Thioredoxin-1 Overexpression In Nucleus Accumbens Promotes The Extinction Of Conditioned Place Preference Induced By Morphine Through Regulating GluN2B

Morphine(Mor)is one kind of opioids which has the strong analgesic effect that was used in clinic.It is easy to cause tolerance and addiction when it binds to the specific receptor in central nervous system(CNS).Morphine addiction is accompanied by compulsive drug-seeking behavior and withdrawal symptoms.The nucleus accumbens(NAc)is closely related to the addictive effect,and involved in the formation and extinction of conditioned place preference(CPP)induced by the morphine.Studies have shown that the N-methyl-D-aspartate receptor 2B subunit(GluN2B)and its downstream extracellular regulated kinase(ERK)and cAMP response elementbinding protein(CREB)are involved in the extinction of morphine-induced CPP.Morphine addiction is related with changes of molecules and induces damage in brain and dysfunction of CNS.Thioredoxin-1(Trx-1)is a redox protein that maintains the balance of redox in cells,inhibits apoptosis,regulates glucocorticoids,endoplasmic reticulum stress,and the activity of transcription factors.Trx-1 plays an important role in neuroprotection.The aim of this study is to investigate the mechanism on Trx-1 in the NAc regulating the extinction of morphine-induce CPP by regulating expression of GluN2 B and phosphorylation levels of ERK/CREB,the downstream of GluN2 B.The model of extinction of morphine-induce CPP was made:(1)After establishing morphine-induced CPP formation in mice,then Ad-mCMV-EGFP-mouse-Trx-1-flag virus was injected bilaterally into the NAc of the mice to increase the expression of Trx-1.Then,the morphine-induced CPP extinction was detected during extinction period.(2)After establishing morphine-induced CPP formation in mice,then GluN2 B specific receptor inhibitor,RO25-6981 was intraperitoneal injected for 30 minits ahead of CPP detection,the morphine-induced CPP extinction was detected.(3)After establishing morphine-induced CPP formation in mice,then Ad-mCMV-EGFP-mouse-Trx-1-flag virus was injected bilaterally into the NAc of the mice to increase the expression of Trx-1,then RO25-6981 was intraperitoneally injected for 30 minits before morphineinduced CPP extinction.In addiction,the expressions of Trx-1 and GluN2 B,the phosphorylated levels of ERK and CREB were detected by Western blot(WB).Results:(1)The expression of Trx-1 was increased in morphine-induced CPP extinction,and overexpression of Trx-1 in the NAc promoted morphine-induced CPP extinction.(2)The specific inhibitor of GluN2 B receptor,RO25-6981 specifically inhibited the GluN2 B / ERK / CREB pathway in the NAc,delayed the extinction of morphine-induced CPP.(3)The overexpression of Trx-1 in the NAc before injection of RO25-6981 during morphine-induced CPP extinction partially reversed the expression of GluN2 B,and the phosphorylated levels of ERK and CREB.The delayed extinction of morphine-induced CPP by RO25-6981 was reversed by Trx-1 overexpression in the NAc.All experimental data demonstrated that Trx-1 regulated morphine-induced CPP extinction by alatering the expression of GluN2 B and the phosphorylated levels of ERK and CREB.Conclusion: Overexpression of Trx-1 in the NAc promotes the extinction of morphine-induced CPP by regulating expression of GluN2 B and the phosphorylated levels of ERK and CREB.