EFFECTS OF LONG-TERM RECOVERY FROM TRANSIENT CEREBRAL-ISCHEMIA IN RAT-BRAIN - TISSUE-LEVELS OF ACETYLCHOLINE, MONOAMINES, AND THEIR METABOLITES

Concentrations of acetylcholine and the monoaminergic neurotransmitter s dopamine, serotonin and their respective metabolites 3,4-dihydroxyph enylacetic acid (DOPAC), 4-hydroxy-3-methoxyphenylacetic acid (HVA), 5 -hydroxyindolacetic acid (5-HIAA) and choline were simultaneously dete rmined in the corpus striatum of rats after 15 min. complete cerebral ischemia (CCI) and in different intervals (1, 24, 48, 72, 96 hours) of postischemic cerebral reperfusion. Results were compared to respectiv e sham-operated control animals. After 15 min. CCI acetylcholine conce ntration decreased to 15%, and dopamine concentration to 56% of the co ntrol values. The metabolite levels of DOPAC decreased to 40% and HVA to 64% of the control values. Acetylcholine, dopamine, serotonin and c holine concentrations were not changed significantly after reperfusion . The metabolites HVA and 5-HLAA showed their maximum increases after 1 and 24 hours of reperfusion, additionally HVA was decreased both, af ter 72 and 96 hours of reperfusion. The data indicate that surprisingl y little permanent damage could be caused by a 15 min. ischemia in the striatum. Tissue levels of the neurotransmitters appeared differentia lly altered but similarly regulated during ischemia and subsequent rec irculation. Acetylcholine and dopamin levels decreased profoundly duri ng ischemia. However, acetylcholine levels could be compensated rapidl y during reperfusion, whereas the dopaminergic system showed a long-la sting change in its turnover rate. Although serotonin levels were unaf fected by CCI, there was an increase of its presumed turnover rate dur ing reperfusion.