Background As a main suppressing neurotransmitter in visual system,gamma-aminobutyric acid (GABA) participates in the transmission and regulation of visual information.GABA and dopamine (DA) coexist in the visual cortex,and their mutual effects should be clarified.Objective This study was to investigate the effect of DA on GABA-activated current in vitro in cultured visual cortical neurons of rats.Methods Neutrons from visual cortex of clean neonatal rats were isolated and cultured by explant culture method.The neutrons cultured for 11 -to 14- days were collected for the record of whole cell currents of GABA-A (IGABA) channels in vitro using patch clamp technique.The DA solution (100mmol/L),SKF38393 (10mmol/L) solution and quinpirole solution(10mmol/L) were prepared with double distilled water and then the extracellular fluid was added to different concentrations.The IGABA changing rate under the action of SKF38393+SCH23390,SKF38393+Quinpirole for different time was recorded respectively and compared with that of action of DA,SKF38393,SCH23390,Quinpirole.The IGABA activated by extracellular fluid along served as control.Results The IGABA was significantly attenuated after activated by ≥10μmol/L of DA or SKF38393 separately in comparison to that of extracellular fluid action (P＜0.05).In various time of action,there were obviously differences in IGABA between DA or SKF38393 action and extracellular fluid (P＜0.05,P＜0.01).No evident change in IGABA changing rate was found after only SCH23390 action in comparison with extracellular cells (P＜0.05).However,after combination of SCH23390 and SKF38393,IGABA changing rate reduced by 19.49%.No significant differences were found in the changing rates of IGABA among different concentrations of quinpirole action groups compared with extracellular fluid group (P＞0.05);while when quinpirole was combined with SKF38393,the IGABA was elevated in comparison with only SKF38393 action group (P＜0.05).Conclusion Dopamine participates in the transfer and regulation of visual information through suppressing GABA-activated currents from neutrons of visual cortex at time-dependent manner in vitro.%背景 γ氨基丁酸(GABA)作为视觉系统主要的抑制性神经递质参与视觉信息的传递和调控.视皮层中GABA和多巴胺(DA)共存,其生理意义,尤其是对GABA能神经元介导的中枢抑制的影响尚待阐明.目的 探讨DA对培养大鼠视皮层神经元GABA-激活电流(IGABA)的影响.方法 取出生后1～3 d清洁级SD大鼠,采用酶消化法取大鼠视皮层神经元进行原代培养.选取培养第11~14天大鼠视皮层神经元,应用膜片钳技术以全细胞模式记录IGABA.首先以双蒸水将DA配制成100mmol/L的母液,将D1受体选择性激动剂SKF38393和D2受体选择性激动剂Quinpirole均配制成10mmol/L的母液,再用细胞外液配置成所需的浓度.分别记录SKF38393+SCH23390、SKF38393+ SKF38393或SKF38393+Quinpirole刺激条件下诱发的IGABA的变化率,并与单独应用DA、SKF38393、SCH23390、Quinpirole诱发的IGABA的变化率进行比较.仅用细胞外液诱发培养细胞的IGABA作为对照.结果 ≥10μmol/L的DA与SKF38393单独作用后,IGABA 均出现明显下降,与对照组相比差异均有统计学意义(P＜0.05).随着DA和SKF38393作用时间的延长,IGABA 均明显下降,与对照组相比差异均有统计学意义(P＜0.05,P＜0.01).单独应用SCH23390作用1~6min后,与对照组比较IGABA的差异无统计学意义(P＜0.05);联合应用SCH23390与SKF38393后,IGABA变化率较单独应用SKF38393减少19.49%.单独应用Quinpirole对IGABA无明显影响,与对照组比较IGABA的差异无统计学意义(P＞0.05).SKF38393及Quinpirole联合应用时与单独应用SKF38393比较,IGABA的抑制作用减弱.结论 DA通过作用于视皮质神经元的GABA-激活电流而参与视觉信息的传递和调控.
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