Postmortem serotonin levels in cerebrospinal and pericardial fluids with regard to the cause of death in medicolegal autopsy

Serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter in the central nervous system (CNS) and a smooth muscle regulator in the cardiovascular and gastrointestinal systems. The present study investigated postmortem 5-HT levels in cerebrospinal fluid (CSF) and pericardial fluid (PCF) with regard to the cause of death in serial medicolegal autopsy cases within 48 h postmortem (n = 351, >20 years of age). CSF and PCF 5-HT slightly increased during the postmortem period (r = 0.298 and 0.253, respectively, p < 0.001), showing no gender-related difference. The CSF level decreased depending on the subject age (r = 0.497, p < 0.001); however, the CSF and PCF levels showed similar findings with regard to the cause of death: these levels were significantly higher for sedative-hypnotic drug intoxication and hyperthermia (heat stroke), but lower for blunt head injury and hypothermia (cold exposure); the cutoff value was estimated as 25.5 ng/ml and 5.0 ng/ml, respectively. For other cause of death groups, some cases showed a higher level. These findings suggest elevations in CSF and PCF 5-HT levels due to systemic toxic or hyperthermic neuronal dysfunction, and systemic stress responses to trauma without CNS involvement.