电刺激大鼠巨细胞网状核对小脑浦肯野细胞自发和诱发电活动的影响

本研究在麻醉并制动的大鼠上观察了电刺激巨细胞网状核(Gi)对小脑浦肯野细胞(PC)自发及诱发简单锋电位的影响。结果如下:(1)刺激Gi可使PC的简单锋电位出现潜伏期小于20ms的抑制性或兴奋性反应,并以抑制性反应为主。抑制性反应持续40-100ms,而兴奋性反应的时程可达200ms以上;(2)注射5-HT_2型受体阻断剂methysergide可以减弱或阻断电刺激Gi对PC自发简单锋电位的抑制作用;(3)条件性Gi刺激可以显著压抑或加强由刺激对侧大脑皮层感觉运动区引起的PC诱发简单锋电位反应。以上结果说明:在大鼠存在Gi-小脑通路,这一通路中的部分纤维是5-HT能的。Gi-小脑纤维可能通过突触和/或非经典突触的化学传递方式对PC的电活动产生某种调制性的影响。推测Gi-小脑传入纤维投射可能在某些小脑功能活动,如肌紧张及姿势的调节等方面发挥重要作用。

EFFECT OF STIMULATION OF GIGANTOCELLULARS RETICULAR NUCLEUS ON THE SPONTANEOUS AND EVOKED ACTIVITIES OF CEREBELLAR PURKINJE CELLS IN THE RAT

In anesthetized and paralyzed rats, the effect of stimulation of GigantocellularsReticular Nucleus (Gi) on spontaneous and evoked simple spike discharges of cerebel-lar Purkinje cells (PCs) was examined. The result were as follows: (1) Stimulationof Gi elicited either inhibitory or excitatory effect on spontaneous simple spikes of PCswith latency less than 20 ms, being inhibitory in the most cases. The inhibitory re-sponses lasted for 40--100 ms, while the excitatory ones were sometimes longer than200 ms; (2) Injection of 5--HT_2 recptor antagonist methypergide could reversibly at-tenuate or block the inhibitory effect of Gi stimulation on spontaneous simple spike dis-charges of PCs; (3) The evoked simple spike responses of PCs elicited by stimulatingthe contralateral cerebral sensorimotor cortex could be markedly suppressed or poenti-ated by the conditioning Gi stimulation. The results demonstrated that Gi--cerebellar pathways exists, with some fibers be-ing serotonergic. Gi-cerebellar afferent fibers may have certain modulatory effects onPCs through synaptic and/or non--classical chemical synaptic transmission. The Gi-cerebellar afferent fiber projection may play important roles in some cerebellar func-tions, such as regulating myotonia and posture.