Effect of p-nitromethylamphetamine on biogenic amines and their amino-acid precursors in rat brain.

1. Low doses of p-nitromethylamphetamine caused small increases in the concentrations of brain noradrenaline and dopamine in the rat; a dose of 60 mg/kg however, caused a decrease in the concentrations of both amines. p-Nitromethylamphetamine caused behavioural hyperexcitability only at doses which approximated to half the LD50 (68 mg/kg).2. p-Nitromethylamphetamine potentiated the action of 4,alpha-dimethyl-m-tyramine in depleting brain noradrenaline. This suggests that it may affect brain noradrenaline concentrations by utilizing a reserpine resistant uptake mechanism.3. p-Nitromethylamphetamine decreased the concentration of brain 5-hydroxytryptamine.4. Changes in the blood and brain concentrations of tyrosine and gamma-amino-n-butyric acid concentration in the brain could not be correlated with the changes in brain amines. However, a rise in the concentration of brain tryptophan appeared to be correlated with the fall in brain 5-hydroxytryptamine.