Project description:BackgroundAttempts to identify opioid users at increased risk of escalating to opioid use disorder have had limited success. Data from a variety of sources suggest that genetic variation may mediate the subjective response to opioid drugs, and therefore contribute to their abuse potential. The goal of the current study was to observe the relationship between select genetic polymorphisms and the subjective effects of oxycodone under controlled clinical laboratory conditions.MethodsNon-dependent, volunteers with some history of prescription opioid exposure (N = 36) provided a blood sample for analyses of variations in the genes that encode for the μ-, κ- and δ-opioid receptors, and the dopamine metabolizing enzyme, catechol-O-methyltransferase (COMT). Participants then completed a single laboratory test session to evaluate the subjective and analgesic effects of oral oxycodone (0, 10, and 20 mg, cumulative dose = 30 mg).ResultsOxycodone produced typical μ-opioid receptor agonist effects, such as miosis, and decreased pain perception. Oxycodone also produced dose-dependent increases in positive subjective responses such as: drug "Liking" and "Good Effect." Genetic variants in the μ- (rs6848893) and δ-opioid receptor (rs581111) influenced the responses to oxycodone administration. Additionally, self-reported "Stimulated" effects of oxycodone varied significantly as a function of COMT rs4680 genotype.DiscussionThe current study shows that the euphoric and stimulating effects of oxycodone can vary as a function of genetic variation. Though the relationship between the stimulating effects of opioids and their abuse liability is not well established, we know that the ability of opioids to provide intense feelings of pleasure is a significant motivator for continued use. If replicated, specific genetic variants may be useful in predicting who is at increased risk of developing maladaptive patterns of use following medical exposure to opioid analgesics.
Project description:<p>The proposed study examined the prevalence of various genetic polymorphisms thought to be involved in opioid abuse among current heroin users. In addition to providing blood samples for genetics analysis, participants completed a number of questionnaires that allowed us to learn detailed information about their current and history of opioid drug use. </p>
Project description:It is estimated that nearly a third of people who abuse drugs started with prescription opioid medicines. Approximately, 11.5 million Americans used prescription drugs recreationally in 2016, and in 2018, 46,802 Americans died as the result of an opioid overdose, including prescription opioids, heroin, and illicitly manufactured fentanyl (National Institutes on Drug Abuse (2020) Opioid Overdose Crisis. https://www.drugabuse.gov/drugs-abuse/opioids/opioid-overdose-crisis . Accessed 06 June 2020). Yet physicians will continue to prescribe oral opioids for moderate-to-severe pain in the absence of alternative therapeutics, underscoring the importance in understanding how drug choice can influence detrimental outcomes. One of the opioid prescription medications that led to this crisis is oxycodone, where misuse of this drug has been rampant. Being one of the most highly prescribed opioid medications for treating moderate-to-severe pain as reflected in the skyrocketed increase in retail sales of 866% between 1997 and 2007, oxycodone was initially suggested to be less addictive than morphine. The false-claimed non-addictive formulation of oxycodone, OxyContin, further contributed to the opioid crisis. Abuse was often carried out by crushing the pills for immediate burst release, typically by nasal insufflation, or by liquefying the pills for intravenous injection. Here, we review oxycodone pharmacology and abuse liability as well as present the hypothesis that oxycodone may exhibit a unique pharmacology that contributes to its high likability and abuse susceptibility. We will discuss various mechanisms that likely contribute to the high abuse rate of oxycodone including clinical drug likability, pharmacokinetics, pharmacodynamics, differences in its actions within mesolimbic reward circuity compared to other opioids, and the possibility of differential molecular and cellular receptor interactions that contribute to its selective effects. We will also discuss marketing strategies and drug difference that likely contributes to the oxycodone opioid use disorders and addiction.
Project description:RationalePrescription opioid abuse has risen dramatically in the United States as clinicians have increased opioid prescribing for alleviation of both acute and chronic pain. Opioid analgesics with decreased risk for abuse are needed.ObjectivePreclinical and clinical studies have shown that opioids combined with ultra-low-dose naltrexone (NTX) may have increased analgesic potency and have suggested reduced abuse or dependence liability. This study addressed whether addition of ultra-low-dose naltrexone might decrease the abuse liability of oxycodone (OXY) in humans.Materials and methodsThis double-blind, placebo-controlled study systematically examined the subjective and physiological effects of combining oral OXY and ultra-low NTX doses in 14 experienced opioid abusers. Seven acute drug conditions given at least 5 days apart were compared in a within-subject crossover design: placebo, OXY 20 mg, OXY 40 mg, plus each of the active OXY doses combined with 0.0001 and 0.001 mg NTX.ResultsThe methods were sensitive to detecting opioid effects on abuse liability indices, with significant differences between all OXY conditions and placebo as well as between 20 and 40 mg OXY doses on positive subjective ratings (e.g., "I feel a good drug effect" or "I like the drug"), on observer- and participant-rated opioid agonist effects, and on a drug-versus-money value rating. There were no significant differences or evident trends associated with the addition of either NTX dose on any abuse liability indices.ConclusionsThe addition of ultra-low-dose NTX to OXY did not decrease abuse liability of acutely administered OXY in experienced opioid abusers.
Project description:Analyse of gene expression modification after chronic analgesic treatment. The hypothesis tested in the present study was that oxycodone and morphine induced gene expression modification. Results provide important information to understand the analgesic effects of oxycodone as compared to morphine in a neuropathic pain model Total RNA obtained from DRG of neuropathic or control animals after oxycodone or morphine treatment
Project description:In addition to their intrinsic rewarding properties. opioids can also evoke aversive reactions that protect against misuse. Cellular mechanisms that govern the interplay between opioid reward and aversion are poorly understood. We used whole-brain activity mapping to show that neurons in the dorsal peduncular nucleus (DPn) are highly responsive to the opioid oxycodone. Connectomic profiling revealed that DPn neurons innervate the parabrachial nucleus (PBn). Spatial and single-nuclei transcriptomics resolved a unique population of PBn-projecting pyramidal neurons restricted to the DPn that express μ-opioid receptors (μORs). Disrupting μOR signaling in these neurons switched oxycodone from rewarding to aversive and exacerbated the severity of opioid withdrawal. These findings identify DPn neurons as key substrates for the abuse liability of opioids.
Project description:Sensitivity to the subjective reinforcing properties of opioids has a genetic component and can predict addiction liability of opioid compounds. We previously identified Zhx2 as a candidate gene underlying increased brain concentration of the oxycodone (OXY) metabolite oxymorphone (OMOR) in BALB/cJ (J) versus BALB/cByJ (By) females that could increase OXY state-dependent reward. A large structural intronic variant is associated with a robust reduction of Zhx2 expression in J mice, which we hypothesized enhances OMOR levels and OXY addiction-like behaviors. We tested this hypothesis by modeling the loss-of-function variant through knocking out the Zhx2 coding exon (E3KO). Integrative transcriptomic and proteomic analysis of E3KO mice identified astrocyte function, cell adhesion, extracellular matrix properties, and endothelial cell functions as pathways influencing brain OXY metabolite concentration and behavior. These results support Zhx2 as a quantitative trait gene underlying brain OMOR concentration that is associated with changes in OXY behavior and implicate potential quantitative trait mechanisms that together inform our overall understanding of Zhx2 in brain function.
Project description:Analyse of gene expression modification after chronic analgesic treatment. The hypothesis tested in the present study was that oxycodone and morphine induced gene expression modification. Results provide important information to understand the analgesic effects of oxycodone as compared to morphine in a neuropathic pain model
Project description:Purpose: The goals of this study are to examine how maternal exposure to oxycodone affects the global transcriptome and histological structure of the mouse placenta at 12.5 dpc of pregnancy.retinal transcriptome profiling (RNA-seq) to microarray and quantitative reverse transcription polymerase chain reaction (qRT–PCR) methods and to evaluate protocols for optimal high-throughput data analysis Methods: A high throughput RNA sequencing method was used to examine the global transcriptomic changes affected by oxycodone in male and female conceptuses. Histomorphometrics were used to assess the various regions of the placenta, namely the labyrinth, spongiotrophoblast, and parietal trophoblast giant cell (pTGC) region. The open-sourced software, weighted correlation network analysis (WGCNA) was used to link gene expression changes and histological (phenotypic) changes. Results: Using an optimized data analysis workflow, we mapped over 40 million sequence reads per sample to the mouse genome (build grcm38). An average of 95.6% of reads (38.7 million) was mapped with HISAT2 workflow. We identified 12,138 transcripts in the placenta of saline control and oxycodone mice with featureCounts workflow. One hundred eighty-eight transcripts showed differential expression between the OXY male vs. CTL male placenta, with a log2Foldchange ≥1 and p value <0.05. Fifty-eight transcripts showed differential expression between the OXY female vs. CTL female placenta, with a log2Foldchange ≥1 and p value <0.05. Hierarchical clustering of differentially expressed genes uncovered several genes that may contribute to placenta function. Conclusions: Our study represents the first detailed analysis of placental transcriptomes in oxycodone-exposed mice, with biologic replicates, generated by RNA-seq technology. The data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. We conclude that oxycodone exposure changed transcriptome characterization and these changes were associated with placenta histological features.