Biology subjects

Pantazopoulos, H.

Publications and source records attributed to Pantazopoulos, H..

10 recordsLinked to original sources

bioRxiv2026

Polysome Profiling Method for Low-Input Human Postmortem Brain

Polysome profiling is a powerful technique used to analyze the association of mRNA with ribosomes, providing insights into the translational status of a cell. It relies on the separation of ribosome-bound mRNAs through sucrose density gradient centrifugation, where the number of ribosomes on an mRNA correlates with its sedimentation rate. While numerous studies have successfully applied this method to cell line and mouse tissue, application to the human postmortem brain remains scarce due to challenges related to sample quality and low concentration of recoverable material. To overcome these challenges, we: O_LIImplemented a protocol specifically optimized for low-concentration human post-mortem brain tissue. C_LIO_LIImplemented a gradient-maker-free method to manually prepare sucrose gradients with tunable sensitivity for low-input samples. C_LIO_LIAdapted the human brain tissue protocol for neuronal cell lines and mouse brain with minimal modification. C_LI

neuroscience↗

bioRxiv2025

Psilocybin decreases reward-seeking behavior accompanied by increased activity of parvalbumin neurons with perineuronal nets in the medial prefrontal cortex

Clinical trials suggest that a single dose of psilocybin is an effective treatment for substance use disorders (SUDs). Choice impulsivity is a value-based decision-making bias that predicts drug-intake escalation and is commonly associated with SUDs. The dorsomedial prefrontal cortex (dmPFC) regulates choice impulsivity and is enriched with 5-HT2A receptors that mediate effects of psilocybin. We hypothesized that psilocybin has long-term ([≥]48 hours) effects on choice impulsivity in association with dmPFC inhibitory interneurons with perineuronal nets (PNNs). Male Long Evans rats were trained in a delay discounting task (DDT) where rats chose between delayed large rewards (LR) and immediate small rewards (SR). 48 hours after psilocybin or vehicle injections, DDT was assessed, and rats brains processed for microscopy analysis of extracellular matrix (PNNs) together with inhibitory parvalbumin (PV) interneurons and c-fos as a marker of neuronal activity. Psilocybin acutely increased head-twitch responses. Psilocybin decreased LR choices and increased the latency to LR choices 48 hours after administration. These effects were independent of delay and therefore not consistent with changes in impulsivity. Psilocybin also increased the density of PNN+PV+cFos triple-labeled neurons in the dmPFC. These results suggest that psilocybin decreases reward seeking through the increased activation of dmPFC PV interneurons with PNNs.

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bioRxiv2025

Cross-Species Evidence for Hippocampal CACNA1C as a Therapeutic Target for Alcohol Use Disorder

Context-induced relapse is a major barrier to recovery from alcohol use disorder (AUD). Identifying molecular targets involved in contextual memories associated with alcohol use may serve as novel pharmacotherapies. Our RNAseq profiling study of the hippocampus from rhesus monkeys with chronic alcohol use identified the voltage-gated calcium channel CACNA1C as a promising therapeutic target. However, data regarding CACNA1C expression in AUD and whether inhibition of CACNA1C can attenuate ethanol contextual memories remains limited. We tested the hypothesis that hippocampal CACNA1C expression is increased in human and nonhuman primates (NHPs) with chronic alcohol use. Further, we used a mouse conditioned place preference (CPP) paradigm to test the hypothesis that Nifedipine, a CACNA1C-selective L-type calcium channel antagonist, can attenuate ethanol-induced CPP. CACNA1C mRNA expression was increased in the hippocampus of subjects with AUD (p<0.03). Increased densities of CACNA1C neurons (p<0.01) and glia (p<0.02) were observed in rhesus monkeys with chronic alcohol use. Ethanol-treated mice spent more time in the ethanol-paired chamber compared to the vehicle animals (p<0.04), demonstrating ethanol-induced CPP. This effect was attenuated by Nifedipine, as time spent in the ethanol-paired chamber in the ethanol + Nifedipine group was not significantly different from the vehicle group. These findings demonstrate that chronic alcohol use increases CACNA1C expression in the hippocampus across species and that a CACNA1C subtype-selective antagonist reduces ethanol-induced CPP. Together, these results support CACNA1C as a promising therapeutic target for context-induced relapse in AUD.

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bioRxiv2025

Altered molecular signaling pathways in the hippocampus of rhesus monkeys following chronic alcohol use

Context-induced relapse is a significant factor limiting recovery from alcohol use disorder (AUD). However, the molecular processes in the hippocampus, a critical region for contextual memory impacted by chronic alcohol use, remain poorly understood. We used a non-human primate model to test the hypothesis that chronic alcohol use impacts hippocampal molecular pathways that may serve as therapeutic targets for context-induced relapse and memory processing issues associated with chronic alcohol use. We conducted RNAseq profiling on hippocampal samples from adult male rhesus monkeys with chronic alcohol use (n=7) and controls (n=5) from the Monkey Alcohol Tissue Research Resource (MATRR). We identified 2,575 differentially expressed genes (DEGs) in subjects with chronic alcohol use, including genes implicated in genome-wide association studies (GWAS) of alcohol dependence, such as GLP2R and GABBR2. Downregulated pathways included chemical synaptic transmission, trans-synaptic signaling, and neuron development, and upregulated pathways involved mitochondrial function. Targeted pathway analysis highlighted significant downregulation of synaptic signaling (e.g., axonal fasciculation) and upregulation of mitochondrial processes (e.g., electron transport). Leading-edge gene analysis revealed several downregulated genes involved in synaptic signaling including GRIN2B, CACNA1C, and NLGN1 as well as upregulated genes such as NDUFS3 and MT-ND1 involved in mitochondrial processes. Drug repurposing analysis identified several targets including epidermal growth factor receptor (EGFR) inhibitors, and L-type calcium channel blockers as potential therapeutic targets. Our results provide critical insights into molecular pathways underlying hippocampal pathology in chronic alcohol use, emphasizing the roles of mitochondrial function, synaptic regulation and calcium channels, and offering potential novel therapeutic targets.

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bioRxiv2025

Developmental time course of social touch, parvalbumin interneurons, perineuronal nets and Mef2c expression reveals a sensitive period of somatosensory cortex development in prairie voles

Social touch facilitates our attachment to others, especially early in life, which may be linked to the maturation of parvalbumin interneurons (PVI) in the somatosensory cortex (S1). These neurons respond to social touch, mature in a sensory experience-dependent manner, and influence both somatosensory processing and social behavior in models of Autism Spectrum Disorder. Prairie voles (Microtus ochrogaster) are an ideal rodent model for studying these concepts since they engage in a species-typical social touch called "huddling". This study first showed that over development from juvenile to adult, same-sex siblings huddled less and explored more. Next, we tracked two markers of plasticity indicative of PVI maturation, extracellular perineuronal nets (PNNs) and nuclear transcription factor Myocyte enhancing factor 2C (Mef2c) - across seven developmental timepoints. We found that, while PV expression in S1 was stable by P21, PNNs and Mef2c continued to shift afterwards, indicating a protracted development. Four unique clusters of PVIs converge during development between P14-P21, suggesting a sensitive period of PVI development. Finally, to determine environmental factors affecting these processes, environmental enrichment between P21-P28 led to accelerated PVI maturation. This developmental mapping provides a particularly salient model to investigate the molecular underpinnings of cortical and social development.

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bioRxiv2025

Sleep Deprivation Alters Hippocampal Dendritic Spines in a Contextual Fear Memory Engram

Sleep is critically involved in strengthening memories. However, our understanding of the morphological changes underlying this process is still emerging. Recent studies suggest that specific subsets of dendritic spines are strengthened during sleep in specific neurons involved in recent learning. Contextual memories associated with traumatic experiences are involved in post-traumatic stress disorder (PTSD) and represent recent learning that may be strengthened during sleep. We tested the hypothesis that dendritic spines encoding contextual fear memories are selectively strengthened during sleep. Furthermore, we tested how sleep deprivation after initial fear learning impacts dendritic spines following re-exposure to fear conditioning. We used ArcCreERT2 mice to visualize neurons that encode contextual fear learning (Arc+ neurons), and concomitantly labeled neurons that did not encode contextual fear learning (Arc-neurons). Dendritic branches of Arc+ and Arc-neurons were sampled using confocal imaging to assess spine densities using three-dimensional image analysis from either sleep deprived (SD) or control mice allowed to sleep normally. Mushroom spines in Arc+ branches displayed decreased density in SD mice, indicating upscaling of mushroom spines during sleep following fear learning. In comparison, no changes were observed in dendritic spines from Arc-branches. When animals were re-exposed to contextual fear conditioning 4 weeks later, we observed lower density of mushroom spines in both Arc+ and Arc-branches, as well as lower density of thin spines in Arc-branches in mice that were SD following the initial fear conditioning trial. Our findings indicate that sleep strengthens dendritic spines in neurons that recently encoded fear memory, and sleep deprivation following initial fear learning impairs dendritic spine strengthening initially and following later re-exposure. SD following a traumatic experience thus may be a viable strategy in weakening the strength of contextual memories associated with trauma and PTSD.

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bioRxiv2024

Spermidine alleviates depression via control of the stress response

Depression is a stress-associated disorder, and it represents a major global health issue. Its pathophysiology is complex and remains insufficiently understood, with current medications often showing limited efficacy and undesirable side effects. Here, we identify imbalanced polyamine levels and dysregulated autophagy as key components of the acute stress response in humans, and as hallmarks of chronic stress and depressive disorders. Moreover, conventional antidepressant pharmacotherapy increases endogenous plasma concentrations of the polyamine spermidine exclusively in patients who respond to the treatment, suggesting a link between spermidine and successful outcomes. In a clinical trial, involving drug-naive depressed individuals, three weeks of spermidine supplementation increased autophagy and alleviated symptoms of depression. Behavioral and mechanistic findings of spermidine supplementation were validated in various mouse stress and depression models. In summary, spermidine supplementation mitigates polyamine dysregulation and stimulates autophagy under pathological stress conditions, offering a novel and well-tolerated treatment approach for stress-related depressive disorders.

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bioRxiv2023

SKA2 regulated hyperactive secretory autophagy drives neuroinflammation-induced neurodegeneration

High levels of proinflammatory cytokines induce neurotoxicity and catalyze inflammation-driven neurodegeneration, but the specific release mechanisms from microglia remain elusive. We demonstrate that secretory autophagy (SA), a non-lytic modality of autophagy for secretion of vesicular cargo, regulates neuroinflammation-mediated neurodegeneration via SKA2 and FKBP5 signaling. SKA2 inhibits SA-dependent IL-1{beta} release by counteracting FKBP5 function. Hippocampal Ska2 knockdown in mice hyperactivates SA resulting in neuroinflammation, subsequent neurodegeneration and complete hippocampal atrophy within six weeks. The hyperactivation of SA increases IL-1{beta} release, initiating an inflammatory feed-forward vicious cycle including NLRP3-inflammasome activation and Gasdermin D (GSDMD)-mediated neurotoxicity, which ultimately drives neurodegeneration. Results from protein expression and co-immunoprecipitation analyses of postmortem brains demonstrate that SA is hyperactivated in Alzheimers disease. Overall, our findings suggest that SKA2-regulated, hyperactive SA facilitates neuroinflammation and is linked to Alzheimers disease, providing new mechanistic insight into the biology of neuroinflammation.

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bioRxiv2022

Molecular Neurobiology of Loss

Psychological loss is a common experience that erodes well-being and negatively impacts quality of life. The molecular underpinnings of loss are poorly understood. Here, we investigate the mechanisms of loss using an enrichment removal (ER) paradigm in rats. A comprehensive multi-omics investigation of the basolateral amygdala (BLA) revealed alterations in microglia and extracellular matrix (ECM). Follow-up studies indicated that ER decreased microglia size, complexity, and phagocytosis, suggesting reduced immune surveillance. Loss also substantially increased ECM coverage, specifically targeting perineuronal nets surrounding parvalbumin interneurons, suggesting decreased plasticity and increased inhibition in the BLA following loss. Behavioral analyses suggest that these molecular effects are linked to impaired BLA salience evaluation, reflecting emotional blunting observed in human loss. These loss-like behaviors could be rescued by depleting BLA ECM during removal, helping us understand the mechanisms underlying loss and revealing novel molecular targets to ameliorate its impact.

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bioRxiv2020

Microglial Associated Circadian Rhythms of Perineuronal Net Composition

Perineuronal Nets (PNNs) are extracellular matrix (ECM) structures that envelop neurons and regulate synaptic functions. Long thought to be stable structures, PNNs have been recently shown to respond dynamically during learning, potentially regulating the formation of new synapses. We postulated that PNNs vary during sleep, a period of active synaptic modification. Notably, PNN components are cleaved by matrix proteases such as the protease cathepsin-S. This protease is diurnally expressed in the mouse cortex, coinciding with dendritic spine density rhythms. Thus, cathepsin-S may contribute to PNN remodeling during sleep, mediating synaptic reorganization. These studies were designed to test the hypothesis that PNN numbers vary in a diurnal manner in the rodent and human brain, as well as in a circadian manner in the rodent brain, and that these rhythms are disrupted by sleep deprivation. In mice, we observed diurnal and circadian rhythms of PNNs labeled with the lectin wisteria floribunda agglutinin (WFA+PNNs) in several brain regions involved in emotional memory processing. Sleep deprivation prevented the daytime decrease of WFA+ PNNs and enhances fear memory extinction. Diurnal rhythms of cathepsin-S expression in microglia were observed in the same brain regions, opposite to PNN rhythms. Finally, incubation of mouse sections with cathepsin-S eliminated PNN labeling. In humans, WFA+PNNs showed a diurnal rhythm in the amygdala and thalamic reticular nucleus (TRN). Our results demonstrate that PNNs vary in a circadian manner and this is disrupted by sleep deprivation. We suggest that rhythmic modification of PNNs may contribute to memory consolidation during sleep.

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