Selective dopamine antagonists reduce nicotine self-administration.

The effects of selective D1 (SCH23390) and D2 (spiperone) dopamine antagonists, as well as of haloperidol, were examined on nicotine self-administration, food-maintained responding, and locomotor activity in rats. Antagonists reduced both operant responding and locomotor activity. Response patterns indicated that motor impairment was not the cause of the decreases, since responding was attenuated only in the latter half of operant sessions. Locomotor activity scores were significantly reduced by SCH23390, but not by spiperone. The effects of dopamine antagonists on nicotine self-administration are different from the effects of these antagonists on cocaine self-administration. Results are discussed in terms of the role of dopamine in drug reinforcement versus its role in sensorimotor integration.