Temporal effects of p-chloroamphetamine on catecholamine synthesis.

Within 0.25 h after the administration of 5 mg/kg of p-chloroamphetamine (PCA), the conversion index of both norepinephrine (NE) and dopamine (DA) was increased. The effect on DA synthesis was similar, but of less magnitude after 1.25 h, while the effect on NE was reversed, i.e. the conversion index was decreased. This biphasic effect of PCA on NE synthesis is discussed the in the context of two opposing regulatory mechanisms for neuronal catecholamine synthesis.