Dopamine-like properties of ephedrine in rat brain.

1 Ephedrine (3.1-50 mg/kg) was given intraperitoneally to rats and was found to cause a marked increase in spontaneous locomotor activity. 2 In rats with a unilateral lesion in the substantia nigra made by stereotaxic injections of 6-hydroxydopamine, ephedrine (12.5-150 mg/kg i.p.) caused a dose-dependent turning towards the lesioned side. 3 Turning behaviour and increase in locomotion produced by ephedrine were antagonized by pretreatment of the animals with pimozide, amino-oxyacetic acid or reserpine plus alpha-methyl-p-tyrosine, but not by pretreatment with phenoxybenzamine, propranolol or methergoline. 4 In in vitro studies with synaptosomes prepared from rat brain, ephedrine blocked the uptake and caused the release of [3H]-dopamine. 5 Similar results with regard to locomotion and turning behaviour were obtained with (+)-amphetamine. 6 It is concluded that the increase in locomotion and turning behaviour produced by ephedrine is mediated through an indirect dopaminergic mechanism.