NAT10 promotes osteoclastogenesis in inflammatory bone loss by catalyzing Fos mRNA ac4C modification and upregulating MAPK signaling pathway.

INTRODUCTION: Excessive osteoclastogenesis is a key driver of inflammatory bone loss. Suppressing osteoclastogenesis has always been considered essential for the treatment of inflammatory bone loss. N-acetyltransferase 10 (NAT10) is the sole enzyme responsible for N4-acetylcytidine (ac4C) modification of mRNA, and is involved in cell development. However, its role in osteoclastogenesis and inflammatory bone loss remained elusive. OBJECTIVES: We aimed to clarify the regulatory mechanism of NAT10 and ac4C modification in osteoclastogenesis and inflammatory bone loss. METHODS: NAT10 expression and ac4C modification during osteoclastogenesis were determined by quantitative real-time PCR (qPCR), western blotting, dot blot and immunofluorescent staining, and the effect of NAT10 inhibition on osteoclast differentiation in vitro was measured by the tartrate-resistant acid phosphatase staining, podosome belts staining assay and bone resorption pit assay. Then, acRIP-qPCR and NAT10RIP-qPCR, ac4C site prediction, mRNA decay assay and luciferase reporter assay were performed to further study the underlying mechanisms. At last, mice models of inflammatory bone loss were applied to verify the therapeutic effect of NAT10 inhibition in vivo. RESULTS: NAT10 expression was upregulated during osteoclast differentiation and highly expressed in alveolar bone osteoclasts from periodontitis mice. Inhibition of NAT10 notably reduced osteoclast differentiation in vitro, as indicated by great reduction of tartrated resistant acid phosphatse positive multinuclear cells, osteoclast-specific gene expression, F-actin ring formation and bone resorption capacity. Mechanistically, NAT10 catalyzed ac4C modification of Fos (encoding AP-1 component c-Fos) mRNA and maintained its stabilization. Besides, NAT10 promoted MAPK signaling pathway and thereby activated AP-1 (c-Fos/c-Jun) transcription for osteoclastogenesis. Therapeutically, administration of Remodelin, the specific inhibitor of NAT10, remarkably impeded the ligature-induced alveolar bone loss and lipopolysaccharide-induced inflammatory calvarial osteolysis. CONCLUSIONS: Our study demonstrated that NAT10-mediated ac4C modification is an important epigenetic regulation of osteoclast differentiation and proposed a promising therapeutic target for inflammatory bone loss.

Comparative transcriptome reveals EphA2 and c-Fos as key factors driving enhanced replication in high-passage porcine deltacoronavirus strain.

Porcine deltacoronavirus (PDCoV), a cross-species transmissible enterovirus, frequently induces severe diarrhea and vomiting symptoms in piglets, which not only pose a significant menace to the global pig industry but also a potential public safety risk. In a previous study, we isolated a vaccine candidate, PDCoV CZ2020-P100, by passaging a parental PDCoV strain in vitro, exhibiting attenuated virulence and enhanced replication. However, the factors underlying these differences between primary and passaged strains remain unknown. In this study, we present the transcriptional landscapes of porcine kidney epithelial cells (LLC-PK1) cells infected with PDCoV CZ2020-P1 strain and P100 strain using the RNA-sequencing. We identified 105 differentially expressed genes (DEGs) in P1-infected cells and 295 DEGs in P100-infected cells. Enrichment analyses indicated that many DEGs showed enrichment in immune and inflammatory responses, with a more and higher upregulation of DEGs enriched in the P100-infected group. Notably, the DEGs were concentrated in the MAPK pathway within the P100-infected group, with significant upregulation in EphA2 and c-Fos. Knockdown of EphA2 and c-Fos reduced PDCoV infection and significantly impaired P100 replication compared to P1, suggesting a novel mechanism in which EphA2 and c-Fos are highly involved in passaged virus replication. Our findings illuminate the resemblances and distinctions in the gene expression patterns of host cells infected with P1 and P100, confirming that EphA2 and c-Fos play key roles in high-passage PDCoV replication. These results enhance our understanding of the changes in virulence and replication capacity during the process of passaging.

Low intensity repetitive transcranial magnetic stimulation enhances remyelination by newborn and surviving oligodendrocytes in the cuprizone model of toxic demyelination.

In people with multiple sclerosis (MS), newborn and surviving oligodendrocytes (OLs) can contribute to remyelination, however, current therapies are unable to enhance or sustain endogenous repair. Low intensity repetitive transcranial magnetic stimulation (LI-rTMS), delivered as an intermittent theta burst stimulation (iTBS), increases the survival and maturation of newborn OLs in the healthy adult mouse cortex, but it is unclear whether LI-rTMS can promote remyelination. To examine this possibility, we fluorescently labelled oligodendrocyte progenitor cells (OPCs; Pdgfrα-CreER transgenic mice) or mature OLs (Plp-CreER transgenic mice) in the adult mouse brain and traced the fate of each cell population over time. Daily sessions of iTBS (600 pulses; 120 mT), delivered during cuprizone (CPZ) feeding, did not alter new or pre-existing OL survival but increased the number of myelin internodes elaborated by new OLs in the primary motor cortex (M1). This resulted in each new M1 OL producing ~ 471 µm more myelin. When LI-rTMS was delivered after CPZ withdrawal (during remyelination), it significantly increased the length of the internodes elaborated by new M1 and callosal OLs, increased the number of surviving OLs that supported internodes in the corpus callosum (CC), and increased the proportion of axons that were myelinated. The ability of LI-rTMS to modify cortical neuronal activity and the behaviour of new and surviving OLs, suggests that it may be a suitable adjunct intervention to enhance remyelination in people with MS.

Light-Controlled Electric Stimulation with Organic Electrolytic Photocapacitors Achieves Complex Neuronal Network Activation: Semi-Chronic Study in Cortical Cell Culture and Rat Model.

Neurostimulation employing photoactive organic semiconductors offers an appealing alternative to conventional techniques, enabling targeted action and wireless control through light. In this study, organic electrolytic photocapacitors (OEPC) are employed to investigate the effects of light-controlled electric stimulation on neuronal networks in vitro and in vivo. The interactions between the devices and biological systems are characterized. Stimulation of primary rat cortical neurons results in an elevated expression of c-Fos within a mature neuronal network. OEPC implantation for three weeks and subsequent stimulation of the somatosensory cortex leads to an increase of c-Fos in neurons at the stimulation site and in connected brain regions (entorhinal cortex, hippocampus), both in the ipsi- and contralateral hemispheres. Reactivity of glial and immune cells after semi-chronic implantation of OEPC in the rat brain is comparable to that of surgical controls, indicating minimal foreign body response. Device functionality is further substantiated through retained charging dynamics following explantation. OEPC-based, light-controlled electric stimulation has a significant impact on neural responsiveness. The absence of detrimental effects on both the brain and device encourages further use of OEPC as cortical implants. These findings highlight its potential as a novel mode of neurostimulation and instigate further exploration into applications in fundamental neuroscience.

Functional Connectivity Favors Aberrant Visual Network c-Fos Expression Accompanied by Cortical Synapse Loss in a Mouse Model of Alzheimer's Disease.

Background: While Alzheimer's disease (AD) has been extensively studied with a focus on cognitive networks, visual network dysfunction has received less attention despite compelling evidence of its significance in AD patients and mouse models. We recently reported c-Fos and synaptic dysregulation in the primary visual cortex of a pre-amyloid plaque AD-model. Objective: We test whether c-Fos expression and presynaptic density/dynamics differ in cortical and subcortical visual areas in an AD-model. We also examine whether aberrant c-Fos expression is inherited through functional connectivity and shaped by light experience. Methods: c-Fos+ cell density, functional connectivity, and their experience-dependent modulation were assessed for visual and whole-brain networks in both sexes of 4-6-month-old J20 (AD-model) and wildtype (WT) mice. Cortical and subcortical differences in presynaptic vulnerability in the AD-model were compared using ex vivo and in vivo imaging. Results: Visual cortical, but not subcortical, networks show aberrant c-Fos expression and impaired experience-dependent modulation. The average functional connectivity of a brain region in WT mice significantly predicts aberrant c-Fos expression, which correlates with impaired experience-dependent modulation in the AD-model. We observed a subtle yet selective weakening of excitatory visual cortical synapses. The size distribution of cortical boutons in the AD-model is downscaled relative to those in WT mice, suggesting a synaptic scaling-like adaptation of bouton size. Conclusions: Visual network structural and functional disruptions are biased toward cortical regions in pre-plaque J20 mice, and the cellular and synaptic dysregulation in the AD-model represents a maladaptive modification of the baseline physiology seen in WT conditions.

Effects of dexmedetomidine on depression-like behaviour in chronic restraint stress mice: Involvement of specific brain regions.

It is crucial to develop novel antidepressants. Dexmedetomidine (DEX) can exert antidepressant effects, but its underlying mechanism remains unclear. We used chronic restraint stress (CRS) to induce depression-like behaviour in mice and administered low-dose DEX (2 µg/kg per day) during CRS modelling or one injection of high-dose DEX (20 µg/kg) after CRS. The results of the behavioural tests revealed that both methods ameliorated CRS-induced depression. The brain slices of the mice were subjected to immunohistochemical staining for c-fos and phosphorylated ERK (pERK). Results showed that the continuous low-dose DEX-treated group, but not the single high-dose DEX-treated group expressed less c-fos in the nucleus locus coeruleus (LC) with a mean optical density (MOD) of 0.06. Other brain regions, including the dentate gyrus (DG), pyriform cortex (Pir), anterior part of paraventricular thalamic nucleus (PVA), arcuate nucleus (Arc), and core or shell of accumbens nucleus (Acbc or Acbs), presented differences in c-fos expression. In contrast, the low-dose DEX-treated group exhibited three-fold greater pERK expression in the LC of the CRS mice, with a MOD of 0.15. Pir, cingulate cortex (Cg) and, anterior and posterior part of paraventricular thalamic nucleus (PVA and PVP) exhibited pERK expression differences due to distinct reagent treatments. These changes indicate that the responses of brain regions to different DEX administration methods and doses vary. This study confirmed the ability of DEX to ameliorate CRS-induced depression and identified candidate target brain regions, thus providing new information for the antidepressant mechanism of DEX.

Pereskia sacharosa Griseb. (Cactaceae) Prevents Lipopolysaccharide-Induced Neuroinflammation in Rodents via Down-Regulating TLR4/CD14 Pathway and GABAA γ2 Activity.

Pereskia sacharosa Griseb. is a plant used in traditional herbal medicine to treat inflammation. We analyzed the phenolic content of P. sacharosa leaves (EEPs) by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and investigated the anti-inflammatory properties of EEPs and its flavonoid fraction (F10) in animal models subjected to acute neuroinflammation induced by bacterial lipopolysaccharide (LPS). Coronal brain sections of C57BL/6JN male mice or Wistar male rats administered with EEPs or F10 before LPS were subjected to in situ hybridization to determine c-fos and CD14 mRNA levels in the hypothalamus or GABAA γ2 mRNA levels in the hippocampus. Theta oscillations were recorded every 6 h in the hippocampus of Wistar rats. In total, five flavonoids and eight phenolic acids were identified and quantified in P. sacharosa leaves. Either EEPs or F10 crossed the blood-brain barrier (BBB) into the brain and reduced the mRNA expression of c-fos, CD14, and GABAA γ2. A decrease in theta oscillation was observed in the hippocampus of the LPS group, while the F10 + LPS group overrode the LPS effect on theta activity. We conclude that the bioactive compounds of P. sacharosa reduce the central response to inflammation, allowing the early return of ambulatory activity and well-being of the animal.

Serine racemase deletion alters adolescent social behavior and whole-brain cFos activation.

Background: Neurodevelopmental disorders (NDDs) can cause debilitating impairments in social cognition and aberrant functional connectivity in large-scale brain networks, leading to social isolation and diminished everyday functioning. To facilitate the treatment of social impairments, animal models of NDDs that link N- methyl-D-aspartate receptor (NMDAR) hypofunction to social deficits in adulthood have been used. However, understanding the etiology of social impairments in NDDs requires investigating social changes during sensitive windows during development. Methods: We examine social behavior during adolescence using a translational mouse model of NMDAR hypofunction (SR-/-) caused by knocking out serine racemase (SR), the enzyme needed to make D-serine, a key NMDAR coagonist. Species-typical social interactions are maintained through brain-wide neural activation patterns; therefore, we employed whole-brain cFos activity mapping to examine network-level connectivity changes caused by SR deletion. Results: In adolescent SR-/- mice, we observed disinhibited social behavior toward a novel conspecific and rapid social habituation toward familiar social partners. SR-/- mice also spent more time in the open arm of the elevated plus maze which classically points to an anxiolytic behavioral phenotype. These behavioral findings point to a generalized reduction in anxiety-like behavior in both social and non-social contexts in SR-/- mice; importantly, these findings were not associated with diminished working memory. Inter-regional patterns of cFos activation revealed greater connectivity and network density in SR-/- mice compared to controls. Discussion: These results suggest that NMDAR hypofunction - a potential biomarker for NDDs - can lead to generalized behavioral disinhibition in adolescence, potentially arising from disrupted communication between and within salience and default mode networks.

Investigations on the Ability of the Insular Cortex to Process Peripheral Immunosuppression.

The brain and immune system communicate through complex bidirectional pathways, but the specificity by which the brain perceives or even remembers alterations in immune homeostasis is still poorly understood. Recent data revealed that immune-related information under peripheral inflammatory conditions, termed as "immunengram", were represented in specific neuronal ensembles in the insular cortex (IC). Chemogenetic reactivation of these neuronal ensembles was sufficient to retrieve the inflammatory stages, indicating that the brain can store and retrieve specific immune responses. Against this background, the current approach was designed to investigate the ability of the IC to process states of immunosuppression pharmacologically induced by the mechanistic target of rapamycin (mTOR) inhibitor rapamycin. We here show that the IC perceives the initial state of immunosuppression, reflected by increased deep-brain electroencephalography (EEG) activity during acute immunosuppressive drug treatment. Following an experienced period of immunosuppression, though, diminished splenic cytokine production as formerly induced by rapamycin could not be reinstated by nonspecific chemogenetic activation or inhibition of the IC. These findings suggest that the information of a past, or experienced status of pharmacologically induced immunosuppression is not represented in the IC. Together, the present work extends the view of immune-to-brain communication during the states of peripheral immunosuppression and foster the prominent role of the IC for interoception.

All IEGs Are Not Created Equal-Molecular Sorting Within the Memory Engram.

When neurons are recruited to form the memory engram, they are driven to activate the expression of a series of immediate-early genes (IEGs). While these IEGs have been used relatively indiscriminately to identify the so-called engram neurons, recent research has demonstrated that different IEG ensembles can be physically and functionally distinct within the memory engram. This inherent heterogeneity of the memory engram is driven by the diversity in the functions and distributions of different IEGs. This process, which we call molecular sorting, is analogous to sorting the entire population of engram neurons into different sub-engrams molecularly defined by different IEGs. In this chapter, we will describe the molecular sorting process by systematically reviewing published work on engram ensemble cells defined by the following four major IEGs: Fos, Npas4, Arc, and Egr1. By comparing and contrasting these likely different components of the memory engram, we hope to gain a better understanding of the logic and significance behind the molecular sorting process for memory functions.

Baclofen prevents morphine rewarding effects and associated biochemical alterations in male and female mice.

Previous studies from our laboratory have shown sex differences in the behavioral, molecular, and neurochemical manifestations of morphine withdrawal and they were related to an increased sensitivity to morphine effects in males. In addition, we observed an interaction between the GABAergic and opioid systems that could also be sex-dependent. Baclofen, a GABAB receptor agonist, prevented the somatic expression and the molecular and neurochemical changes induced by morphine withdrawal syndrome in mice. On the contrary, little is known about baclofen effects in the rewarding properties of morphine in male and female mice. The present study aimed to explore the effect of baclofen (1, 2 and 3 mg/kg, i.p.) pretreatment in the rewarding effects induced by morphine (7 mg/kg, s.c.) and its effect on c-Fos and brain-derived neurotrophic factor (BDNF) expression induced by the rewarding properties of morphine in prepubertal male and female mice. Baclofen (2 mg/kg) pretreatment prevented the rewarding effects of morphine only in male mice, while baclofen (3 mg/kg) reduced these effects in both sexes. Moreover, the rewarding effects of morphine were associated with a decrease of BDNF and c-Fos expression cingulate cortex, nucleus accumbens shell, cornu ammonis 1 (CA1), and cornu ammonis 3 (CA3) areas of the hippocampus only in male mice. In addition, baclofen pretreatment prevented these changes in BDNF, but not in c-Fos expression. In conclusion, our results show that GABAB receptors have a regulatory role in the rewarding effects of morphine that could be of interest for a potential future therapeutic application in opioid use disorders.

The role of serum C-Fos and glial fibriller acidic protein levels in detecting the severity of obstructive sleep apnea.

PURPOSE: Hypoxia and sleep fragmentations that develop during sleep cause central nervous system damage in patients with obstructive sleep apnea (OSA). This study investigates the relationship between OSA severity and glial fibrillary acidic protein (GFAP) and c-Fos, which are considered indicators of neuronal damage. METHODS: The study included 84 participants (70 patients with OSA and 14 healthy individuals). All participants were evaluated with the Epworth Sleepiness Scale (ESS) before polysomnography (PSG), and serum GFAP and c-Fos values were measured after PSG. All participants were grouped according to the apnea-hypopnea index (AHI) score (control: AHI < 5, Mild OSA: 5 ≤ AHI < 15; moderate OSA: 15 ≤ AHI < 30; severe OSA: AHI ≥ 30). RESULTS: The average age of the participants was 48.5 ± 11.4 years. According to AHI scoring, 14 healthy individuals (16.7%) were in the control group, and 70 patients (83.3%) were in OSA groups. The serum GFAP levels and c-Fos levels were increased in the OSA groups (7.1 ± 5.7 ng/mL and 7.9 ± 7.5 pg/mL respectively) compared to the control group (1.3 ± 0.4 ng/mL and 2.7 ± 1.4 pg/mL p < 0.001 and p < 0.01, respectively). There was a significant positive correlation between AHI and oxygen desaturation index (ODI) values, which indicate disease severity, and serum c-Fos (r: 0.381 and r:0.931, p < 0.01, respectively) and GFAP (r: 0.793 and r:0.745, p < 0.01, respectively) values. CONCLUSION: Serum GFAP and c-Fos values, which are considered indicators of neuronal damage, can be used as a serum marker to determine disease severity in OSA.

IGFBP7 promotes endothelial cell repair in the recovery phase of acute lung injury.

IGFBP7 has been found to play an important role in inflammatory diseases, such as acute lung injury (ALI). However, the role of IGFBP7 in different stages of inflammation remains unclear. Transcriptome sequencing was used to identify the regulatory genes of IGFBP7, and endothelial IGFBP7 expression was knocked down using Aplnr-Dre mice to evaluate the endothelial proliferation capacity. The expression of proliferation-related genes was detected by Western blotting and RT-PCR assays. In the present study, we found that knockdown of IGFBP7 in endothelial cells significantly decreases the expression of endothelial cell proliferation-related genes and cell number in the recovery phase but not in the acute phase of ALI. Mechanistically, using bulk-RNA sequencing and CO-IP, we found that IGFBP7 promotes phosphorylation of FOS and subsequently up-regulates YAP1 molecules, thereby promoting endothelial cell proliferation. This study indicated that IGFBP7 has diverse roles in different stages of ALI, which extends the understanding of IGFBP7 in different stages of ALI and suggests that IGFBP7 as a potential therapeutic target in ALI needs to take into account the period specificity of ALI.

Socially activated neurons in the anterior cingulate cortex are essential for social behavior in mice.

Social behavior, defined as any mode of communication between conspecifics is regulated by a widespread network comprising multiple brain structures. The anterior cingulate cortex (ACC) serves as a hub region interconnected with several brain regions involved in social behavior. Because the ACC coordinates various behaviors, it is important to focus on a subpopulation of neurons that are potentially involved in social behavior to clarify the precise role of the ACC in social behavior. In this study, we aimed to analyze the roles of a social stimulus-responsive subpopulation of neurons in the ACC in social behavior in mice. We demonstrated that a subpopulation of neurons in the ACC was activated by social stimuli and that silencing the social stimulus-responsive subpopulation of neurons in the ACC significantly impaired social interaction without affecting locomotor activity or anxiety-like behavior. Our current findings highlight the importance of the social stimulus-responsive subpopulation of neurons in the ACC for social behavior and the association between ACC dysfunction and impaired social behavior, which sheds light on therapeutic interventions for psychiatric conditions.

Neural correlates of learning and memory are altered by early-life stress.

The ability to learn and remember, which is fundamental for behavioral adaptation, is susceptible to stressful experiences during the early postnatal period, such as abnormal levels of maternal care. The exact mechanisms underlying these effects still remain elusive. This study examined whether early life stress (ELS) alters memory and brain activation patterns in male mice. Therefore, we examined the expression of the immediate early genes (IEGs) c-Fos and Arc in the dentate gyrus (DG) and basolateral amygdala (BLA) after training and memory retrieval in a fear conditioning task. Furthermore, we examined the potential of RU38486 (RU486), a glucocorticoid receptor antagonist, to mitigate ELS-induced memory deficits by blocking stress signalling during adolescence. Arc::dVenus reporter mice, which allow investigating experience-dependent expression of the immediate early gene Arc also at more remote time points, were exposed to ELS by housing dams and offspring with limited bedding and nesting material (LBN) between postnatal days (PND) 2-9 and trained in a fear conditioning task at adult age. We found that ELS reduced both fear acquisition and contextual memory retrieval. RU486 did not prevent these effects. ELS reduced the number of Arc::dVenus+ cells in DG and BLA after training, while the number of c-Fos+ cells were left unaffected. After memory retrieval, ELS decreased c-Fos+ cells in the ventral DG and BLA. ELS also altered the colocalization of c-Fos+ cells with Arc::dVenus+ cells in the ventral DG, possibly indicating impaired engram allocation in the ventral DG after memory retrieval. In conclusion, this study shows that ELS alters neuronal activation patterns after fear acquisition and retrieval, which may provide mechanistic insights into enduring impact of ELS on the processing of fear memories, possibly via changes in cell (co-) activation and engram cell allocation.

Exploring Astrocytes Involvement and Glutamate Induced Neuroinflammation in Chlorpyrifos-Induced Paradigm Of Autism Spectrum Disorders (ASD).

Autism spectrum disorders (ASD) are neurodevelopmental disorders manifested mainly in children, with symptoms ranging from social/communication deficits and stereotypies to associated behavioral anomalies like anxiety, depression, and ADHD. While the patho-mechanism is not well understood, the role of neuroinflammation has been suggested. Nevertheless, the triggers giving rise to this neuroinflammation have not previously been explored in detail, so the present study was aimed at exploring the role of glutamate on these processes, potentially carried out through increased activity of inflammatory cells like astrocytes, and a decline in neuronal health. A novel chlorpyrifos-induced paradigm of ASD in rat pups was used for the present study. The animals were subjected to tests assessing their neonatal development and adolescent behaviors (social skills, stereotypies, sensorimotor deficits, anxiety, depression, olfactory, and pain perception). Markers for inflammation and the levels of molecules involved in glutamate excitotoxicity, and neuroinflammation were also measured. Additionally, the expression of reactive oxygen species and markers of neuronal inflammation (GFAP) and function (c-Fos) were evaluated, along with an assessment of histopathological alterations. Based on these evaluations, it was found that postnatal administration of CPF had a negative impact on neurobehavior during both the neonatal and adolescent phases, especially on developmental markers, and brought about the generation of ASD-like symptoms. This was further corroborated by elevations in the expression of glutamate and downstream calcium, as well as certain cytokines and neuroinflammatory markers, and validated through histopathological and immunohistochemical results showing a decline in neuronal health in an astrocyte-mediated cytokine-dependent fashion. Through our findings, conclusive evidence regarding the involvement of glutamate in neuroinflammatory pathways implicated in the development of ASD-like symptoms, as well as its ability to activate further downstream processes linked to neuronal damage has been obtained. The role of astrocytes and the detrimental effect on neuronal health are also concluded. The significance of our study and its findings lies in the evaluation of the involvement of chlorpyrifos-induced neurotoxicity in the development of ASD, particularly in relation to glutamatergic dysfunction and neuronal damage.

Inhibition of Protein Synthesis Attenuates Formation of Traumatic Memory and Normalizes Fear-Induced c-Fos Expression in a Mouse Model of Posttraumatic Stress Disorder.

Posttraumatic stress disorder (PTSD) is a debilitating psychosomatic condition characterized by impairment of brain fear circuits and persistence of exceptionally strong associative memories resistant to extinction. In this study, we investigated the neural and behavioral consequences of inhibiting protein synthesis, a process known to suppress the formation of conventional aversive memories, in an established PTSD animal model based on contextual fear conditioning in mice. Control animals were subjected to the conventional fear conditioning task. Utilizing c-Fos neural activity mapping, we found that the retrieval of PTSD and normal aversive memories produced activation of an overlapping set of brain structures. However, several specific areas, such as the infralimbic cortex and the paraventricular thalamic nucleus, showed an increase in the PTSD group compared to the normal aversive memory group. Administration of protein synthesis inhibitor before PTSD induction disrupted the formation of traumatic memories, resulting in behavior that matched the behavior of mice with usual aversive memory. Concomitant with this behavioral shift was a normalization of brain c-Fos activation pattern matching the one observed in usual fear memory. Our findings demonstrate that inhibiting protein synthesis during traumatic experiences significantly impairs the development of PTSD in a mouse model. These data provide insights into the neural underpinnings of protein synthesis-dependent traumatic memory formation and open prospects for the development of new therapeutic strategies for PTSD prevention.

Tumor-neutrophil cross talk orchestrates the tumor microenvironment to determine the bladder cancer progression.

The immune landscape of bladder cancer progression is not fully understood, and effective therapies are lacking in advanced bladder cancer. Here, we visualized that bladder cancer cells recruited neutrophils by secreting interleukin-8 (IL-8); in turn, neutrophils played dual functions in bladder cancer, including hepatocyte growth factor (HGF) release and CCL3highPD-L1high super-immunosuppressive subset formation. Mechanistically, c-Fos was identified as the mediator of HGF up-regulating IL-8 transcription in bladder cancer cells, which was central to the positive feedback of neutrophil recruitment. Clinically, compared with serum IL-8, urine IL-8 was a better biomarker for bladder cancer prognosis and clinical benefit of immune checkpoint blockade (ICB). Additionally, targeting neutrophils or hepatocyte growth factor receptor (MET) signaling combined with ICB inhibited bladder cancer progression and boosted the antitumor effect of CD8+ T cells in mice. These findings reveal the mechanism by which tumor-neutrophil cross talk orchestrates the bladder cancer microenvironment and provide combination strategies, which may have broad impacts on patients suffering from malignancies enriched with neutrophils.

Central amygdala is related to the reduction of aggressive behavior by monosodium glutamate ingestion during the period of development in an ADHD model rat.

Introduction: Monosodium glutamate (MSG), an umami substance, stimulates the gut-brain axis communication via gut umami receptors and the subsequent vagus nerves. However, the brain mechanism underlying the effect of MSG ingestion during the developmental period on aggression has not yet been clarified. We first tried to establish new experimental conditions to be more appropriate for detailed analysis of the brain, and then investigated the effects of MSG ingestion on aggressive behavior during the developmental stage of an ADHD rat model. Methods: Long-Evans, WKY/Izm, SHR/Izm, and SHR-SP/Ezo were individually housed from postnatal day 25 for 5 weeks. Post-weaning social isolation (PWSI) was given to escalate aggressive behavior. The resident-intruder test, that is conducted during the subjective night, was used for a detailed analysis of aggression, including the frequency, duration, and latency of anogenital sniffing, aggressive grooming, and attack behavior. Immunohistochemistry of c-Fos expression was conducted in all strains to predict potential aggression-related brain areas. Finally, the most aggressive strain, SHR/Izm, a known model of attention-deficit hyperactivity disorder (ADHD), was used to investigate the effect of MSG ingestion (60 mM solution) on aggression, followed by c-Fos immunostaining in aggression-related areas. Bilateral subdiaphragmatic vagotomy was performed to verify the importance of gut-brain interactions in the effect of MSG. Results: The resident intruder test revealed that SHR/Izm rats were the most aggressive among the four strains for all aggression parameters tested. SHR/Izm rats also showed the highest number of c-Fos + cells in aggression-related brain areas, including the central amygdala (CeA). MSG ingestion significantly decreased the frequency and duration of aggressive grooming and attack behavior and increased the latency of attack behavior. Furthermore, MSG administration successfully increased c-Fos positive cell number in the intermediate nucleus of the solitary tract (iNTS), a terminal of the gastrointestinal sensory afferent fiber of the vagus nerve, and modulated c-Fos positive cells in the CeA. Interestingly, vagotomy diminished the MSG effects on aggression and c-Fos expression in the iNTS and CeA. Conclusion: MSG ingestion decreased PWSI-induced aggression in SHR/Izm, which was mediated by the vagus nerve related to the stimulation of iNTS and modulation of CeA activity.

Pain experience reduces social avoidance to others in pain: a c-Fos-based functional connectivity network study in mice.

Pain experience increases individuals' perception and contagion of others' pain, but whether pain experience affects individuals' affiliative or antagonistic responses to others' pain is largely unknown. Additionally, the neural mechanisms underlying how pain experience modulates individuals' responses to others' pain remain unclear. In this study, we explored the effects of pain experience on individuals' responses to others' pain and the underlying neural mechanisms. By comparing locomotion, social, exploration, stereotyped, and anxiety-like behaviors of mice without any pain experience (naïve observers) and mice with a similar pain experience (experienced observers) when they observed the pain-free demonstrator with intraperitoneal injection of normal saline and the painful demonstrator with intraperitoneal injection of acetic acid, we found that pain experience of the observers led to decreased social avoidance to the painful demonstrator. Through whole-brain c-Fos quantification, we discovered that pain experience altered neuronal activity and enhanced functional connectivity in the mouse brain. The analysis of complex network and graph theory exhibited that functional connectivity networks and activated hub regions were altered by pain experience. Together, these findings reveal that neuronal activity and functional connectivity networks are involved in the modulation of individuals' responses to others' pain by pain experience.