Number of cFOS-positive cells in the brain areas shown in d ( n = 7–9 mice per group, two-way ANOVA; PFC: fentanyl effect F (1,28) = 59.68, P < 0.001, naloxone effect F (1,28) = 0.50, P > 0.05, interaction F (1,28) = 0.67, P > 0.05; NAcS: fentanyl effect F (1,28) = 30.84, P < 0.001, naloxone effect F (1,28) = 5.64, P < 0.05, interaction F (1,28) = 0.59, P > 0.05; NAcC: fentanyl effect F (1,29) = 55.43, P < 0.001, naloxone effect F (1,29) = 10.34, P < 0.01, interaction F (1,29) = 2.13, P > 0.05; PVT: fentanyl effect F (1,29) = 48.72, P < 0.001, naloxone effect F (1,28) = 0.47, P > 0.05, interaction F (1,29) = 1.65, P > 0.05; BLA: fentanyl effect F (1,29) = 13.73, P < 0.001, naloxone effect F (1,29) = 0.39, P > 0.05, interaction F (1,29) = 0.73, P > 0.05; CeA: fentanyl effect F (1,29) = 51.86, P < 0.001, naloxone effect F (1,29) = 60.56, P < 0.001, interaction F (1,29) = 18.54, P < 0.001; vHYP: fentanyl effect F (1,25) = 42.72, P < 0.001, naloxone effect F (1,25) = 1.37, P > 0.05, interaction F (1,25) = 0.13, P > 0.05; VTA: fentanyl effect F (1,29) = 51.48, P < 0.001, naloxone effect F (1,29) = 2.00, P > 0.05, interaction F (1,29) = 2.44, P > 0.05, Bonferoni’s multiple comparisons test. * P < 0.05, ** P < 0.01, *** P < 0.001). Data are mean ± s.e.m.
