Cholinergic agonist reverses H1-induced memory deficit in mice

• Chlorpheniramine and PNU-282987 did not induce effects on anxiety in elevated plus maze.
• The PNU-282987 per se did not produce effects on emotional memory.
• Microinjections of PNU-282987 reverse memory deficits induced by chlorpheniramine.

This study investigated the effects of bilateral intraamygdalar microinjections of PNU-282987, a nicotinic cholinergic agonist, on anxiety and the reversal of amnesia induced by chlorpheniramine (CPA), an H1 histaminergic antagonist, in mice subjected to the elevated plusmaze (EPM). Two experiments were performed with seventy-nine adult male Swiss mice. The isolated microinjections of PNU-282987 did not produce effects on emotional memory; however, the combined microinjections of PNU-282987 and CPA were able to reverse the deficit in memory induced by CPA (ANOVA, p < 0.05). Taken together, these results suggest that intraamygdalar injections of PNU-282987 did not induce effects on anxiety and emotional memory per se; however, concurrent microinjections of PNU-282987 and CPA-reverse amnesia induced-CPA which is suggestive of an interaction between the histaminergic and cholinergic systems in the modulation of emotion memory acquisition in mice.