Behavioral Deficits In Mice Research Articles

Importin α4 deficiency induces psychiatric disorder-related behavioral deficits and neuroinflammation in mice

Importin α4, which is encoded by the Kpna4 gene, is a well-characterized nuclear-cytoplasmic transport factor known to mediate transport of transcription factors including NF-κB. Here, we report that Kpna4 knock-out (KO) mice exhibit psychiatric disorder-related behavioral abnormalities such as anxiety-related behaviors, decreased social interaction, and sensorimotor gating deficits. Contrary to a previous study predicting attenuated NF-κB activity as a result of Kpna4 deficiency, we observed a significant increase in expression levels of NF-κB genes and proinflammatory cytokines such as TNFα, Il-1β or Il-6 in the prefrontal cortex or basolateral amygdala of the KO mice. Moreover, examination of inflammatory responses in primary cells revealed that Kpna4 deficient cells have an increased inflammatory response, which was rescued by addition of not only full length, but also a nuclear transport-deficient truncation mutant of importin α4, suggesting contribution of its non-transport functions. Furthermore, RNAseq of sorted adult microglia and astrocytes and subsequent transcription factor analysis suggested increases in polycomb repressor complex 2 (PRC2) activity in Kpna4 KO cells. Taken together, importin α4 deficiency induces psychiatric disorder-related behavioral deficits in mice, along with an increased inflammatory response and possible alteration of PRC2 activity in glial cells.

Neural and molecular investigation into the paraventricular thalamus for chronic restraint stress induced depressive-like behaviors

IntroductionDisturbance of neural circuits and chronic stress contribute to depression onset. Given the crucial role of paraventricular nucleus of thalamus (PVT) in emotional behaviors, however, the specific neural and molecular mechanism of PVT in depression still unclear. ObjectiveOur study aim to explore the neural and molecular mechanism of PVT in depression. MethodsIn the present study, we utilize behavioral tests,chemogenetics, RNA-sequence, molecular profiling and pharmacological approaches to investigate the role of PVT in depression. ResultsWe observed that CamkIIα neurons in PVT were inactivated by chronic restraint stress (CRS) with reduced c-Fos positive neurons. Activation of PVTCamkIIα neurons displayed antidepressant-like effect in both naive and CRS mice, whereas inhibition or ablation of these neurons is sufficient to trigger depressive-like behaviors. Moreover, we found that activating PVT → Nucleus accumbens (NAc) circuit attenuated depressive-like behaviors induced by CRS, while inhibiting this circuit directly caused behavioral deficits in mice. Intriguingly, artificially enhancing PVT → Central amygdala (CeA) pathway failed to alleviate depressive-like behaviors. Importantly, increased expression of neuropeptide Y (NPY) and depressive-like behaviors induced by CRS could be ameliorated via antidepressant treatment, manipulation of PVTCamkIIα neurons (or PVT → NAc circuit) and NPY inhibitor. ConclusionTaken together, our study uncovered that PVT regulated depressive-like behaviors via PVT → NAc circuit together with NPY, thus shedding light on potential target for preventing depression and promoting clinical translation.

Microglial type I interferon signaling mediates chronic stress-induced synapse loss and social behavior deficits.

Inflammation and synapse loss have been associated with deficits in social behavior and are involved in pathophysiology of many neuropsychiatric disorders. Synapse loss, characterized by reduction in dendritic spines can significantly disrupt synaptic connectivity and neural circuitry underlying social behavior. Chronic stress is known to induce loss of spines and dendrites in the prefrontal cortex (PFC), a brain region implicated in social behavior. However, the underlying mechanisms are not well understood. In the present study, we investigated the role of type I Interferon (IFN-I) signaling in chronic unpredictable stress (CUS)-induced synapse loss and behavior deficits in mice. We found increased expression of type I IFN receptor (IFNAR) in microglia following CUS. Conditional knockout of microglial IFNAR in adult mice rescued CUS-induced social behavior deficits and synapse loss. Bulk RNA sequencing data show that microglial IFNAR deletion attenuated CUS-mediated changes in the expression of genes such as Keratin 20 (Krt20), Claudin-5 (Cldn5) and Nuclear Receptor Subfamily 4 Group A Member 1 (Nr4a1) in the PFC. Cldn5 and Nr4a1 are known for their roles in synaptic plasticity. Krt20 is an intermediate filament protein responsible for the structural integrity of epithelial cells. The reduction in Krt20 following CUS presents a novel insight into the potential contribution of cytokeratin in stress-induced alterations in neuroplasticity. Overall, these results suggest that microglial IFNAR plays a critical role in regulating synaptic plasticity and social behavior deficits associated with chronic stress conditions.

Immunosuppression-induced Zika virus reactivation causes brain inflammation and behavioral deficits in mice

Zika virus (ZIKV) is a neurotropic flavivirus that can persist in several tissues. The late consequences of ZIKV persistence and whether new rounds of active replication can occur, remain unaddressed. Here, we investigated whether neonatally ZIKV-infected mice are susceptible to viral reactivation in adulthood. We found that when ZIKV-infected mice are treated with immunosuppressant drugs, they present increased susceptibility to chemically induced seizures. Levels of subgenomic flavivirus RNAs (sfRNAs) were increased, relative to the amounts of genomic RNAs, in the brains of mice following immunosuppression and were associated with changes in cytokine expression. We investigated the impact of immunosuppression on the testicles and found that ZIKV genomic RNA levels are increased in mice following immunosuppression, which also caused significant testicular damage. These findings suggest that ZIKV can establish new rounds of active replication long after acute stages of disease, so exposed patients should be monitored to ensure complete viral eradication.

Probiotics Supplementation Alleviates Endotoxemia-induced Behavioral Deficits in Mice

Probiotics Supplementation Alleviates Endotoxemia-induced Behavioral Deficits in Mice

Metformin normalizes mitochondrial function to delay astrocyte senescence in a mouse model of Parkinson’s disease through Mfn2-cGAS signaling

BackgroundSenescent astrocytes play crucial roles in age-associated neurodegenerative diseases, including Parkinson’s disease (PD). Metformin, a drug widely used for treating diabetes, exerts longevity effects and neuroprotective activities. However, its effect on astrocyte senescence in PD remains to be defined.MethodsLong culture-induced replicative senescence model and 1-methyl-4-phenylpyridinium/α-synuclein aggregate-induced premature senescence model, and a mouse model of PD were used to investigate the effect of metformin on astrocyte senescence in vivo and in vitro. Immunofluorescence staining and flow cytometric analyses were performed to evaluate the mitochondrial function. We stereotactically injected AAV carrying GFAP-promoter-cGAS-shRNA to mouse substantia nigra pars compacta regions to specifically reduce astrocytic cGAS expression to clarify the potential molecular mechanism by which metformin inhibited the astrocyte senescence in PD.ResultsWe showed that metformin inhibited the astrocyte senescence in vitro and in PD mice. Mechanistically, metformin normalized mitochondrial function to reduce mitochondrial DNA release through mitofusin 2 (Mfn2), leading to inactivation of cGAS-STING, which delayed astrocyte senescence and prevented neurodegeneration. Mfn2 overexpression in astrocytes reversed the inhibitory role of metformin in cGAS-STING activation and astrocyte senescence. More importantly, metformin ameliorated dopamine neuron injury and behavioral deficits in mice by reducing the accumulation of senescent astrocytes via inhibition of astrocytic cGAS activation. Deletion of astrocytic cGAS abolished the suppressive effects of metformin on astrocyte senescence and neurodegeneration.ConclusionsThis work reveals that metformin delays astrocyte senescence via inhibiting astrocytic Mfn2-cGAS activation and suggest that metformin is a promising therapeutic agent for age-associated neurodegenerative diseases.

Erythrocyte membrane coated with nitrogen-doped quantum dots and polydopamine composite nano-system combined with photothermal treatment of Alzheimer's disease

Mitochondrial dysfunction and metal ion imbalance are recognized as pathological hallmarks of Alzheimer's Disease (AD), leading to deposition of β-amyloid (Aβ) thereby and inducing neurotoxicity, activating apoptosis, eliciting oxidative stress, and ultimately leading to cognitive impairment. In this study, the red blood cell membrane (RBC) was used as a vehicle for encapsulating carbon quantum dots (CQD) and polydopamine (PDA), creating a nanocomposite (PDA-CQD/RBC). This nanocomposite was combined with near-infrared light (NIR) for AD treatment. The RBC offers anti-immunorecognition properties to evade immune clearance, PDA exhibits enzyme-mimicking activity to mitigate oxidative stress damage, and CQD acts as a chelating agent for metal ions (Cu2+), effectively preventing Cu2+-mediated aggregation of Aβ. Furthermore, the local heating induced by near-infrared laser irradiation can dismantle the formed Aβ fibers and enhance the blood–brain barrier's permeability. Both in vitro and animal experiments have shown that PDA-CQD/RBC, in combination with NIR, mitigates neuroinflammation, and ameliorates behavioral deficits in mice. This approach targets multiple pathological pathways, surpassing the limitations of single-target treatments and enhancing therapeutic efficacy while decelerating disease progression.

Neuroprotective Effects of Bifidobacterium animalis subsp. lactis NJ241 in a Mouse Model of Parkinson’s Disease: Implications for Gut Microbiota and PGC-1α

Intestinal dysbiosis plays a critical role in the pathogenesis of Parkinson’s disease (PD), and probiotics have emerged as potential modulators of central nervous system function through the microbiota-gut-brain axis. This study aimed to elucidate the anti-inflammatory effects and underlying mechanisms of the probiotic strain Bifidobacterium animalis subsp. lactis NJ241 (NJ241) in a mouse model of PD induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The impact of NJ241 was comprehensively assessed in PD mice through behavioral tests, immunofluorescence, Western blotting, enzyme-linked immunosorbent assay (ELISA), 16S rRNA sequencing, and short-chain fatty acid (SCFA) detection. NJ241 exhibited notable efficacy in mitigating MPTP-induced weight loss, gastrointestinal dysfunction, and behavioral deficits in mice. Furthermore, it demonstrated protected against MPTP-induced dopaminergic neuron death and inhibited the activation of glial cells in the substantia nigra (SN). NJ241 demonstrated the ability to normalized dysbiosis in the intestinal microbiota and elevate SCFA levels in PD mice. Additionally, NJ241 reversed MPTP-induced reductions in colonic GLP-1 levels and the expression of GLP-1R and PGC-1α in the SN. Notably, GLP-1R antagonists partially reversed the inhibitory effects of NJ241 on the activation of glial cells in the SN. In summary, NJ241 exerts a neuroprotective effect against MPTP-induced neuroinflammation by enhancing intestinal GLP-1 levels and activating nigral PGC-1α signaling. These findings provide a rationale for the exploration and development of probiotic-based therapeutic strategies for PD.

The liver and muscle secreted HFE2-protein maintains central nervous system blood vessel integrity

Liver failure causes breakdown of the Blood CNS Barrier (BCB) leading to damages of the Central-Nervous-System (CNS), however the mechanisms whereby the liver influences BCB-integrity remain elusive. One possibility is that the liver secretes an as-yet to be identified molecule(s) that circulate in the serum to directly promote BCB-integrity. To study BCB-integrity, we developed light-sheet imaging for three-dimensional analysis. We show that liver- or muscle-specific knockout of Hfe2/Rgmc induces BCB-breakdown, leading to accumulation of toxic-blood-derived fibrinogen in the brain, lower cortical neuron numbers, and behavioral deficits in mice. Soluble HFE2 competes with its homologue RGMa for binding to Neogenin, thereby blocking RGMa-induced downregulation of PDGF-B and Claudin-5 in endothelial cells, triggering BCB-disruption. HFE2 administration in female mice with experimental autoimmune encephalomyelitis, a model for multiple sclerosis, prevented paralysis and immune cell infiltration by inhibiting RGMa-mediated BCB alteration. This study has implications for the pathogenesis and potential treatment of diseases associated with BCB-dysfunction.

Abstract 108: Gut Microbiota Composition Modifies Behavioral Phenotypes Into Adulthood Following Neonatal Hypoxic-Ischemia in Mice

Neonatal hypoxic ischemic encephalopathy (HIE) increases the risk for attention deficit disorder and autism spectrum disorders in children. Perturbations in the gut microbiome are associated with behavioral changes in pre-clinical models of neurological injury and development. However, the role of the gut microbiome in behavior after HIE has not been investigated. Also, the therapeutic potential of gut microbiota modification after HIE remains unexplored. We hypothesize that altering the gut microbiome after HIE can improve chronic behavioral deficits in mice. The Rice Vannucci Model (RVM) was used to model HIE on 9-day old C57BL/6 mice. 2 months after injury, fecal samples were collected for 16s rRNA sequencing and behavioral tests were performed. We treated HIE and sham mice with fecal microbiota transfers (FMT) from naïve donors. To determine if the microbiota from HIE mice drives behavioral deficits, we also gave FMT from HIE or sham donors into naïve. Tests were repeated 1 and 3 months after FMT, and mice were sacrificed at 5 months of age. 2 months after injury, baseline open field tests revealed a hyperactive phenotype in HIE mice. There was increased mean velocity, distance moved, and cumulative time in border coupled with decreased cumulative time in center compared to shams (P&lt0.0001, P&lt0.0001, P=0.0168, P=0.025; T test, two cohorts, n=14-18). PCoA on calculated weighted UniFrac distances reveal a significant difference in β-diversity in males (P=0.015) and females (P=0.033) at 2 months. At 5 months, HIE mice with a naïve FMT had normalization of their hyperactive phenotype, measured by a reduction in mean velocity and distance moved (P=0.028 and P=0.0322; Repeated Measures One-way ANOVA, Dunnett’s test), while sham mice had no change. Surprisingly, naïve mice given a FMT from HIE donors became hypoactive with reduced mean velocity and distance moved (P=0.0004 and P=0.0004; Mixed effects Model, Tukey’s test, 2 cohorts n=6-11), while Naive mice with sham FMT had no change. In conclusion, gut microbiota modification through FMT in adult mice with a history of HIE reduced the severity of their hyperactive phenotype. Conversely, FMT from HIE mice into naïve mice induced mild behavioral changes but did not reproduce the hyperactivity seen in HIE mice.

Potential Novel Treatments for Parkinson’s Disease

This review aims to evaluate novel developments in treatments for Parkinson’s disease that focus on slowing, stopping, and/or reversing the neurodegeneration associated with the disease. Parkinson’s disease (PD) is a neurodegenerative disease that affects dopaminergic neurons in the substantia nigra, located in the basal ganglia of the brain. This region also contains high levels of alpha synuclein, a protein found abundantly in the brain due to its important role in neurotransmitter release. α-synuclein has been found to be misfolded and overexpressed in people with PD, which leads to fibril formation and aggregation, which directly interfere with basic cellular processes and results in neurodegeneration. In PD patients, dopaminergic neurons are most affected; therefore, an artificial supply of dopamine must be provided to them via dopamine precursors that can cross the blood-brain barrier. However, these medications fail to slow, stop, or reverse the progression of PD and merely pose as treatments for physical symptoms, such as tremors. Researchers are now focusing on 2 major avenues for new PD treatments: treatments that target α-synuclein aggregates/Lewy body assemblies and treatments that focus on replacement of lost dopaminergic neurons in the brain. The use of antibodies (immunotherapy) to target and clear αsynuclein aggregates or the upregulation of genes that encode autophagic mechanisms to destroy dysfunctional proteins were shown to reduce α-synuclein aggregation and behavioral deficits in mice. Results from clinical trials have shown a 96.5% reduction in the concentration of extracellular α-synuclein aggregates, and doses were well tolerated with no serious side effects. In order to rebuild the neurons that were lost to PD neurodegeneration, a renewable source of dopamine-producing cells that can integrate into the host brain and survive for years is required. More specifically, the reprogramming of astrocytes can be used to develop functional dopaminergic neurons. To reprogram the astrocytes and fibroblasts, the RNA binding protein PTB was suppressed; PTB suppresses numerous neuronal genes required for neuronal maturation, thus, downregulation of PTB generates functional, mature neurons. When in vivo astrocyte reprogramming was performed in a mouse model of PD, researchers found new, successful dopaminergic neurons in the substantia nigra and increased dopamine levels. Although both avenues for treatment require further clinical trials and testing in human subjects, they both hold significant promise in the future.

Foeniculum vulgare Mill. inhibits lipopolysaccharide-induced microglia activation and ameliorates neuroinflammation-mediated behavioral deficits in mice

Objective: To investigate the effect of Foeniculum vulgare extract against lipopolysaccharide (LPS)-induced microglial activation in vitro as well as cognitive behavioral deficits in mice. Methods: LPS-activated BV-2 cell viability was measured using MTT assay and reactive oxygen species (ROS) was studied using DCF-DA assay. The antioxidative enzymes and pro-inflammatory mediators were analyzed using respective ELISA kits and Western blotting. For in vivo testing, LPS (1 mg/kg, i.p.) was given daily for five days in male Swiss albino mice to produce chronic neuroinflammation. Cognitive and behavioral tests were performed using open-field, passive avoidance, and rotarod experiments in LPS-induced mice. Results: Foeniculum vulgare extract (25, 50 and 100 μg/mL) significantly attenuated the LPS-activated increase in nitric oxide (NO), ROS, cyclooxygenase-2, inducible NO synthase, IL-6, and TNF-alpha (P < 0.05). Moreover, LPS-induced oxidative stress and reduced antioxidative enzyme levels were significantly improved by Foeniculum vulgare extract (P < 0.05). The extract also regulated the NF-κB/MAPK signaling in BV-2 cells. In an in vivo study, Foeniculum vulgare extract (50, 100, and 200 mg/kg) markedly mitigated the LPS-induced cognitive and locomotor impairments in mice. The fingerprinting analysis showed distinctive peaks with rutin, kaempferol-3-O-glucoside, and anethole as identifiable compounds. Conclusions: Foeniculum vulgare extract can ameliorate LPS-stimulated neuroinflammatory responses in BV-2 microglial cells and improve cognitive and locomotor performance in LPS-administered mice.

Gelation of cytoplasmic expanded CAG RNA repeats suppresses global protein synthesis.

RNA molecules with the expanded CAG repeat (eCAGr) may undergo sol-gel phase transitions, but the functional impact of RNA gelation is completely unknown. Here, we demonstrate that the eCAGr RNA may form cytoplasmic gel-like foci that are rapidly degraded by lysosomes. These RNA foci may significantly reduce the global protein synthesis rate, possibly by sequestering the translation elongation factor eEF2. Disrupting the eCAGr RNA gelation restored the global protein synthesis rate, whereas enhanced gelation exacerbated this phenotype. eEF2 puncta were significantly enhanced in brain slices from a knock-in mouse model and from patients with Huntington's disease, which is a CAG expansion disorder expressing eCAGr RNA. Finally, neuronal expression of the eCAGr RNA by adeno-associated virus injection caused significant behavioral deficits in mice. Our study demonstrates the existence of RNA gelation inside the cells and reveals its functional impact, providing insights into repeat expansion diseases and functional impacts of RNA phase transition.

Emotional behaviors as well as the hippocampal reelin expression in C57BL/6N male mice chronically treated with corticosterone

Depression is a common psychiatric disorder affecting around 300 million people worldwide. Serum cortisol and glucocorticoid levels in humans are reportedly higher in patients with depression compared to controls. Furthermore, rodents repeatedly treated with exogenous corticosterone (CORT), a glucocorticoid in rodents, exhibit deficits in emotional behaviors. To confirm the availability of mice with chronic CORT treatment as an animal model of depression, we investigated the effect of chronic CORT treatment on depression-like behavioral and neuropathological phenotypes in C57BL/6N male mice. Behavioral studies showed depression- and anxiety-like behaviors in mice treated with CORT compared with control mice in the forced-swim and elevated-plus maze tests. Additionally, treated mice represented anhedonia and social behavior impairments in the sucrose preference and social interaction tests, respectively. Brains of depression patients have altered expression of reelin, an extracellular matrix protein involved in neuronal development and function. Likewise, in the present study, mice with chronic CORT treatment also exhibited reelin downregulation in cells of the hippocampus. Hence, we investigated therapeutic effects of reelin supplementation on CORT-induced behavioral abnormalities in mice. Microinjections of recombinant reelin protein into the hippocampus did not rescue behavioral deficits in mice with chronic CORT treatment. These results suggest that C57BL/6N male mice chronically treated with CORT are a suitable animal depression model, in which depressive behaviors may occur independently of the alternation of hippocampal Reelin expression.

Excess cerebellar granule neurons induced by the absence of p75NTR during development elicit social behavior deficits in mice.

Recently, the cerebellum has been implicated with non-motor functions, including cognitive and emotional behavior. Anatomical and functional studies demonstrate bidirectional cerebellar connections with brain regions involved in social cognition. Cerebellar developmental abnormalities and injury are often associated with several psychiatric and mental disorders including autism spectrum disorders and anxiety. The cerebellar granule neurons (CGN) are essential for cerebellar function since they provide sensorimotor, proprioceptive, and contextual information to Purkinje cells to modify behavior in different contexts. Therefore, alterations to the CGN population are likely to compromise cerebellar processing and function. Previously we demonstrated that the p75 neurotrophin receptor (p75NTR) was fundamental for the development of the CGN. In the absence of p75NTR, we observed increased proliferation of the granule cell precursors (GCPs), followed by increased GCP migration toward the internal granule layer. The excess granule cells were incorporated into the cerebellar network, inducing alterations in cerebellar circuit processing. In the present study, we used two conditional mouse lines to specifically delete the expression of p75NTR in CGN. In both mouse lines, deletion of the target gene was under the control of the transcription factor Atoh-1 promotor, however, one of the lines was also tamoxifen-inducible. We observed a loss of p75NTR expression from the GCPs in all cerebellar lobes. Compared to control animals, both mouse lines exhibited a reduced preference for social interactions when presented with a choice to interact with a mouse or an object. Open-field locomotor behavior and operant reward learning were unaffected in both lines. Lack of preference for social novelty and increased anxiety-related behavior was present in mice with constitutive p75NTR deletion; however, these effects were not present in the tamoxifen-inducible mice with p75NTR deletion that more specifically targeted the GCPs. Our findings demonstrate that alterations to CGN development by loss of p75NTR alter social behavior, and contribute to the increasing evidence that the cerebellum plays a role in non-motor-related behaviors, including social behavior.

Reversal of memory and autism-related phenotypes in Tsc2+/- mice via inhibition of Nlgn1.

Tuberous sclerosis complex (TSC) is a rare monogenic disorder co-diagnosed with high rates of autism and is caused by loss of function mutations in the TSC1 or TSC2 genes. A key pathway hyperactivated in TSC is the mammalian/mechanistic target of rapamycin complex 1 (mTORC1), which regulates cap-dependent mRNA translation. We previously demonstrated that exaggerated cap-dependent translation leads to autism-related phenotypes and increased mRNA translation and protein expression of Neuroligin 1 (Nlgn1) in mice. Inhibition of Nlgn1 expression reversed social behavior deficits in mice with increased cap-dependent translation. Herein, we report elevated translation of Nlgn1 mRNA and an increase in its protein expression. Genetic or pharmacological inhibition of Nlgn1 expression in Tsc2 +/- mice rescued impaired hippocampal mGluR-LTD, contextual discrimination and social behavior deficits in Tsc2 +/- mice, without correcting mTORC1 hyperactivation. Thus, we demonstrate that reduction of Nlgn1 expression in Tsc2 +/- mice is a new therapeutic strategy for TSC and potentially other neurodevelopmental disorders.

Danshensu Enhances Cerebral Angiogenesis in Mice by Regulating the PI3K/Akt/Mtor/VEGF Signaling Axis.

Cerebral infraction seriously affects the life quality of patients. Danshensu has been reported to exhibit anti-inflammatory and vascular protective effects. However, the therapeutic function of Danshensu in cerebral vascular injury is still unclear. Middle cerebral artery occlusion (MCAO) was used to construct the cerebral infraction model. Wound healing and tube formation assays were used to evaluate angiogenesis in vitro. Western blot assay was used to evaluate the activation of the PI3K/Akt/mTOR signaling pathway. The laser Doppler scanner was used to measure the regional cerebral blood flow (rCBF) in the area around the infarction, and the adhesion removal test was used to measure the sensorimotor function. The Modified Neurological Severity Score was performed to evaluate the cognitive functions of mice. Danshensu promoted the proliferation of bEnd.3 cells and angiogenesis in vitro. Danshensu upregulated the expression of VEGF through PI3K/Akt/mTOR signaling pathway in bEnd.3 cells. Danshensu improved rCBF restoration and attenuated the behavioral deficits in mice post-MCAO/R. Danshensu enhances angiogenesis through the PI3K/Akt/mTOR/VEGF signaling pathway in a mouse model of cerebral ischemic injury.

Irisin attenuates ethanol-induced behavioral deficits in mice through activation of Nrf2 and inhibition of NF-κB pathways.

This study aims to investigate the effect of irisin on ethanol-induced behavioral deficits and explore the underlying mechanisms. A mouse model of ethanol addiction/withdrawal was constructed through chronic ethanol administration. Depressive-like behaviors were evaluated by the tail suspension test and forced swimming test, and anxiety-like behaviors were evaluated by the marble-burying test and elevated plus maze test. The expression of Nrf2 was measured by western blotting. Levels of inflammatory mediators (NF-κB, TNF-α, IL-1β and IL-6) and oxidative stress factors (ROS, MDA, GSH and SOD) were detected by ELISA. The ethanol-induced PC12/BV2 cell injury model was used to elucidate whether the effect of irisin on ethanol-induced neurological injury was related to anti-inflammatory and antioxidant mechanisms. Ethanol-induced ethanol preference and emotional deficits were improved by chronic irisin treatment; however, these improvements were partly reversed by cotreatment with the Nrf2 inhibitor ML385. Further results implied that the improvement effect of irisin on behavioral abnormalities may be related to its anti-inflammatory and antioxidant effects. In detail, irisin inhibited ethanol-induced abnormal expression of ROS and MDA and upregulated the expression of GSH and SOD. Meanwhile, irisin treatment inhibited ethanol-induced overexpression of NF-κB, TNF-α, IL-1β and IL-6 in the hippocampus and cerebral cortex. The regulation of oxidative stress factors by irisin was reversed after ML385 treatment. In the in vitro study, overexpression of oxidative stress factors in ethanol-treated PC12 cells was inhibited by irisin treatment; however, the prevention was reversed after the knockdown of Nrf2 siRNA. Moreover, ethanol-induced overexpression of inflammatory mediators in BV2 cells was also inhibited by irisin treatment. Irisin improved depressive and anxiety-like behaviors induced by ethanol addiction/withdrawal in mice, and this protection was greatly associated with the NF-κB-mediated anti-inflammatory signaling pathway and Nrf2-mediated antioxidative stress signaling pathway.

Protective effect of Nr4a2 (Nurr1) against LPS-induced depressive-like behaviors via regulating activity of microglia and CamkII neurons in anterior cingulate cortex

Neuroinflammation is tightly associated with onset of depression. The nuclear receptor related 1 protein (Nurr1, also called Nr4a2), its roles in dopaminergic neurons is well understood, which can alleviate inflammation. Nevertheless, potential effects of Nr4a2 on neuroinflammation associated with depression still remains unclear. Chronic lipopolysaccharides (LPS) stress induced depressive-behaviors were confirmed via behavioral tests. Differentially expressed genes were detected by using RNA-sequencing. The anterior cingulate cortex (ACC) tissues were collected for biochemical experiments. The Golgi-Cox staining and virus labeling were used to evaluate the dendritic spines. We applied fluoxetine (FLX) and amodiaquine dihydrochloride (AQ, a highly selective agonist of Nr4a2) in mice. Overexpression experiments were performed by injecting with AAV-Nr4a2-EGFP into ACC. Chemogenetic activation of CamkII neurons via injecting the hM3Dq virus. Mice treated with LPS displayed depressive- and anxiety-like behaviors. The reduction of Nr4a2 and FosB induced by LPS were rescued by pretreatment with FLX or AQ. More importantly, LPS-induced behavior deficits in mice were also alleviated via fluoxetine treatment and pharmacological activation the expression of Nr4a2. Meanwhile, enhancing the level of Nr4a2 could improve dendritic spines loss of neuron and morphological changes in microglia. Overexpression of Nr4a2 in ACC reversed the depressive- and anxiety-like behaviors caused by LPS administration. Activation of CamkII neurons in ACC could robustly increase the expression of Nr4a2 and improve LPS-induced behavior deficits. Our findings demonstrate that the Nr4a2 may regulate depressive-like behaviors via alleviating the impairment of morphology and function on microglia and CamkII neurons induced by chronic neuroinflammation.

Role of nuclear factor of activated T Cells-1 in Sepsis-induced behavioral deficits in mice

IntroductionThe nuclear factor of activated T cells-1 (NFAT1) is involved in both neuroinflammation and cognitive dysfunction. In this study, we examined the role of NFAT1 in sepsis-induced cognitive impairment in a mouse model. MethodsSepsis was established in adult mice by cecal ligation and puncture (CLP). Novel object recognition tests on days 14–21 and fear conditioning tests on days 22–23 post-surgery showed that CLP impaired both behaviors. BV2 microglia cells exposed to lipopolysaccharide (LPS) were used to examine the effects of short interfering RNA targeting NFAT1 on autophagy and inflammatory cytokines. ResultsCLP increased the expression of NFAT1 in hippocampal microglia and induced hippocampal autophagy by downregulating p62, upregulating beclin-1 and autophagy-related gene-5, and increasing the ratio of microtubule-associated protein 1 light chain 3-I (LC3-I) to LC3-II. In addition, CLP shifted microglial polarization from M2 to M1 and the production of inflammatory cytokines, similar to the effects of lipopolysaccharide on BV2 microglia cells. Conversely, NFAT1 knockdown or the autophagy inhibitor 3-methyladenine attenuated the effects of CLP on autophagy and inflammation in vitro and in vivo, while rapamycin partially reversed the protective effects of NFAT1 inhibition. ConclusionThis study suggests that NFAT1 downregulation attenuates sepsis-induced behavioral deficits by inhibiting autophagy, microglia polarization, and neuroinflammation..