Overexpression of Oprki gene expression and alcohol use disorder
Creators: name: Shinn, Grace E.
Publisher: name: Washington State University
Year: 2023

description: The kappa-opioid receptor (KOR) is an important regulator of dopamine (DA)
description: neurotransmission implicated in motivation, emotion and executive function. Previous research
description: has identified alcohol dependence dysregulates KOR in a manner that promotes multiple
description: symptoms of dependence including escalated alcohol self-administration. Based on our
description: assessment of Oprk1 (gene for KOR) in non-dependent and alcohol dependent rats,
description: neuroadaptations involving mesolimbocortical DA projections originating in the ventral
description: tegmental area (VTA) are implicated as a basis for escalated alcohol self-administration during
description: acute withdrawal. To test the hypothesis that KOR dysregulation occurs in VTA DAergic
description: neurons to increase alcohol self- administration, we utilized transgenic TH::Cre rats that have
description: Cre recombinase under control of tyrosine hydroxylase (TH; catecholamine synthetic pathway
description: enzyme) promotor in conjunction with use of a floxed Oprk1 viral construct to capitalize on CreLox gene manipulation technology. Initially, we phenotyped TH::Cre rats for operant alcohol
description: self-administration which confirmed normal non-dependent alcohol self-administration, and
description: normal dependence-induced escalation of self-administration during acute withdrawal. These results positioned us to test whether inducible overexpression of Oprk1 in non-dependent TH::Cre
description: rats in VTA DAergic neurons, recapitulates phenotypes of alcohol dependence such as escalated
description: alcohol self-administration. Following optimization of viral infusions involving confirmation of
description: VTA TH+ immunostaining / viral EYFP overlap via fluorescent microscopy and RT-qPCR
description: confirmation of viral construct-induced increases in Oprk1 mRNA expression in VTA of TH::Cre
description: rats, we tested the hypothesis that overexpression of Oprk1 in the VTA of alcohol non-dependent
description: TH::Cre rats would increase alcohol self-administration. TH::Cre rats were trained for alcohol
description: self-administration until stable responding during 30-min sessions was achieved, separated into
description: groups matched for alcohol self- administration and site-specifically infused with floxed Oprk1
description: viral construct (AAV5-Ef1a- OPRK1-DIO-EYFP) or control construct (AAV5-Ef1a-DIOEYFP). Four weeks after viral infusion, non-dependent TH::Cre rats could again self-administer
description: alcohol in 30-min sessions. Results indicated both male and female non-dependent TH::Cre rats
description: infused with floxed Oprk1 viral construct in the VTA demonstrated escalated operant alcohol
description: self-administration over a two- week testing period when compared to TH::Cre rats infused with
description: control construct. These data support the hypothesis that dysregulation of KOR signaling within
description: mesolimbocortical DA system is an important contributor to maladaptive symptoms of alcohol
description: dependence.