α7 nicotinic acetylcholine receptor activation ameliorates scopolamine-induced behavioural changes in a modified continuous Y-maze task in mice

The alpha7 (α7) nicotinic acetylcholine receptor may represent a drug target for the treatment of disorders associated with working memory/attentional dysfunction. We investigated the effects of three distinct α7 nicotinic acetylcholine receptor agonists: 2-methyl-5-(6-phenyl-pyridazin-3-yl)-octahydro-pyrrolo[3,4-c]pyrrole (A-582941; 0.01–0.1 mg/kg), 4-bromophenyl 1,4-diazabicyclo(3.2.2) nonane-4-carboxylate (SSR180711; 0.3–3 mg/kg) and N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]-4-chlorobenzamide (PNU-282987; 1–10 mg/kg), on scopolamine-induced deficits in a modified Y-maze procedure. Mice were forced to choose one of two visually distinct arms, and were confined there for a 5 min exploration period before being allowed to explore both arms for a 2 min test session, immediately thereafter. The time spent in each arm, entries and total distance travelled were recorded using an automated system. Characterisation experiments showed that scopolamine-treated (1 mg/kg) mice spent less time exploring the unfamiliar arm, when compared with vehicle-treated animals. Combination experiments showed that all three α7 agonists ameliorated scopolamine-induced changes in unfamiliar arm exploration. In conclusion, the present data support the idea that α7 nicotinic acetylcholine receptors may represent an interesting target for the treatment of conditions associated with attentional/working memory dysfunction.