Spatial working memory improvement by an α 2-adrenoceptor agonist dexmedetomidine is not mediated through α 2C-adrenoceptor

Abstract

1. Aged α 2C-adrenoceptor knockout and wild type mice were used to investigate whether α 2C-adrenoceptors are involved in mediating the beneficial effects of α 2-adrenoceptor agonist, dexmedetomidine, on spatial working memory. 2. A win-stay task in the radial arm maze was used to dissociate the effects of dexmedetomidine on working vs. reference memory. In addition, the animals were tested in simple response habit learning in the T-maze. 3. Knockout mice made more working memory errors after the change of the baited arm in radial arm maze, but after training reached again as accurate level of performance as wild type controls. Dexmedetomidine 5 and 10 μg/kg alleviated the increase in spatial working memory errors after the change of the baited arm in knockout mice. Knockout and wild type mice performed equally well in T-maze, and dexmedetomidine had no effect on this simple response learning. 4. The present results indicate that α 2-adrenoceptor agonists have a selective effect on spatial working memory not only in monkeys but also in mice. Further, this study confirms our earlier finding that the presence of α 2C-adrenoceptors is not necessary for the spatial working memory enhancing effect of α 2-adrenoceptor agonists.