Naloxone-induced morphine withdrawal results in activation of extended amygdala. SB-334867 attenuated c-Fos expression in the NAc, BNST and CeA in morphine-withdrawn rats.

<p>Rats were pretreated with the selective OX1R antagonist SB334867 20 min prior naloxone injection and were sacrificaed 120 min after naloxone administration. (A, D, G) Schematic anatomic representation of NAc shell, BNST and CeA adapted from Paxinos and Watson atlas (2007). Labeled areas delineate regions where c-Fos expression was examined. (B I) Representative photographs of c-Fos expression in the NAc, BNST (oval) and CeA in animals pretreated with morphine-vehicle-naloxone (B, E, H) or with morphine-SB-334867-naloxone (C, F, I). LV, lateral ventricle; ac, anterior comissure; BLA, basolateral amygdala. Scale bar, 200 µm. (J) Quantification of neurons expressing c-Fos in the NAc shell, BNST (oval) and CeA. Bars represent mean ± SEM. ***p<0.001 versus placebo + vehicle (veh) + naloxone (nx); ⁺⁺p<0.01; ⁺⁺⁺p<0.001 versus placebo + SB-334867+ naloxone; ^##p<0.01, ^###p<0.001 versus morphine + vehicle + naloxone.