Preexposure to nicotine alters the subsequent locomotor stimulant effects of bupropion in rats

Little is known about the interaction between nicotine and bupropion (Zyban), but many studies suggest they have neurological and behavioral similarities. One feature of drugs with common profiles is the ability to cross-sensitize possibly through neurological changes in the reward pathway. Activation of this pathway might explain the effectiveness of bupropion as a smoking cessation aid. The present research investigated whether repeated nicotine administration altered the subsequent locomotor effects of bupropion. In experiment 1, rats were preexposed to nicotine (0.4 mg/kg subcutaneously) or saline on eight separate occasions in the home cage and then tested with bupropion (0, 20, or 30 mg/kg) in locomotor chambers. The acute stimulant effect of 30 mg/kg of bupropion was potentiated by nicotine preexposure. In experiment 2, rats received nicotine repeatedly paired with the locomotor chambers or home cages. An additive effect was observed between acute bupropion and nicotine-conditioned hyperactivity in the chamber-paired group. This enhancement of the acute locomotor effects of bupropion might reflect alterations in common dopaminergic processes.