Dissertations, Theses, and Capstone Projects

Date of Degree

9-2022

Document Type

Dissertation

Degree Name

Ph.D.

Program

Psychology

Advisor

Robert Ranaldi

Committee Members

Carolyn Pytte

Richard Bodnar

Nancy Foldi

Veronica Hinton

Subject Categories

Behavioral Neurobiology | Pharmacology | Substance Abuse and Addiction

Keywords

cue-induced relapse, dopamine, D1-D3, opioid use disorder, pharmacology

Abstract

Chemical compounds that target dopamine (DA) D1 or D3 receptors have shown promise as potential interventions in animal models of cue-induced relapse. However, undesirable side effects or pharmacodynamic profiles have limited the advancement of new compounds in preclinical studies when administered as independent treatments. In this series of experiments, we explored the effects of co-administration of a D1-recepter partial agonist (SKF 77434) and a D3-receptor antagonist (NGB 2904) in heroin-seeking rats within a ‘conflict’ model of abstinence and cue-induced relapse. Rats were first trained to press a lever to self-administer heroin and drug delivery was paired contingently with cues (e.g., light, pump noise). Self-initiated abstinence was facilitated by applying electrical current to the flooring in front of the levers. Lastly, a relapse response was provoked by noncontingent presentation of conditioned cues. Prior to provocation, rats received a systemic injection of SKF 77434, NGB 2904, or a combination of both compounds to assess treatment effects on lever pressing. Results indicated that the co-administration of low (i.e., independently ineffective) doses of both compounds was more effective in reducing cue-induced relapse to heroin seeking than either compound alone, with some evidence of drug synergism. Follow-up studies indicated that this reduction was not due to motoric impairment nor enhanced sensitivity to the electrified flooring and that this treatment did not significantly affect motivation for food. Implications for the treatment of opiate use disorder and recommendations for further research are discussed.

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