Representative images show distribution of ΔFosB staining in coronal sections at the level of the NAc, amygdala and VTA derived from A, C, E) water- and B, D, F) oxycodone-consuming mice respectively. The scale bar equals 500 μm. (Nucleus accumbens – NAc, Basolateral amygdalar nucleus - BLA, Central amygdalar nucleus capsular part – CeC, Ventral tegmental area - VTA)