The 5-hydroxytryptamine content of mouse brain and whole mice after treatment with some drugs affecting the central...

A number of drugs were examined for their ability to change the concentration of 5-hydroxytryptamine in mouse brain and in whole mice treated with 5-hydroxytryptophan. After beta-phenylisopropylhydrazine or iproniazid, two inhibitors of monoamine oxidase, the brain 5-hydroxytryptamine rose to a maximum value in 8 hr., after which it declined, although a slight rise remained for as long as 6 days. Dose-effect relationships, determined 6 hr. after administration, showed beta-phenyl-isopropylhydrazine to be approximately 60 times as effective as iproniazid in raising the brain 5-hydroxytryptamine. When mice were given 5-hydroxytryptophan and the amine content of the whole mice estimated, pretreatment with beta-phenylisopropylhydrazine increased their 5-hydroxytryptamine content whereas pretreatment with iproniazid did not change it. The concentration of the amine in mouse brain and in whole mice was lower after reserpine, but was raised when reserpine and beta-phenylisopropylhydrazine were given together. A small rise in brain 5-hydroxytryptamine was found after chlorpromazine; when chlorpromazine was given with iproniazid, however, the resulting increase was less than that found after iproniazid alone. Brain 5-hydroxytryptamine was unaltered after prolonged treatment with morphine.