Blockade of Cannabinoid CB1 receptor attenuates the acquisition of morphine-induced conditioned place preference along with a downregulation of ERK, CREB phosphorylation, and BDNF expression in the nucleus accumbens and hippocampus.

•Morphine-induced CPP but not NO-CPP elevated CB1R expression both in the NAc and hippocampus.•AM251 attenuated morphine-induced CPP and CB1R expression in the NAc and Hippocampus.•CB1R mediated downstream ERK-CREB-BDNF signaling is implicated in morphine reward.