Studies of chlorpromazine-induced enhancement of the potentials evoked by peripheral stimulation of the cat cerebellum.
1) In the experiments reported here, we investigated effects of CPZ on the amplitude of cerebellar potentials using decerebrated or spinal cat; furthermore, we also examined the effects of microinjecting CPZ, DA or NE into the precerebellar nuclei on the amplitude of the cerebellar potentials. 2) Purkinje cell spontaneous discharge was either hardly changed or was depressed by CPZ. 3) CPZ did not change the potentials evoked by peripheral stimulation on the dorsal surface of the spinal cord. 4) CPZ depressed significantly the cerebellar potentials evoked by stimulation of the nucleus reticularis lateralis (LRN) or nucleus olivaris inferior (ION) in intact, decerebrated and spinal cats. 5) The cerebellar potentials evoked by the peripheral nerve stimulation were increased by microinjection of CPZ into the bilateral LRN but not into the bilateral ION. Microinjection of NE or CPZ into the contralateral LRN hardly influenced the cerebellar evoked potentials. 6) Although electrical stimulation at high frequencies of the ipsilateral LRN depressed significantly the cerebellar evoked potentials; similar stimulation after i.v. pretreatment of CPZ failed to affect them. Microinjection of CPZ into the ipsilateral LRN enhanced the cerebellar evoked potentials, and microinjection of NE or DA depressed them significantly. Furthermore, after pretreatment with CPZ, microinjection of DA failed to depress the potentials. 7) We suggest that intravenous CPZ-induced enhancement of the cerebellar potentials may be due to depression of the descending inhibitory mechanism, resulting from CPZ-induced blockage of the catecholamine receptors of the ipsilateral LRN and of the spinal level.
Hagiwara
Y
Y
Department of Pharmacology, Showa College of Pharmaceutical Sciences, Tokyo, Japan.
Suzuki
Y
Y
D000818:Animals; D002415:Cats; D002531:Cerebellum / Q000187:drug effects*; D002746:Chlorpromazine / Q000494:pharmacology*; D003655:Decerebrate State; D004298:Dopamine / Q000494:pharmacology; D005071:Evoked Potentials / Q000187:drug effects; D005260:Female; D008297:Male; D008845:Microinjections; D009638:Norepinephrine / Q000494:pharmacology; D011689:Purkinje Cells / Q000187:drug effects; D013116:Spinal Cord / Q000502:physiology
D002746:Chlorpromazine; D004298:Dopamine; D009638:Norepinephrine