Tryptophan and biogenic amine metabolites in post-mortem human cisternal fluid: effects of post-mortem interval and agonal time.

Cisternal fluid (CF) tryptophan (TRP), 5-hydroxyindole-3-acetic acid (5-HIAA), 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 3-methoxy-4-hydroxyphenylglycol (MHPG) concentrations were measured from 40 adult cadavers. They were divided into 4 groups (n = 10 in each group), with samples taken 2, 4, 10 and 24 h after death. The CF concentrations of TRP and all determined biogenic amine metabolites were distinctly higher than in lumbar CSF during life, and concentrations of 5-HIAA were also higher in post-mortem samples than in cisternal or ventricular CSF in living humans. The means of the samples of 5-HIAA, DOPAC, HVA and MHPG were not statistically significantly different over time, but some trends were evident. TRP concentrations in CF increased linearly with time (from 4.6 to 23.6 mumol/l, P less than 0.001). CF DOPAC and HVA concentrations were dependent on agonal time and dopamine infusions. Our results imply that both ante-mortem and post-mortem conditions may influence monoamine metabolite and TRP concentrations in CF. These conditions should be accounted for in studies using post-mortem samples to study differences between patient groups in CNS neurochemistry.