STRAIN-DEPENDENT EFFECTS OF D-2 DOPAMINERGIC AND MUSCARINIC-CHOLINERGIC AGONISTS AND ANTAGONISTS ON MEMORY CONSOLIDATION PROCESSES IN MICE

The interaction between muscarinic-cholinergic and dopaminergic system s in the modulation of memory storage of Y-maze discrimination (YMD) t ask was examined in C57BL/6 and DBA/2 strains of mice. In C57BL/6 mice ; post-training systemic (i.p.) administration of the D-2-agonist quin pirole facilitated retention and the D-2-antagonist (-)-sulpiride impa ired retention. Opposite effects were observed in DBA/2 strain. The fa cilitating or impairing effects of quinpirole and (-)-sulpiride were b locked by simultaneous post-training administration of muscarinic-chol inergic agonists and antagonists. The memory enhancing effects of the cholinergic agonist oxotremorine were not blocked by simultaneous admi nistration of sulpiride in C57BL/6 mice or quinpirole in DBA/2 mice. F urthermore, the memory impairing effects of the cholinergic antagonist atropine were not blocked by simultaneous administration of quinpirol e in C57BL/6 mice or sulpiride in DBA/2 mice. These findings indicate that the effects of D-2-receptor agonists and antagonists on retention of YMD task are strain-dependent and mediated through muscarinic-chol inergic mechanisms. (C) 1997 Elsevier Science B.V.