Effects of intravenous cocaine administration on cerebellar Purkinje cell activity

The goal of the present study was to investigate the effects of intravenous cocaine administration on cerebellar Purkinje cell firing. Extracellular n euron activity was recorded and cells were locally excited with spaced micr oiontophoretic pulses of glutamate. Glutamate-evoked and spontaneous discha rges were compared before and immediately following cocaine administration. Cocaine injections (1.0 and 0.25 mg/kg, i.v.) induced a reversible suppres sion of both spontaneous activity and glutamate-evoked excitation. Procaine was ineffective in producing similar actions. Cocaine only inhibited gluta mate-induced excitation in animals pre-treated with reserpine (5 mg/kg. i.p .). Propranolol injections (10 mg/kg, i.p.) were ineffective in blocking co caine-induced inhibitions. Yohimbine (5 mg/kg, i.p.) pre-treatment abolishe d cocaine-induced suppressions of either spontaneous or glutamate-evoked ex citation. Therefore, cocaine administration decreases Purkinje cell spontan eous and glutamate-evoked discharges by a mechanism involving alpha (2)-adr enoceptor activation. It is suggested that by changing the normal function of the cerebellum cocaine can produce drug-related alterations in overt beh avior and cognition. (C) 2000 Elsevier Science B.V. All rights reserved.