Fig. 1: Cellular determinant of fentanyl reward and aversion.
From: Distinct µ-opioid ensembles trigger positive and negative fentanyl reinforcement
a, Experimental schedule. i.p., intraperitoneal injection. b, Representative example of speed dynamics following intraperitoneal injection of fentanyl and during precipitation of withdrawal by naloxone. c, Box plot of jumps and immobility time in dependent mice without precipitation (grey, n = 14), in dependent mice with precipitation (red, n = 13) and in non-dependent mice with naloxone injection (white, n = 13; jump Kruskal–Wallis test: H(3) = 26.79, P < 0.001; immobility time Kruskal–Wallis test H(3) = 28.94, P < 0.001; Dunn’s multiple comparisons test, **P < 0.01, ***P < 0.001). F, fentanyl; N, naloxone; S, saline. d, Representative images of cFOS staining in prefrontal cortex (PFC), NAc shell (NAcS), NAc core (NAcC), paraventricular thalamus (PVT), basolateral amygdala (BLA), CeA, ventral hippocampus (vHIP) and VTA in a non-dependent mouse after saline injection (top row), naloxone injection (second row), dependent mice without precipitated withdrawal (third row) and dependent mice with precipitated withdrawal (bottom row). Scale bar, 100 μm. e, 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. f, Schematic of mouse preparation to induce µOR knockdown in various brain regions (control (CTL), n = 12; VTA, n = 13; NAc, n = 13; BLA, n = 12; CeA, n = 14; PVT, n = 13). g, Left, schedule of experiment to induce fentanyl dependence. Right, behavioural test to evaluate precipitated withdrawal induced by intraperitoneal injection of 5 mg kg−1 naloxone. h,i, Left, box plot of precipitated jump (h) and immobility (i) withdrawal symptoms after µOR deletion in indicated brain areas (CTL, n = 12; VTA, n = 13; NAc, n = 13; BLA, n = 12; CeA, n = 14; PVT, n = 13). Right, proportion of mice showing the presence of at least one precipitated jump (h) and at least 5 min of immobility (i) withdrawal symptoms. Kruskal–Wallis test: jumps, H(6) = 15.39, P < 0.01; immobility, H(6) = 8.774, P = 0.12; Dunn’s multiple comparisons test, *P = 0.0218. In box plots, the centre line is the median, box edges delineate first and third quartiles, and whiskers extend to maximum and minimum values.
