Ionic mechanism underlying recovery of rhythmic activity in adult isolated neurons
Ionic mechanism underlying recovery of rhythmic activity in adult isolated neurons
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DOI：
10.1152/jn.00385.2006
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发表时间：
2006-10-01
影响因子：
2.5
通讯作者：
Golowasch, Jorge
中科院分区：
文献类型：
--
作者：
Haedo, Rodolfo J.;Golowasch, Jorge
神经元表现出长期的兴奋性变化，这些变化对于维持适当的细胞和网络活动以响应各种输入和扰动是必要的。例如，成年甲壳动物幽门网络可以自发地恢复节律性活动后，完全关闭造成永久删除的神经调节输入。分离的龙虾胃神经节（STG）神经元已被证明通过兴奋性变化自发地产生振荡活动。有节奏的电刺激可以消除某些细胞中的这些振荡模式。这些变化背后的离子机制只是部分理解。我们使用分离的螃蟹STG神经元研究自发恢复节律活动和刺激诱导的活动变化的离子机制。与龙虾神经元类似，螃蟹STG神经元中自发地产生节律活动。节律性超极化刺激可以消除，但更常见的是加速，出现稳定的振荡活动取决于钙离子流入超极化电压。我们的主要发现是，上调的Ca2+电流和下调的高阈值K+电流的振荡活动的自发稳态发展的基础。然而，由于对刺激频率的非线性依赖，超极化诱导的振荡似乎与活动的稳态调节不一致。我们发现，在隔离的第一个10天期间，快速幽门和慢速胃磨网络的神经元之间的活动模式或相关离子电流没有差异。动态钳实验证实，这些电导修改可以解释所观察到的活动变化。我们的结论是自发的和刺激诱导的兴奋性变化，在STG神经元都可以导致内在的振荡活动，通过调节相同的两个电导。
Neurons exhibit long-term excitability changes necessary for maintaining proper cell and network activity in response to various inputs and perturbations. For instance, the adult crustacean pyloric network can spontaneously recover rhythmic activity after complete shutdown resulting from permanent removal of neuromodulatory inputs. Dissociated lobster stomatogastric ganglion (STG) neurons have been shown to spontaneously develop oscillatory activity via excitability changes. Rhythmic electrical stimulation can eliminate these oscillatory patterns in some cells. The ionic mechanisms underlying these changes are only partially understood. We used dissociated crab STG neurons to study the ionic mechanisms underlying spontaneous recovery of rhythmic activity and stimulation-induced activity changes. Similar to lobster neurons, rhythmic activity spontaneously develops in crab STG neurons. Rhythmic hyperpolarizing stimulation can eliminate, but more commonly accelerate, the emergence of stable oscillatory activity depending on Ca2+ influx at hyperpolarized voltages. Our main finding is that upregulation of a Ca2+ current and downregulation of a high-threshold K+ current underlies the spontaneous homeostatic development of oscillatory activity. However, because of a nonlinear dependence on stimulus frequency, hyperpolarization-induced oscillations appear to be inconsistent with a homeostatic regulation of activity. We find no difference in the activity patterns or the underlying ionic currents involved between neurons of the fast pyloric and the slow gastric mill networks during the first 10 days in isolation. Dynamic-clamp experiments confirm that these conductance modifications can explain the observed activity changes. We conclude that spontaneous and stimulation-induced excitability changes in STG neurons can both result in intrinsic oscillatory activity via regulation of the same two conductances.