Biology subjects

Gallino, D.

Publications and source records attributed to Gallino, D..

11 recordsLinked to original sources

bioRxiv2025

In vivo and in silico alpha-synuclein propagation dynamics: The role of genotype, epicentre, and connectivity

Neurodegeneration observed in synucleinopathies, like Parkinsons disease (PD), are hypothesized to be a consequence of the progressive accumulation and spread of misfolded alpha-synuclein (aSyn) throughout the brain. Here, we study the generalizability of this hypothesis across multiple biologically-relevant factors including genotype, aSyn species, and regional vulnerability (i.e.: does the introduction of aSyn into different brain regions have a similar impact) using a detailed longitudinal brain (using magnetic resonance imaging; [MRI]) and behavioural approaches. We first examined wild-type and M83 A53T hemizygous transgenic (engineered to over-express human aSyn) C57BL/6 x C3H mice receiving striatal inoculation with human or mouse preformed fibrils (PFFs) (n=89 mice at the last time point; n=687 MRI). Longitudinal analyses demonstrated a time-dependent increase in network-like atrophy and motor deficits, generalized across genotype and PFF species. We further derived latent dimensions relating brain-behaviour relationships revealing a pattern of sex- and genotype-relevant atrophy. Overall, atrophy was most prominent in M83 mice with mouse PFFs, while human PFFs or wild-type hosts showed attenuated effects. Changing the inoculation site to the hippocampus, a major connectivity hub, revealed differential regional vulnerability in the form of localized atrophy. Computational models previously validated in clinical PD further indicated regional vulnerability with increased predictive ability for atrophy patterns associated with striatal compared to hippocampal inoculation. Our findings reveal atrophy resulting from aSyn spreading is generalizable across genotype and PFF species, but not disease epicentres, emphasizing the role of regional vulnerability in disease progression.

neuroscience↗

bioRxiv2025

Evidence-based guidelines for improving network detectability in rodent fMRI

Mouse resting-state functional magnetic resonance imaging (rs-fMRI) is an increasingly popular tool for probing brain activity under experimental manipulations; however, there remains considerable variability in data quality throughout the field. There is a need for an accessible set of acquisition guidelines such that a baseline level of data quality can be attained regardless of domain expertise or specialized equipment (i.e. in anesthetized, free-breathing mice). In particular, there is a gap in the literature regarding the interpretation of physiological parameters as markers of anesthetic depth, and ultimately, data quality. To this end, we developed a set of acquisition guidelines after examining whether continuous physiological variables predict network detectability above and beyond categorical external variables (anesthetic dose, session, time) in C57Bl/7 and C3HeB/FeJ mice anesthetized with isoflurane-dexmedetomidine. Standard physiological metrics (respiration rate and heart rate) did not predict network detectability above and beyond anesthetic dose but instead depended strongly on strain and subject, thus we advise against tuning anesthesia based on respiration or heart rate when the goal is obtaining clear resting-state networks. The most important predictor of improved network detectability was a low isoflurane dose of 0.23%, hence we recommend that researchers prioritize piloting the minimal possible isoflurane dose for their mouse model. In summary, our work examines the contributions from sources of variability that impact rs-fMRI data quality and synthesizes the findings into practical guidelines to help experimenters adapt their acquisition protocols and improve data quality.

neuroscience↗

bioRxiv2025

Whole brain dimensional approach identifies shared and sex-specific networks of stress susceptibility in male and female mice.

Stress is a major risk factor for depression and anxiety, two highly comorbid disorders with sex differences in symptom presentation and prevalence. Accumulating evidence on the chronic variable stress (CVS) mouse model has revealed that stress susceptibility is sex-specific, as females require less stress exposure (6 days) compared to males (21-28 days) to develop comparable adaptations in depressive- and anxiety-like behaviors. However, the neuroanatomical changes associated with stress susceptibility remain unclear in each sex. Given this differential susceptibility, elucidating these mechanisms requires a phenotype-matched approach in which stress duration is titrated in a sex-specific manner to induce comparable behavioral adaptations. Here, we used a multi-variate brain-behavior and connectomic analysis to examine signatures of stress susceptibility in female and male mice. Using structural magnetic resonance imaging (MRI), we investigate whole-brain neuroanatomical changes associated with behavioral susceptibility within each sex. We then examined the structural connectome underlying neuroanatomical changes associated with behavioral susceptibility within each sex, and putative molecular basis for behaviorally-relevant changes using spatial gene expression analyses. CVS induced significant neuroanatomical changes in regions commonly implicated in anxiety- and depressive-like phenotypes in both sexes (e.g. nucleus accumbens and hippocampus); however qualitative differences between sexes in the direction of change were observed. In addition to these changes, in females stress-induced neuroanatomical changes were associated with both depressive- and anxiety-like behavior, whereas in males we observed two orthogonal dimensions of neuroanatomical changes associated with anxiety-like behavior or social preference. The connectomic topology underlying these brain-behavior dimensions revealed the cortical hub regions for females and subcortical hub regions for males. In females, neuroanatomical changes were associated with genes enriched for protein localization to the cell surface, suggesting alterations in cholinergic signaling By implementing a phenotype-matched CVS protocol, our findings indicate that the neuroanatomical signature of stress susceptibility encompasses similar brain regions across both sexes, however the direction of change, association to behavior and connectomic properties may differ in each sex.

neuroscience↗

bioRxiv2025

Examining Alzheimer's Disease Modifiable Risk Factors: Impact of Physical Activity and Diet on Neuroanatomy and Behaviour in Mice

Dementia is a global public health challenge, with obesity emerging as an important modifiable risk factor. Here, we examined whether lifestyle interventions can mitigate the effects of diet-induced obesity on body weight, behaviour, and brain anatomy in mouse models. Using a longitudinal design, wild-type and triple-transgenic (3xTgAD) mouse models of Alzheimers disease were exposed to a high-fat diet and assigned to one of three interventions: voluntary physical activity, a low-fat diet, and their combination. A high-fat diet significantly increased body weight and induced widespread neuroanatomical changes, with effects modulated by sex and genotype. The combined intervention led to significant weight loss in males of both genotypes. Neuroanatomical analyses revealed that a high-fat diet significantly reduced hippocampal and cerebellar volumes in wild-type mice but had a less pronounced effect on 3xTgAD mice; nevertheless, interventions, particularly the combined approach, increased localized brain volumes in these regions regardless of genotype. Multivariate integration of behavioural and neuroanatomical measures identified a brain pattern linking hippocampal and cerebellar volumes to intervention and behavioural performance. Spatial gene enrichment analysis of this pattern identified biological processes, including glucose homeostasis, as potential biological mechanisms underlying intervention effects. Overall, these findings suggest that voluntary physical activity and a low-fat diet can modulate brain structure and behaviour, partially counteracting the effects of a high-fat diet, and potentially recruiting biological processes that may support brain health.

neuroscience↗

bioRxiv2024

Impact of prenatal delta-9-tetrahydrocannabinol exposure on mouse brain development: a fetal-to-adulthood magnetic resonance imaging study

While cannabis use during pregnancy is often perceived as harmless, little is known about its consequences on offspring neurodevelopment. There is an urgent need to map the effects of prenatal cannabis exposure on the brain through the course of the lifespan. We used magnetic resonance imaging spanning nine timepoints, behavioral assays, and electron microscopy to build a trajectory from gestation to adulthood in mice exposed prenatally to delta-9-tetrahydrocannabinol (THC). Our results demonstrate a spatio-temporal patterning, with ventriculomegaly in THC-exposed embryos followed by a deceleration of brain growth in neonates that is sustained until adulthood, especially in females. We observed consistently impacted regions in both the cortex and subcortex, aligned with sex-dependent changes to social behavior in neonates and increased anxiety-like behavior in adolescents. Our results suggest prenatal THC exposure has a sustained sex-dependent impact on neurodevelopment that may persist into early adulthood.

neuroscience↗

bioRxiv2024

Sex-focused analyses of M83 A53T hemizygous mouse model with recombinant human alpha-synuclein preformed fibril injection identifies female resilience to disease progression: A combined magnetic resonance imaging and behavioural study.

Alpha-synuclein (aSyn) pathology has been extensively studied in mouse models harbouring human mutations. In spite of the known sex differences in age of onset, prevalence and disease presentation in human synucleinopathies, the impact of sex on aSyn propagation has received very little attention. To address this need, we examined sex differences in whole brain signatures of neurodegeneration due to aSyn toxicity in the M83 mouse model using longitudinal magnetic resonance imaging (MRI; T1-weighted; 100 m3 isotropic voxel; acquired -7, 30, 90 and 120 days post-injection [dpi]; n[≥]8 mice/group/sex/time point). To initiate aSyn spreading, M83 mice were inoculated with recombinant human aSyn preformed fibrils (Hu-PFF) or phosphate buffered saline (PBS) injected in the right dorsal striatum. We observed more aggressive neurodegenerative profiles over time for male M83 Hu-PFF-injected mice when examining voxel-wise trajectories. However, at 90 dpi, we observed widespread patterns of neurodegeneration in the female Hu-PFF-injected mice. These differences were not accompanied with any differences in motor symptom onset between the male and female Hu-PFF-injected mice. However, male Hu-PFF-injected mice reached their humane endpoint sooner. These findings suggest that post-motor symptom onset, even though more accelerated disease trajectories were observed for male Hu-PFF-injected mice, neurodegeneration may appear sooner in female Hu-PFF-injected mice (prior to motor symptomatology). These findings suggest that sex-specific synucleinopathy phenotypes urgently need to be considered to improve our understanding of neuroprotective and neurodegenerative mechanisms.

neuroscience↗

bioRxiv2022

Presymptomatic neuroanatomical and cognitive biomarkers of alpha-synuclein propagation in a mouse model of synucleinopathy

There is significant evidence suggesting aggregated misfolded alpha-synuclein, a major component of Lewy bodies, propagates in a prion-like manner contributing to disease progression in Parkinsons disease (PD) and other synucleinopathies. Animal models are essential for understanding and developing treatments for these diseases. However, despite modelling human pathology, most endpoints studied in mice do not translate to humans. Furthermore, the progression by which alpha-synuclein misfolding affects human-relevant measures such as brain volume and underlying subtle, high-level cognitive deficits is poorly understood. Here we used a mouse model of synucleinopathy; hemizygous M83 human A53T alpha-synuclein transgenic mice inoculated with recombinant human alpha-synuclein preformed fibrils (PFF) injected in the right striatum to initiate alpha-synuclein misfolding and aggregation. We examined alpha-synuclein-induced atrophy at 90 days post-injection using ex vivo magnetic resonance imaging as well as high-level cognition and motor function, as biomarkers of alpha-synuclein toxicity. We observed widespread atrophy in bilateral regions that project to or receive input from the injection site, highlighting a network of regions that are consistent with structural changes observed in humans with PD. Moreover, we detected early deficits in reversal learning with touchscreen testing in PFF-injected mice prior to motor dysfunction, consistent with the pathology observed in cortical-striatal and thalamic loops. We show, using translational approaches in mice, that progression of prion-like spreading of alpha-synuclein causes selective atrophy via connected brain regions leading to high-level cognitive deficits. We propose that precise imaging and cognitive biomarkers can provide a more direct and human-relevant measurement of alpha-synuclein-induced toxicity in pre-clinical testing. Significance StatementThe work described in this manuscript showcases the utility of state-of-the-art methodologies (magnetic resonance imaging and touchscreen behavioural tasks) to examine endophenotypes, both in terms of symptomatology and neuroanatomy, of alpha-synuclein propagation in a mouse model of synucleinopathy. Our work further validates the M83-Hu-PFF mouse model of synucleinopathy-associated pathogenesis of neurodegenerative diseases while highlighting precise imaging and cognitive biomarkers of protein misfolding toxicity. Specifically, we identified rapid and translational biomarkers that can serve as a proxy for the direct examination of cellular levels for pathology. We anticipate that these biomarkers can measure progression of toxicity, specifically in the early phases, and may be more reliable than end stage pathology and more useful as endpoints in the examination of novel therapeutics.

neuroscience↗

bioRxiv2022

Examining Litter Specific Variability in Mice and its Impact on Neurodevelopmental Studies

Our current understanding of litter variability in neurodevelopmental studies using mouse may limit translation of neuroscientific findings. Higher variance of measures across litters than within, often termed intra-litter likeness, may be attributable to pre- and postnatal environment. This study aimed to assess the litter-effect within behavioral assessments (2 timepoints), and anatomy using T1-weighted magnetic resonance images (4 timepoints) across 72 brain region volumes (36 C57bl/6J inbred mice; 7 litters: 19F/17M). Between-litter comparisons of brain and behavioral measures and their associations were evaluated using univariate and multivariate techniques. A power analysis using simulation methods was then performed modeling neurodevelopment and evaluating trade-offs between number-of-litters, mice-per-litter, and sample size. Our results show litter-specific developmental effects, from the adolescent period to adulthood for brain structure volumes and behaviors, and their associations in adulthood. Our power simulation analysis results suggest increasing the number-of-litters in experimental design to achieve the smallest total sample size for detecting different rates of change in specific brain regions. Our results also demonstrate how litter-specific effects may influence development and that increasing the litters to the total sample size ratio should be strongly considered when designing neurodevelopmental studies.

neuroscience↗

bioRxiv2022

Investigating the "two-hit hypothesis": effects of prenatal maternal immune activation and adolescent cannabis use on neurodevelopment in mice

BackgroundPrenatal exposure to maternal immune activation (MIA) and chronic adolescent cannabis use are both risk factors for neuropsychiatric disorders. However, exposure to a single risk factor may not result in major mental illness, indicating that multiple exposures may be required for illness onset. Here, we examine whether combined exposure to prenatal MIA and adolescent delta-9-tetrahydrocannabinol (THC), the main psychoactive component of cannabis, lead to enduring neuroanatomical and behavioural changes in adulthood. MethodsMice were prenatally exposed to viral mimetic, poly I:C (5mg/kg), or vehicle at gestational day (GD)9, and postnatally exposed to chronic THC (5mg/kg, intraperitoneal) or vehicle during adolescence (postnatal day [PND]28-45). Longitudinal magnetic resonance imaging (MRI) was performed pre-treatment, PND25, post-treatment, PND50, and in adulthood, PND85, followed by behavioural tests for anxiety-like, social, and sensorimotor gating. Postmortem assessment of cannabinoid (CB)1 and 2 receptor expressing cells was performed in altered regions identified by MRI (anterior cingulate and somatosensory cortices, striatum, and hippocampus). ResultsSubtle deviations in neurodevelopmental trajectory and subthreshold anxiety-like behaviours were observed in mice exposed to both risk factors. Sex-dependent effects were observed in patterns of shared brain-behaviour covariation, indicative of potential sex differences in response to MIA and THC. Density of CB1 and CB2 receptor positive cells was significantly decreased in all mice exposed to MIA, THC, or both. ConclusionsThese findings suggest that there may be a cumulative effect of risk factor exposure on gross neuroanatomical development, and that the endocannabinoid system may be sensitive to both prenatal MIA, adolescent THC, or the combination.

neuroscience↗

bioRxiv2020

Early or late gestational exposure to maternal immune activation alters neurodevelopmental trajectories in mice: an integrated neuroimaging, behavioural, and transcriptional study

Prenatal maternal immune activation (MIA) is a risk factor for neurodevelopmental disorders. How gestational timing of MIA-exposure differentially impacts downstream development remains unclear. Here, we characterize neurodevelopmental trajectories of mice exposed to MIA induced by poly I:C either early (gestational day [GD]9) or late (GD17) in gestation using longitudinal structural magnetic resonance imaging from weaning to adulthood. Early MIA-exposure associated with accelerated brain volume increases in adolescence/early-adulthood that normalized in later adulthood, in regions including the striatum, hippocampus, and cingulate cortex. Similarly, alterations in anxiety, stereotypic, and sensorimotor gating behaviours observed in adolescence normalized in adulthood. In contrast, MIA-exposure in late gestation had less impact on anatomical and behavioural profiles. Using a multivariate technique to relate imaging and behavioural variables for the time of greatest alteration, i.e. adolescence/early adulthood, we demonstrate that variation in anxiety, social, and sensorimotor gating associates significantly with volume of regions including the dorsal and ventral hippocampus, and anterior cingulate cortex. Using RNA sequencing to explore the molecular underpinnings of region-specific alterations in early MIA-exposed mice in adolescence, we observed the most transcriptional changes in the dorsal hippocampus, with regulated genes enriched for fibroblast growth factor regulation, autistic behaviours, inflammatory pathways, and microRNA regulation. This indicates that MIA in early gestation perturbs brain development mechanisms implicated in neurodevelopmental disorders. Our findings demonstrate the inherent strength of an integrated hypothesis- and data-driven approach in linking brain-behavioural alterations to the transcriptome to understand how MIA confers risk for major mental illness.

neuroscience↗

bioRxiv2019

Common functional networks in the mouse brain revealed by multi-centre resting-state fMRI analysis

Preclinical applications of resting-state functional magnetic resonance imaging (rsfMRI) offer the possibility to non-invasively probe whole-brain network dynamics and to investigate the determinants of altered network signatures observed in human studies. Mouse rsfMRI has been increasingly adopted by numerous laboratories world-wide. Here we describe a multi-centre comparison of 17 mouse rsfMRI datasets via a common image processing and analysis pipeline. Despite prominent cross-laboratory differences in equipment and imaging procedures, we report the reproducible identification of several large-scale resting-state networks (RSN), including a murine default-mode network, in the majority of datasets. A combination of factors was associated with enhanced reproducibility in functional connectivity parameter estimation, including animal handling procedures and equipment performance. Our work describes a set of representative RSNs in the mouse brain and highlights key experimental parameters that can critically guide the design and analysis of future rodent rsfMRI investigations.

neuroscience↗