The distribution and turnover of tryptamine in the brain and spinal cord

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Abstract
Tryptamine levels have been determined in mouse brain regions and spinal cord and in rat spinal cord. They were; caudate nucleus 2.5 ng·g−1, hypothalamus −1, hippocampus −1, olfactory bulb −1, olfactory tubercles −1, brain stem −1, cerebellum −1, and the “rest” 0.9 ng·g−1. The mouse whole brain was found to have 0.5 ng·g−1, the mouse spinal cord 0.3 ng·g−1, and the rat spinal cord 0.3 ng·g−1. These concentrations increased rapidly to 22.8 ng·g−1, 14.2 ng·g−1, and 6.6 ng·g−1 respectively at 1 hr after 200 mg·kg−1 pargyline. The turnover rates and half lives of tryptamine in the mouse brain and spinal cord and rat spinal cord were estimated to be 0.14 nmol·g−1·h−1 and 0.9 min; 0.054 nmol·g−1·h−1 and 1.5 min and 0.04 nmol·g−1·h−1 and 1.6 min respectively. The aromaticl-aminoacid decarboxylase inhibitors NSD 1034 and NSD 1055 reduced synthesis of tryptamine in controls and pargyline pretreated animals. Tryptophan increased the concentrations of mouse striatal tryptamine and 5-hydroxytryptamine and brain stem 5-hydroxyindole acetic acid.p-Chlorophenylalanine reduced formation of 5-hydroxytryptamine and 5-hydroxyindoleacetic acid but did not change that of tryptamine.