The influence of morphine treatment on the opioid propeptide gene expression in the forebrain of two inbred mouse strains with different sensitivity to opioids

Our results suggest that Penk-expressing neurons of the CeA, which are critical for some withdrawal symptoms, adapt differently to chronic morphine in C57BL/6 vs. DBA/2 mice. We discuss how this may correspond to the inter-strain disparity in the opioid withdrawal syndrome intensity. We also analyze possible causes and consequences of the presumed inter-strain differences in morphine effects within the NAc.