谷氨酸对家鸽顶盖脑片Ⅱa～f亚层神经元自发电活动的影响

Effects of glutamate on the spontaneous discharge of sublayer Ⅱ a-f neurons in pigeon optic tectum slices

应用离体脑片技术，胞外记录观察了家鸽顶盖Ⅱa～f亚层神经元的自发放电特征，以及灌流和微电泳给予谷氨酸（glutamate，Glu）及其受体措抗剂谷氨酸二乙酯（glutamatediethylester，GDEE）对自发电活动的影响．在46例脑片上观察了80个Ⅱa～f亚层神经元的自发放电活动，其放电形式有3种：慢而不规则型（50个，占62．5％）；连续重复放电型（24，占30．0％）；周期性簇状放电型（6个，占7．5％）．分别用灌流和微电泳方式给予Glu后，受试神经元均出现明显的增频反应，且呈现剂量一效应关系．GDEE对自发放电有抑制作用，且能阻断Glu的兴奋作用一以上结果提示，家鸽顶盖Ⅱa～f亚层内存在Glu敏感神经元，外源性的Glu对这些神经元有兴奋作用，Glu可能作为神经递质参与了家鸽顶盖Ⅱa～f亚层神经元的活动．

The properties of the spontaneous discharge recorded extracellularly in sublayer Ⅱ a-f neurons wereobserved in pigeon optic tectum slices using in vitro technique. Effect of glutamate (Glu) and its antagonist glutamatic diethylester (GDEE) applied perfusedly and microiontophoretically on the discharge wereanalysed. The spontaneous discharge of 80 sublay Ⅱ a-f neurons in 46 slices were divided into 3 pot.terns: slow and irregular discharge (n = 50, 62. 5%), continous repetitive discharge(n = 24,30%), phasic burst firing (n =6, 7.5%). Respectively, perfused and microiontophoresis with Gln,the firing rate of the tested neurons were both significantly increased (P<0.01), and showed an obvious dose-dependent relation. GDEE decreased the frequency of the spontaneous discharge, and blockedthe excitation ary effect of Glu. It is suggested that there are some GlU sensitive neurons in sublayerⅡ a- f of pigeon optic tectum, the most of which show excitation to exogeous Glu. These data observedin slices provide a strong evidence that Glu may act as a neurotransmitter involving in the activity of thesublayer Ⅱa-f neurons in pigeon optic tectum