In the present study, we used in vivo brain microdialysis to examine the effects of
ion channel blockers
tetrodotoxin (TTX),
EGTA-free Ca2+ and
verapamil on rapid
postmortem changes in extracellular levels of
dopamine (DA),
serotonin (5-HT) and their metabolites dihydroxyphenylacetic
acid (
DOPAC) and 5-hydroxyindoleacetic
acid (5-HIAA) in the ACC of freely moving rats. Extracellular ACC DA levels decreased following the perfusion of the three
ion channel blockers in freely moving rats, and then, at death by cervical dislocation, maximum respective 220-, 60- and 90-fold increases were observed in the extracellular output of DA in animals treated with
EGTA,
verapamil and TTX, respectively. Also, ACC
5-HT decreased following perfusion with the three blockers in the freely moving rats, and then maximum increases of 80-, 30- and 45-fold in the extracellular output of
5-HT were observed at death in animals treated with
EGTA,
verapamil and TTX, respectively, compared to the baseline. Cervical dislocation-induced rapid
postmortem changes were inhibited markedly by perfusion with CSF containing the CA2+ entry blocker
verapamil. These observations suggested that rapid
postmortem changes in ACC DA and
5-HT release were associated with the action of
calcium ion channels and/or voltage gated channels in the CNS.