Chronic nicotine-induced improvement of spatial working memory and D2 dopamine effects in rats

Nicotine improves working memory function in a variety of different testing situations. In a series of studies, we have found that chronic nicotine infusion improves working memory performance of rats in the win-shift version of the radial-arm maze. In the current studies, we examined the interaction of chronic nicotine effects in the radial-arm maze with dopamine D₂ agonist and antagonist drugs, since we have previously found significant interactions of acute nicotinic agonist and antagonist effects with D₂ systems. Replicating our earlier results, significant nicotine-induced improvements in working memory performance were seen. Chronic co-infusion of raclopride, a D₂ antagonist, or quinpirole, D₂/D₃ agonist, were not found to significantly interact with the choice accuracy improvement caused by nicotine. Acute challenge with a range of quinpirole doses also did not affect the facilitating effect of chronic nicotine. This stands in contrast to the significant interactions of D₂ systems with acute nicotine effects. Acute and chronic nicotine administration have similar effects of facilitating memory performance in the radial-arm maze. However, these effects appear to have differential interactions with D₂ systems. Drug Dev. Res. 39:29–35. © 1997 Wiley-Liss, Inc.