Dynamic changes of dopamine and its metabolite levels in the rat striatum after cerebral ischemia-reperfusion and electroacupuncture

OBJECTIVE: To explore the involvement of dopamine (DA) and its metabolites in the extracellular fluid of the striatum on the resisting action of electroacupuncture (EA) for acute cerebral ischemia-reperfusion (CI/R) injury. METHODS: A total of 50 SD male rats were randomly divided into normal control, sham-operation (sham), sham + EA, CI/R model, CI/R + EA groups. CI/R model was induced by right middle cerebral artery occlusion (MCAO) for 90 min and reperfusion for 225 min. EA (2 Hz, 3 mA, continuous waves) was applied to "Fengchi" (GB 20) for 20 min, with a 10 min rest, and given once again fo 20 min. The concentrations of DA and its metabolites [3,4- dihydroxy-phenyl acetic acid (DOPAC) and homovanillic acid (HVA)] in the extracellular fluid of the striatum were determined by microdialysis and high performance liquid chromatography (HPLC). RESULTS: The extracellular levels of DA, DOPAC and HVA in normal group, sham group and sham+ EA group had no significant changes during the whole study. The extracellular level of DA peaked 15-45 min after CI and 0-30 min after CI/R (P < 0.05). A rising trend was also observed 120 min following CI/R. DOPAC level peaked 15 min and 75 min after CI and 75 min after CI/R. After EA, DA level was significantly lower in EA group than that in model group 90 min after CI/R (P < 0.05), and no peak was observed again. After EA, DOPAC level maintained its basic level, and no peak was found after CI/R. The changing trend of HVA was similar to that of DOPAC, and the extracellular HVA level in EA + model group was significantly lower than that in model group 75 min after CI/R. CONCLUSION: EA can decrease the accumulation of DA and its metabolites in the extracellular fluid of the striatum, which may contribute to its effect in preventing the brain from CI/R injury.