An inhibitory role for brain serotonin-containing systems in the locomotor effects of d-amphetamine.
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.
D000818:Animals; D001921:Brain / Q000378:metabolism / Q000502:physiology*; D002395:Catecholamines / Q000378:metabolism; D003913:Dextroamphetamine / Q000378:metabolism / Q000494:pharmacology*; D004032:Diet; D010134:Fenclonine / Q000494:pharmacology; D005508:Food Deprivation; D006897:Hydroxyindoleacetic Acid / Q000494:pharmacology; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D010293:Pargyline / Q000494:pharmacology; D011339:Probenecid / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000502:physiology*; D013268:Stimulation, Chemical; D014364:Tryptophan / Q000494:pharmacology
D002395:Catecholamines; D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D010293:Pargyline; D011339:Probenecid; D010134:Fenclonine; D003913:Dextroamphetamine