The effects of imidazole-4-acetic acid on cerebral indole amine metabolism.

The effects of imidazole-4-acetic acid (IMA, 100–400 mg/kg) on indole amine metabolism were studied by measurement of the cerebral hemisphere and brain stem contents of tryptophan, 5-hydroxytryptophan (5-HTP), 5-hydroxytryptamine (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA). The results indicated that IMA does not alter the steady-state contents of brain indole amines. Furthermore, IMA failed to alter the levels of 5-HTP, 5-HT, or 5-HIAA in animals pretreated with 3-hydroxybenzyl hydrazine (a decarboxylase inhibitor), pargyline (a monoamine oxidase inhibitor), or probenecid (a compound which blocks 5-HIAA transport out of brain). These results suggest that altered serotonin metabolism is not a factor in the genesis of the behavioral or electroencephalographic changes produced by IMA.