The Alterations of Unit Discharges of Hippocampal Formation in Acupuncture Analgesia / 第三军医大学学报

ABSTRACT

The actions of the hippocampal formation were studied by recording the electrical activities of a single neuron of that area. Two different reactions of some neurons in CAl, CA2 and the dentate gyrus might occur after peripheral noxious stimulations, that is, the increasing of the reaction frequency of the nociceptive excited neurons(NEN) and the decreasing of the reaction frequency of the nociceptive inhibited neurons (NIN). Electrical acupuncture of the "points" would result in inhibiting effect on most of the NENs but disinhibiting effect on NINs, Identical effect to that of acupuncture could be created by injecting morphine to the experimental animals. Electrical stimulation of the nucleus raphe magnus or para-aqueduct gray matter(PAG) could affect the NENs and NINs in the hippocampus, and the results were similar to that of acupuncture. When 5-HT was injected into the lateral ventricle or applied to the hippocampal neurons through micro-iontophoresis, effects similar to that of acupuncture also occurred. These facts imply that the effects of peripheral "point" acupuncture on the electrical activities of the neurons of the hippocampal formation might be related to the activities of the endogenous 5-HTergic neurons, or to the endogenous morphine-like substance. The NENs would be inhibited after large amounts of GABA were injected into the lateral ventricle. The inter-relationship between this phenomenon and the activities of GABAergic interneu.rons in the hippocampus awaits further investigation.