Cross state-dependency of learning between WIN55, 212-2 and scopolamine in rat dorsal hippocampus.

In the current study, cross state-dependent learning between the cannabinoid CB1/CB2 receptor agonist WIN55, 212-2 (WIN) and muscarinic receptor antagonist scopolamine (SCO) in a step-through inhibitory avoidance task was investigated. All drugs were injected bilaterally into the dorsal hippocampus (intra-CA1) of rats. Data indicated that the immediate post-training administration of WIN (0.25 and 0.5μg/rat) and SCO (2 and 4μg/rat) decreased memory consolidation and induced amnesia. Moreover, the amnesia induced by the post-training injections of WIN (0.5μg/rat) or SCO (2μg/rat) was restored by either pre-test injections of WIN (0.25 and 0.5μg/rat) or SCO (2 and 4μg/rat). Furthermore, pre-test co-administration of ineffective doses of WIN (0.1μg/rat) with SCO (1μg/rat) restored amnesia induced by the post-training injections of WIN (0.5μg/rat) or SCO (2μg/rat). In conclusion, the data strongly revealed a cross state-dependent learning between WIN and SCO in the rat dorsal hippocampus.