大鼠皮质-纹状体-黑质脑片中等多棘神经元的电生理特性

Electrophysiological characteristics of medium spiny neurons in neocortex-striatum-substantia nigrabrain slices of rats

目的通过制备大鼠皮质－纹状体－黑质脑片，在可视条件下观察纹状体中等多棘神经元（MSN）的电活动，探讨其电生理特性。方法选用出生7～10d的健康SD大鼠，制备皮质－纹状体－黑质旁矢状位脑片，通过红外微分干涉相差（IR－DIC）显微镜直视下定位纹状体MSN，并采用膜片钳放大器全细胞记录，电流钳模式下记录MSN的自发性电活动，采用步阶电流注人，观察膜电位变化。结果成功记录的92个MSN表现为三种状态：14个细胞为持续的极化状态，无动作电位发放；61个细胞表现为持续的极化状态间隔短阵的去极化至阈电位水平伴发动作电位；17个细胞为持续的极化状态间隔突然出现的去极化状态。三种表现形式细胞的静息电位、阈电位均数差异无统计学意义（P〉0．05）。注人电流时，膜电位变化表现为一定程度的延迟，电位变化随注入电流增强有减少趋势。结论旁矢状位脑片中的纹状体MSN保留了在体的电牛理特性，为深入研究黑质－纹状体通路电信号的发生和传递在帕金森病发病机制中的作用奠定了基础。

Objective To establish the neocortex-striatum-substantia nigwa brain slices of rats and observe the medium spiny neurons of striatum under a visible condition so as to explore their electrophysiological characteristics. Methods The brain slices containing the neocortex-striatum-substantia nigra were prepared from SD rats of postnatal 7 - 10 days. With infrared differential interference contrast （IR-DIC） microscope and patch clamp amplifier whole-cell recording technique, the medium spiny neurons were located in stfiatum and their spontaneous electrical activity was recorded in the current clamp mode. By infusing the step current, we observed the variation of membrane potentials. Results There were three types of conditions in the 92 medium spiny neurons successfully recorded. Among them, 14 were in persistent down state without action potential firing; 61 displayed persistent down state accompanied with interval temporal depolarizing to the threshold potential with action potential firing; and the remaining 17 showed persistent down state with the interval emergent up state. There was no statistical significance in the difference of mean resting and threshold potentials in three neuronal types （ P 〉 0. 05 ）. When the neurons received an infused current, their membrane potentials displayed some delays. The variance of electric potentials showed a tendency of reduction along with the reinforcement of infusing current. Conclusion The medium spiny neurons of striatum in parasagittal section brain slices reserve their in vivo electrophysiological characteristics. It establishes rationales for an in-depth study of the role of electrical generation and transmission of nigrostriatal access in the pathogenesis of Parkinson＇s disease.