CB2 Cannabinoid Receptor Knockout in Mice Impairs Contextual Long-Term Memory and Enhances Spatial Working Memory
Acute blockade of CB2Rs had no effect on working memory, locomotion, or anxiety. (a) Adult male C57BL/6J mice were injected with AM630 (3 mg/kg, i.p.) and, 1 h after the injection, used for behavioral tests in a Y-maze, an open field arena, and an elevated zero maze. (b) The rate of spontaneous alternation or the number of arm entries of AM630-treated mice in a Y-maze was not different from that of control mice. (c) In an open field arena, AM630- and vehicle-injected mice displayed similar behavioral patterns in the time spent in the center area, distance traveled in the center area, total travel distance, and travel speed. (d) In an elevated zero maze, the time and distance in the closed quadrants and the total travel distance of AM630-administered mice were similar to those of control mice. Error bars represent SEM.