大鼠海马神经元群体对于高频电刺激的响应

Response of Neuronal Population to High Frequency Electrical Stimulation in Rat Hippocampus

脑深部电刺激(DBS)在帕金森和癫痫等疾病治疗中的应用不断发展,但DBS对于神经元的作用机制尚无定论。为了研究DBS对于大脑神经网络的作用,在麻醉大鼠海马CA1区的输入和输出轴突纤维上,分别施加正向和反向高频电刺激(HFS),考察CA1区锥体神经元的同步动作电位(即群峰电位)发放情况。结果表明,50 Hz的正向HFS可以诱发持续发放的群峰电位,而100和200 Hz的正向HFS诱发的群峰电位却要少得多。在不同频率的反向HFS中,每个刺激脉冲均诱发群峰电位,但它们的幅值逐渐减小;而且,刺激频率越高,幅值减小得越快。可见,作用于轴突的HFS对于上游和下游神经元群体都具有兴奋作用,但频率越高,兴奋作用越小。这些结果,对于深入了解DBS的作用机制以及安全有效地推广其临床应用都具有重要的意义。

Deep brain stimulations （DBS） have been developed for treating brain diseases such as Parkinson＇ s disease and epilepsy. But the mechanisms underlying DBS are not clear yet. In order to study the effects of DBS on the neural networks of brain, both orthodromic- and antidromic-high frequency stimulation （HFS） were respectively applied on afferent fibers and efferent fibers of the hippocampal CA1 region in anaesthetized rats. Synchronized firings of neuronal action potential （i. e. , population spike, PS） of CA1 pyramidal cells were examined. Results showed that 50 Hz orthodromic-HFS induced persistent PS firings, while 100 and 200 Hz orthodromic-HFS induced much less PS firings. During antidromic-HFS with different frequencies, every stimulation pulse evoked a PS. However, the PS amplitude decreased gradually. The decrease of PS amplitude was more rapid with higher stimulation frequency. Taken together, the HFS of axons has excitatory effects on the neuronal populations both upstream and downstream. But the higher the stimulation frequency is, the less the excitatory effect is. These results are important for the further understanding of DBS mechanisms and for the safe and effective application of DBS in clinic.