The effects of some antipsychotic drugs, D-amphetamine, and reserpine on the concentration and rate of accumulation of tryptamine and 5-hydroxytryptamine in the mouse striatum.

The mouse striatum contains about 2 ng/g of tryptamine and 600 ng/g of 5-hydroxytryptamine. No significant changes in mouse striatal tryptamine were observed after the administration of chlorpromazine, haloperidol, spiperone, or alpha-flupenthixol. The levels of 5-hydroxytryptamine were moderately reduced by chlorpromazine, spiperone, and alpha-flupenthixol but not by haloperidol. The administration of antipsychotic drugs to mice pretreated with a monoamine oxidase inhibitor (pargyline) produced an increase in the rate of accumulation of striatal tryptamine compared with that of pargyline-treated mice. In contrast, the rate of accumulation of 5-hydroxytryptamine after monoamine oxidase inhibition was reduced by chlorpromazine, spiperone, and alpha-flupenthixol but not haloperidol. D-Amphetamine administration did not change either tryptamine or its 5-hydroxyderivative while reserpine increased tryptamine and reduced 5-hydroxytryptamine. The results suggest that changes in striatal tryptamine may be controlled by the availability of tryptophan, the amino acid precursor of tryptamine.