Rapid postmortem changes of rat striatum dopamine, serotonin, and their metabolites as monitored by brain microdialysis

Brain microdialysis was used to monitor changes in extracelluar dopamine (DA), serotonin (5-HT), and their metabolite levels in the rat striatum at death by cervical dislocation. Maximum respective 450-fold and 150-fold increases in the extracelluar output of DA and 5-HT were observed within the first 30 min of death. DA and 5-HT outputs remained elevated over the following 2 h at levels about 100-fold and 50-fold above pre-death values, respectively. In contrast with monoamine outputs, the outputs of the DA metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), and the 5-HT metabolite, 5-hydroxyindoleacetic acid (5-HIAA), rapidly decreased by 10% and 20%, respectively 1 h after death. 5-Hydroxytryptophol (5-HTOL) gradually decreased after death. Before death both the extracellular DOPAC/DA and 5-HIAA/5-HT ratios were about 400; after death these ratios dropped to 0.56 and 4.0, respectively at 30 min. These observations suggested that regulation of neurotransmitter releases through the neuronal membrane and metabolisms in the rat striatum were seriously disrupted at death. This finding may be helpful in the determination of death in the field of forensic medicine.