Chronic haloperidol administration does not block acute nicotine-induced improvements in radial-arm maze performance in the rat.

Nicotine has been found to improve cognitive performance in a variety of tasks including the radial maze. Nicotine has also been shown to promote the release of a variety of neurotransmitters including dopamine (DA). DA has been found to be important for nicotine's reinforcing effects. DA involvement with nicotine's cognitive effects is unclear. In the current study, the effects of acute nicotine injections (0, 0.1, 0.2, or 0.4 mg/kg) were examined on radial-arm maze performance in rats given chronic infusions the DA antagonist haloperidol (0, 0.2, or 0.6 mg/kg/day). Chronic haloperidol infusion was not found to attenuate the memory improvement caused by acute nicotine injection. In fact, the dose-related nicotine-induced memory improvement was clearer in the haloperidol-treated groups than in controls. This is similar to the effect of nicotine we saw in human subjects given chronic doses of haloperidol. Our previous studies demonstrated significant nicotinic-DA interactions with regard to memory function. The current results suggest that in the DA-nicotinic relationship DA stimulation is not necessary for the memory improvement caused by nicotine.