPSCs in rat cerebellar stellate cells
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DOI：
10.1111/j.1469-7793.1998.233bo.x
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发表时间：
1998-05-15
影响因子：
5.5
通讯作者：
Marty, A
中科院分区：
文献类型：
--
作者：
Kondo, S;Marty, A
1.采用突触前松散细胞贴壁记录和突触后全细胞记录，观察去甲肾上腺素(NA)对大鼠小脑片星状细胞间突触的调制作用。NA可增加星状细胞记录的自发性IPSCs的频率，但不改变其平均幅度。NA可增加星状细胞的放电频率。这种作用在阻断离子型谷氨酸受体和GABA受体后持续存在，表明它不依赖突触输入。NA对动作电位频率的影响可被β受体激动剂异丙肾上腺素所模拟，但不被α受体激动剂6-氟去甲肾上腺素所模拟，且不能被α受体拮抗剂酚妥拉明阻断，表明它们是由β受体介导的。在对连接的星状细胞的配对记录中，NA略微降低了突触传递的成功率。NA6的平均IPSC波幅(不包括故障)略有下降，潜伏期略有增加。这些结果表明，尽管NA通过增加星状细胞的放电频率来增加动作电位依赖的IPSCs的数量，但它实际上降低了诱发释放的可能性。由于先前的研究表明，NA增加了这种准备过程中微型IPSCs的比率，我们得出结论，不同的机制可能是NA对动作电位依赖和动作电位非依赖性递质释放的调节。
1. The modulation by noradrenaline (NA) of synapses among stellate cells was investigated in rat cerebellar slices by using presynaptic loose cell-attached recording and postsynaptic whole-cell recording.2. NA increased the frequency of spontaneous IPSCs recorded from stellate cells without changing their mean amplitude.3. NA increased the firing rate of stellate cells. This effect persisted after blocking ionotropic glutamate receptors and GABA receptors, indicating that it was independent of synaptic input.4. The effects of NA on action potential frequency were mimicked by the beta-receptor agonist isoprenaline but not by the alpha-receptor agonist 6-fluoro noradrenaline, and they were not blocked by the alpha-receptor antagonist phentolamine, indicating that they were mediated by beta-receptors.5. In paired recordings of connected stellate cells, NA slightly decreased the success rate of synaptic transmission. A small decrease in mean IPSC amplitude (excluding failures) and a slight increase in latency were also observed in NA.6. These results show that, while NA increases the number of action potential-dependent IPSCs by increasing the firing rate of stellate cells, it actually reduces the probability of evoked release. Since previous studies showed that NA increases the rate of miniature IPSCs in this preparation, we conclude that different mechanisms underly the modulation by NA of action potential-dependent and action potential-independent transmitter release.