Synaptic regulation of single substantia nigra pars reticulata neurons

描述（由申请人提供）：丘脑底核（subthalamic nucleus，简称STN）通过对黑质网状部（substantia nigra pars reticulata，简称SNR）（基底神经节的主要输出结构）施加兴奋性影响，在运动控制中发挥重要作用。在帕金森氏病中， 丘脑下黑质途径被认为有助于运动症状，例如僵硬、运动迟缓和震颤。我们实验室的初步数据表明，局灶性电刺激的突触诱发一个初始的单突触EPSC，随后由一系列的晚EPSC叠加在一个缓慢的向内转移，保持电流，持续200 - 500 ms。结果迄今支持这一假设，即这种复杂的EPSC是由激活的复发轴突侧支内的突触。因为电刺激会唤起 当在电流钳下记录动作电位时，复合EPSC可能代表了促进SNR神经元爆发性放电的新机制。与此相反，在黑质多巴胺神经元中，多巴胺刺激仅引起单相EPSC，这表明对SNR的多巴胺输出可能不同于对SNC多巴胺神经元的多巴胺输出。我们提出的研究的主要目标是表征复杂的EPSCs的神经生理学和神经递质系统的调节。实验将使用标准的全细胞贴片移液管记录技术来记录大鼠脑切片中的神经元。将通过对脑皮层的局灶性电刺激在SNR神经元中诱发复杂的EPSC，并且将使用快速流动的微涂药器将药物溶液递送到脑切片的特定区域。计划中的实验将使用SNR和SNC的逆向刺激技术来表征突触内的复发性多突触连接。其他实验将研究GABA和多巴胺受体配体调节复杂EPSC的作用位点和受体药理学特征。结合 在神经生理学实验中，脑切片也将用于使用电子显微镜记录海马神经元的复发性轴突侧支神经支配。由于丘脑底黑质通路在调节SNR神经元放电模式中的重要性，这些研究的结果可能对帕金森病的病理生理学和可能的治疗具有重要意义。公共卫生相关性：许多研究表明，大脑通路中的过度爆发活动， 丘脑底核到黑质网状部的神经传导通路有助于帕金森病的症状以及某些类型的癫痫发作的传播。我们的研究表明，丘脑底黑质通路的激活引起长时间的去极化和动作电位的网状神经元记录在大鼠脑片的爆发。通过表征突触连接和调节性递质系统如何调节这一通路，我们的研究可能为改善这些人类疾病的治疗提供有用的信息。

DESCRIPTION (provided by applicant): The subthalamic nucleus (STN) plays an important role in movement control by exerting its excitatory influence on the substantia nigra pars reticulata (SNR), a major output structure of the basal ganglia. In Parkinson's disease, increased bursting activity in the subthalamonigral pathway is thought to contribute to motor symptoms such as rigidity, bradykinesia and tremor. Preliminary data from our lab show that focal electrical stimulation of the STN evokes an initial monosynaptic EPSC followed by a series of late EPSCs superimposed on a slow inward shift in holding current that lasts 200 - 500 ms. Results thus far support the hypothesis that this complex EPSC is generated by activation of recurrent axon collaterals within the STN. Because STN stimulation evokes a burst of action potentials when recording under current-clamp, the complex EPSC may represent a novel mechanism for promoting burst firing in SNR neurons. In contrast, STN stimulation only evokes monophasic EPSCs in substantia nigra pars compacta (SNC) dopamine neurons, which suggests that the STN output to SNR may differ from the STN output to SNC dopamine neurons. The major goals of our proposed studies are to characterize the neurophysiology of complex EPSCs and their regulation by neurotransmitter systems. Experiments will use standard whole-cell patch pipette recording techniques to record from neurons in the rat brain slice. Complex EPSCs will be evoked in SNR neurons by focal electrical stimulation of the STN, and drug solutions will be delivered to specific regions of the brain slice using a fast-flow microapplicator. Planned experiments will use antidromic stimulation techniques of the SNR and SNC to characterize recurrent, polysynaptic connections within the STN. Other experiments will investigate sites of action and characterize receptor pharmacology for the regulation of complex EPSCs by GABA and dopamine receptor ligands. In conjunction with neurophysiological experiments, brain slices will also be used to document recurrent axonal collateral innervation of STN neurons using electron microscopy. Due to the importance of the subthalamonigral pathway in regulating firing pattern of SNR neurons, results of these studies may have important implications for the pathophysiology and possible treatment of Parkinson's disease. PUBLIC HEALTH RELEVANCE: Many studies suggest that excessive bursting activity in the brain pathway from subthalamic nucleus to substantia nigra pars reticulata contributes to symptoms of Parkinson's disease as well as the propagation of some types of seizures. Our studies show that activation of the subthalamonigral pathway causes long-lasting depolarization and bursts of action potentials in reticulata neurons recorded in the rat brain slice. By characterizing how synaptic connections and modulatory transmitter systems regulate this pathway, our studies may provide useful information to improve the therapy of these human disorders.