CNO blocked effects of sexual experience on morphology of VTA dopamine cells. A, B, Quantitative analyses of VTA dopamine soma perimeter (A) and area (B) in saline + naive (SAL+NAIVE; white bars; n = 6), CNO + naive (CNO+NAIVE; light blue bars; n = 6; 97% perimeter, 97% area compared with SAL+NAIVE), saline + experienced (SAL+EXP; black bars; n = 9; 92% perimeter, 87% area compared with SAL+NAIVE), and CNO + experienced (CNO+EXP; dark blue bars; n = 10; 95% perimeter, 92% area compared with SAL+NAIVE) groups. Data represent mean ± SEM. *, Significant difference from SAL+NAIVE or CNO+NAIVE. #, Significant difference from SAL+EXP. C–F, Representative images of TH-immunoreactive cells in the PBP of SAL+NAIVE (C), CNO+NAIVE (D), SAL+EXP (E), and CNO+EXP (F) groups. Scale bar, 10 μm.