Genetic Modulation of Oxycodone Self-Administration Trajectories: From Initiation to Escalating Burst Patterns.
Caleb I Hodges1, Eamonn P Duffy2,3, Jonathan O Ward1
1Department of Psychology and Neuroscience, University of Colorado Boulder, Boulder, CO, United States.
Biorxiv : the Preprint Server for Biology
|June 29, 2026
Summary
Genetic background significantly impacts opioid use disorder (OUD) susceptibility and patterns. Rat strains show distinct oxycodone intake behaviors, highlighting genetic influences on substance use trajectories.
Area of Science:
- Neuroscience
- Genetics
- Pharmacology
Background:
- Opioid Use Disorder (OUD) is a major global health concern.
- Genetic factors influencing OUD susceptibility are not fully understood.
- Inbred rat strains offer valuable models for genetic discovery in OUD.
Purpose of the Study:
- To compare OUD-related phenotypes across seven inbred rat strains.
- To investigate the influence of genetic background on oxycodone self-administration.
- To identify strain-specific patterns in substance use escalation and consumption.
Main Methods:
- Utilized a two-phase oxycodone self-administration paradigm in seven rat strains.
- Assessed acquisition (2-h sessions) and escalation (12-h sessions) of drug intake.
- Analyzed within- and between-session intake patterns and sex differences.
Main Results:
- Genetic background significantly influenced oxycodone acquisition and intake.
- Escalation of oxycodone intake and within-session consumption patterns were strain-dependent.
- The M520/N strain exhibited rapid initiation and burst-like responding; sex differences were noted.
Conclusions:
- Rat strain genetics profoundly affect OUD development and consumption patterns.
- Specific intake metrics reveal genetic influences across the substance use trajectory.
- These findings aid in identifying genetic pathways contributing to OUD.
Related Concept Videos
01:15Opioid Analgesics: Synthetic and Semisynthetic Opioids
Synthetic and semisynthetic opioids are pivotal in pain management and tackling opioid addiction. Semisynthetic opioids, including morphinans (morphine derivatives), oxycodone, oxymorphone, hydrocodone, and hydromorphone, have improved pharmacokinetic profiles compared to morphine. Additionally, heroin and 6-MAM (6-Monoacetylmorphine) show better CNS penetration than morphine due to heightened lipid solubility. Hydromorphone, a potent opioid, undergoes hepatic metabolism to form the active...
01:25Analgesia and Pain Management
Pain is critical to various clinical pathologies, provoking an urgent need for effective management. Pain, whether acute or chronic, is a complex neurochemical process. Its alleviation depends on the type, with nonopioid analgesics effective for mild to moderate pain, such as musculoskeletal or inflammatory pain, while neuropathic pain responds best to anticonvulsants, tricyclic antidepressants, or serotonin/norepinephrine reuptake inhibitors. For severe acute or chronic pain, opioids may be...
01:20Opioid Analgesics: Morphine and Other Natural Cogeners
Opioids are a class of drugs that mimic endogenous opioid peptides and act on opioid receptors, and help in pain relief. These compounds are classified as natural, synthetic, or semi-synthetic. Natural opioids, like morphine, codeine, and thebaine, are derived from the opium poppy plant (Papaver somniferum or Papaver album) and are termed opiates. Synthetic opioids are artificial, while semi-synthetic opioids combine natural and synthetic compounds. Morphine, a prototypical opioid, possesses a...
01:21Drug Accumulation During Multiple Dosing: Repetitive IV Injections
Calculating drug dosage and accumulation in multiple-dose regimens is crucial for achieving therapeutic efficacy while avoiding toxicity. This involves determining the plasma drug concentrations over time to optimize dosing schedules. The principle of superposition is fundamental in this process, allowing for the prediction of drug concentration in plasma following multiple doses based on single-dose data.The principle of superposition asserts that the plasma concentration-time curves from...
01:15Drug Abuse and Addiction: Pharmacological Phenomena
Drug dependence, abuse, and addiction are complex phenomena that can precipitate various abnormal states. Physical dependence refers to a state of pharmacological adaptation to a drug. This adaptation often results in tolerance—a reduced response to the drug after repeated administrations. When the drug use is abruptly stopped, withdrawal symptoms occur due to the body's need to readjust from the pharmacologically induced imbalance. However, tolerance and withdrawal symptoms do not necessarily...
01:24Drug Accumulation During Multiple Dosing: Intermittent IV Infusions
Intermittent intravenous (IV) infusion is a method of drug administration where medications are delivered over short infusion periods followed by intervals of no drug delivery. This approach helps to prevent sustained high drug concentrations in the bloodstream, reducing the risk of adverse effects associated with prolonged exposure. Unlike continuous infusion, steady-state concentrations may not be achieved during a single dosing cycle but can be reached through repeated...