微电泳GABA和5－HT对大鼠丘脑束旁核单位痛放电的影响

EFFECTS OF MICROIONTOPHORETICALLY APPLIED GABA AND 5-HT ON THE ELECTRIC ACTIVITIES OF NEURONS IN NUCLEUS PARAFASCICULARIS OF THALAMUS IN RATS

本实验用多管微电极细胞外记录和离子微电泳方法，在水含氯醛麻醉的ＳＤ大鼠上观察了γ－氨基丁酸（ＧＡＢＡ）和５－羟色胺（５－ＨＴ）以及它们的受体阻断剂（印防已毒素和赛庚啶）对丘脑束旁核（Ｐｆ）单位痛放电的影响。结果表明：（１）电泳ＧＡＢＡ可抑制Ｐｆ神经元的痛放电，这作用可被电泳印防已毒素所阻断，而单独电泳印防己毒素可加强Ｐｆ的痛放电。（２）电泳５－ＨＴ对Ｐｆ单位痛放电在有些单位表现加强作用，另一些单位表现抑制作用，仅前者可被电泳赛庚啶所阻断。上述结果提示：在Ｐｆ神经元的痛放电活动中，ＧＡＢＡ可能起抑制性作用，而５－ＨＴ可能通过不同的受体亚型既发挥其兴奋作用，也可有抑制作用。

The effects of GABA and5-HTon the electric activities of neurons of nucleusparafascicularis thalami(Pf)were observed in anesthetized rats with multimicropipeteand iontophoresis and technique.It was found that:(1) Pain discharges of the Pf neurons were inhibited by microiontophoretically applied(MIA) GABA, an effect thatcould be reversed by MIA picrotoxin. Picrotoxin alone could enhance the pain discharges.The results indicate that GABA may be an inhibitory neurotransmitter responsible for the electric activities of Pf neurons. (2) MIA 5-HT has both excitstory andinhibitory effects on the pain discharge of Pf neurons, while only the former could beblocked by MIA cyproheptadine.It was suggested that 5-HT may particioate in themodulation of the electric activities of the Pf neurons with different subtypes of receptors.