Objective: To establish the neocortex-striatum-substantia nigra 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 striatum 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.