Microiontophoretic studies of the effects of false transmitter candidates and amphetamine on cerebellar Purkinje cells

Abstract

The effects of microiontophoretic applications of equivalent doses (ejection times and currents) of noradrenaline, amphetamine, octopamine and p-hydroxynorephedrine on the spontaneous firing of Purkinje and unidentified cells in the cerebellum of rats were examined. In addition, the effects of amphetamine of Purkinje cells were examined in animals pretreated with the tyrosine hydroxylase inhibitor, alpha-methyltyrosine (alpha-MpT) or with a combination of reserpine plus alpha-MpT. The results indicate that the "false transmitters" are weak agonists when compared to noradrenaline in inhibiting the firing of Purkinje cells. The results of the iontophoretic studies with amphetamine are not consistent with a pre-synaptic releasing effect by amphetamine at noradrenergic synapses in the cns since the efficacy of amphetamine on Purkinje cells was unaltered after pretreatment with alpha-MpT or alpha-MpT plus reserpine.