Fig. 5.

circOprm1 RNAs accumulate in mouse whole brain with chronic morphine exposure. CD-1 male mice were subcutaneously implanted with a morphine [(M), 75 mg free base] or placebo (P) pellet every 3 days, for a total of three pellets/animal (n = 5 to 6 mice per group). Tissues were harvested on day 10 for qPCR analysis for Oprm1 RNAs to compare circRNA and linRNA levels in whole brain and spinal cord. Tissues were examined for circOprm1.e2.e3 (A), circOprm1.e2.e3.e4(302) (B), and linear mRNA (linOprm1.e1.e3) (C) levels. Data are shown as 2^−ΔCt. For each Oprm1 target RNA for each tissue, morphine vs. placebo comparisons were analyzed by t test, and circOprm1.e2.e3 circOprm1.e2.e3.e4(302) increases in whole brain were significant (*P < 0.05).