(A) Representative image of enhanced green fluorescent protein immunofluorescence in the spinal cord on day 7 after injection of LV-miRNA-365 or LV-control vector. Scale bar = 100 μm. (B) miR-365 expression levels in the L4 ~ 5 spinal cord after lentivirus injection. Rats were injected with control or miR-365 lentivirus vector 3 days before chronic normal saline infusion. Values are expressed as percentage of values of the LV-control + NS group, n = 6, ***P < 0.001 by two-way repeated-measures ANOVA followed by Bonferroni test. (C and D) Effect of injection of lentivirus miR-365 on the development of morphine tolerance. (C) Groups of rats were pretreated with vehicle (normal saline), LV-control vector, or LV-miR-365 vector 3 days before chronic injection of morphine or saline. Data are presented as mean ± s.e.m, n = 6, ***P < 0.001 compared with the Vehicle + NS group. ###P < 0.001 compared with the LV-control + Mor group by two-way repeated-measures ANOVA followed by Bonferroni test. (D) Groups of rats were injected with morphine twice a day for 17 consecutive days. LV-control vector or LV-miR-365 vector was administered on day 7 after establishment of morphine tolerance. Data are presented as mean ± s.e.m., n = 6, **P < 0.01, ***P < 0.001 compared with the LV-control group by two-way repeated-measures ANOVA followed by Bonferroni test. Each experiment was performed in triplicate with the indicated number of samples. miR = microRNA, MPE = maximum possible effect, NS = normal saline, Mor = morphine.