Depression-like Behavior In Mice Research Articles

Ketamine attenuates kidney damage and depression-like behaviors in mice with cisplatin-induced acute kidney injury

Acute kidney injury (AKI) is a serious condition characterized by decreased urine output, often accompanied by psychiatric symptoms like depression. However, there are limited pharmacological treatments available for AKI and its associated depressive symptoms. In this study, we investigated whether cisplatin-induced AKI in mice leads to depression-like behaviors and whether ketamine could alleviate both the kidney injury and these behaviors. Mice with cisplatin-induced AKI exhibited elevated levels of creatinine and urea, kidney damage, increased kidney injury molecule-1 protein, and pathological changes in the liver, colon, and spleen. They also showed depression-like behaviors and reduced expression of synaptic proteins in the prefrontal cortex. Remarkably, a single dose of ketamine significantly reduced these symptoms and pathological changes. Interestingly, the beneficial effects of ketamine on the kidneys, other organs, and depression-like behaviors, were reversed by the tropomyosin receptor kinase B (TrkB) inhibitor ANA-12. Western blot analysis revealed the involvement of the TrkB and ERK (extracellular signal-regulated kinase)-CREB (cAMP response element binding protein) signaling pathway. Additionally, metabolomics analysis indicated that blood metabolites, such as C16-ceramide, may contribute to the effects of ketamine in this model. These findings suggest that cisplatin-induced nephrotoxicity in AKI mice contributes to depression-like behaviors, and ketamine can alleviate both kidney damage and depression-like symptoms by modulating the TrkB and ERK-CREB signaling pathways, as well as altering blood metabolites. However, the role of the kidney-brain axis in these depression-like behaviors remains unclear. Furthermore, ketamine may have therapeutic potential for treating kidney diseases such as AKI, along with associated depressive symptoms.

Luteolin ameliorates chronic stress-induced depressive-like behaviors in mice by promoting the Arginase-1+ microglial phenotype via a PPARγ-dependent mechanism.

Accumulating evidence shows that neuroinflammation substantially contributes to the pathology of depression, a severe psychiatric disease with an increasing prevalence worldwide. Although modulating microglial phenotypes is recognized as a promising therapeutic strategy, effective treatments are still lacking. Previous studies have shown that luteolin (LUT) has anti-inflammatory effects and confers benefits on chronic stress-induced depression. In this study, we investigated the molecular mechanisms by which LUT regulates the functional phenotypes of microglia in mice with depressive-like behaviors. Mice were exposed to chronic restraint stress (CRS) for 7 weeks, and were administered LUT (10, 30, 40 mg· kg-1 ·day-1, i.g.) in the last 4 weeks. We showed that LUT administration significantly ameliorated depressive-like behaviors and decreased hippocampal inflammation. LUT administration induced pro-inflammatory microglia to undergo anti-inflammatory arginase (Arg)-1+ phenotypic polarization, which was associated with its antidepressant effects. Furthermore, we showed that LUT concentration-dependently increased the expression of PPARγ in LPS + ATP-treated microglia and the hippocampus of CRS-exposed mice, promoting the subsequent inhibition of the NLRP3 inflammasome. Molecular dynamics (MD) simulation and microscale thermophoresis (MST) analysis confirmed a direct interaction between LUT and peroxisome proliferator-activated receptor gamma (PPARγ). By using the PPARγ antagonist GW9662, we demonstrated that LUT-driven protection, both in vivo and in vitro, resulted from targeting PPARγ. First, LUT-induced Arg-1+ microglia were no longer detected when PPARγ was blocked. Next, LUT-mediated inhibition of the NLRP3 inflammasome and downregulation of pro-inflammatory cytokine production were reversed by the inhibition of PPARγ. Finally, the protective effects of LUT, which attenuated the microglial engulfment of synapses and prevented apparent synapse loss in the hippocampus of CRS-exposed mice, were eliminated by blocking PPARγ. In conclusion, this study showed that LUT ameliorates CRS-induced depressive-like behaviors by promoting the Arg-1+ microglial phenotype through a PPARγ-dependent mechanism, thereby alleviating microglial pro-inflammatory responses and reversing microglial phagocytosis-mediated synapse loss.

Study on the Mechanism of Dictyophora duplicata Polysaccharide in Reducing Depression-like Behavior in Mice

Background/Objectives: Depression is a prevalent worldwide mental health disorder that inflicts significant harm to individuals and society. Dictyophora duplicata is an edible fungus that contains a variety of nutrients, including polysaccharides. This study aims to investigate the monosaccharide composition and molecular weight of the Dictyophora duplicata polysaccharide (DDP-B1), followed by an exploration of its antidepressant effects in chronic unpredictable mild stress (CUMS) mice. Methods: Dictyophora duplicata was purified using a DEAE-52 column and an S-400 column to obtain DDP-B1. The monosaccharide composition and molecular weight of DDP-B1 were investigated via high-performance gel permeation chromatograph. Six-week-old C57BL/6 male mice were utilized for the CUMS modeling to evaluate the antidepressant efficacy of DDP-B1. Fluoxetine served as the positive control group. The depressive-like behaviors and brain pathology of mice were evaluated. Immunofluorescence (IF) staining, metabolomics analysis, and western blot were employed to further investigate the underlying mechanisms. Results: DDP-B1 significantly alleviated the depression-like behavior of CUMS mice and increased the expression of SYN and PSD-95 in the mice’s brains, which was further validated by western blot. Metabolomics analysis indicated a reduction in serum glutamate in CUMS mice following DDP-B1 treatment. Moreover, DDP-B1 treatment led to an increase in levels of GABAAR, BDNF, p-TrkB and p-p70S6K. Conclusions: DDP-B1 regulated abnormalities in the glutamatergic system, subsequently activated the BDNF-TrkB-mTOR pathway and mitigated the pathological manifestations of CUMS mice. This study validated the potential of DDP-B1 as an antidepressant medication and established a theoretical foundation for the development of fungi with similar properties.

Xylopia parviflora (A. rich.) benth. Mitigates anxiety behavior and chronic mild stress-induced depression-like behavior in mice: The involvement of biogenic amine neurotransmitters, cyclooxygenase-2 and stress biomarkers in its antidepressant activity

BackgroundXylopia parviflora is a novel botanical in Modern Chinese Medicine that contains bioactive constituents including alkaloids, flavonoids, and terpenoids, which are the pharmacologically active components in various Chinese herbal formulations such as Coptis chinensis (alkaloid-rich herbs), Ginkgo biloba (flavonoid-rich herbs) and Artemisia annua (terpenoid-rich herbs). ObjectiveThis investigation sought to evaluate the anxiolytic and antidepressant-like effects of the hydroethanol leaf extract of Xylopia parviflora using mouse models. We elucidated the roles of noradrenaline, serotonin, cyclooxygenase-2, and reactive oxidative species in mediating its antidepressant effects, providing a fresh perspective on the pharmacological activity of Xylopia parviflora. MethodsThe acute toxicity of XPE was assessed following OECD guideline 420. Established behavioral tests were used to evaluate the anxiolytic (including the hole-board, open field, elevated plus maze, and light/dark exploration assessments) and antidepressant (encompassing the forced swim and tail suspension tests) effects of the extract. Mice received treatments of distilled water (10 mL/kg, serving as the negative control), fluoxetine (20 mg/kg, acting as the reference medication), and XPE (at doses of 50, 100, and 200 mg/kg). The concentrations of noradrenaline, serotonin, and COX-2 within the brain tissue were quantified using ELISA kits. The levels of antioxidant biomarkers were evaluated using standardized commercial assay kits. ResultsThe oral/intraperitoneal LD50 for the extract was established at 2000 mg/kg. In the behavioral assessments designed to measure anxiolytic effects, XPE significantly mitigated anxiety levels in mice, as evidenced by an increase in exploratory behaviors (including head dips, sectional crossings, general square crossings, rearing, and assisted rearing) and an increased time spent in the brightly illuminated compartments. Concerning the antidepressant evaluations, XPE significantly reduced depression-like behaviors in mice, which was indicated by an increased latency to immobility and a decrease in the duration of immobility. XPE was found to modulate noradrenaline and serotonin transmissions, attenuate oxidative species, and inhibit COX-2 activity. ConclusionThe findings above demonstrate that Xylopia parviflora possesses anxiolytic and antidepressant-like activities. The antidepressant property of XPE, as revealed in this study, may be attributable to the enhancement of biogenic amines (specifically noradrenaline and serotonin), the suppression of oxidative species, and the inhibition of COX-2 activity.

Taurine Reverses Arsenic-Induced Inhibition of Hippocampal Neurogenesis and Depression-Like Behavior in Mice.

Arsenic exposure results in damage to the neurological system. We previously demonstrated the arsenic-induced inhibition of hippocampal neurogenesis and its reversibility after exposure is terminated. The present study aimed to reveal whether arsenic-induced inhibition of hippocampal neurogenesis was ameliorated when taurine was co-administered, and we also investigated depression-like behavioral changes using the forced swim test. Mice were randomly divided into four groups. The first group received distilled water only for 4 months (control group), the second group received 4.0 mg/L As2O3 via drinking water for 4 months (arsenic group), the third group received 4.0 mg/L As2O3 and taurine (150 mg/kg body weight, by gavage, twice a week) for 4 months (arsenic + taurine group), and the fourth group received taurine only by gavage for 4 months (taurine group). The percentage of new mature neurons decreased in the arsenic group compared with the control group (64% ± 0.90% vs. 76% ± 1.9%, p < 0.01); however, this percentage was reversed to control levels in the arsenic + taurine group (76% ± 1.4%, p > 0.05). In the forced swim test, the immobility time during the last 4 min was significantly increased in the arsenic group, but restored to control levels in the arsenic + taurine group. The possible mechanisms of this taurine amelioration of hippocampal damage were further investigated, and included a reduction in oxidative stress as indicated by carbonyl content, inflammation, and aquaporin1, 4, and 8 expressions, as well as an increase in Wnt3a and brain-derived neurotrophic factor expression in western blot analyses.

Effect of Voluntary Wheel Running on Anxiety- and Depression-Like Behaviors in Fluoride-Exposed Mice.

Fluoride, an environmental toxicant, could induce endoplasmic reticulum stress (ERS) in neuronal cells ultimately leading to apoptosis and emotional dysfunction. Meanwhile, voluntary wheel running contributes to mitigate anxiety and depression. Our investigation aimed to study the effect of voluntary wheel running on anxiety- and depression-like behaviors in fluoride-exposure mice. The results showed that exposure to 100 mg/L sodium fluoride (NaF) for 6 months can induce anxiety- and depression-like behavior in mice. Fluorosis mice subjected to voluntary wheel running have less anxiety- and depression-like behaviors. Nissl and TUNEL staining demonstrated that fluoride led to a reduced proportion of Nissl body area in the cerebral cortex and an increased apoptotic ratio of nerve cells in the cerebral cortex. In contrast, these pathologic damages were improved in voluntary wheel running mice exposed to NaF. Moreover, the expressions of mRNA in the cerebral cortex GABA, GAD65, GAD67, DR, vGLU, 5-HT1A, BDNF, NMDAR1, and Bcl2 were downregulated and the levels of c-fos, GRP78, PERK, eIF2α, CHOP, Caspase-12, and Caspase-3 mRNA were upregulated in mice exposed to fluoride. NaF treatment had increased the PERK, ATF6, IRE1, p-eIF2α, and Caspase-3 protein levels and reduced the expressions of proteins, including GAD67, VGAT, BDNF, NMDAR1, PSD95, and SYN. By contrast, fluorosis mice subjected to voluntary wheel running enhanced the expression of GAD65, GAD67, VGAT, and neuroplasticity-related proteins in mice and inhibited the PERK-CHOP pathway. It is worth noting that the correlation between the amount of exercise and the behavioral indicators as well as neurotransmitter levels was found. In conclusion, voluntary wheel running inhibits the fluoride-induced ERS and GRP78 expression through the PERK-CHOP pathway and plays an anti-apoptotic role, ultimately ameliorating emotional dysfunction in NaF-exposed mice.

Inhibition of Glycolysis Alleviates Chronic Unpredictable Mild Stress-Induced Neuroinflammation and Depression-like Behavior

Background: Growing evidence suggests that glucose metabolism plays a crucial role in activated immune cells, significantly contributing to the occurrence and development of neuroinflammation and depression-like behaviors. Chronic stress has been reported to induce microglia activation and disturbances in glucose metabolism in the hippocampus. Aims: This study aims to investigate how chronic stress-mediated glycolysis promotes neuroinflammation and to assess the therapeutic potential of the glycolysis inhibitor, 2-deoxy-D-glucose (2-DG), in a model of chronic stress-induced neuroinflammation and depression-like behavior. Methods: In in vitro studies, we first explored the effects of 2-DG on the inflammatory response of microglia cells. The results showed that corticosterone (Cort) induced reactive oxygen species (ROS) production, increased glycolysis, and promoted the release of inflammatory mediators. However, these effects were reversed by intervention with 2-DG. Subsequently, we examined changes in depression-like behavior and hippocampal glycolysis in mice during chronic stress. The results indicated that chronic stress led to prolonged escape latency in the Morris water maze, increased platform-crossing frequency, reduced sucrose preference index, and extended immobility time in the forced swim test, all of which are indicative of depression-like behavior in mice. Additionally, we found that the expression of the key glycolytic enzyme hexokinase 2 (HK2) was upregulated in the hippocampus of stressed mice, along with an increased release of inflammatory factors. Further in vivo experiments investigated the effects of 2-DG on glycolysis and pro-inflammatory mediator production, as well as the therapeutic effects of 2-DG on chronic stress-induced depression-like behavior in mice. The results showed that 2-DG alleviated chronic stress-induced depression-like behaviors, such as improving escape latency and platform-crossing frequency in the Morris water maze, and increasing the time spent in the center of the open field. Additionally, 2-DG intervention reduced the level of glycolysis in the hippocampus and decreased the release of pro-inflammatory mediators. Conclusions: These findings suggest that 2-DG can mitigate neuroinflammation and depressive behaviors by inhibiting glycolysis and inflammatory responses. Overall, our results highlight the potential of 2-DG as a therapeutic agent for alleviating chronic stress-induced neuroinflammation through the regulation of glycolysis.

Alleviation of Immobilization Stress or Fecal Microbiota-Induced Insomnia and Depression-like Behaviors in Mice by Lactobacillus plantarum and Its Supplement

Insomnia (sleeplessness) is a potential symptom of stress-induced depression/anxiety (DA), which induces TNF-α expression. Therefore, this study aimed to examine the effect of Lactobacillus (Lactiplantibacillus) plantarum P72, isolated as a strain suppressing lipopolysaccharide-induced expression of TNF-α in Caco2 cells, on DA and insomnia in immobilization stress (IS)- or cultured fecal microbiota (cFM)-treated mice. Oral administration of live or heat-killed P72 (hP72) reduced IS- or cFM-induced DA-like behaviors. They also reduced sleep latency time (SLT) and enhanced sleep duration (SLD). Additionally, P72 upregulated γ-aminobutyric acid (GABA), GABAA receptor α1, serotonin, and 5-HT1A receptor expression, which were downregulated by IS or cFM. Hempseed oil (HO) alone was ineffective against IS-induced DA- and insomnia-like behaviors, but its combination with P72 (PH) or hP72 (hPH) showed enhanced efficacy, reducing DA- and insomnia-like behaviors more strongly than P72 or HO alone. These also reduced the number of NF-κB-positive cells and the expression of TNF-α in the prefrontal cortex and colon. These results imply that P72 and its combination with HO can alleviate DA and insomnia by upregulating serotonergic and GABAergic systems through the suppression of NF-κB signaling.

Moringa oleifera Lam. seed lectin (WSMoL) reduces chronic stress-induced anxiety and depression in mice by lessening inflammation and balancing brain chemicals

Phyto-based treatments for anxiety and depression are gaining attention. The efficacy of the water-soluble Moringa oleifera seed lectin (WSMoL) in reducing acute anxiolytic and depressive-like behaviors in mice has been previously demonstrated. In the present study, it was evaluated the effects of WSMoL on reducing anxiety and depressive-like symptoms in a mouse model of unpredictable chronic mild stress (UCMS). The animals were divided into groups and exposed to a four-week UCMS regimen. Following this, the mice received daily intraperitoneal injections of vehicle (non-stressed and UCMS control groups), WSMoL (2 or 4 mg/kg), or fluoxetine (10 mg/kg) for 21 days. Neurobehavioral tests included the open field test and elevated plus maze test to assess anxiety-like behavior, and the tail suspension test and sucrose preference test to evaluate depression-like behavior. Biochemical analyses measured serum corticosterone and cytokines as well brain levels of cytokines and monoamines. All tests indicated that WSMoL significantly (p < 0.05) reversed the anxiety and depression-like behaviors induced by UCMS. The stress protocol increased serum corticosterone levels and WSMoL treatment was not able to normalize corticosterone secretion. WSMoL treatment reduced serum and brain levels of IL-2, IL-6, and TNF-α, indicating reduced neuroinflammation, and increased brain levels of dopamine, serotonin, and noradrenaline. In summary, WSMoL mitigated UCMS-induced anxiety and depression-like behaviors by reducing neuroinflammation and modulating brain monoamine levels.

Apple Polyphenol Extracts Attenuated Depressive-Like Behaviors of High-Sucrose Diet Feeding Mice by Farnesoid X Receptor-Mediated Modulation of Bile Acid Circulation within the Liver-Gut-Brain Axis.

Although the association between high-sugar diets and depression has been verified, few studies have explored the antidepressant mechanisms of apple polyphenol extracts (APE). Therefore, fifty-four C57BL/6 male mice aged 5 weeks were randomly assigned into five groups: the control group with the standard diet (CON), the constant high-sucrose diet group (HSD), the "2 + 5" alternate diet group (A-HSD), and the 500 mg/(kg·bw) APE treatment for the HSD group (APE) and the A-HSD group (A-APE), respectively. The data of hypothalamic-pituitary-adrenal (HPA) axis function and behavioral experiments confirmed the success in the establishment of depression-like mouse models in both HSD and A-HSD groups, which were significantly alleviated after APE treatment. Meanwhile, APE reduced serum levels of corticosterone and adrenocorticotrophic hormone, alleviated histopathological damage of the liver, colon, and brain, respectively, elevated the protein expressions of Occludin, ZO-1, and MUC-2, and decreased Firmicutes/Bacteroidota ratio and Dubosiella abundance with the increased microbiota of Tannerellaceae_unclassified, Muribaculum, and Lachnospiraceae_unclassified. Moreover, APE treatment reduced Farnesoid X receptor (FXR) protein levels along with the increased expressions of CYP7A1 and TGR5, lowered the contents of serum and fecal total bile acids, and modulated fecal BA compositions, particularly glycocholic acid (GCA) and isolithocholic acid (ILCA). Thus, both the constant and alternate high-sucrose diets successfully induced depression-like behaviors in mice, and APE might be a potential nutraceutical to attenuate high-sucrose diet-induced depression by regulating BAs circulation within the liver-gut-brain axis mediated by FXR.

Follicle-stimulating hormone induces depression-like phenotype by affecting synaptic function.

Depression is one of the most common affective disorders in people's life. Women are susceptibility to depression during puberty, peripartum and menopause transition, when they are suffering from sex hormone fluctuation. A lot of studies have demonstrated the neuroprotective effect of estrogen on depression in women, however, the effect of FSH on depression is unclear. In this study, we investigated the role of FSH on depression in mice. Our study demonstrated that FSH induced depression-like behaviors in mice in a dose-dependent manner. This induction was associated with elevated levels of pro-inflammatory cytokines, including IL-1β, IL-6, and TNF-α in both serum and hippocampal tissues. Additionally, FSH treatment resulted in impaired synaptic plasticity and a reduction in the expression of key synaptic proteins. It is noteworthy that the depression-like behaviors, inflammatory cytokines expression and synaptic plasticity impairment induced by FSH could be alleviated by knocking down the expression of FSH receptor (FSHR) in the hippocampus of the mice. Therefore, our findings reveal that FSH may play an important role in the pathogenesis of depression and targeting FSH may be a potential therapeutic strategy for depression during hormone fluctuation in women.

Asiaticoside improves depressive-like behavior in mice with chronic unpredictable mild stress through modulation of the gut microbiota.

Asiaticoside, the main active ingredient of Centella asiatica, is a pentacyclic triterpenoid compound. Previous studies have suggested that asiaticoside possesses neuroprotective and anti-depressive properties, however, the mechanism of its anti-depressant action not fully understood. In recent years, a growing body of research on anti-depressants has focused on the microbiota-gut-brain axis, we noted that disruption of the gut microbial community structure and diversity can induce or exacerbate depression, which plays a key role in the regulation of depression. Behavioral experiments were conducted to detect depression-like behavior in mice through sucrose preference, forced swimming, and open field tests. Additionally, gut microbial composition and short-chain fatty acid (SCFA) levels in mouse feces were analyzed 16S rRNA sequencing and gas chromatography-mass spectrometry (GC-MS). Hippocampal brain-derived neurotrophic factor (BDNF) and 5-hydroxytryptamine receptor 1A (5-HT1A) expression in mice was assessed by western blotting. Changes in serum levels of inflammatory factors, neurotransmitters, and hormones were measured in mice using ELISA. This study revealed that oral administration of asiaticoside significantly improved depression-like behavior in chronic unpredictable mild stress (CUMS) mice. It partially restored the gut microbial community structure in CUMS mice, altered SCFA metabolism, regulated the hypothalamic-pituitary-adrenal axis (HPA axis) and inflammatory factor levels, upregulated BDNF and 5-HT1A receptor protein expression, and increased serum serotonin (5-hydroxytryptamine, 5-HT) concentration. These findings reveal that asiaticoside exerts antidepressant effects via the microbiota-gut-brain axis. These results suggested that asiaticoside exerts antidepressant effects through the microbiota-gut-brain axis in a CUMS mouse model.

Brain Specific RagA Overexpression Triggers Depressive-Like Behaviors in Mice via Activating ADORA2A Signaling Pathway.

Neuroinflammation hallmarks the pathology of depression although the etiological complexity has not yet been resolved. Previous studies demonstrate that bacterial lipopolysaccharide induces depressive-like behaviors by activating RagA-mTOR-p70S6K signaling pathway. The current project aims to investigate whether and how brain-specific RagA overexpression triggers depressive-like behaviors in mice. Full-length RagA cDNA is cloned into the mammalian expression vector under the control of brain specific promoter, and subsequently overexpressed in the brain of mouse embryos. Indeed, RagA transgenic mice exhibit depressive-like behaviors and memory impairments. RNA-seq profiling of the prefrontal cortex (PFC) transcriptome highlights adenosine A2a receptor (ADORA2A) as a key differentially expressed gene (DEG). Western blotting confirms that ADORA2A and phospho-p70S6K are markedly elevated in RagA transgenic mice. Behavioral assessments demonstrate that ADORA2A inhibitor istradefylline markedly attenuates depressive-like behaviors. Further metabolomics reveals that N-acetylserotonin and several depression-related metabolites are downregulated while proteomic profiling showed that OLIG1 and other proteins are significantly regulated in RagA transgenic mice. Collectively, RagA overexpression alters the expression patterns of signaling proteins and the metabolism of depression-associated metabolites. RagA may cause depressive-like behaviors in mice via activating p70S6K/ADORA2A signaling pathway. Thus, RagA-p70S6K-ADORA2A signaling pathway may be a target for the development of new antidepressant therapies.

Purkinje cell hyperexcitability and depressive-like behavior in mice lacking erg3 (ether-à-go-go-related gene) K+ channel subunits.

Potassium channels stabilize the resting potential and neuronal excitability. Among them, erg (ether-à-go-go-related gene) K+ channels represent a subfamily of voltage-gated channels, consisting of erg1, erg2, and erg3 subunits; however, their subunit-specific neuronal functions in vivo are barely understood. To find erg3- and erg1-mediated functions, we generated global Kcnh7 (erg3) and conditional Kcnh2 (erg1) knockout mice. We found that erg3 channels stabilize the resting potential and dampen spontaneous activity in cerebellar Purkinje cells (PCs) and hippocampal CA1 neurons, whereas erg1 channels have suprathreshold functions. Lack of erg3 subunits induced hyperexcitability with increased action potential firing in PCs, but not in CA1 neurons. Notably, erg3 depletion caused depressive-like behavior with reduced locomotor activity, strongly decreased digging behavior, and shorter latencies to fall off a rotating wheel, while learning and memory remained unchanged. Our data show that erg K+ channels containing erg3 subunits mediate a neuronal subthreshold K+ current that plays important roles in the regulation of locomotor behavior in vivo.

Prebiotic inulin alleviates anxiety and depression-like behavior in alcohol withdrawal mice by modulating the gut microbiota and 5-HT metabolism

BackgroundAlcohol dependence (AD) is a common psychiatric disorder, often accompanied by anxiety and depression. These comorbidities are linked to disturbances in serotonin (5-HT) metabolism and gut microbiota dysbiosis. Clinical studies suggest that inulin, a prebiotic, can alleviate anxiety and depression in AD patients by affecting the gut microbiota, although the mechanisms remain unclear. PurposeThe purpose of this study is to investigate the potential mechanisms by which inulin, a prebiotic, improves anxiety and depression-like behaviors in AD withdrawal mice. This research is based on the drug and food homology and intestinal treatment of encephalopathy, with the goal of developing new clinical strategies for AD treatment. Study DesignFor this purpose, fecal samples from AD patients were analyzed to identify microorganisms associated with AD. An AD withdrawal mouse model was created, with inulin as the intervention and fluvoxamine maleate as the control. Techniques such as 16S microbiome sequencing and UPLC-TQMS-targeted metabolomics were used to assess gut microbiota, short-chain fatty acids (SCFAs) levels, and 5-HT metabolism. MethodsThe AD withdrawal model was built using the "Drinking-in-the-dark" protocol over 6 weeks. Inulin (2 g/kg/day) and fluvoxamine maleate (30 mg/kg/day) were administered for 4 weeks. The open field test, forced swim test, and tail suspension test were used to evaluate anxiety and depression-like behaviors in mice. ELISA and qRT-PCR assessed 5-HT metabolism in the colon, blood, and prefrontal cortex, while 16S microbiome sequencing analyzed changes in gut microbiota and UPLC-TQMS examined SCFAs levels. Immunohistochemistry was used to study intestinal barrier integrity. ResultsAD patients showed reduced SCFA-producing bacteria such as Faecalibacterium and Roseburia. In mice, AD withdrawal led to anxiety, depression-like behaviors, disrupted 5-HT metabolism, and gut microbiota dysbiosis. Inulin supplementation alleviated these behaviors, increased 5-HT and 5-hydroxytryptophan (5-HTP) levels, upregulated colonic tryptophan hydroxylase 1 (TPH1) expression, and promoted the growth of beneficial bacteria such as Faecalibacterium and Roseburia, while also increasing SCFAs levels. ConclusionInulin increases the abundance of Faecalibacterium and Roseburia, enhances SCFAs production, and regulates 5-HT metabolism, improving anxiety and depression-like behaviors in AD withdrawal mice. These findings suggest that inulin may serve as a nutritional intervention for mental health in AD patients by targeting the microbiome-gut-brain axis.

Pinocembrin alleviates LPS-induced depressive-like behavior in mice via the NLRP3/DCC signaling pathway

ObjectiveDepression, a prevalent and severe mental disorder, continues to be a significant area of research concerning its pathogenesis and therapeutic approaches. Conventional antidepressants are often limited by delayed therapeutic effects and notable adverse reactions, necessitating the development of innovative and efficacious treatment modalities. Multiple lines of evidence suggest that peripheral and central inflammation play a role in depression, and that anti-inflammatory drugs can ameliorate depressive symptoms in patients with inflammation-related depression. Pinocembrin (PB), a natural bioactive compound, is renowned for its anti-inflammatory and antioxidant properties, while the effect and mechanism of PB are still unclear. Consequently, this study employs PB as an intervention to investigate its effects on depression in mice model, with the objective of establishing a novel therapeutic strategy and foundational data for the treatment of depression. Methods(1) The acute inflammation model used lipopolysaccharide (LPS) to induce depression-like behavior in mice by injecting LPS intraperitoneally at a dose of 0.83mg/kg. The effects of PB (20 mg/kg, i.p.) and the NLRP3 inflammasome inhibitor MCC950 (10 mg/kg, i.p.) on improving depression behavior in mice were evaluated. (2) To explore the specific mechanism of PB in improving depression-like behavior in LPS mice by regulating NLRP3 and Netrin-1/DCC pathway. ResultsThe results showed that after intraperitoneal injection of LPS, the mice exhibited a significant decrease in body weight, sucrose preference score, and a significant increase in tail suspension immobility time. Treatment with PB and MCC950 increased the sucrose preference score and decreased the tail suspension immobility time. Besides, PB and MCC950 could inhibit the expression of NLRP3 related neuroinflammation, down-regulated the Netrin-1/DCC signaling pathway, and improved hippocampal neuroplasticity in mice. ConclusionIn conclusion, PB significantly improved LPS-induced depression-like behavior in mice by reducing the expression of hippocampal NLRP3 inflammasome and down-regulating the Netrin-1/DCC signaling pathway. Additionally, PB was found to regulate α-amino-3-hydroxy-5-methyl-4 isoxazole receptor (AMPAR) and postsynaptic density 95 (PSD95), protecting excitatory synaptic transmission and enhancing synaptic plasticity. This study demonstrates the effectiveness of PB in improving depressive symptoms induced by LPS and provides a new strategy for the clinical treatment of depression.

A small population of stress-responsive neurons in the hypothalamus-habenula circuit mediates development of depression-like behavior in mice.

Accumulating evidence has shown that various brain functions are associated with experience-activated neuronal ensembles. However, whether such neuronal ensembles are engaged in the pathogenesis of stress-induced depression remains elusive. Utilizing activity-dependent viral strategies in mice, we identified a small population of stress-responsive neurons, primarily located in the middle part of the lateral hypothalamus (mLH) and the medial part of the lateral habenula (LHbM). These neurons serve as "starter cells" to transmit stress-related information and mediate the development of depression-like behaviors during chronic stress. Starter cells in the mLH and LHbM form dominant connections, which are selectively potentiated by chronic stress. Silencing these connections during chronic stress prevents the development of depression-like behaviors, whereas activating these connections directly elicits depression-like behaviors without stress experience. Collectively, our findings dissect a core functional unit within the LH-LHb circuit that mediates the development of depression-like behaviors in mice.

Defective regulation of the eIF2-eIF2B translational axis underlies depressive-like behavior in mice and correlates with major depressive disorder in humans

Major depressive disorder (MDD) is a significant cause of disability in adults worldwide. However, the underlying causes and mechanisms of MDD are not fully understood, and many patients are refractory to available therapeutic options. Impaired control of brain mRNA translation underlies several neurodevelopmental and neurodegenerative conditions, including autism spectrum disorders and Alzheimer’s disease (AD). Nonetheless, a potential role for mechanisms associated with impaired translational control in depressive-like behavior remains elusive. A key pathway controlling translation initiation relies on the phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF2α-P) which, in turn, blocks the guanine exchange factor activity of eIF2B, thereby reducing global translation rates. Here we report that the expression of EIF2B5 (which codes for eIF2Bε, the catalytic subunit of eIF2B) is reduced in postmortem MDD prefrontal cortex from two distinct human cohorts and in the frontal cortex of social isolation-induced depressive-like behavior model mice. Further, pharmacological treatment with anisomycin or with salubrinal, an inhibitor of the eIF2α phosphatase GADD34, induces depressive-like behavior in adult C57BL/6J mice. Salubrinal-induced depressive-like behavior is blocked by ISRIB, a compound that directly activates eIF2B regardless of the phosphorylation status of eIF2α, suggesting that increased eIF2α-P promotes depressive-like states. Taken together, our results suggest that impaired eIF2-associated translational control may participate in the pathophysiology of MDD, and underscore eIF2-eIF2B translational axis as a potential target for the development of novel approaches for MDD and related mood disorders.

Polysaccharides from Polygonatum cyrtonema Hua prevent depression-like behaviors in mice with chronic unpredictable mild stress through refining gut microbiota-lipopolysaccharide-paraventricular nucleus signal axis

As natural polysaccharide cannot directly pass the blood-brain barrier, it is of potential importance to investigate the systemic anti-depression mechanisms of polysaccharides (PSP) from Polygonatum cyrtonema Hua, a well-known herbal medicine with the anti-depressant activity. Here, we explored the underlying mechanisms of effects of PSP on chronic unpredictable mild stress (CUMS)-induced depression-like behavior in mice from the perspective of the microbiota-gut-brain axis. The results demonstrated that PSP intervention for 14 days significantly improved CUMS-induced depressive-like behaviors. Interestingly, PSP treatment increased the relative abundance of Muribaculaceae, Dubosiella and Lactobacillus and decreased the relative abundance of Akkermansia, Helicobacter and Clostridium_methylpentosum in the colon of CUMS mice. Meanwhile, PSP blocked CUMS-induced impairment of intestinal barrier function, inhibited the levels of corticosterone and lipopolysaccharide (LPS), and increased the level of 5-hydroxytryptamine in the serum. Importantly, PSP treatment prevented abnormal neuronal activation and altered local field potential (LFP) in the paraventricular nucleus of CUMS mice, especially the decrease of power spectral density in delta and theta frequency bands. Finally, the results of LFP and c-fos staining after multiple repetitions of LPS injection showed consistencies with CUMS. Taken together, our study indicates that PSP ameliorates depression-like behavior likely via modulating the gut microbiota-lipopolysaccharide-paraventricular nucleus signal axis.

Sinisan Alleviates Stress-Induced Intestinal Dysfunction and Depressive-like Behaviors in Mice with Irritable Bowel Syndrome by Enhancing the Intestinal Barrier and Modulating Central 5-Hydroxytryptamine

Irritable bowel syndrome (IBS) is a common chronic functional bowel disorder and is strongly associated with an increased risk of depression and anxiety. The brain–gut axis plays an important role in the pathophysiologic changes in IBS, yet effective treatments for IBS are still lacking. Sinisan, originating from the Treatise on Typhoid Fever by the medical sage Zhang Zhongjing, is a classic formula in the Eight Methods of Traditional Chinese Medicine (TCM) that focuses on dispersing the liver and regulating the spleen, relieving depression and transmitting evils, and has been widely used in the treatment of liver-depression and spleen-deficiency, diarrhea, and related liver and stomach disorders. However, the therapeutic effect of sinisan in IBS has not been clarified. The aim of this study was to investigate the effects of sinisan on stress-induced intestinal dysfunction and depressive behavior in IBS mice. We established a diarrhea-predominant irritable bowel syndrome (IBS-D) mouse model using a 4% acetic acid enema combined with restraint stress, and analyzed the results using behavioral tests, relevant test kits, hematoxylin-eosin (HE) staining, immunofluorescence (IF), Western blot (WB), and quantitative fluorescence polymerase chain reaction (qRT-PCR). The results showed that sinisan administration significantly alleviated intestinal dysfunction and depressive-like behaviors in IBS-D mice, improved mild colonic inflammation and intestinal mucosal permeability, up-regulated the expression of tight junction proteins ZO-1 and occludin. Sinisan significantly alleviated intestinal dysfunction and depressive-like behaviors in IBS-D mice by decreasing the expression of TNF-α, promoting the expression of tight junction proteins (occludin, ZO-1) expression, and inhibiting the Tlr4/Myd88 signaling pathway, thereby attenuating the inflammatory response, protecting the intestinal barrier, and alleviating symptoms in the IBS-D mouse model. Taken together, sinisan may ameliorate intestinal inflammation and the intestinal barrier by regulating 5-HT expression and the Tlr4/Myd88 pathway, thereby alleviating stress-induced intestinal dysfunction and depressive behaviors in IBS-D mice.