The effects of electroconvulsive shock on the discriminative stimulus properties of d-amphetamine and apomorphine: evidence for dopamine receptor alteration subsequent ECS.

Sprague-Dawley male rats responding for sweetened milk on a variable interval 20 s schedule of reinforcement were trained to discriminate which of two levers to press on the basis of whether they had been injected with 1.0 mg/kg of d-amphetamine or saline prior to daily training sessions. Following acquisition of the discrimination a dose-response generalization function was determined by testing animals on 0.10, 0.15, 0.25, 0.35, 0.50 and 0.75 mg/kg of amphetamine. Subjects then received either three electroconvulsive shock (ECS) treatments of sham-ECS forty-eight hours after the final treatment all subjects were injected with 0.25 mg/kg of amphetamine and retested. ECS was found to enhance the ability of the animals to discriminate amphetamine. In a second experiment it was found that ECS also facilitated the ability of animals to discriminate the cue properties of apomorphine, a direct dopamine receptor agonist. These results suggest that dopamine receptor sensitivity is altered by electroconvulsive shock.