Role of glucagon-like peptide-1 in prescription opioid relapse and pain

U.S. National Institute On Drug Abuse, Baltimore MD

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Abstract

Project Summary The current prescription opioid epidemic is a major health concern, characterized by high lifetime rates of relapse that are often precipitated by experiences of pain. However, preclinical rodent studies of prescription opioids relapse (e.g., oxycodone) are limited, and to our knowledge, preclinical models examining the effect of pain on opioid relapse do not exist. Drug craving and relapse have been modeled in laboratory rats using the incubation of drug craving model, which refers to the time-dependent increase in drug seeking after withdrawal, a phenomenon that occurs in both rat models and humans. The objective of this proposal is to develop an animal model of prescription opioid craving and relapse and study the putative shared neurobiological mechanisms of prescription opioid relapse and pain. This proposal is focused on the central amygdala (CeA), a region involved in both the incubation of drug craving across drug classes and pain, and the neuropeptide glucagon-like peptide-1 (GLP-1). This neuropeptide has been classically associated with the control of food intake and recent studies showed that it also modulates neurotransmission in extrahypothalamic areas and decreases nicotine and cocaine self-administration. GLP-1 receptors (GLP-1Rs) are expressed in the CeA and modulate local neurotransmission to decrease feeding, but no studies have examined the role of CeA GLP- 1Rs in drug craving and relapse. Additionally, systemic injections of GLP-1R agonists decrease pain sensitivity, but the brain areas mediating this effect are unknown. My central hypothesis is that CeA GLP-1R signaling is a critical shared mechanism for incubation of oxycodone craving and pain. Based upon preliminary work from the Shaham lab, I propose to develop a rat model of incubation of oxycodone craving and test the role of CeA GLP-1Rs in this model. Furthermore, given that the duration of pain in classical rodent models of pain is not under experimenter control, I propose to develop a novel DREADD-based chemogenetic model of pain, in which repeated intermittent administration of the designer drug, clozapine n-oxide (CNO), will cause intermittent pain that is under experimenter control. I will test the role of CeA GLP-1R signaling in this novel model of pain and determine the effect of this intermittent pain on the incubation of oxycodone craving. The proposed studies will characterize the role of CeA GLP-1Rs in a model of prescription opioid craving and relapse and pain, and will introduce a novel approach to study the neurobiological mechanisms underlying pain-induced prescription opioid relapse.