The effects of phenylpropanolamine and other sympathomimetics on food consumption and motor activity in mice.

The effects of phenylpropanolamine on motor activity and on food intake were compared with those of S-amphetamine, ephedrine, 2-aminoindane and fenfluramine in groups of mice. Motor activity was additionally measured in mice pretreated with levodopa and benserazide, and food intake in mice pretreated with alpha-methyl-p-tyrosine. Amphetamine (2.5 mg kg-1) increased motor activity, phenylpropanolamine (10-40 mg kg-1) and 2-aminoindane (2.5-10 mg kg-1) decreased activity whilst ephedrine (2.5-40 mg kg-1) had a biphasic effect. Fenfluramine (10-40 mg kg-1) had negligible effect on activity. In mice pretreated with levodopa and benserazide both phenylpropanolamine and 2-aminoindane caused a massive increase in motor activity whilst fenfluramine's action was not affected in the same way. Whilst the anorectic action of fenfluramine was considerably potentiated in mice pretreated with alpha-methyl-p-tyrosine, that of amphetamine, ephedrine, 2-aminoindane and phenylpropanolamine was either unaffected or initially antagonized. It is concluded that the mechanisms of motor and anorectic actions of phenylpropanolamine are similar to those of amphetamine.