Biology subjects

Hing, B.

Publications and source records attributed to Hing, B..

8 recordsLinked to original sources

bioRxiv2026

Sub-Chronic Chlorpyrifos Exposure Leads to Epigenetic and Sex-Specific Behavioral Changes in Adult Mice

Chlorpyrifos is a widely used organophosphate pesticide that exerts its primary toxic effect through inhibition of acetylcholinesterase (AChE). Although the acute neurotoxicity of chlorpyrifos is well characterized, the lasting biochemical, behavioral, and epigenetic consequences of sub-chronic exposure remain poorly understood, particularly when considering sex-specific differences. Therefore, we exposed male and female C57BL/6J mice to either peanut oil (n=19), low chlorpyrifos exposure (1 mg/kg/day; n=19), or high chlorpyrifos exposure (10 mg/kg/day n=10) repeatedly for 21 days via subcutaneous injection. Blood AChE activity, behavior, and hippocampal DNA methylation were measured across groups. During exposure, AChE activity decreased in both males and females but only returned to baseline after behavioral testing in females exposed to low chlorpyrifos levels. Behavioral tests also revealed a sex-specific phenotype, with females in the low exposure group exhibiting reduced forced swim test immobility and a significant time by exposure interaction in open field habituation. No significant behavioral effects were observed in males. Significant DNA methylation changes were observed at 3,538 CpG sites in male and female mice after high exposure. Sex-specific analyses revealed two female-specific differentially methylated CpGs after high exposure. Pathways enriched for differentially methylated genes included several related to synaptic remodeling, cholinergic synapse, and various endocrine systems. These findings demonstrate that repeated high chlorpyrifos exposure leads to persistent cholinergic disruption and DNA methylation changes. However, the female-specific behavioral changes seen are independent of AChE activity and widespread DNA methylation changes, suggesting additional mechanisms, present only in females, may underlie behavioral sensitivity to chlorpyrifos. New and NoteworthySub-chronic chlorpyrifos exposure in adult mice produced dose-dependent blood AChE suppression and widespread hippocampal DNA methylation changes in both sexes, with pathway enrichment including cholinergic synapse and endocrine systems. Behavioral effects were subtle, with females in the low exposure group showing reduced forced swim immobility and altered locomotor habituation. Notably, the female-specific behavioral changes seen are independent of AChE activity and DNA methylation changes, suggesting novel mechanisms may underlie female behavioral sensitivity to chlorpyrifos.

neuroscience↗

bioRxiv2025

Psychiatric risk implications of adolescent exposure to environmental insecticides: a systematic review of rodent studies

Adolescence is a sensitive period of neurodevelopment marked by remodeling of brain circuits that support cognitive development and emotion and behavior regulation. These maturation processes heighten psychiatric vulnerability to environmental exposures, including to toxicants such as insecticides. Epidemiological studies show widespread adolescent insecticide exposure and increasingly link this with psychiatric outcomes, yet underlying neural mechanisms remain poorly understood. Preclinical studies can clarify these associations and identify insecticide-induced mechanisms that may disrupt neurodevelopment and produce consequent long-term behavioral outcomes. Here, we performed a systematic review of rodent studies following PRISMA guidelines. 50 original articles met inclusion criteria, examining neurotoxic outcomes following insecticide exposure during adolescence (postnatal days 21-60). Outcomes were categorized into four domains: neurocognitive, neuropsychiatric, neurobiological, and general neurotoxicity. Risk of bias was assessed using the SYRCLE Risk of Bias tool. Across studies, insecticide exposure during adolescence led to learning and memory impairments and tended to increase depression relevant behaviors, alter locomotor activity, and produce general neurotoxic effects. Mechanistic findings highlighted disruptions in cholinergic and monoaminergic signaling, oxidative stress, neuroimmune changes, and cell death and other neurodegenerative processes. Together, these findings indicate adolescent insecticide exposure disrupts multiple neural systems with behavioral consequences relevant to adolescent development and psychiatric risk. Future research should model real-world exposures (e.g. dose, timing) to better inform translational understanding of adolescent psychiatric vulnerability. Because many life-long neuropsychiatric disorders emerge in adolescence, identifying how modifiable environmental exposures shape risk offers an opportunity for prevention and intervention strategies to alter the course of disease across the lifespan.

neuroscience↗

bioRxiv2025

Maternal α-cypermethrin and permethrin exert differential effects on fetal growth, placental morphology, and fetal neurodevelopment in mice

Pyrethroid insecticides represent a broad class of chemicals used widely in agriculture and household applications. Human studies show mixed effects of maternal pyrethroid exposure on fetal growth and neurodevelopment. Assessment of shared pyrethroid metabolites as a biomarker for exposure obscures effects of specific chemicals within this broader class. To better characterize pyrethroid effects on fetal development, we investigated maternal exposure to permethrin, a type I pyrethroid, and -cypermethrin, a type II pyrethroid, on fetal development in mice. Pregnant CD1 mice were exposed to permethrin (1.5, 15, or 50 mg/kg), -cypermethrin (0.3, 3, or 10 mg/kg), or corn oil vehicle via oral gavage on gestational days (GD) 6-16. Effects on fetal growth, placental toxicity, and neurodevelopment were evaluated at GD 16. Cypermethrin, but not permethrin, significantly reduced fetal growth and altered placental layer morphology. Placental RNAseq analysis revealed downregulation of genes involved in extracellular matrix remodeling in response to -cypermethrin. Both pyrethroids induced shifts in fetal dorsal forebrain microglia morphology from ramified to ameboid states; however, effects of -cypermethrin were more pronounced. The -cypermethrin transcriptome of fetal dorsal forebrain implicated altered glutamate receptor signaling, synaptogenesis, and c-AMP signaling. Coregulated gene modules in individual placenta and fetal dorsal forebrain pairs were correlated and overlapped in biological processes characterizing synapses, mitotic cell cycle, and chromatin organization, suggesting placenta-fetal brain shared mechanisms with -cypermethrin exposure. In summary, maternal type II pyrethroid -cypermethrin exposure but not type I pyrethroid permethrin significantly affected placental development, fetal growth, and neurodevelopment, and these effects were linked.

pharmacology and toxicology↗

bioRxiv2024

Peripheral CGRP engages brain-wide electrical network activity of migraine

BackgroundMigraine is a disorder of severe, recurrent headaches and debilitating sensory, cognitive and affective symptoms, often triggered by stress. Early life stress in childhood has been shown to increase the likelihood of migraine in adulthood in humans. Calcitonin-gene relate peptide (CGRP) has been shown to reliably and acutely induce migraine or migraine-like behavior in both humans and rodent models. Here we investigate the impact of early life stress and CGRP on migraine-related neural circuitry, as well as the impact of early life stress on CGRP-mediated migraine-like activity in order to better understand the mechanisms by which early life stress predisposes neural circuitry to migraine brain activity. MethodsWe implemented an early life stress paradigm in the outbred strain of mice, CD1. We evaluated the impact of peripheral CGRP on migraine-like behavior and employed multi-site in vivo neurophysiology in freely behaving mice. A changepoint analysis was used to dissect differences in individual CGRP-induced responses. ResultsWe found that early life stress exacerbated migraine-related behavioral and network physiology. CGRP alone caused disruptions in neural oscillatory activity across a network of brain regions including the anterior cingulate cortex (ACC), amygdala (AMY), thalamus (Po, VPM, and MDthal), and parabrachial nucleus (PBN). We found that power across the network was lowered within 10 minutes of peripheral CGRP exposure, which was sustained for [~]40-50 min. Coherence was mostly disrupted in amygdalar brain region pairings, and took on a shorter timecourse, with partial rescue of these responses by migraine abortive, sumatriptan. We found that early life stress exacerbated most of these responses, especially AMY-thalamic coherence pairings, although early life stress in the absence of CGRP demonstrated no impact on the network overall. We further identified individual mice with brain-network activity hypersusceptible to migraine. ConclusionsOur findings demonstrate that early life stress confers vulnerability to migraine, simultaneously impacting behavior and brain network activity responses to peripheral CGRP.

neuroscience↗

bioRxiv2023

Transcriptomic Evaluation of Stress Vulnerability Network using Single Cell RNA-Seq in mouse Prefrontal Cortex

Increased vulnerability to stress is a major risk factor for the manifestation of several mood disorders, including major depressive disorder (MDD). Despite the status of MDD as a significant donor to global disability, the complex integration of genetic and environmental factors that contribute to the behavioral display of such disorders has made a thorough understanding of related etiology elusive. Recent developments suggest that a brain-wide network approach is needed, taking into account the complex interplay of cell types spanning multiple brain regions. Single cell RNA-sequencing technologies can provide transcriptomic profiling at the single-cell level across heterogenous samples. Furthermore, we have previously used local field potential oscillations and machine learning to identify an electrical brain network that is indicative of a predisposed vulnerability state. Thus, this study combined single cell RNA-sequencing (scRNA-Seq) with electrical brain network measures of the stress-vulnerable state, providing a unique opportunity to access the relationship between stress network activity and transcriptomic changes within individual cell types. We found especially high numbers of differentially expressed genes between animals with high and low stress vulnerability brain network activity in astrocytes and glutamatergic neurons but we estimated that vulnerability network activity depends most on GABAergic neurons. High vulnerability network activity included upregulation of microglia and mitochondrial and metabolic pathways, while lower vulnerability involved synaptic regulation. Genes that were differentially regulated with vulnerability network activity significantly overlapped with genes identified as having significant SNPs by human GWAS for depression. Taken together, these data provide the gene expression architecture of a previously uncharacterized stress vulnerability brain state, enabling new understanding and intervention of predisposition to stress susceptibility. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=91 SRC="FIGDIR/small/540705v2_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@1ebe036org.highwire.dtl.DTLVardef@cd2131org.highwire.dtl.DTLVardef@13e3519org.highwire.dtl.DTLVardef@1100e62_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

A critical role for touch neurons in a skin-brain pathway for stress resilience

Social touch can act as a stress buffer, reducing behavioral and physiological responses to stressful scenarios. However, skin-brain touch pathways that promote stress resilience remain unknown. Here, we show that mice with an early life genetic ablation of Mrgprb4-lineage touch neurons display stress vulnerability behaviors in adulthood. Chemogenetic activation of these touch neurons reduced corticosterone levels under mild acute stress conditions. In addition, whole-brain c-Fos activity mapping while chemogenetically turning on these neurons uncovered differential neural activity patterns in brain areas relevant to somatosensation, reward, and affect. To gain mechanistic insight into this skin-brain touch pathway for stress susceptibility, we used multi-circuit neurophysiological recordings across seven brain regions at baseline and after stress in mice that had Mrgprb4-lineage touch neurons ablated in early life. Interestingly, the Mrgprb4-lineage neuron-ablated mice have alterations in local field potential phase directionality and power in the theta frequencies in mesolimbic reward regions, which may underlie our observed stress susceptibility phenotype. Together, these studies revealed that sensory neurons in the skin engage networks across the brain to promote stress resilience.

neuroscience↗

bioRxiv2021

An ancient polymorphic regulatory region within the BDNF gene associated with obesity modulates anxiety-like behaviour in mice and humans.

Obesity and anxiety are morbidities notable for their increased impact on society during the recent COVID-19 pandemic. Understanding the mechanisms governing susceptibility to these conditions will increase quality of life and our resilience to future pandemics. In the current study we explored the function of a highly conserved regulatory region (BE5.1) within the BDNF gene that harbours a polymorphism strongly associated with obesity (rs10767664; p=4.69x10-26). Analysis in primary cells suggested that the major T-allele of BE5.1 was an enhancer whereas the obesity associated A-allele was not. However, CRISPR/CAS9 deletion of BE5.1 from the mouse genome (BE5.1KO) produced no significant effect on the expression of BDNF transcripts in the hypothalamus, no change in weight gain after 28 days and only a marginally significant increase in food intake. Nevertheless, transcripts were significantly increased in the amygdala of female mice and elevated zero maze and marble burying tests demonstrated a significant increase in anxiety-like behaviour that could be reversed by diazepam. Consistent with these observations, human GWAS cohort analysis demonstrated a significant association between rs10767664 and anxiousness in human populations. Intriguingly, interrogation of the human GTEx eQTL database demonstrated no effect on BDNF mRNA levels associated with rs10767664 but a highly significant effect on BDNF-antisense (BDNF-AS) gene expression and splicing suggesting a possible mechanism. We discuss our findings within the context of the known function and regulation of BDNF in obesity and anxiety whilst exploring the validity of interrogating GWAS data using comparative genomics and functional analysis using CRISPR genome editing in mice.

genetics↗

bioRxiv2020

PACAP induces light aversion in mice by an inheritable mechanism independent of CGRP

The neuropeptides CGRP and PACAP have emerged as mediators of migraine, yet the potential overlap of their mechanisms remains unknown. Infusion of PACAP, like CGRP, can cause migraine in people, and both peptides share similar vasodilatory and nociceptive functions. In this study, we have used light aversion in mice as a surrogate for migraine-like photophobia to compare CGRP and PACAP and ask whether CGRP or PACAP actions were dependent on each other. Similar to CGRP, PACAP induced light aversion in outbred CD-1 mice. The light aversion was accompanied by increased resting in the dark, but not anxiety in a light-independent open field assay. Unexpectedly, about a third of the CD-1 mice did not respond to PACAP, which was not seen with CGRP. The responder and nonresponder phenotypes were stable, inheritable, and not sex-linked, although there was generally a trend for greater responses among male mice. RNA-seq analysis of trigeminal ganglia yielded hieriechial clustering of responder and nonresponder mice and revealed a number of candidate genes, including greater expression of pituitary hormones and receptors in a subset of responder mice. Importantly, an anti-PACAP monoclonal antibody could block PACAP-induced light aversion but not CGRP-induced light aversion. Conversely, an anti-CGRP antibody could not block PACAP-induced light aversion. Thus, we propose that CGRP and PACAP act by independent convergent pathways that cause a migraine-like symptom in mice. SignificanceThe relationship between the neuropeptides CGRP and PACAP in migraine is relevant given that both peptides can induce migraine in people, yet to date only drugs that target CGRP are available. Using an outbred strain of mice, we were able to show that most, but not all, mice respond to PACAP in a preclinical photophobia assay. Our finding that CGRP and PACAP monoclonal antibodies do not cross-inhibit the other peptide indicates that CGRP and PACAP actions are independent and suggests that PACAP-targeted drugs may be effective in patients who do not respond to CGRP-based therapeutics.

neuroscience↗