Ethanol effects on harmaline-induced tremor and increase of cerebellar cyclic GMP

The spectra of pharmacological effects of ethanol and the benzodiazepines show a degree of overlap. Neurophysiological and neurochemical evidence indicates that both ethanol and benzodiazepines facilitate inhibitory neurotransmission mediated by GABA. Diazepam has been reported to inhibit both the tremor and increase of cerebellar cyclic GMP caused by harmaline by a mechanism postulated to involve enhancement of GABA-mediated neurotransmission in the cerebellum. Because of the similarities between ethanol and benzodiazepines, the effects of ethanol on harmaline-induced tremor and increase of cerebellar cyclic GMP were studied. Ethanol inhibited harmaline-induced tremor at doses as low as 0.1 g/kg. At this low dose, however, a dissociation between inhibition of harmaline tremor and inhibition of the harmaline-induced increase of cerebellar cyclic GMP was observed.