Anxiety-like Behavior Research Articles

Physiological and behavioral responses to social isolation and starvation in a social fish

Changes in the social environment, such as segregating an individual who would typically reside within a social group, may elicit physiological and behavioral responses to external stimulus such as starvation. However, such changes in phenotypic traits receive a little attention in social fish. Here, we used qingbo (Spinibarbus sinensis) with high level of sociability as animal model in order to examine the physiological and behavioral responses of this fish species to social environment (isolation vs. grouping) and nutritional state (well-fed vs. starvation). We found that differences in the reduction of body masses between the group-reared and the isolation-reared fish during periods of starvation can be partially attributed to variations in water volume within the tanks. Additionally, the decrease in standard metabolic rate was more pronounced in the group-reared fish compared to the isolation-reared fish when deprived of food, except for maximum metabolic rate and aerobic scope. Interestingly, only the group-reared fish experienced a decline in constant acceleration swimming performance after food deprivation, while this was not observed in the isolated fish. Neither social isolation nor starvation had any impact on personality expression (e.g., exploration, activity, and boldness). However, both exploration and boldness exhibited temporal effects with an increase in these two personality traits. Social isolation tended to elevate anxiety-like behavior levels. Both social isolation and starvation did not affect upper thermal tolerance; however, starvation enhanced cold resistance of the fish. Our findings contribute to a better understanding of how social environment combined with trophic stress influences phenotypic traits and may offer valuable insights into animal welfare considerations for both natural habitats and aquaculture practices.

Integrated multi-omics approaches reveal the neurotoxicity of triclocarban in mouse brain

Triclocarban (TCC) is an antimicrobial ingredient that commonly incorporated in many household and personal care products, raising public concerns about its potential health risks. Previous research has showed that TCC could cross the blood–brain barrier, but to date our understanding of its potential neurotoxicity at human-relevant concentrations remains lacking. In this study, we observed anxiety-like behaviors in mice with continuous percutaneous exposure to TCC. Subsequently, we combined lipidomic, proteomic, and metabolic landscapes to investigate the underlying mechanisms of TCC-related neurotoxicity. The results showed that TCC exposure dysregulated the proteins involved in endocytosis and neurodegenerative disorders in mouse cerebrum. Brain energy homeostasis was also altered, as evidenced by the perturbation of pyruvate metabolism, TCA cycle, and oxidative phosphorylation, which in turn caused mitochondrial dysfunction. Meanwhile, the changing trends of sphingolipid signaling pathway and overproduction of mitochondrial reactive oxygen species (mROS) could enhance the neural apoptosis. The in vitro approach further demonstrated that TCC exposure promoted apoptosis, accompanied by the overproduction of mROS and alteration in the mitochondrial membrane potential in N2A cells. Together, dysregulated endocytosis, mROS-related mitochondrial dysfunction and neural cell apoptosis are considered to be crucial factors for TCC-induced neurotoxicity, which may contribute to the occurrence and development of neurodegenerative disorders. Our findings provide novel perspectives for the mechanisms of TCC-triggered neurotoxicity.

Dynamic changes in seizure state and anxiety-like behaviors during pentylenetetrazole kindling in rats

IntroductionExcessive anxiety is a mental disorder, and its treatment involves the use of benzodiazepines, a class of drugs that enhance the effects of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABAA receptor. Anxiety disorders are frequent comorbidities in patients with epilepsy, and it has been speculated that anxiety disorders and epileptic seizures share common neurobiological mechanisms. However, conflicting results regarding anxiolytic and anxiogenic effects have been reported in animal models of epilepsy induced by pentylenetetrazole (PTZ) injections, and the causes of this discrepancy are unknown. We hypothesized that anxiety-like behaviors would change dynamically according to the changes in epilepsy susceptibility that occur during the PTZ kindling process. Therefore, we attempted to change anxiety-like behaviors bidirectionally depending on the number of PTZ injections. MethodsAdult male rats were injected with PTZ 20 times every other day, and stages of seizure onset were classified according to the Racine staging system. Anxiety-like behaviors were measured after 10 and 20 injections. The control group was injected with an equal volume of saline solution. Anxiety-like behaviors were investigated using the open-field, light/dark transition, elevated plus maze, and social interaction tests. ResultsBimodal changes in seizure stage were observed in response to PTZ kindling. The increase in the seizure stage was transiently suppressed after 10 injections, and this decrease in epileptic sensitivity disappeared after 20 injections. However, none of the rats reached a fully kindled state after 20 PTZ injections. After 10 PTZ injections, anxiety-like behaviors decreased compared with those of the control group in the open field, light/dark transition, and elevated plus-maze tests. The anxiolytic effects correlated with the seizure stage in individual rats. After 20 PTZ injections, anxiety-like behaviors returned to control levels. ConclusionPTZ kindling induced bimodal changes in the seizure stage. Anxiety-like behaviors decreased with transient decrease in epileptic sensitivity and returned to control levels with the disappearance of these states. These findings suggest a common neurobiological mechanism underlying anxiety disorders and epileptic seizures. In addition, the discrepancy in the previous studies, in which anxiety levels increase or decrease in PTZ-kindled animals, may be due to examination at different phases of the kindling process.

Chemogenetic inhibition of pain-related neurons in the posterior insula cortex reduces mechanical hyperalgesia and anxiety-like behavior during acute pain

Pain is a complex phenomenon that involves sensory, emotional, and cognitive components. The posterior insula cortex (pIC) has been shown to integrate multisensory experience with emotional and cognitive states. However, the involvement of the pIC in the regulation of affective behavior in pain remains unclear. Here, we investigate the role of pain-related pIC neurons in the regulation of anxiety-like behavior during acute pain. We combined a chemogenetic approach with targeted recombination in active populations (TRAP) in mice. Global chemogenetic inhibition of pIC neurons attenuates chemically-induced mechanical hypersensitivity without affecting pain-related anxiety-like behavior. In contrast, inhibition of pain-related pIC neurons reduces both mechanical hypersensitivity and pain-related anxiety-like behavior. The present study provides important insights into the role of pIC neurons in the regulation of sensory and affective pain-related behavior.

Insights into Vincristine-Induced Peripheral Neuropathy in Aged Rats: Wallerian Degeneration, Oxidative Damage, and Alterations in ATPase Enzymes.

This study aimed to elucidate vincristine (VCR)-induced peripheral neuropathy in aged rats, a poorly understood neurotoxicity. Both young and old Wistar rats were administered VCR (0.1 mg/kg, intraperitoneally (i.p.)) and compared to age-matched controls (0.9% saline; 10 mg/mL, i.p.). Mechanical (MN) and thermal nociceptive (TN) responses were assessed on days 0, 6, 11, and 17. Locomotor response, cognitive ability, and anxious-like behavior were evaluated on days 14, 15, and 16. Results showed MN and TN responses in both young and old VCR-exposed rats. In old rats, VCR exacerbated MN (on days 6, 11, and 17) and TN (on days 6 and 17) responses. VCR also induced cognitive impairments and anxiety-like behavior. Histological analysis revealed Wallerian degeneration in the spinal cords of VCR-exposed rats accompanied by macrophage migration. Furthermore, VCR increased Ca2+-ATPase activity while inhibiting Na+, K+-ATPase activity in young and old rats. VCR altered the homeostasis of Mg2+-ATPase activity. Lipid peroxidation and nitrite and nitrate levels increased in young and old rats exposed to VCR. This study provides valuable insights into VCR's mechanistic pathways in aged rats, emphasizing the need for further research in this area.

The posterior intralaminar thalamic nucleus promotes nose-to-nose contacts leading to prosocial reception in the sequence of mouse social interaction.

Efficient social interaction is essential for an adaptive life and consists of sequential processes of multisensory events with social counterparts. Social touch/contact is a unique component that promotes a sequence of social behaviours initiated by detection and approach to assess a social stimulus and subsequent touch/contact interaction to form prosocial relationships. We hypothesized that the thalamic sensory relay circuit from the posterior intralaminar nucleus of the thalamus (pIL) to the paraventricular nucleus of the hypothalamus (PVN) and the medial amygdala (MeA) plays a key role in the social contact-mediated sequence of events. We found that neurons in the pIL along with the PVN and MeA were activated by social encounters and that pIL activity was more abundant in a direct physical encounter, whereas MeA activity was dominant in an indirect through grid encounter. Chemogenetic inhibition of pIL neurons selectively decreased the investigatory approach and sniffing of a same-sex, but not an opposite-sex, stimulus mouse in an indirect encounter situation and decreased the facial/snout contact ratio in a direct encounter setting. Furthermore, chemogenetic pIL inhibition had no impact on anxiety-like behaviours or body coordinative motor behaviours, but it impaired whisker-related and plantar touch tactile sense. We propose that the pIL circuit can relay social tactile sensations and mediate the sequence of nonsexual prosocial interactions through an investigatory approach to tactile contact and thus plays a significant role in establishing prosocial relationships in mouse models.

Chinese acupuncture: A potential treatment for autism rat model via improving synaptic function

PurposeAutistic symptom improvement can be observed in children treated with acupuncture, but the mechanism is still being explored. In the present study, we used scalp acupuncture to treat autism rat model, and then their improvement in the abnormal behaviors and specific mechanisms behind were revealed by detecting animal behaviors, analyzing the RNA sequencing of the prefrontal cortex (PFC), and observing the ultrastructure of PFC neurons under the transmission electron microscope. MethodsOn gestational day 12.5, Wistar rats were given valproic acid (VPA) by intraperitoneal injection, and their offspring were considered to be reliable rat models of autism. They were randomized to VPA or VPA-acupuncture group (n = 8). Offspring of Wistar pregnant rats that were simultaneously injected with saline were randomly selected as the wild-type group (WT). VPA_acupuncture group rats received acupuncture intervention at 23 days of age for 4 weeks, and the other two groups followed without intervention. After the intervention, all experimental rats underwent behavioral tests. Immediately afterward, they were euthanized by cervical dislocation, and their prefrontal cortex was isolated for RNA sequencing and transmission electron microscopy. ResultsThe main results are as follows: 1. Animal behavioural tests: VPA group rats showed more anxiety-like behaviour and repetitive, stereotyped behaviour than WT group rats. While VPA group rats showed less spatial exploration ability, activity level, social interaction, and social novelty preference than WT group rats. It was gratifying to observe that acupuncture indeed improved these abnormal behaviors of autism rat model. 2. RNA-sequencing: The three groups of rats differed in the expression and enrichment pathways of multiple genes related to synaptic function, neural signal transduction, immune-inflammatory responses and circadian rhythm regulation. Our experiments indicated that acupuncture can alleviate the major symptoms of ASD by improving these neurological abnormalities. 3. Under the transmission electron microscopy, several lysosomes and mitochondrial structural abnormalities were observed in the prefrontal neurons of VPA group rats, which were manifested as atrophy of the mitochondrial membrane, blurring or disappearance of the mitochondrial cristae, and even vacuolization. Moreover, the number of synapses and synaptic vesicles was relatively small. Conversely, the mitochondrial structure of rats in the WT group and VPA_acupuncture was normal, and the number of synapses and synaptic vesicles was relatively large. ConclusionAcupuncture effectively improved the abnormal behaviors of autism rat model and the ultrastructure of the PFC neurons, which might worked by improving their abnormal synaptic function, synaptic plasticity promoting neuronal signal transduction and regulating immune-inflammatory responses.

LT-102, an AMPA receptor potentiator, alleviates depression-like behavior and synaptic plasticity impairments in prefrontal cortex induced by sleep deprivation

BackgroundSleep loss is closely related to the onset and development of depression, and the mechanisms involved may include impaired synaptic plasticity. Considering the important role of glutamate α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate receptors (AMPARs) in synaptic plasticity as well as depression, we introduce LT-102, a novel AMPARs potentiator, to evaluate the potential of LT-102 in treating sleep deprivation-induced depression-like behaviors. MethodsWe conducted a comprehensive behavioral assessment to evaluate the effects of LT-102 on depression-like symptoms in male C57BL/6J mice. This assessment included the open field test to measure general locomotor activity and anxiety-like behavior, the forced swimming test and tail suspension test to assess despair behaviors indicative of depressive states, and the sucrose preference test to quantify anhedonia, a core symptom of depression. Furthermore, to explore the impact of LT-102 on synaptic plasticity, we utilized a combination of Western blot analysis to detect protein expression levels, Golgi-Cox staining to visualize neuronal morphology, and immunofluorescence to examine the localization of synaptic proteins. Additionally, we utilized primary cortical neurons to delineate the signaling pathway modulated by LT-102. ResultsTreatment with LT-102 significantly reduced depression-like behaviors associated with sleep deprivation. Quantitative Western blot (WB) analysis revealed a significant increase in GluA1 phosphorylation in the prefrontal cortex (PFC), triggering the Ca2+/calmodulin-dependent protein kinase II/cAMP response element-binding protein/brain-derived neurotrophic factor (CaMKII/CREB/BDNF) and forkhead box protein P2/postsynaptic density protein 95 (FoxP2/PSD95) signaling pathways. Immunofluorescence imaging confirmed that LT-102 treatment increased spine density and co-labeling of PSD95 and vesicular glutamate transporter 1 (VGLUT1) in the PFC, reversing the reductions typically observed following sleep deprivation. Golgi staining further validated these results, showing a substantial increase in neuronal dendritic spine density in sleep-deprived mice treated with LT-102. Mechanistically, application of LT-102 to primary cortical neurons, resulted in elevated levels of phosphorylated AKT (p-AKT) and phosphorylated glycogen synthase kinase-3 beta (p-GSK3β), key downstream molecules in the BDNF signaling pathway, which in turn upregulated FoxP2 and PSD95 expression. LimitationsIn our study, we chose to exclusively use male mice to eliminate potential influences of the estrous cycle on behavior and physiology. As there is no widely accepted positive drug control for sleep deprivation studies, we did not include one in our research. ConclusionOur results suggest that LT-102 is a promising therapeutic agent for counteracting depression-like behaviors and synaptic plasticity deficits induced by sleep deprivation, primarily through the activation of CaMKII/CREB/BDNF and AKT/GSK3β/FoxP2/PSD95 signaling pathways.

Jabuticaba (Myrciaria trunciflora) extract improves metabolic and behavioral markers of obese rats fed on a hypercaloric diet.

Obesity is a metabolic disease that affects many individuals around the world, related to imbalance between energy consumption and expenditure, which can lead to comorbidities. A healthy diet can significantly contribute to the prevention or treatment of this condition. Jabuticaba is an emerging fruit presenting a wide range of bioactive compounds and is being extensively studied due to its effects on lipid metabolism. The aim of this study was to evaluate the jabuticaba extract in the anxious-like behavior and in the lipid and oxidative metabolism in the context of obesity. Forty male Wistar rats divided into five groups were used. The animals received a standard diet and/or a hypercaloric diet and after 60 days of induction, interventions were carried out with jabuticaba extract (5% and 10%) via gavage for 30 days. It can be observed that the jabuticaba extract was able to reverse the anxious behavior observed in obese animals and modulate parameters of lipid and oxidative metabolism. We observed a reduction in cholesterol and triglyceride levels compared to obese animals. Furthermore, we observed an improvement in oxidative parameters, with a reduction in protein carbonylation in the liver and modulation of antioxidant enzymes such as superoxide dismutase and catalase. Contrary to expectations, we did not observe changes in leptin, adiponectin and tumor necrosis factor alpha (TNF-α) levels. Our work demonstrates that jabuticaba extract can improve metabolic, oxidative and behavioral changes in animals with obesity. © 2024 Society of Chemical Industry.

Neuritin Controls Axonal Branching in Serotonin Neurons: A Possible Mediator Involved in the Regulation of Depressive and Anxiety Behaviors via FGF Signaling.

Abnormal neuronal morphological features, such as dendrite branching, axonal branching, and spine density, are thought to contribute to the symptoms of depression and anxiety. However, the role and molecular mechanisms of aberrant neuronal morphology in the regulation of mood disorders remain poorly characterized. Here, we show that neuritin, an activity-dependent protein, regulates the axonal morphology of serotonin neurons. Male neuritin knock-out (KO) mice harbored impaired axonal branches of serotonin neurons in the medial prefrontal cortex and basolateral region of the amygdala (BLA), and male neuritin KO mice exhibited depressive and anxiety-like behaviors. We also observed that the expression of neuritin was decreased by unpredictable chronic stress in the male mouse brain and that decreased expression of neuritin was associated with reduced axonal branching of serotonin neurons in the brain and with depressive and anxiety behaviors in mice. Furthermore, the stress-mediated impairments in axonal branching and depressive behaviors were reversed by the overexpression of neuritin in the BLA. The ability of neuritin to increase axonal branching in serotonin neurons involves fibroblast growth factor (FGF) signaling, and neuritin contributes to FGF-2-mediated axonal branching regulation in vitro. Finally, the oral administration of an FGF inhibitor reduced the axonal branching of serotonin neurons in the brain and caused depressive and anxiety behaviors in male mice. Our results support the involvement of neuritin in models of stress-induced depression and suggest that neuronal morphological plasticity may play a role in controlling animal behavior.

Chronic corticosterone administration alters synaptic mitochondrial function within the hippocampus of C57Bl/6NTac mice

Chronic activation of the hypothalamic-pituitary-adrenal axis increases circulating corticosterone levels, causing a host of downstream behavioral, molecular, and metabolic changes. Here, we assess the effects of chronic exogenous CORT administration on changes in behavior and mitochondrial respiration in hippocampal synaptosomes of male and female mice. Adult male (n = 15) and female (n = 17) C57Bl/6NTac mice were given 35ug/mL CORT or vehicle dissolved in their drinking water for 21 consecutive days. Chronic CORT increased piloerection in males only. Although volume of CORT-containing water consumed was similar between males and females, circulating plasma and fecal corticosterone levels were only elevated in CORT-exposed males. Behavioral effects of CORT were evident in the Y-maze such that CORT caused a decrease in direct revisits in both sexes. There was no observed presentation of anxiety-like behavior following chronic CORT administration. Functional hippocampal synaptosomes were analyzed for mitochondrial respiration using Agilent's Cell Mito Stress test. Chronic CORT caused a decrease in synaptic mitochondria basal respiration, maximal respiration, proton leak, and ATP production in both sexes. Despite only observing an effect of chronic CORT on corticosterone concentrations in fecal and blood samples of males, chronic CORT induced marked changes in hippocampal synaptic mitochondrial function of both sexes. These data highlight the importance of considering effects of stress hormone exposure on neural function even in the absence of measurable peripheral elevations in females.

Glucocorticoid alleviates hypothalamic nerve injury via remodeling HPA axis homeostasis in stressed rats

Excessive stress can exceed the adjustment ability of body and cause injury and dysfunction, while elucidation of the mechanism and prevention measures of stress-related injury are still insufficient. The present study was to observe the effect of glucocorticoid (GC) on stress-induced hypothalamic nerve injury and elucidate the potential mechanism. The present study intended to establish a chronic restraint stress rat model for follow-up study. Open field test and elevated plus maze test were used to observe behavioral changes of stress rats; Enzyme-linked immunosorbent assay (ELISA) was used to detect changes in the levels of hypothalamus-pituitary-adrenal (HPA) axis-related hormones and inflammatory factors in hypothalamus; toluidine blue staining was used to observe pathological changes of hypothalamus. The results showed that stress rats showed obvious anxiety-like behaviors, the levels of HPA axis-related hormones and inflammatory factors showed abnormal fluctuations, and morphological results showed significant nerve injury in hypothalamus. Low-dose GC treatment significantly improved behavioral changes, alleviated hypothalamic nerve injury, and restored hypothalamic levels of inflammatory factors, serum levels of GC, corticotropin-releasing hormone (CRH), and adrenocorticotropic hormone (ACTH) and GC level in adrenal cortex of stressed rats, while GC receptor (GR) inhibitor, CRH receptor inhibitor, and adrenalectomy reversed the ameliorative effects of low-dose GC. Our study clarified that low-dose GC can restore stress coping ability by reshaping the homeostasis of the HPA axis, thus alleviating behavioral abnormalities and hypothalamic nerve injury in stressed rats.

The Involvement of the Ventral Tegmental Area in the Electroacupuncture Alleviation of Anxiety-Like Behaviors Induced by Chronic Restraint Stress in Mice.

Emotional stress is a significant environmental risk factor for various mental health disabilities, such as anxiety. Electroacupuncture (EA) has been demonstrated to have pronounced anxiolytic effects. However, the neural mechanisms underlying these effects and their contribution to behavioral deficits remain poorly understood. Here, we addressed these issues using a classical mouse anxiety model induced by chronic restraint stress (CRS).Anxiety-like behaviors were evaluated with the open field test and elevated plus maze. Neuronal activation in various brain regions was marked using c-Fos, followed by calculations of interregional correlation to characterize a network that became functionally active following EA at the HT7 acupoint (EA-HT7). We selected the hub regions and further investigated their functions and connections in regulating anxiety-like behaviors by using a combination of chemogenetic manipulations and behavioral testing. CRS exposure induced anxiety-like behaviors. Interestingly, EA-HT7 mitigated these behavioral abnormalities. The c-Fos expression in 30 brain areas revealed a vital brain network for acupuncture responsiveness in naïve mice. Neural activity in the NAcSh (nucleus accumbens shell), BNST (bed nucleus of the stria terminalis), VMH (Ventromedial Hypothalamus), ARC (arcuate nucleus), dDG (dorsal dentate gyrus), and VTA (ventral tegmental area) was significantly altered following acupuncture. Notably, both c-Fos immunostaining and brain functional connectivity analysis revealed the significant activation of VTA following EA-HT7. Interestingly, blocking the VTA eliminated the anxiolytic effects of EA-HT7, whereas chemogenetic activation of the VTA replicated the therapeutic effects of EA-HT7. EA-HT7 has demonstrated benefits in treating anxiety and enhances brain functional connectivity. The VTA is functionally associated with the anxiolytic effects of EA-HT7.

Knockout of AMPA receptor binding protein Neuron-Specific Gene 2 (NSG2) enhances associative learning and cognitive flexibility.

The vast majority of gene mutations and/or gene knockouts result in either no observable changes, or significant deficits in molecular, cellular, or organismal function. However, in a small number of cases, mutant animal models display enhancements in specific behaviors such as learning and memory. To date, most gene deletions shown to enhance cognitive ability generally affect a limited number of pathways such as NMDA receptor- and translation-dependent plasticity, or GABA receptor- and potassium channel-mediated inhibition. While endolysosomal trafficking of AMPA receptors is a critical mediator of synaptic plasticity, mutations in genes that affect AMPAR trafficking either have no effect or are deleterious for synaptic plasticity, learning and memory. NSG2 is one of the three-member family of Neuron-specific genes (NSG1-3), which have been shown to regulate endolysosomal trafficking of a number of proteins critical for neuronal function, including AMPAR subunits (GluA1-2). Based on these findings and the largely universal expression throughout mammalian brain, we predicted that genetic knockout of NSG2 would result in significant impairments across multiple behavioral modalities including motor, affective, and learning/memory paradigms. However, in the current study we show that loss of NSG2 had highly selective effects on associative learning and memory, leaving motor and affective behaviors intact. For instance, NSG2 KO animals performed equivalent to wild-type C57Bl/6n mice on rotarod and Catwalk motor tasks, and did not display alterations in anxiety-like behavior on open field and elevated zero maze tasks. However, NSG2 KO animals demonstrated enhanced recall in the Morris water maze, accelerated reversal learning in a touch-screen task, and accelerated acquisition and enhanced recall on a Trace Fear Conditioning task. Together, these data point to a specific involvement of NSG2 on multiple types of associative learning, and expand the repertoire of pathways that can be targeted for cognitive enhancement.

Chronic social isolation leads to abnormal behavior in male mice through the hippocampal METTL14 mediated epitranscriptomic RNA m6A modifications

BackgroundSocial isolation not only increases the risk of mortality in later life but also causes depressive symptoms, cognitive and physical disabilities. Although RNA m6A modifications are suggested to play key roles in brain development, neuronal signaling and neurological disorders, both the roles of m6A and the enzymes that regulate RNA m6A modification in social isolation induced abnormal behavior is unknown. The present study aims to explore the possible epitranscriptomic role of RNA m6A modifications and its enzymes in social isolation induced impaired behavior. Methods3–4 weeks mice experiencing 8 weeks social isolation stress (SI) were used in the present study. We quantified m6A levels in brain regions related to mood and cognitive behavior. And the expression of hippocampal m6A enzymes was also determined. The role of hippocampal m6A and its enzymes in SI induced abnormal behavior was further verified by the virus tool. ResultsSI led to not only depressive and anxiety-like behaviors but also cognitive impairment, with corresponding decreases in hippocampal m6A and METTL14. Hippocampal over-expression METTL14 with lentivirus not only rescued these behaviors but also enhanced the hippocampal m6A level. Hippocampal over-expression METTL14 resulted in increased synaptic related genes. ConclusionsWe provide the first evidence that post-weaning social isolation reduces hippocampal m6A level and causes altered expression of m6A enzyme in mice. Importantly, hippocampal METTL14 over-expression alleviated the SI-induced depression/anxiety-like and impaired cognitive behaviors and enhanced m6A level and synaptic related genes expression.

The role of thyroid hormone receptor A1 (TRA1) signaling in parvalbumin-expressing interneurons in the central regulation of the cardiovascular system and anxiety-like behavior

The role of thyroid hormone receptor A1 (TRA1) signaling in parvalbumin-expressing interneurons in the central regulation of the cardiovascular system and anxiety-like behavior

Gut microbiota mediates anxiety-like behaviors induced by chronic infection of Toxoplasma gondii in mice

ABSTRACT Background Chronic infection with the neurotropic parasite Toxoplasma gondii (T. gondii) can cause anxiety and gut microbiota dysbiosis in hosts. However, the potential role of gut microbiota in anxiety induced by the parasite remains unclear. Methods C57BL/6J mice were infected with 10 cysts of T. gondii. Antibiotic depletion of gut microbiota and fecal microbiota transplantation experiments were utilized to investigate the causal relationship between gut microbiota and anxiety. Anxiety-like behaviors were examined by the elevated plus maze test and the open field test; blood, feces, colon and amygdala were collected to evaluate the profiles of serum endotoxin (Lipopolysaccharide, LPS) and serotonin (5-hydroxytryptamine, 5-HT), gut microbiota composition, metabolomics, global transcriptome and neuroinflammation in the amygdala. Furthermore, the effects of Diethyl butylmalonate (DBM, an inhibitor of mitochondrial succinate transporter, which causes the accumulation of endogenous succinate) on the disorders of the gut-brain axis were evaluated. Results Here, we found that T. gondii chronic infection induced anxiety-like behaviors and disturbed the composition of the gut microbiota in mice. In the amygdala, T. gondii infection triggered the microglial activation and neuroinflammation. In the colon, T. gondii infection caused the intestinal dyshomeostasis including elevated colonic inflammation, enhanced bacterial endotoxin translocation to blood and compromised intestinal barrier. In the serum, T. gondii infection increased the LPS levels and decreased the 5-HT levels. Interestingly, antibiotics ablation of gut microbiota alleviated the anxiety-like behaviors induced by T. gondii infection. More importantly, transplantation of the fecal microbiota from T. gondii-infected mice resulted in anxiety and the transcriptomic alteration in the amygdala of the antibiotic-pretreated mice. Notably, the decreased abundance of succinate-producing bacteria and the decreased production of succinate were observed in the feces of the T. gondii-infected mice. Moreover, DBM administration ameliorated the anxiety and gut barrier impairment induced by T. gondii infection. Conclusions The present study uncovers a novel role of gut microbiota in mediating the anxiety-like behaviors induced by chronic T. gondii infection. Moreover, we show that DBM supplementation has a beneficial effect on anxiety. Overall, these findings provide new insights into the treatment of T. gondii-related mental disorders.

Effects of DNA Methylation of HPA-Axis Genes of F1 Juvenile Induced by Maternal Density Stress on Behavior and Immune Traits in Root Voles (Microtus oeconomus)-A Field Experiment.

The literature shows that maternal stress can influence behavior and immune function in F1. Yet, most studies on these are from the laboratory, and replicated studies on the mechanisms by which maternal stress drives individual characteristics are still not fully understood in wild animals. We manipulated high- and low-density parental population density using large-scale field enclosures and examined behavior and immune traits. Within the field enclosures, we assessed anti-keyhole limpet hemocyanin immunoglobulin G (anti-KLH IgG) level, phytohemagglutinin (PHA) responses, hematology, cytokines, the depressive and anxiety-like behaviors and prevalence and intensity of coccidial infection. We then collected brain tissue from juvenile voles born at high or low density, quantified mRNA and protein expression of corticotropin-releasing hormone (CRH) and glucocorticoid receptor gene (NR3C1) and measured DNA methylation at CpG sites in a region that was highly conserved with the prairie vole CRH and NR3C1 promoter. At high density, we found that the F1 had a lower DNA methylation level of CRH and a higher DNA methylation level of NR3C1, which resulted in an increase in the expression levels of the CRH mRNA and protein expression and further reduced the expression levels of the NR3C1 mRNA and protein expression, and ultimately led to have delayed responses to acute immobilization stress. Juvenile voles born at high density also reduced anti-KLH IgG levels and PHA responses, increased cytokines, and depressive and anxiety-like behaviors, and the effects further led to higher coccidial infection. From the perspective of population density inducing the changes in behavior and immunity at the brain level, our results showed a physiological epigenetic mechanism for population self-regulation in voles. Our results indicate that altering the prenatal intrinsic stress environment can fundamentally impact behavior and immunity by DNA methylation of HPA-axis genes and can further drive population fluctuations in wild animals.

Electroacupuncture alleviates neuropathic pain by regulating hippocampal SP/NK1R/ARRB1 pathway.

To observe the effect of electroacupuncture (EA) on pain, anxiety like behavior, and substance P(SP) /neurokinin-1 receptor (NK1R) /β -arrestin 1(ARRB1) pathway related protein expression in hippocampus of chronic constriction injury (CCI) rats, so as to explore its mechanisms underlying improvement of neuropathic pain. Twenty-seven male SD rats were randomly divided into sham operation, model and EA groups, with 9 rats in each group. The CCI model was established by ligature of the left sciatic nerve. On the 8th day following modeling, EA (2 Hz, 0.5-1.5 mA) was applied to the left "Huantiao" (GB34) and "Yanglingquan" (GB34) for 30 min, once every other day for 13 times. Mechanical paw withdrawal threshold (MWT), thermal paw withdrawal threshold (TWL) and difference of the weight distribution of the hind limbs were detected before operation and at the 5th, 9th, 17th, 25th and 33rd days after operation. Open field test was used to evaluate the anxiety-like behavior of rats. The content of SP in hippocampus was determined by ELISA. The protein expression of NK1R and ARRB1 in hippocampus was detected by Western blot. Compared with the sham operation group, the MWT and TWL of the left hind limb at the 5th, 9th, 17th, 25th and 33rd days after operation, the time of entering the central area and the total distance of movement, and the content of SP in the hippocampus were significantly decreased (P<0.001, P<0.01), while the difference of the weight distribution of the hind limbs at the 5th, 9th, 17th, 25th and 33rd days after operation and the protein expression of NK1R and ARRB1 were significantly increased (P<0.001, P<0.05) in the model group. After EA intervention, the MWT and TWL of the left hind limb, the time of entering the central area and the total moving distance, and the expression of SP in the hippocampus were significantly increased (P<0.01, P<0.001, P<0.05), while the difference in the weight distribution of the hind limbs was significantly reduced, and the expression of NK1R and ARRB1 protein in the hippocampus were significantly decreased (P<0.001, P<0.05) in the EA group. EA can effectively improve the pain and anxiety behaviors in CCI rats, and reverse the abnormal expression of SP, NK1R and ARRB1 proteins in the hippocampus, which may be related to its effects in regulating the SP/NK1R/ARRB1 pathway in the hippocampus.

Specific Activation of Dopamine Receptor D1 Expressing Neurons in the PrL Alleviates CSDS-Induced Anxiety-Like Behavior Comorbidity with Postoperative Hyperalgesia in Male Mice.

Postoperative pain is a type of pain that occurs in clinical patients after surgery. Among the factors influencing the transition from acute postoperative pain to chronic postoperative pain, chronic stress has received much attention in recent years. Here, we investigated the role of dopamine receptor D1/D2 expressing pyramidal neurons in the prelimbic cortex (PrL) in modulating chronic social defeat stress (CSDS)-induced anxiety-like behavior comorbidity with postoperative hyperalgesia in male mice. Our results showed that preoperative CSDS induced anxiety-like behavior and significantly prolonged postoperative pain caused by plantar incision, but did not affect plantar wound recovery and inflammation. Reduced activation of dopamine receptor D1 or D2 expressing neurons in the PrL is a remarkable feature of male mice after CSDS, and chronic inhibition of dopamine receptor D1 or D2 expressing neurons in the PrL induced anxiety-like behavior and persistent postoperative pain. Further studies found that activation of D1 expressing but not D2 expressing neurons in the PrL ameliorated CSDS-induced anxiety-like behavior and postoperative hyperalgesia. Our results suggest that dopamine receptor D1 expressing neurons in the PrL play a crucial role in CSDS-induced anxiety-like behavior comorbidity with postoperative hyperalgesia in male mice.