An inhibitory role for brain serotonin-containing systems in the locomotor effects of d-amphetamine
Hollister, A.S.; Breese, G.R.; Kuhn, C.M.; Cooper, B.R.; Schanberg, S.M.
Journal of Pharmacology and Experimental Therapeutics 198(1): 12-22
1976
ISSN/ISBN: 0022-3565 PMID: 132524 Document Number: 107875
Locomotor activity induced by d-amphetamine was found to be potentiated by food deprivation, a tryptophan-free diet, p-chlorophenylalanine and drugs proposed to antagonize serotonin receptors in brain. Administration of L-tryptophan 1 hour prior to d-amphetamine injection was found to antagonize the enhanced response to d-amphetamine in starved rats and in rats which had tryptophan removed from their diet. However, tryptophan did not block the potentiated response to d-amphetamine in animals pretreated with p-chlorophenylalanine. These findings suggested that the antagonism of d-amphetamine-induced activity by tryptophan in starved rats and rats fed a tryptophan-free diet was not due to a nonspecific depressant effect of the amino acid. Since accumulation of d-amphetamine and its metabolites was not affected by any of the treatments which enhanced its activity, it seems unlikely that an alteration in the metabolism of d-amphetamine can explain these findings. The present work provides additional support for the view that serotonergic fibers play an important role in the actions of d-amphetamine.