烟碱和槟榔碱对离体大鼠海马脑片CA_1锥体细胞外诱发电位的影响

在离体Ｗｉｓｔａｒ大鼠海马脑片上，用微电极记录刺激顶树突层Ｓｃｈａｆｆｅｒ侧支引起的ＣＡ＿１区锥体细胞外群峰电位（ＰＳ）。观察用半浸式浴槽或多管微电极气压微量注射给予Ｎ受体激动剂烟碱（Ｎｉｃ）和Ｍ受体激动剂槟榔碱（Ａｒｅ）对ＰＳ的影响，探讨Ｍ和Ｎ受体功能。结果表明：Ｎｉｃ对ＰＳ幅度无明显影响，浓度１．０ｍｍｏｌ／Ｌ时约１／４脑片诱发出第二个群峰电位（ＰＳ＿２），浓度增加，ＰＳ＿２发生率增加，ＰＳ＿２幅度较ＰＳ低。美加明能部分对抗烟碱诱发的ＰＳ＿２，表明ＰＳ＿２出现与Ｎ受休关系密切。Ａｒｅ降低ＰＳ幅度，当浓度达到０．００１ｍｍｏｌ／Ｌ即能使ＰＳ幅度降低为正常的７４％，ＰＳ幅度降低存在有效量关系，低浓度阿托品能选择性地对抗之，表明Ａｒｅ所致ＰＳ幅度下降是通过兴奋Ｍ受体的结果。

EFFECTS OF ARECOLINE AND NICOTINE ON EVOKED FIELD POTENTIALS OF CA_1 PYRAMIDAL CELLS IN HIPPOCAMPAL SLICES OF RAT

In isolated Wistar rat hippocampal slices extracellular population spikes(PS)were evoked by Schaffer collateral stimulation to study their function and relation to mAchR and nAchR.Bath-applied arecoline reduced the amplitude of PS dose-dependently at concentrations ranging from 0.001 to 1.0mmol / L. This reduction could be prevented by atropine,showing the possible involvement of mAchR. Bath-application or pressure injection of nicotine showed no influenceon PS,but could induce second PS(PS_2) in 13 out of 36 slices(36%)at concentrations rangingfrom 1.0 to 5.0mmol / L. PS_2,was also induced by pressure injection of nicotion(100mmol / L)in 5 out of 11 slices (4.5%).The percentage of the occurrence ofPS_2,was decreased from 45.5%to .1%(1 out of 11 slices in presence of mecamylamine 1.0 mmol/ L in the bath).It is suggestedthat nAchR may be involved in PS_2, in some extent.