Enhancing translation: A need to leverage complex preclinical models of addictive drugs to accelerate substance use treatment options

A case against purity: prioritizing translational polysubstance use research

PURPOSE OF REVIEW

Preclinical (nonhuman) research on neurobehavioral underpinnings of addiction often focuses on one addictive drug studied in isolation, however, this does not reflect real-world substance use patterns of polysubstance use (PSU). Here we make a case against purity, incorporating patterns of clinically relevant PSU into preclinical models. We argue that the meaningful inclusion of people with living experience as integral collaborators in translational addiction models is critical to advance the identification of novel efficacious therapeutics to reduce the harms associated with PSU.

RECENT FINDINGS

Substance use disorders are complex as clinically defined and diagnosed. Further, PSU is highly prevalent and individuals may use multiple substances within the illicit drug supply which continually evolves and is tracked via surveillance efforts (e.g., the National Drug Early Warning System). Preclinical models often model monosubstance use patterns which do not reflect real world drug use and omits expertise from people who use drugs in driving preclinical addiction science.

SUMMARY

Here, we argue a case against purity in the development, design, and implementation of preclinical translational studies of addictive drugs, a need for inclusion of individuals with living experience, and highlight the need for additional research on PSU across the translational spectrum.

The neuroplastic brain: current breakthroughs and emerging frontiers

Neuroplasticity, the brain's capacity to reorganize itself by forming new neural connections, is central to modern neuroscience. Once believed to occur only during early development, research now shows that plasticity continues throughout the lifespan, supporting learning, memory, and recovery from injury or disease. Substantial progress has been made in understanding the mechanisms underlying neuroplasticity and their therapeutic applications. This overview article examines synaptic plasticity, structural remodeling, neurogenesis, and functional reorganization, highlighting both adaptive (beneficial) and maladaptive (harmful) processes across different life stages. Recent strategies to harness neuroplasticity, ranging from pharmacological agents and lifestyle interventions to cutting-edge technologies like brain-computer interfaces (BCIs) and targeted neuromodulation are evaluated in light of current empirical evidence. Contradictory findings in the literature are addressed, and methodological limitations that hamper widespread clinical adoption are discussed. The ethical and societal implications of deploying novel neuroplasticity-based interventions, including issues of equitable access, data privacy, and the blurred line between treatment and enhancement, are then explored in a structured manner. By integrating mechanistic insights, empirical data, and ethical considerations, the aim is to provide a comprehensive and balanced perspective for researchers, clinicians, and policymakers working to optimize brain health across diverse populations.

Expecting medication misuse: a proactive approach to drug discovery to prevent fatal overdose

Misuse of central nervous system (CNS) depressants (alprazolam, fentanyl, etc.) is a major cause of fatal overdose, with a high prevalence of deaths involving polydrug interactions from the victim's own prescriptions. Thus, there is an urgent need to improve the safety of CNS depressants to prevent fatalities. Pharmacological pursuits aiming to prevent harm through the design of non-addictive alternatives have either failed before clinical trials or produced mediocre treatment alternatives. Therefore, we propose a new perspective for medicinal chemists: rather than aiming to prevent misuse, we must design new central nervous system (CNS) depressants under the expectation of misuse. By shifting the design focus to partial modulators rather than full agonists, we can develop novel chemical entities (NCEs) that intrinsically minimize physical harm caused by misuse without sacrificing therapeutic efficacy. In this perspective, we provide an overview of the two most widely misused classes of medications (opioid and GABAA receptor modulators) in relation to pharmacodynamic properties and clinical outcomes. We then suggest a drug discovery pathway focused on physiological parameters. It is our opinion that this approach would dramatically decrease the lethality of overdose and improve outcomes of treatments for pain, anxiety, and withdrawal from alcohol, benzodiazepines, and opioids.

The rodent electronic nicotine delivery system: Apparatus for voluntary nose-only e-cigarette aerosol inhalation

Tobacco use is the leading cause of death globally and in the United States. After decades of decline, driven by decreases in combusted tobacco use, nicotine product use has increased due to electronic nicotine delivery systems, also known as e-cigarettes or vapes. Preclinical models of nicotine self-administration can serve as important lodestars in the search for effective intervention and prevention tactics. Current variants of the preclinical models have substantial limitations, however. Therefore, we created the rodent electronic nicotine delivery system (RENDS), a novel low-cost nonproprietary nose-only preclinical model of nicotine aerosol self-administration. We confirmed that RENDS sequesters nicotine aerosol in the nose port by measuring fine particulate matter (PM <2.5 microns) generated by e-cigarettes. We also showed that rats robustly self-administer flavored nicotine aerosol, resulting in high blood levels of cotinine (the major nicotine metabolite) and spontaneous somatic withdrawal symptoms. Thus, we provide validation of the operation and function of the RENDS, opening the door to an open-source preclinical aerosol model of nicotine self-administration that is relatively low in cost. Four existing operant chambers can be retrofitted with the RENDS for less than $325/chamber. All RENDS diagrams and plans for custom-designed components are on Open Science Framework (https://osf.io/x2pqf/?view_only=775b55435b8e428f98e6da384ef7889d).