Prescription opioid addiction is a significant problem characterized by compulsive drug seeking, withdrawal and chronic relapse. Despite the growing impact of prescription opioids on public health, relatively few pre-clinical studies have investigated the neurobiological mechanisms underlying self-administration of oxycodone, a commonly prescribed medication. Neural circuits in the extended amygdala mediate emotional behaviors, and dysregulation of these reward and stress systems is a hallmark of drug dependence and withdrawal. Models of intravenous drug self-administration are a standard paradigm for investigating the reinforcing effects of drugs, and I have developed a model of oxycodone self-administration under extended access conditions (12 hours/day) that produces robust escalation of drug-seeking behavior and provides a translationally relevant model of opioid abuse. We hypothesize that escalation of oxycodone abuse and dependence are mediated by withdrawal-induced changes in neural signaling mechanisms, and that the manipulation of these underlying neural systems will attenuate the promotion of drug-seeking behavior. We will test this hypothesis using behavioral pharmacology, chemogenetics, and immunohistochemistry in a rat model of oxycodone self-administration under extended access conditions. My research training will be supervised by my mentors, Drs. Michael Taffe, Thomas Kash and Candice Contet, with additional support from Dr. Bryan Roth as consultant and Drs. Marisa Roberto, Kim Janda and Michael Forster as advisors for my career development. We have designed a multidisciplinary project that utilizes different experimental modalities that allow for behavioral, biochemical, and immunohistochemical investigation of oxycodone addiction and dependence. Precise characterization of KOR activation will be achieved through the use of the chemogenetic technology, designer receptors exclusively activated by designer drugs (DREADDs). We will employ neural circuit manipulations, specifically the inhibitory Gi-coupled kappa opioid receptor DREADD (KORD) in the central nucleus of the amygdala (CeA) GABAergic projection to paraventricular nucleus of the hypothalamus (PVN) to understand the effect of opioid-induced neuroadaptations mediating drug-seeking behavior. I will train in DREADD-based and immunohistochemical techniques to complement my experience in behavioral opioid pharmacology. These skills will be acquired during my K99 phase at The Scripps Research Institute and will be further implemented at my new institution during the R00 phase. My mentor team will help me establish these techniques in my independent laboratory to ensure experimental reproducibility. Collectively, this work will provide insight into the influence of kappa opioid receptor signaling in amygdalar pathways mediating opioid addiction and dependence-induced behavior.
The exponential growth in the nonmedical use of prescription opioids, including the commonly-prescribed oxycodone, has contributed strongly to devastating national public health consequences including addiction, overdose and transition to use of illicit opioids such as heroin. This proposal combines a novel rodent model of oxycodone abuse with cutting-edge chemogenetic technology for dissection of the neural circuits and mechanisms which underlie the development of opioid dependence and to help identify potential therapeutic approaches and targets for medications development.
