Effect of amphetamine and fenfluramine on brain noradrenaline and MOPEG-SO4.

I.p. administration of d-amphetamine sulphate and fenfluramine-HCl at various doses induced significant modifications of brain noradrenaline (NA) and MOPEG-SO4 (3-methoxy-4-hydroxyphenylethyleneglycol) in the rat. Both drugs induced a decrease in brain noradrenaline but the two compounes seem to interact with the central noradrenergic system through a different mechanism. The decreased levels of noradrenaline after 1-fenfluramine administration were paralleled by increased MOPEG-SO4 levels. The d-isomer of fenfluramine was less active than the l-isomer. Amphetamine was considerably more effective than l-fenfluramine in reducing NA concentration. However, in spite of the long lasting effect on noradrenaline levels the i.p. administration of amphetamine did not lead to an increased MOPEG-SO4 concentration suggesting a more complex interaction with the noradrenergic system.