Classically conditioned ethanol stimulus control of a motor behavior.

Rats with extensive unilateral 6-hydroxydopamine lesions of substantia nigra rotate (turn in circles) in response to administration of dopamine agonists. Here apomorphine administration, but not single or repeated administrations of ethanol, resulted in rotation in such lesioned animals. When apomorphine and ethanol were administered simultaneously to lesioned animals, rapid contralateral rotation resulted. After five of these conditioning trials in which ethanol and apomorphine were paired, ethanol alone elicited apomorphine-like rotation. Saline administration did not result in rotation in the conditioned animals, indicating that ethanol rather than the injection procedure exerted stimulus control over the behavior. Control animals which were treated five times with apomorphine and ethanol in an unpaired manner showed no conditioned rotation to ethanol.