平行绑定多电极技术研究大鼠基底核毁损对海马自发放电的影响

目的:研究应用平行绑定多电极细胞外记录技术探讨海人藻酸(KA)注射毁损Meynert基底核(NBM)后海马CA1区自发放电活动的改变。方法:雄性SD大鼠在水合氯醛麻醉和脑立体定位仪引导下,KA注射后破坏双侧NBM,一周后用改装的平行绑定多电极记录大鼠海马CA1区自发放电活动。结果:(1)与传统的细胞外单电极或多电极记录相比,本方法电极制备简单、灵活、造价低廉,细胞损伤小,可同时记录单个核团内多个神经元或相邻脑区多个神经元的活动,便于进一步对神经元环路活动进行分析。结合锋电位分类技术,可对单一通道获得的多个神经元活动进行甑别,大大提高实验精度和效率;(2)比较NBM毁损组和对照组核团放电发现:NBM毁损组大鼠CA1区自发放电频率明显减少,其中单个放电与爆发式(burst)放电类型的平均放电频率同时降低;NBM毁损组自发放电类型发生改变,burst数量增加,但burst内发放频率下降,burst间隔延长。结论:(1)平行绑定多电极技术简便、易行、灵活,结合多通道记录技术可为开展神经元环路活动研究提供有力工具;(2)NBM毁损可致大鼠海马CA1区自发放电频率减少和放电模式改变,提示NBM胆碱能系统参与海马环路的神经活动调控,NBM损伤所致海马自发放电活动的改变可能有助于解释阿尔茨海默病认知功能的下降。

Study on the spontaneous discharges in the hippocampal CA1 region with parallel multi-channel recording technique after the lession of meynert basalis nucleus in rats

Objective:To study the change of spontaneous discharges in the hippocampal CA1 region after injection of kainic acid (KA) into the nucleus basalis of Meynert (NBM)of rat with in vivo multi-channel recording technique.Methods:Male SD rats were anesthetized with chloral hydrate and fixed on a stereotaxic device for acute surgery and electrophysiological recording;KA was injected into rat’s brain to demage the bilateral NBM;spontaneous discharges were recorded in the hippocampal CA1 area of rats by using a self-made bound recording electrode a week after injection of KA.Results:(1) Compared to the conventional intracellular and extracellular recording,the electrodes-binding technique has the following advantages:the method is quite simple and flexible,with a low cost;the activities from multiple neurons can be recorded simultaneously,and the neuronal circuits and the cross-correlation between neurons can be analyzed;together with spike sorting and multichannel recording,the electrodes-binding technique greatly improves the experiments’ precision and efficiency;(2) The average frequency of the spontaneous discharges in the CA1 area in NBM-lesion rats was significantly lower than that in control rats,which was observed not only in regular firing,but also in burst firing.Meanwhile,the percentage of burst firing in NBM-lesion rats has a significant increase,but the spike frequency in burst and the burst frequency still showed an obvious decline than that in control group.Conclusion:(1) The parallel electrodes-binding technique has multiple advantages in extracellular recording and can be used as a strong and useful electrophysiological tool in the research of neural circuits;(2) The change of the spontaneous discharge frequency and the firing pattern induced by the bilateral NBM lesion indicates that cholinergic system in NBM is involved in the control of neuronal activities in hippocampal circuits,and the NBM-lesion-induced alteration in hippocampal discharges may be helpful to explain the impairment of learning and memory in Alzheimer’s disease.