Persistant effects of amphetamine on cerebellar Purkinje neurons following chronic administration

The spontaneous discharge of cerebellar Purkinje neurons was studied in rats after withdrawal from chronic treatment with amphetamine (2 mg/kg per day × 21 days). Discharge rates in withdrawn animals remained significantly lower than those of controls for up to 50 days. Disruption of the adrenergic input to these neurons from the locus coeruleus by treatment with propranolol, clonidine or reserpine, partially restored these discharge rates. Acute administration of amphetamine in amphetamine-withdrawn rats did not further depress Purkinje neuron discharge rate, whereas in a previous study in this lab, Purkinje neurons from naive animals were markedly slowed. Moreover, Purkinje neurons from amphetamine-withdrawn rats were also significantly less sensitive than controls to locally applied norepinephrine. These results demonstrate that chronic amphetamine can lead to very long-term changes in neuronal activity, and suggest that these changes may be mediated, in part, by the noradrenergic transmitter systems.