Ipsiversive rotation in awake rats following chronic electrical stimulation of one caudate nucleus

Rats were chronically implanted with stimulating electrodes in one caudate nucleus. Under light anaesthesia they received daily electrical stimulation (100-400 microA/HZ) for 30 min on 4 consecutive days. During this period, and for up to 3 subsequent days, tests for possible circling behaviour in response to administration of apomorphine i.p. were performed daily. Turning occurred towards the treated side and was reversible. The possibility is discussed that high levels of dopamine are released into the striatum during electrical stimulation, inducing transient subsensitivity of striatal dopamine receptors.