Fig. 4

Effect of chronic morphine on the expression of microRNAs and the binding of miR-105 and D1 mRNA. a Expression of microRNAs in the mPFC in saline and chronic morphine groups using hierarchical clustering and heatmap. Green color on the heatmap indicates a decrease in microRNA expression level and red color indicates an increase in miRNA expression level as compared to saline group. b Panel 1: the overlap of 38 downregulated microRNAs and 62 microRNAs related to D1R gene (Drd1a) using bioinformatics analysis method in the chronic morphine group; panel 2: the averaged miR-105 expression in saline and chronic morphine groups by RT-PCR in the mPFC (n = 8, **P < 0.01, compared to saline group); panel 3: the averaged miR-105 expression in saline and chronic morphine groups by RT-PCR in the hippocampus (n = 4, P > 0.05, compared to saline group); panel 4: the averaged miR-105 expression in saline and chronic morphine groups by RT-PCR in the thalamus (n = 5, P > 0.05, compared to saline group). c Upper panel: bioinformatic analysis of the predicted miR-105 binding site in the 3′UTR of the Drd1 gene. Bottom panel: the luciferase activity with D1 mRNA 3′UTR wild-type (wt) in the presence of miR-105 miRNA NC and miR-105 mimics (n = 3, *P < 0.05, compared to miRNA NC group). Data are shown as the mean ± SEM