Arrhythmic firing in dopamine neurons of rat substantia nigra evoked by activation of subthalamic neurons.
Arrhythmic firing in dopamine neurons of rat substantia nigra evoked by activation of subthalamic neurons.
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由丘脑底神经元激活引起的大鼠黑质多巴胺神经元的心律失常放电。
DOI：
10.1152/jn.1999.82.3.1632
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Futami,T
中科院分区：
文献类型：
--
作者：
Kang,Y;Futami,T
用离体脑片记录大鼠黑质多巴胺能神经元的细胞内记录，研究丘脑底核（STh）对突触的影响。微刺激STh后，多巴胺能神经元产生单突触兴奋性突触后电位（EPSP）。STh诱导的EPSPs由6-氰基-7-硝基喹啉-2，3-二酮和2-氨基-5-磷酸戊酸敏感成分组成。刺激STh诱发的阈下EPSP可根据基线膜电位水平不同，不同程度地触发起搏样慢除极（PLSD）和低阈值钙锋电位（LTS）。当STh刺激诱发阈下EPSP时，STh诱发的EPSP可使PLSD移位或升高到更高的去极化水平，从而在更早的节律性放电时间产生锋电位，重新启动节律性放电。放电峰后的峰间期几乎保持不变。相反，当在节律性放电期间由STh刺激产生用于诱发棘波的阈上EPSP时，STh诱发的棘波正好介于两个自发棘波之间，其棘波间间期与在前一个节律性放电期间所观察到的几乎相同。这种异位诱导的尖峰没有干扰或重置节律性放电。结论：SNc多巴胺能神经元接受STh的单突触电刺激输入，STh刺激诱发的阈下和阈上EPSP可诱导SNc多巴胺能神经元产生两种类型的电刺激放电，类似于房性和室性心律失常心电图中QRS波群的电刺激发生。多巴胺能神经元的前放电可能在多巴胺能神经元的去兴奋过程中起重要作用。
Intracellular recordings were made from dopaminergic neurons of the rat substantia nigra compacta (SNc) in in vitro slice preparations to study the synaptic influence from the subthalamic nucleus (STh). After microstimulation of STh, monosynaptic excitatory postsynaptic potentials (EPSPs) were produced in dopaminergic neurons. STh-induced EPSPs were composed of 6-cyano-7-nitroquinoxalene-2,3-dione- and 2-amino-5-phosphonovaleric acid-sensitive components. Subthreshold EPSPs evoked by STh stimulation could differentially trigger pacemaker-like slow depolarization (PLSD) and low-threshold Ca2+spike (LTS) depending on the level of baseline membrane potentials. When a subthreshold EPSP was evoked by STh stimulation during rhythmic firing, the STh-induced EPSP could shift or elevate PLSD to a more depolarized level, resulting in generation of a spike at an earlier arrhythmic timing to restart the rhythmic firing. The interspike interval after the arrhythmic spike remained almost unchanged. In contrast, when a suprathreshold EPSP for evoking spikes was produced by STh stimulation during rhythmic firing, the STh-induced spike was just interposed between two spontaneous spikes the interspike interval of which was almost the same as those seen during the preceding rhythmic firing. This ectopically induced spike did not disturb or reset rhythmic firing. It was concluded that SNc dopaminergic neurons receive monosynaptic glutamatergic inputs from STh, and subthreshold and suprathreshold EPSPs evoked by STh stimulations can induce two types of arrhythmic firing in SNc dopaminergic neurons, similar to arrhythmic occurrences of the QRS complex seen in the electrocardiogram of the atrial and ventricular arrhythmias, respectively. The former arrhythmic firing may play a crucial role in desynchronization of dopaminergic neurons.