电刺激多巴胺能神经纤维或末梢对纹状体多巴胺释放的影响

EFFECTS OF ELECTRICAL STIMULATION OF THE DOPAMINERGIC NERVE FIBER OR NERVE TERMINAL ON STRIATAL DOPAMINE RELEASE IN THE RAT

采用快速周期伏安法，以碳纤维微电极在体研究了电刺激黑质－纹状体多巴胺（ＤＡ）能神经通路前脑内侧束（ＭＦＢ）或刺激纹状体内的神经纤维末梢对纹状体ＤＡ释放量的影响。结果如下：电刺激ＭＦＢ与刺激纹状体诱发纹状体的ＤＡ释放量明显不同。二者的ＤＡ释放量取决于所用的刺激强度、脉冲和频率；当给予２．０ｍＡ，２００次脉冲，１２５Ｈｚ电刺激ＤＡ能神经纤维ＭＦＢ时，可诱发纹状体（２１．５６±５．７７）μｍｏｌ／Ｌ的最大ＤＡ释放量，而在ｎｏｍｉｆｅｎｓｉｎｅ存在的前提下，给予０．１０ｍＡ，３０次脉冲，２０Ｈｚ电刺激纹状体ＤＡ能神经末梢时，仅诱发（９．０２±２．７２）μｍｏｌ／Ｌ的最大ＤＡ释放量。以上结果表明，尽管刺激强度、脉冲、频率均构成影响ＤＡ释放的相关因素，但刺激ＤＡ能神经纤维和末梢诱发的ＤＡ释放量及所用刺激参数均不相同，提示在刺激不同部位的实验研究中，应重视适宜刺激参数的选择和应用，以便获得更好的实验结果。

Stimulusevoked dopamine(DA) release from the striatum(Str) was examined by means of fast cyclic voltammetry with carbonfiber microelectrodes in vivo.Squarewave electrical stimulation was used to stimulate nigrostriatal dopaminergic nerve pathwaymedian forebrain bundle(MFB) or dopaminergic nerve terminal in the striatum.We found that:In the absence of the DA uptake inhibitor(nomifensine),electrical stimulation of MFB resulted in DA release in the Str,while DA release following intrastriatal stimulation could only be monitored in the presence of nomifensine.In both cases,DA release was dependent on the intensity,number of pulses and frequency of the electrical stimulation.When stimulation of MFB at 2.0 mA,200 pulses and 125 Hz was applied,DA release within Str reached maximum of (21.56577) mol/L without nomifensine,but stimulation of dopaminergic nerve terminal at 0.1mA,30 pulses and 20 Hz produced the maximun of (9.02272) mol/L only even in the presence of nomifensine.Our data suggest that although the stimulatory parameters(intensity,pulse number,and frequency)influence the amount of DA release,different parameters should be used according to the different sites of stimulation in order to get the maximal DA release during the experiment.