[Dynamic changes of striatal monoamines with in vivo microdialysis in ischemic rats]

Using intracerebral microdialysis, high performance liquid chromatography and electrochemical detection (HPLC-ECD), we determined the contents of extracellular dopamine (DA), serotonin (5-HT) and their metabolites 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid(HVA) and 5-hydroxy-indole acetic acid (5-HIAA) in the striatum of rats after the occlusion of middle cerebral artery (MCAO). The dialysis tube was implanted stereotaxically in the lateral 2/3 of the striatum. No significant effects of stressors were noted on the concentration of neurotransmitter mentioned above. A step rise of extracellular DA and 5-HT accompanied by significant reduction of DOPAC, HVA and 5-HIAA was found 10 minutes after MCAO. From then on, the enhanced concentrations of DA and 5-HT decreased gradually. At 3 hours after MCAO, however, DA and 5-HT were still high with respect to the basal levels. Their metabolites were kept at low levels at 3 hours of MCAO. In conclusion, the massive leakage of DA and its over production of oxygen free radicals are important for the development of ischemic cell damage in the striatum.