| Autor: |
Schmidt HD; Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA., McFarland KN; Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA., Darnell SB; MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Boston, MA, USA., Huizenga MN; MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Boston, MA, USA., Sangrey GR; MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Boston, MA, USA., Cha JH; Merck, North Wales, PA, USA., Pierce RC; Center for Neurobiology and Behavior, Department of Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA., Sadri-Vakili G; MassGeneral Institute for Neurodegenerative Disease, Massachusetts General Hospital, Boston, MA, USA. |
| Abstrakt: |
Activation of AMPA receptors (AMPARs) in the nucleus accumbens is necessary for the reinstatement of cocaine-seeking behavior, an animal model of drug craving and relapse. AMPARs are tetrameric protein complexes that consist of GluA1-4 subunits, of which GluA2 imparts calcium permeability. Adenosine deaminase acting on RNA 2 (ADAR2) is a nuclear enzyme that is essential for editing GluA2 pre-mRNA at Q/R site 607. Unedited GluA2(Q) subunits form calcium-permeable AMPARs (CP-AMPARs), whereas edited GluA2(R) subunits form calcium-impermeable channels (CI-AMPARs). Emerging evidence suggests that the reinstatement of cocaine seeking is associated with increased synaptic expression of CP-AMPARs in the nucleus accumbens. However, the role of GluA2 Q/R site editing and ADAR2 in cocaine seeking is unclear. In the present study, we investigated the effects of forced cocaine abstinence on GluA2 Q/R site editing and ADAR2 expression in the nucleus accumbens. Our results demonstrate that 7 days of cocaine abstinence is associated with decreased GluA2 Q/R site editing and reduced ADAR2 expression in the accumbens shell, but not core, of cocaine-experienced rats compared with yoked saline controls. To examine the functional significance of ADAR2 and GluA2 Q/R site editing in cocaine seeking, we used viral-mediated gene delivery to overexpress ADAR2b in the accumbens shell. Increased ADAR2b expression in the shell attenuated cocaine priming-induced reinstatement of drug seeking and was associated with increased GluA2 Q/R site editing and surface expression of GluA2-containing AMPARs. Taken together, these findings support the novel hypothesis that an increased contribution of accumbens shell CP-AMPARs containing unedited GluA2(Q) promotes cocaine seeking. Therefore, CP-AMPARs containing unedited GluA2(Q) represent a novel target for cocaine addiction pharmacotherapies. |
