Effect of uptake inhibitors on the depletion of brain norepinephrine and serotonin after alpha-methyl-m-tyrosine administration to rats.

The depletion of brain norepinephrine after alpha-methyl-m-tyrosine injection into rats was antagonized by pretreatment with an uptake inhibitor (protriptyline or chlorimipramine) but was not completely prevented. Administration of protriptyline after alpha-methyl-m-tyrosine injection, at a time when norepinephrine had been depleted, partially reversed the depletion. Serotonin depletion after alpha-methyl-m-tyrosine was not altered by pretreatment with fluoxetine, an inhibitor of uptake into serotonin neurons. Apparently part of the norepinephrine (but not serotonin) depletion occurring after alpha-methyl-m-tyrosine injection is due to the action of amine products that enter the norepinephrine neuron via the membrane uptake pump and whose presence within the nerve terminals is maintained by the uptake pump.