Biology subjects

Winter, M. J.

Publications and source records attributed to Winter, M. J..

4 recordsLinked to original sources

bioRxiv2025

Fentanyl and Alcohol Co-Exposure Induce Robust, Sustained Hyperlocomotion and Neural Circuit Disruption in Larval Zebrafish

The constantly evolving trends in substance abuse are a major concern for health authorities worldwide, and these trends include an increasing prevalence of poly-substance misuse. For instance, opioid overdoses are frequently accompanied by alcohol co-use, yet the combined effects of these substances remain poorly understood. Using zebrafish as a highly relevant vertebrate model of neuropharmacology, we investigated the interactions between fentanyl and alcohol, uncovering a unique and robust hyperlocomotor response characterized by initial locomotor suppression followed by persistent, erratic hyperlocomotion. Alcohol was found to be critical to this phenomenon, as substitution with other GABAA modulators failed to replicate the effect. However, the response was replicable with heroin and remifentanil, suggesting an opioid-class wide effect. In vivo whole brain imaging further demonstrated dysregulated neuronal activity, with co-administration with alcohol causing potentiated neuronal activity compared to individual drug exposures and controls. Collectively, these findings suggested an integral role of ethanol and fentanyl co-administration in dysregulated neuronal responses and reveals a complex neurobehavioral mechanism. These observations suggest further investigation is warranted into the use of the larval zebrafish model for studying the neuropharmacological interactions of multiple substances of abuse.

animal behavior and cognition↗

bioRxiv2025

Neural and Behavioral Dynamics of Acute Fentanyl Administration and Implications for Hazard Assessment of Novel Synthetic Opioids in Larval Zebrafish

Rationale Synthetic opioids pose a significant public health risk due to their rapid synthesis and potentially lethal potency. New compounds are emerging continuously, meaning current testing platforms struggle to keep pace. Objectives Consequently, there is a critical need for simple, rapid, translatable models to provide a scalable screening platform to identify and hazard-assess emerging synthetic opioids, and test potential intervention strategies. Methods Here, we exposed 4 days post-fertilization (dpf) larval zebrafish to a range of concentrations of the prototypical class representative, fentanyl, to investigate behavioral and neural responses. Results Fentanyl caused low concentration hyperactivity, and high concentration hypolocomotion (sedation) which was reversed by the opioid antagonist naloxone. We confirmed predictive validity by replicating the behavioral responses with other class representatives (diacetylmorphine [heroin] and remifentanil). We also confirmed, pharmacologically, that low concentration hyperlocomotion was mediated by dopamine D2 receptors, replicating effects observed in mammals. Further mechanistic investigation using whole-brain in vivo imaging revealed disrupted connectivity in opioid-related circuits, such as the habenulae and dorsal thalamus, alongside novel pathways, including circuits associated with the pineal gland, torus semicircularis and eminentia granularis, potentially highlighting previously uncharacterized sensory and cerebellar neuronal networks. Conclusions These findings support the use of the larval zebrafish as a scalable model for assessment of synthetic opioids to provide novel insights into opioid-induced behaviors and mechanisms of action that may aid strategies in the growing challenge of interventive treatments for synthetic opioid intoxication. Impact StatementLarval zebrafish reveal neurobehavioral pathways affected by synthetic opioids, offering a valuable tool for rapid hazard assessment.

animal behavior and cognition↗

bioRxiv2021

Human rare variant and zebrafish CRISPR/Cas9-mediated mutant analyses reveal novel functions for API5, HSPB7, and LMO2 in heart failure

The clinical heterogeneity of heart failure has challenged our understanding of the underlying genetic mechanisms of this disease. In this respect, large-scale patient DNA sequencing studies have become an invaluable strategy for identifying potential genetic contributing factors. The complex aetiology of heart failure, however, also means that in vivo models are vital to understand the links between genetic perturbations and functional impacts. Traditional approaches (e.g. genetically-modified mice) are optimal for assessing small numbers of proposed target genes, but less practical when multiple targets are identified. The zebrafish, in contrast, offers great potential for higher throughput in vivo gene functional assessment to aid target prioritisation and support definitive studies undertaken in mice. Here we used whole-exome sequencing and bioinformatics on human patient data to identify 3 genes (API5, HSPB7, and LMO2) suggestively associated with heart failure that were also predicted to play a broader role in disease aetiology. The role of these genes in cardiovascular system development and function was then further investigated using in vivo CRISPR/Cas9-mediated gene mutation analysis in zebrafish. We observed multiple impacts in F0 knockout zebrafish embryos (crispants) following effective somatic mutation, including reductions in ventricle size, pericardial oedema, and chamber malformation. In the case of lmo2, there was also a significant impact on cardiovascular function as well as an expected reduction in erythropoiesis. The data generated from both the human in silico and zebrafish in vivo assessments undertaken supports roles for API5, HSPB7, and LMO2 in human cardiovascular disease and identifies them as potential drug targets for further investigation. The data presented also supports the use of human in silico genetic variant analysis, in combination with zebrafish crispant phenotyping, as a powerful approach for assessing gene function as part of an integrated multi-level drug target validation strategy.

molecular biology↗

bioRxiv2021

Estrogen regulates early embryonic development of the olfactory sensory system via estrogen responsive glia

Estrogen is well-known to regulate development of sexual dimorphisms of the brain, however its role in the brain during early embryonic development prior to sex-differentiation is unclear. Using estrogen biosensor zebrafish models, we found that estrogen activity in the embryonic brain occurs specifically in a type of glia located within the OB, which we name estrogen-responsive olfactory bulb/EROB cells. With estrogen activity, EROB cells extend their ramified projections that overlay the OB outermost layer and tightly interact with olfactory sensory neurons (OSNs) at the olfactory glomeruli. Pharmacologically inhibiting estrogen activity and/or EROB cell ablation impedes olfactory glomerular development, including OSN pathfinding, topological organisation of olfactory glomeruli and inhibitory neurogenesis in the OB. Furthermore, activation of this estrogen/EROB-dependent mechanism decreases the intrinsic neuronal activity primarily in the OB, and this alteration of estrogen signalling disrupts olfaction-mediated behaviour. We propose that estrogen acts on glia to regulate development of functional OB circuits, thereby modulating the local intrinsic excitability in the OB and olfaction-mediated behaviour. Our data also suggest a possibility that the estrogen/EROB cascade may be an important site of action for environmental estrogens causative of neurodevelopmental impairments in animals and humans.

developmental biology↗