Examining opioid withdrawal scoring and adaptation of global scoring systems to male and female C57BL/6J mice

Abstract

Opioid Use Disorder (OUD) is a chronic and relapsing psychiatric condition which is currently the leading cause of accidental death in the US. Symptoms of acute opioid withdrawal resemble a flu-like illness which is accompanied by a dysphoric state. Psychological comorbidities such as anxiety, depression, and disordered sleep can persist for months or years, well into the abstinence period. These symptoms are thought to drive further opioid intake in order to alleviate this unpleasant internal state. Many differences in OUD have been documented between male and female patients, with females at higher risk for relapse and overdose. This study sets out to characterize sex differences in symptoms and behavioral adaptations in mice during early withdrawal. Using our moderate dose, three day precipitated withdrawal paradigm, we discovered significant effects of sex, time, and drug treatment on early withdrawal behaviors, locomotor activity, and gut motility in C57BL/6J mice. Here I will discuss previous methods of condensing behavioral phenotypes into one global withdrawal score, and propose a new methodology. This method increases the ability to detect nuanced effects and allows for more accurate translation across strain, sex, paradigm, and experimental context. Classification of opioid withdrawal-induced behavioral adaptations will allow for improved behavioral analysis of pharmacological manipulations, and investigations of brain circuitry involved in opioid withdrawal, as well as future screening of compounds with potential therapeutic benefit for the treatment of OUD.

Xylazine is an agonist at kappa opioid receptors and exhibits sex-specific responses to naloxone administration

“…Mice were returned to their home cages and precipitated withdrawal was repeated for 2 more days (35)(36)(37). Total counts for each behavior were recorded and a z-score was computed for each animal on each day of withdrawal (38). On the third day of withdrawal, mice were perfused for immunohistochemistry 75-90 minutes following antagonist administration.…”

All Hands on Deck: We Need Multiple Approaches To Uncover the Neuroscience behind the Opioid Overdose Crisis

“…Not only do withdrawal symptoms present differently across sexes, but they also manifest differently across species and strains within species. Recently we proposed a new method to adapt previous Global Withdrawal scoring systems to allow for better comparisons across strains, sex, and species . In this method, the global withdrawal score is computed as a z-score instead of as a weighted average or summation of points.…”

“…Recently we proposed a new method to adapt previous Global Withdrawal scoring systems to allow for better comparisons across strains, sex, and species. 78 In this method, the global withdrawal score is computed as a z-score instead of as a weighted average or summation of points. This allows for animals that exhibit very different symptoms of withdrawal to be directly compared without placing more importance on specific behaviors.…”

Machine learning and deep learning frameworks for the automated analysis of pain and opioid withdrawal behaviors

“…In rodents, opioid dependence is generally achieved through either continual access (e.g., volitional self-administration) or through a paradigm of escalating doses of injections (i.e., non-volitional exposure) ( Spanagel, 2022 ). Opioid dependence in rodents has been shown to produce a range of withdrawal symptoms, including increased grooming, wet-dog shakes, tremors, jumping, rearing, wall climbing, diarrhea, and anxiety-like behavior, among others ( Bravo et al, 2020 , 2021 ; Gipson et al, 2020 ). Along with a withdrawal-like syndrome, opioid dependence in rodents also induces opioid-induced hyperalgesia ( Liang et al, 2006 ; Roeckel et al, 2016 ).…”

“…A natural aspect of these preclinical experiments is the characterization of behavioral responses in translational models, particularly rodent models, which to date has primarily relied on human visual perception. As such, current behavioral paradigms in pain or opioid withdrawal research in rodents still rely on manual scoring ( Deuis et al, 2017 ; Bravo et al, 2020 , 2021 ). This process is often time-consuming, labor-intensive, and error-prone, even when conducted by trained researchers.…”