Knockdown of µ opioid receptor ( oprm1 ). Expression levels of grb2, acox1, dao.1, wls, grik-l, otpb, copb2, bnip4, camk1gb, sox19b, magi1b and plg of the Control group, the Morpholine (MO) control, Morpholine oprm1 (oprm1-MO) and oprm1-MO exposure to morphine (oprm1-MO + morphine). The expression levels were quantified using RT-qPCR analysis and were normalized to β-actin expression. Each bar represents the FC ± SD (n = 8). Data were analyzed by one-way ANOVA and using the Tukey post-hoc test. P values of < 0.05 being considered statistically significant (***p < 0.001; **p < 0.01; *p <0.05).