(A-B) fgf8 mRNA expression is increased in the ShA rats in comparison to control and LgA-H rats. (C-D) NAc fgf9 mRNA levels are increased after exposure to oxycodone. (E-F) Striatal fgf8 mRNA expression showed no significant changes after oxycodone and withdrawal. (G-H) Striatal fgf9 mRNA levels are decreased in the ShA rats. The values in the bar graphs represent means ± SEM (n=5–15 animals per group). Note the differences in scales on the Y-axis. Key to statistics: *, **, *** = p < 0.05, 0.01, 0.001, respectively, in comparison to saline rats; #, ## = p < 0.05, 0.01, respectively, in comparison to ShA rats.