Src-dependent phosphorylation of l-opioid receptor at Tyr modulates opiate withdrawal

Opiate withdrawal/negative reinforcement has been implicated as one of the mechanisms for the progression from impulsive to compulsive drug use. Increase in the intracellular cAMP level and protein kinase A (PKA) activities within the neurocircuitry of addiction has been a leading hypothesis for opiate addiction. This increase requires the phosphorylation of l-opioid receptor (MOR) at Tyr by Src after prolonged opiate treatment in vitro. Here, we report that the Src-mediated MOR phosphorylation at Tyr is a prerequisite for opiate withdrawal in mice. We observed the recruitment of Src in the vicinity of MOR and an increase in phosphorylated Tyr (pY336) levels during naloxone-precipitated withdrawal. The intracerebroventricular or stereotaxic injection of a Src inhibitor (AZD0530), or Src shRNA viruses attenuated pY336 levels, and several somatic withdrawal signs. This was also observed in Fyn / mice. The stereotaxic injection of wild-type MOR, but not mutant (Y336F) MOR, lentiviruses into the locus coeruleus of MOR / mice restored somatic withdrawal jumping. Regulating pY336 levels during withdrawal might be a future target for drug development to prevent opiate addictive behaviors.