Thesis
Overexpression of Oprki gene expression and alcohol use disorder
Washington State University
Master of Science (MS), Washington State University
05/2020
DOI:
https://doi.org/10.7273/000000041
Handle:
https://hdl.handle.net/2376/119584
Abstract
The kappa-opioid receptor (KOR) is an important regulator of dopamine (DA)
neurotransmission implicated in motivation, emotion and executive function. Previous research
has identified alcohol dependence dysregulates KOR in a manner that promotes multiple
symptoms of dependence including escalated alcohol self-administration. Based on our
assessment of Oprk1 (gene for KOR) in non-dependent and alcohol dependent rats,
neuroadaptations involving mesolimbocortical DA projections originating in the ventral
tegmental area (VTA) are implicated as a basis for escalated alcohol self-administration during
acute withdrawal. To test the hypothesis that KOR dysregulation occurs in VTA DAergic
neurons to increase alcohol self- administration, we utilized transgenic TH::Cre rats that have
Cre recombinase under control of tyrosine hydroxylase (TH; catecholamine synthetic pathway
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
self-administration which confirmed normal non-dependent alcohol self-administration, and
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
rats in VTA DAergic neurons, recapitulates phenotypes of alcohol dependence such as escalated
alcohol self-administration. Following optimization of viral infusions involving confirmation of
VTA TH+ immunostaining / viral EYFP overlap via fluorescent microscopy and RT-qPCR
confirmation of viral construct-induced increases in Oprk1 mRNA expression in VTA of TH::Cre
rats, we tested the hypothesis that overexpression of Oprk1 in the VTA of alcohol non-dependent
TH::Cre rats would increase alcohol self-administration. TH::Cre rats were trained for alcohol
self-administration until stable responding during 30-min sessions was achieved, separated into
groups matched for alcohol self- administration and site-specifically infused with floxed Oprk1
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
alcohol in 30-min sessions. Results indicated both male and female non-dependent TH::Cre rats
infused with floxed Oprk1 viral construct in the VTA demonstrated escalated operant alcohol
self-administration over a two- week testing period when compared to TH::Cre rats infused with
control construct. These data support the hypothesis that dysregulation of KOR signaling within
mesolimbocortical DA system is an important contributor to maladaptive symptoms of alcohol
dependence.
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Details
- Title
- Overexpression of Oprki gene expression and alcohol use disorder
- Creators
- Grace E. Shinn
- Contributors
- CARRIE CUTTLER (Degree Supervisor) - Washington State University, Psychology, Department ofBrendan Walker (Committee Member) - Washington State University, Integrative Physiology and Neuroscience, Department ofDAVID ROSSI (Committee Member) - Washington State University, Integrative Physiology and Neuroscience, Department of
- Awarding Institution
- Washington State University
- Academic Unit
- Psychology, Department of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Format
- pdf
- Number of pages
- 32
- Identifiers
- 99900590962601842
- Language
- English
- Resource Type
- Thesis