Neuroscience Bulletin

Experimental surgery is one of the most fundamental fields of biomedical research, recreating clinical conditions on living organisms similar to clinical patients, to facilitate the design of novel therapies. For modeling neurological and psychiatric disorders, the majority of operative techniques mandatorily include craniotomy for consecutive interactions with the open brain. The most wide-spread methodology involves stereotactic surgery in rodents, implementing a specific head holder, attached to the coordinate table, providing the precise animal head positioning according to the brain structures topology. Despite the high efficiency, such systems require complex instrumental skills and long procedure duration per animal even for simple implantation protocols. Hence, novel alternative model species could be a valuable supplementary tool for such manipulations. Therefore, the zebrafish (Danio rerio) fits perfectly, due to its low cost, easy husbandry, rapid development, optic transparency, and high genetic and physiological similarity to rodents and humans. Furthermore, the everted zebrafish telencephalon provides excellent accessibility to critical mammalian-like structures involved in emotion processing and cognition. However, conventional avian- or rodent-inspired craniotomies in adult zebrafish often trigger inadvertent disruption of the brain vessels network, resulting in high operative mortality. A novel, geometry-driven, non-lethal cranial window protocol preserving neurovascular integrity and ensuring 90-100% post-operative survival is presented to overcome above mentioned limitations. This rapid, simple, and high reproducible technique opens new avenues for precise region-specific in vivo neurosurgery, high-throughput psychopharmacological screening, and neurostimulation in a powerful non-mammalian model species

The FoxP family of transcription factors has been linked to neurodevelopmental disorders. FoxP1 and FoxP2 were identified as genes associated with autism spectrum disorders (ASD). FoxP1, FoxP2, and FoxP4 are expressed in many brain regions, including the cerebellum that has been of particular interest in the context of ASD. However, their role in the development of the peripheral nervous system (PNS) has been neglected. In view of the fact that a majority of ASD patients show some signs of sensory perception deficits that could go beyond the central nervous system, we focused on neural circuit formation in the PNS. Our in vivo and in vitro studies revealed a role of all three FoxP transcription factors in neural circuit formation in the hindlimb of the chicken embryo. Silencing of FoxP genes altered motor axon guidance and also impacted neural crest cell migration. This in turn resulted in aberrant formation of dorsal root ganglia and deficits in neural circuits in the PNS. Taken together, our results are in line with the hypothesis that some of the sensory perception deficits in ASD patients, either hyper- or hyposensitivity, are due to aberrant neural circuits in the PNS.

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by repetitive behavior and impaired social interactions. Recent reports from human postmortem brain samples of ASD show transcriptome-wide dysregulations, including changes in differential gene expression and alternative splicing. An important mechanism regulating transcriptome function is the editing of double-stranded RNA by adenosine deaminases acting on RNA (ADARs), which play regulatory roles in neurodevelopment and innate immunity. We explore the ADAR editing changes associated with the use of Selective Serotonin Reuptake Inhibitors (SSRIs) in Arid1b haploinsufficient mouse models. Our results show dynamic changes in site-specific editing rates in autistic mice. We further demonstrate the transcriptome-wide effects of differential ADAR editing in terms of changes in miRNA-mRNA interactions. Moreover, our findings highlight a site-specific change in editing rates for evolutionarily conserved sites in mammals and ASD associated risk genes, such as Gria2. Our analysis of significant biological processes shows the association of differentially edited genes with processes vital for neurotransmission. Overall, our findings imply that the use of SSRIs can induce distinct ADAR editing signatures, potentially contributing to ASD pathology.

Autism spectrum disorder (ASD) is a common neurodevelopmental disease with no currently effective treatments. In this study, Xenon (Xe), a noble gas used clinically as an anesthetic and a neuroprotectant, has been investigated for its potential therapeutic effects in ASD. Two genetic ASD mouse models (Mef2c mutant and Shank3-/- mice) were exposed to a low concentration of xenon (25%) mixed with oxygen (30%) and balanced with nitrogen for a single exposure of 30 min or for 10 min per day for 10 days. These Xe exposure paradigms rescued ASD-like behaviors in both male and female mice. The behavioral improvements persisted for up to 10 days following termination of the 10-day exposure paradigm. Mechanistically, Xe reduced glutamic acid decarboxylase expression in the inhibitory neurons (verified with RNAseq) of the paraventricular thalamic nucleus (PVT) and decreased GABA release during social interaction. Targeted infusion of the GABAA receptor agonist muscimol into the PVT abolished the Xe-mediated behavioral improvements. Reduced GABAergic transmission following Xe exposure increased PVT glutamatergic neuronal activity. Chemogenetic inhibition of these neurons eliminated the therapeutic effects of Xe, whereas chemogenetic activation mimicked the Xe-induced behavioral improvements. Furthermore, opto-inhibition of PVT glutamatergic projections to the central amygdala (CeA) blocked Xe-mediated behavioral improvement. Opto-activation of the PVT-CeA glutamatergic circuit reversed ASD-like behaviors. These findings demonstrate that Xe ameliorates ASD-like phenotypes in mouse models by modulating the PVT Glu-CeA circuit, supporting Xe as a novel potential therapy for ASD.

The phenotype of a focal individual can be affected not only by the individuals own genes (direct genetic effects, DGE) but also by genes of other individuals it interacts with (indirect genetic effects, IGE). Better understanding IGE can help better understand the impact and mechanisms of social effects. Here, we investigated, in laboratory mice, the modulation of IGE by genetic background of the focal individual (social epistasis) and by sex. We focused on IGE arising from Epha4, a gene that has been associated with the individuals own stress-related and social behaviours (i.e. DGE) and the stress-coping behaviour and wound healing of the other mice in the cage (i.e. IGE). Among four different genetic backgrounds for focal mice, significant IGE from Epha4 were detected in CBA females only. A formal model selection analysis was consistent with the modulation of IGE by the similarity of the genetic backgrounds of the focal mouse and its Epha4 cage mate, as well as by sex. Observations of fighting in cages of males with dissimilar genetic backgrounds suggested aggression might underpin these modulatory effects, which prompted to us to expand the conceptual framework describing the mechanisms of social epistasis. Thus, our results strengthen the emerging view that IGE are not fixed properties of social genotypes but can depend on the genetic and sex context of interacting individuals, revealing an underexplored layer of their genetic architecture.

Mammalian cochlear hair cells (HC) are crucial for hearing, and histone modifications may play an important role in HC maturation and functions. However, whether and how NSD2, a histone H3 lysine 36 (H3K36) dimethyltransferase, affects cochlear HC maturation remains unclear. Here, we established an HC-specific Nsd2 knockout mouse model and discovered that the loss of NSD2 results in severe structural defects in stereociliary bundles and profound hearing impairment. Integrated multi-omics profiling revealed that NSD2 deficiency leads to a decreased expression of H3K36me2, which in turn alters genome-wide chromatin accessibility and gene expression. Mechanistically, NSD2 deficiency triggers the aberrant upregulation of extracellular matrix (ECM) genes at the transcriptional level, causing excessive collagen accumulation and compromising tissue structure. Crucially, ECM intervention can mitigate NSD2-deficiency mediated hearing damage. Our study reveals an epigenetic mechanism by which NSD2 regulates cochlear HC maturation through inhibition of chromatin remodeling-induced ECM accumulation, and provides a potential new therapeutic direction for hearing impairment.

Abstract Rationale: Vagal sensory neurons are molecularly and functionally diverse, and they play critical roles in visceral sensation and homeostasis. The vagal system is anatomically divided into jugular and nodose ganglia, which exhibit distinct peripheral innervation patterns and physiological functions. Although recent transcriptomic studies have characterized nodose neuronal subtypes in detail, the molecular profiles of jugular sensory neurons remain poorly defined. Objectives: To define the molecular profiles of genetically identified jugular sensory neurons and determine the transcriptional responses of jugular and nodose airway afferents to allergic airway inflammation. Methods: We performed deep transcriptomic profiling of two genetically defined jugular nociceptor populations, MrgprC11 and MrgprD neurons, and compared them with airway-innervating P2ry1 nodose neurons and Phox2b nodose neurons. We further examined transcriptional changes of MrgprC11 and P2ry1 neurons following OVA-induced allergic airway inflammation. Measurements and Main Results: Transcriptomic analyses revealed distinct molecular signatures of jugular nociceptive neurons and identified subtype-specific genes across diverse functional categories. Following OVA challenge, MrgprC11 and P2ry1 neurons exhibited strikingly divergent transcriptional responses. More than 400 genes that were differentially expressed in both neuronal populations were regulated in opposite directions. GO enrichment analysis suggested that MrgprC11 jugular neurons adopted a metabolically restrained state with reduced translation and bioenergetic activities, whereas P2ry1 nodose neurons exhibited metabolically active state with enhanced translation and bioenergetic activities. Conclusions: These findings provide new insight into vagal sensory neuron diversity and reveal distinct transcriptional adaptations of jugular and nodose airway afferents during allergic inflammation.

Extracellular cold-inducible RNA-binding protein (eCIRP) is a crucial neuroinflammatory mediator in ischemic stroke and alcohol-induced memory impairment. We have recently discovered that amyloid{beta} causes microglia to release eCIRP, prompting us to investigate its role in Alzheimer's disease (AD). We found that eCIRP levels were significantly elevated in the cerebrospinal fluid (CSF) and plasma of AD patients compared with age-matched non-AD subjects, as well as in hTau.P301S mice (a model of AD tauopathy) compared with wildtype control mice. Plasma eCIRP strongly correlated with astrocyte activation marker glial fibrillary acidic protein (GFAP) in AD patients. eCIRP induced neurotoxic astrocyte-specific genes and astrocyte release of proinflammatory and neurotoxic factors in C8-D1a cells, primary murine astrocytes and intracerebroventricular eCIRP-injected C57BL/6 mice brains. In particular, eCIRP increased Complement 3, an astrocytic marker involved in neuroinflammation-associated neurodegeneration. Primary astrocytes from TREM-1 knockout mice were resistant to eCIRP induction of neurotoxic astrocytes. eCIRP increased TREM-1 expression and activation in astrocytes. Blocking CIRP/TREM-1 interaction using peptide M3, effectively attenuated eCIRP's induction of neurotoxic astrocytes. Thus, eCIRP strongly correlates with astrocyte reactivity in AD patients, and eCIRP induces neurotoxic astrocytes via TREM-1, which is attenuated by M3, suggesting a novel therapeutic opportunity to target neurotoxic astrocytes in AD.

Traumatic brain injury (TBI) is a leading cause of long-term neurological disability, affecting 50-60 million people annually. Cascading secondary injury mechanisms, including oxidative stress and neuroinflammation, impair motor and cognitive function, while current therapies often manage symptoms rather than restore lost neurological function. This study investigated an ultrasound-activated piezoelectric hydrogel scaffold composed of barium titanate nanoparticles (BTNPs), sodium alginate (SA), and polyethylene oxide (PEO). The hypothesis was that TBI flies receiving the scaffold and ultrasound would display a higher climbing assay pass rate than TBI flies receiving no treatment or BTNPs alone. TBI was induced in Drosophila melanogaster with a high-impact trauma (HIT) apparatus. Treatments were applied by opening and resealing the fly head cuticle, followed by ultrasound stimulation. Motor recovery was quantified with a climbing assay across four groups (N=10 flies per group), which measured the percentage of flies that could cross a 5 cm mark within 30 seconds. Assay validity was supported by a statistically significant difference between flies without TBI and those with TBI using Mann-Whitney U testing (p=0.0035). Although TBI treatment groups did not differ significantly (p>0.05), median pass rates increased from injury control (35%) to BTNPs (45%) to scaffold (50%). However, high inter-trial variation, a 45.2% procedural mortality rate, and small sample size limited statistical power. These results suggest that piezoelectric electrospun hydrogel scaffolds may be a pathway for safer and more biocompatible restoration after TBI, but provide insufficient evidence to conclude that the scaffold significantly improved motor recovery.

Amyloid[beta]; (A[beta];) plaques are a hallmark of Alzheimer[prime]s disease (AD). A human cellular neuronal model that recaptures A[beta];-induced pathology is critical for advancing AD research. However, comprehensive proteomic profiling of A[beta];-induced cellular model remains elusive. In this study, we investigated the proteomic changes in induced pluripotent stem cell (iPSC)-derived neurons (iNs) exposed to synthetic A[beta]; (1-42) peptides (A[beta];42A) to improve our understanding of the cellular responses of A[beta]; aggregates and to establish a human-related platform for AD research. A[beta];42A formed extracellular aggregates around neuronal soma and neurites, impaired neurite outgrowth, and induced the expression of multiple AD-associated genes, such as APOE, BACE1, ADAM10. To define the molecular landscape of A[beta];-induced neuronal dysfunction, we performed proteomic analyses of whole-cell lysates as well as soma- and neurite-enriched fractions. Proteomic profiling revealed extensive gene alterations in pathways associated with synaptic function, neuronal maintenance, and AD pathogenesis, such as the upregulation of APOE. Importantly, the A[beta];42A-iNs system recapitulated molecular signatures observed in AD brain tissue and cerebrospinal fluid. Representative protein changes, including APOE upregulation and its colocalization with A[beta]; aggregates, were further validated in postmortem human AD brain tissue. Together, these findings manifest that the A[beta];42A-iNs system reproduces multiple cellular and molecular features of AD and exhibits strongly consensus with clinical observations. It provides a valuable platform for investigating A[beta];-driven neurodegeneration and for the discovery of therapeutic targets for AD.

Numerous studies have been conducted to investigate touch on the hand and forearm, but less is known about the rest of the body, particularly the torso and breasts, which play an important role in affective touch. We conducted psychophysical tests on three skin sites on the torso: upper breast, nipple-areola complex (NAC), and under the breast, as well as on two control sites: palm and forearm. We studied touch pleasantness and intensity by applying gentle caress-like strokes using a soft brush, and measured temperature and tactile detection thresholds. The results show an inverted U-shaped relationship for pleasantness over increasing stroking velocity for all skin sites, although we found some differences between sites, particularly at 30 cm.s-1, where participants found stroking on the NAC to be more intense and women additionally found it to be less pleasant. For temperature detection, we found that the NAC was more sensitive in men. For tactile detection, we mainly observed that the areola was far less sensitive than the other areas. Together, these results provide insights into tactile perception in the torso on a fundamental level, which can be applied to understanding how to regain sensations after mastectomy.

Hearing loss and deafness as a result of hair cell loss cannot be restored due to the incapacity of spontaneous regeneration of these cells. Compounds that manipulate key signaling pathways can potentially regenerate cochlear hair cells. In order to test different compounds that promote hair cell regeneration in vitro models can be used. Three-dimensional cultures have allowed the expansion and experimentation of human and mouse inner ear organoids. This is mainly performed in the embryonic or the early postnatal developmental stage. However, since the majority of patients with hearing loss are adult, it is crucial to understand the adult inner ear regenerative capacity. Here, we evaluated progenitor cell markers in the adult human and mouse inner ear and the generation, expansion and differentiation of cochlear organoids derived from the adult human and mouse inner ear. Cochlear and vestibular sensory epithelium from adult humans; and from adult and aged mice express the progenitor markers SOX2 and LGR5; and can generate organoids in vitro. By optimizing the culture conditions, organoids derived from the cochlea and vestibular organ from adult human and adult and aged mouse differentiated to Myosin 7A positive cells. This indicates that the adult inner ear has regenerative capacity. These findings are encouraging for future regenerative therapies to cure hair cell-related hearing loss and deafness.

Background: Parkinson's disease (PD) is characterized by the progressive loss of midbrain dopaminergic (DA) neurons and aberrant alpha-synuclein (alpha-syn) aggregation, yet disease-modifying therapies that simultaneously retard neurodegeneration and foster regeneration remain lacking. Methods: In this study, we isolated extracellular vesicles (TH and FOXA2 double-positive cell-derived EVs) from TH and FOXA2 double-positive differentiated neural cells, a distinct midbrain floor-plate-derived neural cell population that co-expresses the floor-plate transcription factor FOXA2 together with TH and should therefore not be equated with conventional mature midbrain dopaminergic neurons, and systematically evaluated their therapeutic potential across three complementary models: A53T transgenic mice, 6-OHDA-lesioned rats, and 6-OHDA-treated human midbrain organoids. Integrative transcriptomic and single-cell sequencing analyses, together with toxicological evaluations in rodents and non-human primates, were performed to investigate the underlying mechanisms and safety profile. These TH and FOXA2 double-positive cells were generated using a fully suspension-based, matrix-free, and chemically defined differentiation system devoid of N2/B27 supplements and fetal bovine serum (FBS). This approach offers a simple, controllable, low-cost, and scalable platform with high batch-to-batch consistency for EV manufacturing. Throughout this study, the term "TH and FOXA2 double-positive cells" refers to this distinct TH and FOXA2 double-positive cell population and should not be interpreted as conventional terminally differentiated dopaminergic neurons. Results: Intranasal administration of TH and FOXA2 double-positive cell-derived EVs in A53T mice and 6-OHDA-lesioned rats significantly ameliorated motor deficits, increased nigral tyrosine hydroxylase (TH)-positive neuron counts, reduced alpha-syn aggregation, and suppressed gliosis. In human midbrain organoids, TH and FOXA2 double-positive cell-derived EVs preserved DA neuronal morphology and reduced GFAP and alpha-syn expression. Notably, when EVs were administered simultaneously with 6-OHDA modeling rather than after modeling was completed, the protective effect was stronger. Multi-omics analysis revealed that TH and FOXA2 double-positive cell-derived EVs reversed pathological signatures of interferon-responsive microglia and oxidative stress-adapted astrocytes, while restoring WNT- and non-canonical WNT-mediated intercellular communications. Safety evaluations showed no discernible organ toxicity. Conclusions: TH and FOXA2 double-positive cell-derived EVs exert neuroprotective effects across multiple PD models by modulating specific glial subpopulations and reinstating development-associated signaling pathways. Together with a fully suspension-based, matrix-free, and N2/B27-free differentiation process that enables low-cost, scalable, and highly reproducible manufacturing, TH and FOXA2 double-positive cell-derived EVs represent a promising therapeutic candidate for Parkinson's disease.

Neuropathic pain involves spinal microglial activation and metabolic changes.Forsythoside B (FB) has anti-inflammatory effects, but its role in neuropathic pain and microglial glycolysis remains unclear. We investigated the effects and mechanisms of FB in mice with chronic constriction injury (CCI) and in LPS-stimulated BV2 microglia.FB reduced mechanical allodynia and thermal hyperalgesia in CCI mice. FB also reduced the spinal levels of HIF-1, HK2, PKM2, LDHA, and CD86. It decreased the proportion of IBA1+/CD86+ cells and the levels of IL-1{beta}, IL-6, and TNF-. In LPS20 stimulated BV2 microglia, FB reduced glycolysis-related proteins, proinflammatory markers, and cytokine release. FB also reduced glycolytic activity and partly restored basal mitochondrial respiration. FB did not change Hif1a mRNA levels. However, it Manuscript Click here to access/download;Manuscript;Manuscript.docx increased HIF-1 ubiquitination and promoted its proteasome-dependent degradation. HIF-1 overexpression partly reversed the effects of FB on glycolytic enzymes, CD86 expression, and proinflammatory cytokine production. Immunoprecipitation followed by mass spectrometry and UbiBrowser analysis identified USP7 as a candidate HIF27 1-associated deubiquitinase. Molecular docking and cellular thermal shift assays supported a possible interaction between FB and USP7. FB reduced the association between USP7 and HIF-1. USP7 knockdown produced effects similar to those of FB on HIF-1 ubiquitination and downstream glycolytic and inflammatory responses.Overall, FB alleviated neuropathic pain and reduced proinflammatory microglial responses. These effects may involve the promotion of HIF-1 degradation through modulation of the USP7-HIF-1 regulatory axis.

Ogerin, a positive regulator of GPR68, reduces infarct volume and attenuates blood-brain barrier (BBB) leakage post transient middle cerebral artery occlusion (tMCAO). These data support the potential use of Ogerin for ischemic protection. For therapeutic interventions, tissue distribution, kinetics, and brain penetration are important characteristics for a compound. For these reasons, we performed liquid chromatography-mass spectrometry (LC-MS) analysis of Ogerin in mice. At 3 hours following intraperitoneal (IP) injection, liver exhibited highest level of Ogerin among all major organs assessed. We further analyzed time-dependent changes in Ogerin concentration in serum following intravenous delivery. Brain Ogerin level was ~140 ng/g at 2 hour and ~0.06ng/g at 24 hours. The brain-to-serum ratio of Ogerin was ~0.6 at 5 hr. To determine the effect of Ogerin on signaling, we collected samples 24 hours after tMCAO with or without Ogerin delivered and performed Western blotting. Consistent with the diminished level of Ogerin in brain at 24 hour, tMCAO increased similar changes in phosphorylation of PKA substrates and PKC substrates in vehicle- and Ogerin-treated groups. The pharmacokinetic data suggests that Ogerin is effective mainly during acute hours after injection. This finding generates important insights on the design of effective protocol for Ogerin delivery to potentiate GPR68 function in vivo.

Adeno-associated viral (AAV) vectors possess immense potential for gene therapy applications. However, microglia can mount an immune response against AAV vectors. Yet, microglia are therapeutic targets since they play a driving role in the progression of neurodegenerative diseases. Thus, it is critical to understand the cellular processes driving the microglia-mediated immune response against AAV vectors. To this end, we modelled AAV6 induced inflammation upon retinal gene therapy in minipigs. Upon AAV6 administration, the IBA1+ cells demonstrated a morphological transition to the amoeboid form, indicating microglial reactivity. We also observed the invasion of peripheral immune cells in the retina. To elucidate the underlying molecular mechanisms, we transduced human iPSC derived microglia-like cells (iMGLs) in vitro with AAV6 and AAV8 respectively. Only AAV6 transduced iMGLs exhibited morphological features and a transcriptomic signature of microglial reactivity. The magnitude of intracellular AAV6 viral genomes was significantly higher as compared to the AAV8 condition. The elevated levels of intracellular AAV6 genomes induced a DNA damage response in AAV6-transduced iMGLs, which is a key feature of neuroinflammation-linked microglial reactivity. Thus, our work highlights the impact of intracellular viral genome accumulation on microglial reactivity and its implications for retinal gene therapy associated inflammation.

Background: Insufficient oxygen (hypoxia) or complete lack of oxygen (anoxia) causes cellular dysfunction and death in terrestrial animals. As a result, animals have developed homeostatic strategies, including changes in movement strategies to escape and survive stressful environments. Caenorhabditis elegans respond to changes in oxygen by increasing the frequency of reversals (backward movement) and increasing locomotor speed; these behaviors enable them to escape unfavorable environments and move to more suitable ones. The molecular and neural mechanisms underlying behavioral responses to low-oxygen environments are incomplete. Neuropeptides regulate C. elegans behaviors by modifying neural circuit function in response to hypoxia. Loss of function in C. elegans neuropeptide nlp-40 and its receptor aex-2 increased survival to anoxia [1]. However, the cells in which NLP-40 and AEX-2 function for anoxia, as well as the mechanisms underlying responses to anoxia, remain elusive. We hypothesized that NLP-40 and AEX-2 regulate anoxia by altering escape behaviors. Results: We found that neuropeptide NLP-40 functions in cholinergic neurons and AEX-2 functions in cholinergic or GLR-1 interneurons or motor neurons to regulate susceptibility to anoxia. We found that loss of either nlp-40 or aex-2 decreased locomotor activity and reversal frequency early during 48 hours of anoxia, suggesting that nlp-40 and aex-2 are required for the proper execution of these behaviors. We found that neuronal knockdown of nlp-40 recapitulated the behaviors observed in nlp-40 mutant animals and increased survival; however, restoring aex-2 function in glr-1 interneurons or motor neurons was sufficient to rescue behaviors to wild-type and restore vulnerability to anoxia. Conclusions: Overall, our results suggest that NLP-40 and AEX-2 likely function in cholinergic or glr-1 interneurons or motor neurons to regulate escape behaviors during anoxia. Escape behaviors are part of the homeostatic response and are typically protective in the wild; however, in our paradigm, we show that loss of either nlp-40 or aex-2 reduces escape responses and confers protection against 48 hours of anoxia. Collectively, these results highlight a new role for NLP-40 and AEX-2 in anoxia and shed light on mechanisms underlying the adaptive responses to anoxia.

Context processing is an essential function in the cognitive repertoire of numerous species, including humans and mice, allowing them to learn from their environment and adapt their future behavior. Impairments or alterations in context processing are hypothesized to represent one of the core etiological mechanisms underlying trauma- and stressor-related disorders such as post-traumatic stress disorder (PTSD). Individual behavioral traits are key determinants of post-stress responses; however, how they influence distinct phases of contextual encoding and processing remains incompletely understood. This knowledge gap is further exacerbated by the limited availability of contextual fear protocols based on social stress, even though the latter is among the most frequent and impactful forms of stress exposure. Here, based on social defeat paradigms, we establish a longitudinal social conditioned place aversion (sCPA) protocol that leads to avoidance of the defeat-associated chamber in adult male mice. Prior characterization of mice according to anxiety-related phenotypes revealed that mice displaying high novelty-induced thigmotaxic (i.e. high anxiety-like) behavior showed lasting long-term memory of the defeat-associated chamber as denoted by persistent avoidance. On the other hand, lower levels of exploration/locomotor behaviors prior to stress exposure predicted greater avoidance of the defeat-associated chamber in the short-term. Finally, we reveal that inhibiting the activity of VTAVgat neurons during conditioning sessions abolished sCPA acquisition, while disrupting the predictive ability of locomotor/exploratory profiles derived prior to the sCPA. Our data establishes a robust temporally structured social stress-based conditioning protocol and reveals how prior individual anxiety- and exploration/locomotion-related traits influence distinct stages of context processing.

Amacrine cells (ACs) are the most diverse neuron in the retina, with more than sixty different subtypes, each contributing to the detection of specific visual features. Despite their importance in visual feature detection, the genetic basis for this diversity is still not well understood. Recent single-cell transcriptomic datasets have identified several potential genes that may regulate cellular diversity, but the underlying mechanisms have not been investigated. For example, the transcription factor Meis2 is selectively expressed in the GABAergic subclass of ACs. In this study, we focused on how Meis2 regulates the development of GABAergic ACs. We hypothesized that Meis2 is required for specification and survival of GABAergic ACs. To test this, we used the Meis2 conditional knockout mouse (Meis2-CKO) where Meis2 was deleted from either the entire retina or specifically from AC precursor cells. The deletion of Meis2 led to a ~60% reduction in total GABAergic ACs in the retina. This loss of GABAergic ACs occurred only after postnatal day 5 (P5), suggesting Meis2 is not required for early specification but may be required for survival. To further investigate cell death and survival, we quantified cleaved caspase-3 positive cells in the retina at several developmental timepoints. In Meis2-CKO mice, we found an increase in cleaved caspase-3 immunolabeling at P5 and P6 timepoints coinciding with the reduction of GABAergic ACs. Further analysis of GABAergic AC subtypes demonstrated a subtype-specific cell death in Meis2-CKO retinas. For example, the total number of dopaminergic (TH) ACs were significantly reduced, whereas starburst (ChAT) ACs remained unchanged. These findings suggest that Meis2 is important for the survival of a subset of GABAergic AC subtypes in the mammalian retina. In addition, Meis2 may control the expression of specific survival factors that prevent apoptosis during developmental cell death in the retina.

Parkinsons disease (PD) is the second most prevalent neurodegenerative disease in the elderly population, characterized by a wide variety of motor and non-motor symptoms. Its complex biochemical and molecular mechanisms make it challenging to study PD directly in patients or to replicate it in vitro, underscoring the need for careful model characterization to advance translational research. The free-living nematode Caenorhabditis elegans has been widely used in neuroscience studies. Technological advancements enabled the development of transgenic strains that mimic aspects of neurodegenerative diseases, such as the OW13 strain [grk-1(ok1239) X; pkIs2386 IV (unc-54p::alpha-synuclein::YFP + unc-119(+))], which expresses human -synuclein in body wall muscle cells in a sensitized G-protein coupled receptor kinase-deficient background. This study conducted an exploratory proteomic analysis of the OW13 strain. A cross-species comparative analysis using post-mortem substantia nigra proteomics from PD individuals identified a convergent signature of 76 conserved C. elegans proteins, corresponding to 70 human orthologs, derived from the 373 DAPs. Among these conserved candidates, 68 proteins were upregulated, and 8 were downregulated. Functional enrichment linked these DAPs to the tricarboxylic acid cycle, mitochondrial function, and protein quality control, suggesting that -synuclein aggregation triggers a broad proteostatic and bioenergetic remodeling resembling PD pathophysiology. This first proteomic and cross-species characterization of the OW13 strain strongly supports C. elegans as a robust PD model.