Agmatine inhibits morphine-induced memory impairment in the mouse step-down inhibitory avoidance task

The effect of agmatine on memory formation in morphine-treated mice on the step-down inhibitory avoidance test was examined. Pre-training and pre-test administration of agmatine (5, 10 and 20 mg/kg, s.c.) facilitated memory formation and retrieval while post-training administration of agmatine (5, 10 and 20 mg/kg, s.c.) had no effect on memory consolidation. Idazoxan (5 mg/kg, i.p.) inhibited the effect of agmatine on memory formation and retrieval. Pre-training administration of morphine (1.25, 2.5 and 5 mg/kg, s.c.) impaired memory formation while post-training and pre-test administration of morphine (1.25, 2.5 and 5 mg/kg, s.c.) had no effect on memory consolidation and retrieval. Pre-training agmatine treatment reversed the impairment of morphine on memory formation. Moreover, pre-test administration of agmatine inhibited morphine-induced amnesia. Pre-training and pre-test idazoxan (5 mg/kg, i.p.) treatment inhibited the effect of agmatine on morphine induced memory impairment. In conclusion, agmatine inhibited morphine-induced memory impairment on the mice step-down inhibitory avoidance test. The mechanism was exerted, at least in part, through activation of imidazoline receptors.

Research Highlights
► Agmatine facilitated memory formation and retrieval.
► Pre-training and pre-test agmatine treatment inhibited the memory impairment induced by morphine.
► Idazoxan antagonized the effect of agmatine.