Neuroinflammation, memory, and depression: new approaches to hippocampal neurogenesis

Association between methylmalonic acid and prevalence of depression in US adults: evidence from NHANES 2011-2014

Background: Depression is a prevalent mental disorder with high morbidity and mortality globally. Methylmalonic acid (MMA) is involved in the pathogenesis of numerous diseases. However, it is unclear whether there is an association between MMA and the prevalence of depression.Methods: This study enrolled 7866 US adults from the 2011-2014 survey of the National Health and Nutrition Examination Survey (NHANES). Individuals were categorized into depression group and non-depression group based on Patient's Health Questionnaire-9 (PHQ-9) score. The association between MMA concentrations and prevalence of depression was analysed by multivariate logistic and linear regression, restricted cubic spline regression, and subgroup analysis. Mediation analysis was used to explore the role of inflammation in the relationship between MMA and depression.Results: MMA concentrations were higher in participants with depression than those without depression. There was a positive and linear relationship of MMA concentrations with PHQ-9 score and depression risk, respectively. Moreover, the association was stable in most subgroups. Furthermore, inflammatory factors were positively correlated to MMA concentrations and prevalence of depression. In addition, white blood cell, neutrophil and alkaline phosphatase (ALP) mediated the relationship between MMA and depression.Conclusion: Our findings revealed that there was a linear and positive correlation between MMA and the prevalence of depression in US adults, which might be mediated by inflammation.

Spinal astrocyte-derived M-CSF mediates microglial reaction and drives visceral hypersensitivity following DSS-induced colitis

Visceral hypersensitivity is one of the most prevalent symptoms of inflammatory bowel disease (IBD), and it can be difficult to cure despite achieving endoscopic remission. Accumulating studies have described that macrophage colony-stimulating factor (M-CSF) modulates neuroinflammation in the central nervous system (CNS) and the development of chronic pain, while the underlying mechanism for whether and how M-CSF/CSF1R signaling pathway regulates visceral hypersensitivity following colitis remains unknown. In the present study, using the dextran sulfate sodium (DSS)-induced colitis model, we determined that microglial accumulation occurred in the spinal dorsal horn during remission phase. The reactive microglia released inflammatory factor, increased neuronal excitability in the dorsal horn, and produced chronic visceral pain behaviors in DSS-treated adult male mice. In addition, we also found significantly increased signaling mediated by astrocytic M-CSF and microglial CSF1R in dorsal horn in the mice with colitis. Exogenous M-CSF induced microglial activation, neuronal hyperactivity and behavioral hypersensitivity in the control group, inhibition of astrocyte/microglia by fluorocitrate/minocycline significantly suppressed microglial and neuronal activity, and relieved the visceral hypersensitivity in the model mice. Overall, our experimental study uncovers the critical involvement of spinal astrocyte-derived M-CSF and reactive microglia in the initiation and maintenance of visceral hypersensitivity following colitis, thereby identifying spinal M-CSF as a target for treating chronic visceral pain. This may provide more accurate theoretical guidance for clinical patients with IBD.

SGK1 upregulation in GFAP+ neurons in the frontal association cortex protects against neuronal apoptosis after spinal cord injury

Spinal cord injury (SCI) casts devastating and long-lasting impacts on the well-being of patients. Cognitive deficits and emotional disorders are common in individuals with SCI, yet the underlying mechanisms are not completely understood. Astrogliosis and glial scar formation occur during the subacute phase post-injury, playing complicated roles in remyelination and neurite regrowth. Therefore, we constructed a GFAP-IRES-Venus-AkaLuc knock-in mouse model for the corresponding studies. Surprisingly, complete spinal cord transection (SCT) surgery led to earlier and more prominent augmentation of bioluminescence in the brain than in the spinal cord. Bulk RNA sequencing revealed the activation of apoptotic signaling and the upregulation of serum and glucocorticoid-regulated kinase 1 (SGK1). The pattern of GFAP signals changed throughout the brain after SCT, as indicated by tissue clearing and immunostaining. Specifically, GFAP signals were intensified in the frontal association cortex (FrA), an encephalic region involved in associative learning and recognition memory processes. Further exploration unraveled that intensified GFAP signals in the FrA were attributed to apoptotic neurons with SGK1 upregulation, which was induced by sustained high glucocorticoid levels after SCT. The introduction of SGK1 silencing vectors confirmed that SGK upregulation in these FrA neurons exerted anti-apoptotic effects through NRF2/HO-1 signaling. In addition, SGK1 knockdown in FrA neurons aggravated the post-SCI depressive-like behaviors. Thus, ectopic SGK1 expression designated for limbic neurons could serve as a promising therapeutic target for the future development of treatments for spinal cord injuries.

Gut microbiota causes depressive phenotype by modulating glycerophospholipid and sphingolipid metabolism via the gut-brain axis

Emerging evidence suggests that changes in the gut microbiota (GM) are related to prenatal depression onset, but the underlying molecular mechanisms remain obscure. This study was conducted to explore how disordered GM is involved in the onset of prenatal depression through the microbiome-gut-brain (MGB) axis. We transplanted fecal microbiota from women with and without prenatal depression into germ-free mice. Fecal metagenomic sequencing and LC-MS untargeted metabolomics analysis were performed to identify the GM composition, function, and metabolites in mice. Lipid metabolomics analysis was then used to characterize the lipid metabolism of brain tissue in mice. We found that mice transplanted with fecal microbiota from women with prenatal depression exhibited depressive-like behaviors as well as characteristic disorders of the phylum Firmicutes. Weighted Gene Correlation Network Analysis identified three microbial and one metabolic module in the gut, alongside two lipid metabolic modules in the brain, as significantly related to all depressive-like behaviors. These modules were enriched for glycerophospholipid and sphingolipid metabolism. In addition, the GM of mice with depressive-like behaviors were enriched and deficient in relevant functions and enzymes in the glycerophospholipid (mainly phosphatidylethanolamine) and sphingolipid (mainly hexosyl-ceramide) metabolic pathways, respectively. Consistently, glycerophospholipid and sphingolipid metabolites in the brains of depressive-like mice were up- and down-regulated. Increased phosphatidylethanolamine and decreased hexosyl-ceramide were significantly related to differential genera in the gut. Collectively, our findings provide a novel microbial and metabolic framework for understanding the role of the MGB axis in prenatal depression, indicating that the GM may be involved in the onset of depressive phenotypes by modulating central glycerophospholipid and sphingolipid metabolic homeostasis.

Decreased gut microbiome-derived indole-3-propionic acid mediates the exacerbation of myocardial ischemia/reperfusion injury following depression via the brain-gut-heart axis

Despite the increasing recognition of the interplay between depression and cardiovascular disease (CVD), the precise mechanisms by which depression contributes to the pathogenesis of cardiovascular disease remain inadequately understood. The involvement of gut microbiota and their metabolites to health and disease susceptibility has been gaining increasing attention. In this study, it was found that depression exacerbated cardiac injury, impaired cardiac function (EF%: P < 0.01; FS%: P < 0.05), hindered long-term survival (P < 0.01), and intensified adverse cardiac remodeling (WGA: P < 0.01; MASSON: P < 0.0001) after myocardial ischemia/reperfusion (MI/R) in mice. Then we found that mice receiving microbiota transplants from chronic social defeat stress (CSDS) mice exhibited worse cardiac function (EF%: P < 0.01; FS%: P < 0.01) than those receiving microbiota transplants from non-CSDS mice after MI/R injury. Moreover, impaired tryptophan metabolism due to alterations in gut microbiota composition and structure was observed in the CSDS mice. Mechanistically, we analyzed the metabolomics of fecal and serum samples from CSDS mice and identified indole-3-propionic acid (IPA) as a protective agent for cardiomyocytes against ferroptosis after MI/R via NRF2/System xc-/GPX4 axis, played a role in mediating the detrimental influence of depression on MI/R. Our findings provide new insights into the role of the gut microbiota and IPA in depression and CVD, forming the basis of intervention strategies aimed at mitigating the deterioration of cardiac function following MI/R in patients experiencing depression.

Amomum tsao-ko crevost et lemaire ameliorates depression-like behaviors and hippocampal inflammation by inhibiting microglia activation and HMGB1/TLR4/NF-κB pathway in diabetic mice with depression

Diabetic depression may be closely related to hippocampal inflammation. We hypothesized that Amomum tsao-ko Crevost et Lemaire (A. tsao-ko) might ameliorate depression-like behavior and glucose intolerance by modulating hippocampal inflammation. UPLC-Q-Exactive-MS/MS was used to identified the constituents in the ethanol extract of A. tsao-ko (EEAT). Then a diabetic depression (DD) model was established and treated for 4 weeks. Depression-like behaviors were assessed using the open field test, sucrose preference test and tail suspension test. The neuronal injury was observed by hematoxylin-eosin staining and Nissl staining. Oral glucose tolerance test, fasting blood glucose, hemoglobin Alc, fasting insulin and homeostasis model assessment of insulin resistance were used to evaluate the effects of EEAT on glucose metabolism. Serum lipids, neurotransmitters, neuroendocrine and inflammation levels were detected by biochemical kits and enzyme-linked immunosorbent assay. Activation of microglia markers was detected by immunofluorescence. Western blotting was used to detect the effect of EEAT on the HMGB1/TLR4/NF-κB protein expression. 48 chemical components were identified from EEAT. Animal experiments showed that EEAT improved the levels of glucose and lipid metabolism, alleviated depression-like behaviors, decreased the level of neurotransmitters and increased the secretion of neuroendocrine-related hormones. The activation of microglia and immunofluorescence intensity of neurogenesis also improved. At the same time, the expression of HMGB1, TLR4 and NF-κB proteins in the inflammatory pathway was also inhibited. EEAT had effects on improving DD symptoms, which may be achieved by down-regulating the HMGB1/TLR4/NF-κB protein expression.

Chaihu-Shugan-San Alleviates Post-Stroke Depression in Mice: Mechanistic Insights into Exosome-Mediated Neuroprotection

ETHNOPHARMACOLOGICAL RELEVANCE

Post-stroke depression (PSD) is common among stroke survivors and negatively impacts recovery. Chaihu-Shugan-San (CSS), a traditional Chinese medicine, has shown therapeutic potential for mood disorders, particularly PSD. Recent studies suggest that CSS's effects may be mediated by exosomes, but the mechanisms remain unclear.

AIM OF STUDY

This study aimed to evaluate the therapeutic effects of CSS on PSD in mice and investigate the underlying mechanisms, particularly the role of exosomes.

MATERIALS AND METHODS

Active compounds in CSS were identified from rat serum using liquid chromatography-mass spectrometry (LC-MS) and analyzed through network pharmacology. In vitro, an oxygen-glucose deprivation/reperfusion (OGD/R) BV2 microglia model was used to assess the effects of CSS-containing serum (CSS-S). Exosomes from OGD/R-treated BV2 microglia were isolated, labeled with PKH26, and analyzed using transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA). In vivo, a photothrombotic stroke (PT) model combined with chronic unpredictable mild stress (CUMS) was used to induce PSD in mice. Behavioral assessments and histological analysis were performed, along with immunofluorescence (IF), ELISA and q-PCR to measure key protein and miR-146 expression in the hippocampus.

RESULTS

CSS treatment significantly alleviated depressive-like behaviors in the PSD mouse model. Mice treated with high-dose CSS (4.2 g/kg) exhibited increased sucrose preference, reduced immobility in the tail suspension test (TST) and forced swimming test (FST), and enhanced exploratory activity in the open field test (OFT). Histological analysis demonstrated that CSS treatment improved brain tissue integrity, alleviating neuronal damage and reducing neuroinflammation. Exosome analysis revealed that CSS increased the expression of microglia-derived exosomes in the hippocampus, which were shown to carry miR-146. Further examination of miR-146 isoforms in the hippocampal tissue revealed significant changes: miR-146b-3p and miR-146a-5p were upregulated, while miR-146a-3p and miR-146b-5p were downregulated in PSD mice. Treatment with CSS reversed the altered miRNA expression, indicating a potential mechanism for its neuroprotective effects. Additionally, CSS treatment reduced the expression of inflammatory cytokines such as S100A8, IL1β, IL6, and TNF-α, while restoring the levels of angiogenic factors VEGFC and VEGFR3. ELISA measurements showed significant decreases in cyclic AMP response element-binding protein (CREB), brain-derived neurotrophic factor (BDNF), 5-hydroxytryptamine (5-HT), dopamine (DA), and noradrenaline (NE) in PSD mice; high-dose CSS notably elevated CREB and BDNF levels and showed comparable effects to fluoxetine in restoring 5-HT and DA levels. Additionally, the calcium signaling pathway was implicated, with altered mRNA expressions of CaMKIIα, CREB, phosphorylated CREB (p-CREB), PDE4D, and BDNF, although fluoxetine demonstrated stronger modulatory effects than CSS.

CONCLUSIONS

CSS alleviates PSD in mice by modulating exosome-mediated signaling, particularly through the regulation of miR-146. The treatment reversed abnormal miRNA expression, reduced neuroinflammation, and improved synaptic function. These findings highlight CSS's potential as an effective therapeutic strategy for PSD by targeting exosome-mediated neuroprotection and miR-146 regulation.

Deer antler polypeptides inhibit microglial activation via TREM2 to improve behavior and neuroinflammation in CUMS mice

To investigate the effects and mechanisms of deer antler total polypeptides (VAP-T) and its active component Y (VAP-Y) in treating depression in CUMS mice.VAP-T improved depression-like behavior in CUMS mice, reduced microglial activation, and tissue inflammation. VAP-Y showed better improvement in depression-like behavior in CUMS mice compared to VAP-T, significantly inhibiting microglial activation and tissue inflammation. Chromatographic analysis of VAP-Y revealed that short peptides had good binding activity with TREM2. VAP-T and VAP-Y have significant improvement effects on depression-like behavior in CUMS mice, which is related to the inhibition of TREM2-mediated microglial activation. VAP-Y has better activity than the total polypeptides and is a polypeptide with potential for treating depression.

Tabersonine ameliorates depressive-like behavior by inhibiting NLRP3 inflammasome activation in a mouse model

Depression, a common mental disorder, is intimately linked to neuroinflammation. In the central nervous system, microglia, the principal cells involved in immunity, are crucial in neuroinflammation and closely associated with the pathogenesis of depression. Several studies have demonstrated that depressive-like behaviors could be ameliorated by improving brain inflammation. Notably, natural products occupy a critical position in the study of antidepressants. Herein, we explored the antidepressant effects of tabersonine (Tab), a natural inhibitor of NLRP3. Tab significantly improved depressive-like behaviors and anxiety in lipopolysaccharide (LPS)-treated mice. To further elucidate mechanisms underlying the antidepressant actions of Tab, BV2 microglial cells were exposed to LPS and ATP in vitro. Tab effectively inhibited NLRP3 inflammasome activation, subsequent Caspase-1 cleavage, and interleukin-1β secretion both in the hippocampi of mice in vivo and BV2 cells in vitro. Additionally, Tab strongly decreased the concentrations of the proinflammatory cytokines interleukin-1β, tumor necrosis factor, and interleukin-6 in BV2 cell culture supernatants and sera of mice. Further studies indicated that Tab improved LPS-induced neuronal loss, as indicated by a significant rise in the quantity of Nissl-positive cells within the hippocampal regions CA1, CA3, and dentate gyrus. Importantly, Tab counteracted the LPS-induced microglial activation in the hippocampus. Our results indicate that Tab significantly improves LPS-triggered depressive-like behaviors and reverses injuries to hippocampal microglia and neurons, implying its potential as a therapeutic agent for depression.

[Hypericin ameliorates stress-induced depressive-like behaviors in mice by modulating the CN-NFAT calcium signaling pathway in microglia]

OBJECTIVES

To investigate the role of the calcium/calmodulin (CaM)-mediated activation of calcineurin (CN)-nuclear factor of activated T cells (NFAT) signaling pathway in mediating the regulatory effect of hyperforin (HY) on stress-induced depression-like disorder (DP) in mice.

METHODS

C57BL/6J mice were randomly divided into control group, DP model group, and hyperforin treatment group (n=15). Behavioral changes of the mice were assessed using open field test (OFT), sucrose preference test (SPT), tail suspension test (TST), light/dark box test (LDB), and novel object suppression test (NSFT). Immunohistochemistry was used to detect tyrosine hydroxylase (TH) expression in the CA1 region of the hippocampus, and serum serotonin (5-HT) and norepinephrine (NA) levels were detected with ELISA. Western blotting was used to analyze the expressions of TNF-α, IL-1β, IL-2, and CN-NFAT pathway proteins. In cultured BV-2 microglial cells with lipopolysaccharide (LPS) stimulation, the effects of hyperforin and CN inhibitor (CNIS) on expressions of ionized calcium-binding adapter molecule 1 (IBA-1), 5-HT, NA, inflammatory cytokines and CN-NFAT pathway proteins were examined using immunofluorescence assay, ELISA or Western blotting.

RESULTS

Compared with the control mice, the mice in DP group showed significantly reduced activity in OFT, decreased sucrose consumption in SPT, reduced shuttle crossing in LDB, and lowered food intake in NSFT with significantly increased immobility in TST. The mice with DP showed significantly decreased TH-positive neurons, lowered 5-HT and NA levels, and increased expressions of TNF-α, IL-1β, IL-2 and CaM-CN-NFAT pathway proteins. In cultured BV-2 cells, LPS stimulation strongly increased cellular IBA-1 expression, decreased the levels of neurotransmitters (5-HT and NA), and increased the levels of inflammatory cytokines and CN-NFAT signaling, and these changes were effectively reversed by treatment with hyperforin or CNIS.

CONCLUSIONS

Hyperforin improves stress-induced depression-like behaviors in mice and activated BV-2 cells by targeting the CN-NFAT signaling pathway.

Rethinking Depression-Beyond Neurotransmitters: An Integrated Psychoneuroendocrineimmunology Framework for Depression's Pathophysiology and Tailored Treatment

It is known that the effectiveness of drug treatment for depression, ammine deficit based, is largely unsatisfactory. In this review, we examine the proposal of a precision therapy has emerged and has received a strong push by the identification of the role of inflammation in depression. However, precision psychiatry risks being caught in the reductionist trap of searching for the molecular switch that resets the whole system and switches off the disease. This is an illusion since the human being is complex and depression is a systemic and variable disorder. In this study, we show the inadequacy of the reductionist paradigm, and, at the same time, illustrate the superiority of the systemic paradigm centered on psychoneuroendocrineimmunology (PNEI). According to the PNEI paradigm, depression is a disease of the whole human being, caused by different sources working together: psychological, biological, and behavioral. This means knowing the biological and psychological history of the subject, identifying relational and biological crisis factors, and building personalized treatments targeting those factors with the tools of medicine and psychology, which are not reducible to the combination of drugs and psychotherapy. Our proposal presents a paradigm shift that is both theoretical and practical, which enables clinicians to assess patients experiencing depression in a unified way and treat them in an integrated manner.

Changes in dementia risk along with onset age of depression: a longitudinal cohort study of elderly depressed patients

BACKGROUND

Depression in late-life is linked to an increased risk of Alzheimer's dementia (AD), with the risk potentially varying according to the age at onset of depression. Previous studies have typically dichotomized depression onset ages between 55 and 65 years; however, the specific age at which depression onset increases AD risk in older adults remains unclear. In this study, we aimed to investigate the relationship between the age at onset of depression and AD risk, and compare the characteristics between different age groups.

METHODS

A longitudinal cohort of 251 older patients diagnosed with major depressive disorder was followed for up to 22 years. Participants were categorized into four groups based on depression onset age: ≤ 54 years, 55-64, 65-74, and ≥ 75 years. Annual cognitive assessments were conducted using the Korean Mini-Mental State Examination, with further neuropsychological testing when cognitive decline was suspected. Cox proportional hazards models were used to assess AD conversion risk across groups, adjusting for covariates.

RESULTS

During follow-up ranging from 1.0 to 22.9 years, 75 patients (29.88%) converted to AD. Depression onset after age 75 years was significantly associated with a higher risk of AD conversion (hazard ratio [HR], 8.95; 95% confidence interval [CI], 3.41-23.48; p < 0.0001) and a shorter time to conversion compared to onset before age 55 (40.93 vs. 83.40 months). After adjusting for covariates, depression onset after age 75 remained significantly associated with AD conversion (adjusted HR, 5.20; 95% CI, 1.04-25.93; p = 0.0431). This group also had milder depressive symptoms and a higher prevalence of hypertension and cerebrovascular disease than those with depression onset before 55 years of age.

CONCLUSIONS

The onset of depression after the age of 75 years was strongly associated with an increased risk of AD and a shorter time to dementia onset. Individuals with depression onset after age 75 appear more closely linked to vascular comorbidities, while those with depression onset before age 55 are characterized by severe and recurrent depressive episodes. The mechanisms underlying AD in individuals with depression may differ from those in individuals without prior depression.

The combined impact of neutrophil-percentage-to-albumin ratio and depressive symptoms on mortality in US arthritis patients: insights from NHANES (2005-2018)

Background

The neutrophil-to-albumin ratio (NPAR) reflects inflammation and nutritional status, while depression significantly impacts survival in chronic disease patients. This study examines the independent and combined effects of NPAR and depressive symptoms on all-cause and cardiovascular mortality in arthritis patients.

Methods

We analyzed a nationally representative sample of people with arthritisaged 40 and older from NHANES (2005-2018). NPAR assessed inflammation and nutritional status, while depressive symptoms were measured by PHQ-9. Weighted Cox regression examined the independent and joint associations of NPAR and PHQ-9 with all-cause and cardiovascular disease (CVD) mortality.

Results

Our analysis indicated that higher NPAR levels combined with lower depressive symptoms (PHQ-9 < 10) significantly increased all-cause and CVD mortality risks in arthritis patients. In this group, the hazard ratio (HR) for all-cause mortality was 2.087, with a similarly elevated CVD mortality risk (HR = 2.614), underscoring NPAR's predictive strength in non-depressed individuals. Among those with higher depressive symptoms, while elevated NPAR was still associated with increased mortality, its impact on CVD mortality was less marked, highlighting the need for further research into the NPAR-depression interaction.

Conclusion

This study identifies NPAR as a key predictor of mortality in arthritis patients, particularly those with fewer depressive symptoms. NPAR significantly predicts all-cause and CVD mortality, underscoring its value as an inflammation and nutrition biomarker. Integrating NPAR in clinical practice could enhance individualized risk assessment and intervention for arthritis patients.

Sex differences in the microglial response to stress and chronic alcohol exposure in mice

BACKGROUND

Women are more susceptible to stress-induced alcohol drinking, and preclinical data suggest that stress can increase alcohol intake in female rodents; however, a comprehensive understanding of the neurobiological processes underlying this sex difference is still emerging. Neuroimmune signaling, particularly by microglia, the brain's macrophages, is known to contribute to dysregulation of limbic circuits following stress and alcohol exposure. Females exhibit heightened immune reactivity, so we set out to characterize sex differences in the microglial response to stress and alcohol exposure.

METHODS

Male and female C57BL/6J mice were administered alcohol over 15 or 22 trials of a modified Drinking in the Dark paradigm, with repeated exposure to inescapable footshock stress and the stress-paired context. Mice were perfused immediately after drinking and we performed immunohistochemical analyses of microglial density, morphology, and protein expression in subregions of the amygdala and hippocampus.

RESULTS

We observed dynamic sex differences in microglial phenotypes at baseline and in response to stress and alcohol. Microglia in the hippocampus displayed more prominent sex differences and heightened reactivity to stress and alcohol. Chronic alcohol exposure decreased density of amygdala microglia and lysosomal expression.

CONCLUSION

We analyzed multiple measures of microglial activation, resulting in a comprehensive assessment of microglial changes mediated by sex, stress, and alcohol. These findings highlight the complexity of microglial contributions to the development of AUD and comorbid mood and stress disorders in men and women.

Exercise-induced Activation of SIRT1/BDNF/mTORC1 Signaling Pathway: A Novel Mechanism to Reduce Neuroinflammation and Improve Post-stroke Depression

BACKGROUND

Neuroinflammation and neurogenic disorders lead to depression in stroke patients. As, exercise intervention, a non-drug therapy, has been proven effective in post-stroke depression (PSD) patients. However, the underlying molecular mechanism by which exercise improves PSD still needs to be explored. Therefore, utilizing the mice model, this study aimed to observe the pathological changes in PSD and to investigate the mechanism by which exercise improves PSD symptoms.

METHODS

A middle cerebral artery occlusion (MCAO)+chronic unpredictable mild stress (CUMS) method was used to establish the PSD mice model, and the model mice were subjected to exercise interventions. Behavior tests were conducted to validate changes in depression-like behaviors. Western blot and reverse transcription-polymerase chain reaction (RT-qPCR) analyses were used to evaluate the expression levels of silent information regulator factor 2-related enzyme 1 (SIRT1), brain-derived neurotrophic factor (BDNF), and mammalian target of rapamycin complex 1 (mTORC1) signaling pathway in brain tissue. Enzyme linked immunosorbent assay (ELISA) analyses were performed to assess the effects of exercise on neuroinflammatory markers. Hematoxylin-Eosin (HE) and Nissl staining were used to examine exercise-induced histopathological change in the brain tissue. Furthermore, SIRT1 was knocked down using an adenovirus-mediated approach, and glial fibrillary acidic protein (GFAP) staining was used to determine the number of astrocytes in brain tissue.

RESULTS

Exercise significantly alleviates the symptoms of neurological dysfunction in model mice (p < 0.01). Exercise decreased the immobile time of PSD mice (p < 0.05) and increased the total exploration distance and crossing area (p < 0.05). Furthermore, exercise significantly reduced inflammatory marker levels, such as interleukin (IL)-6, tumor necrosis factor-alpha (TNF-α), and IL-1β (p < 0.05), and elevated anti-inflammatory factor IL-10 levels (p < 0.01). Moreover, exercise training alleviated inflammatory infiltration, increased the number of Nissl bodies (p < 0.05), and improved pathological changes in PSD mice. Additionally, exercise enhanced the expression levels of SIRT1, BDNF (p < 0.01), synaptophysin (Syn1), and postsynaptic density (PSD) 95 (p < 0.01), thereby improving synaptic plasticity and enhancing astrocyte activity (p < 0.05). Furthermore, compared to the model+exercise+con-shRNA group, SIRT1 knockdown inhibited protein expression in the mammalian target of rapamycin (mTOR) pathway (p < 0.05), reversing exercise-induced effects.

CONCLUSION

Exercise intervention reduces post-stroke depression-like behavior by activating SIRT1/BDNF/mTORC1 signaling pathway and reducing neuroinflammation. These findings provide insights into understanding the role of exercise in treating post-stroke depression and offer a theoretical basis for developing novel antidepressant strategies.

Ketogenic metabolic therapy in the remission of chronic major depressive disorder: a retrospective case study

Background

There is limited evidence describing the use of ketogenic metabolic therapy (KMT), also known as a ketogenic diet (KD), to achieve full remission of treatment-resistant major depressive disorder (MDD) in real-world clinical settings. This case study examines a 47-year-old woman with lifelong treatment-resistant MDD who achieved complete remission of depressive symptoms and improved functioning through a ketogenic diet.

Methods

The patient engaged in KMT with a 1.5:1 macronutrient ratio under the supervision of a treatment team consisting of a medical professional, psychotherapist, and ketogenic-informed nutrition professional through an online program that provided both individual and group support. Interventions included dietary modifications, micronutrient supplementation, and participation in a group coaching program. Outcomes were assessed using validated tools for symptom severity, including PHQ-9 for depression and GAD-7 for anxiety, at baseline, 2 months, and 4 months post-intervention. Qualitative data on patient experiences and functional improvements were also collected.

Results

The patient achieved remission of MDD within 8 weeks of initiating KMT, with PHQ-9 scores decreasing from 25 (severe depression) at baseline to 0 at 2- and 4-month assessments. GAD-7 scores decreased from 3 (minimal anxiety) to 0 over the same period. Qualitative findings revealed significant improvements in emotional regulation, energy levels, and cognitive function.

Conclusion

This case study demonstrates the potential of KMT as a non-pharmacological intervention for achieving full remission in treatment-resistant MDD. These findings suggest further research to evaluate feasibility, efficacy, and broader applicability in diverse clinical settings.

Costunolide normalizes neuroinflammation and improves neurogenesis deficits in a mouse model of depression through inhibiting microglial Akt/mTOR/NF-κB pathway

Neuroinflammation is crucial for the pathogenesis of major depression. Preclinical studies have shown the potential of anti-inflammatory agents, specifically costunolide (COS), correlate with antidepressant effects. In this study, we investigated the molecular mechanisms underlying the antidepressant actions of COS. Chronic restraint stress (CRS) was induced in male mice. The mice were treated with either intra-DG injection of COS (5 μM, 1 μL per side) or COS (20 mg/kg, i.p.) for 1 week. We showed that administration of COS through the both routes significantly ameliorated the depressive-like behavior in CRS-exposed mice. Furthermore, administration of COS significantly improved chronic stress-induced adult hippocampal neurogenesis deficits in the mice through attenuating microglia-derived neuroinflammation. We demonstrated that COS (5 μM) exerted anti-neuroinflammatory effects in LPS-treated BV2 cells via inhibiting microglial Akt/mTOR/NF-κB pathway; inactivation of mTOR/NF-κB/IL-1β pathway was required for the pro-neurogenic action of COS in CRS-exposed mice. Our results reveal the antidepressant mechanism of COS that is normalizing neuroinflammation to improve neurogenesis deficits, supporting anti-inflammatory agents as a potential therapeutic strategy for depression.

PARP14 inhibits microglial activation via NNT to alleviate depressive-like behaviors in mice

Microglial inflammation has been implicated in the pathophysiology of major depressive disorder; however, the underlying biological mechanisms remain inadequately understood. Consequently, we conducted a screening of the Poly ADP-ribose (PAR) polymerase (PARP) family expression in the hippocampus of chronic unpredictable stress (CUS) mouse models and investigated the specific role of PARP14 in microglial inflammation and its association with depression. Here, this study demonstrated the elevated PARP14 expression in the hippocampus of CUS mice. The knockdown of PARP14 in the hippocampus did not mitigate depressive-like behaviors in mice, whereas overexpression of PARP14 significantly mitigated these behaviors. Furthermore, PARP14 was abundant in microglia, and microglial-targeted PARP14 overexpression significantly alleviated depressive-behaviors in CUS, reduced microglial activation, and inhibited the central inflammatory responses. Mechanistically, PARP14 positively regulated nicotinamide nucleotide transhydrogenase (NNT) expression in microglia, and the inflammatory response of microglia induced by PARP14 knockdown was suppressed through NNT overexpression. Additionally, deficiency in NNT led to an accumulation of reactive oxygen species (ROS) and subsequent microglial inflammation, which was effectively inhibited by the ROS inhibitor N-Acetylcysteine. These findings suggest that PARP14 alleviates depressive-like behaviors in mice by inhibiting microglial activation via NTT-mediated clearance of ROS.

Hippocampal GPR35 is involved in the depression-like behaviors induced by inflammation and mediates the antidepressant effects of fluoxetine in mice

BACKGROUND

Neuroinflammation plays a pivotal role in the pathogenesis of depression. G protein-coupled receptor 35 (GPR35) is expressed in the brain and plays a role in regulating inflammatory processes. However, its specific role in depression remains unclear. Herein, we investigate the role of GPR35 in depressive behaviors induced by lipopolysaccharide (LPS) in mice.

METHODS

We employed an LPS-induced depression mouse model and conducted behavioral tests, molecular analyses, and morphological assessments, along with chemogenetic techniques, to investigate the role of GPR35 in depression.

RESULTS

Our results showed a significant increase in GPR35 expression in the brain of LPS-treated mice. Both pharmacological inhibition and genetic knockdown of GPR35 alleviated LPS-induced depressive-like behaviors by mitigating neuroinflammation, oxidative stress, synaptic plasticity deficits, and TLR4/NF-κB signaling in mice. Conversely, pharmacological activation of GPR35 notably exacerbated LPS-induced depressive-like behaviors in mice. Additionally, the GPR35 antagonist ML-145 effectively prevented LPS-induced inflammation responses in BV-2 microglia cells. Moreover, fluoxetine treatment effectively mitigated the upregulation of hippocampal GPR35 expression induced by LPS in mice. However, administration of the GPR35 agonist zaprinast reversed the antidepressant effects of fluoxetine. Chemogenetic activation of hippocampal glutamatergic neurons attenuated LPS-induced depression-like behaviors, accompanied by decreased GPR35 expression.

CONCLUSION

Hippocampal GPR35 is closely associated with depressive behaviors in the inflammatory model, highlighting its potential as a therapeutic target for antidepressant drug development.

Imipramine, an Acid Sphingomyelinase Inhibitor, Promotes Newborn Neuron Survival in the Hippocampus After Seizure

Epilepsy, a chronic neurological disorder, is triggered by various insults, including traumatic brain injury and stroke. Acid sphingomyelinase (ASMase), an enzyme that hydrolyzes sphingomyelin into ceramides, is implicated in oxidative stress, neuroinflammation, and neuronal apoptosis. Ceramides, which have pro-apoptotic properties, contribute to oxidative damage and lysosomal dysfunction, exacerbating neuronal injury. This study investigates the role of ASMase in epilepsy, hypothesizing that seizure activity upregulates ASMase, increasing ceramide levels, DNA damage, and neuronal apoptosis. We employed a pilocarpine-induced rat seizure model and examined the effects of imipramine, an ASMase inhibitor, administered intraperitoneally (10 mg/kg) for four weeks post-seizure induction. Histological and cognitive analyses showed that while imipramine did not prevent early neuronal death within the first week, it significantly reduced markers of neuronal apoptosis by four weeks. Imipramine also promoted hippocampal neurogenesis and preserved cognitive function, which is often impaired following seizures. These findings suggest that ASMase inhibition could mitigate neuronal apoptosis and improve cognitive recovery after seizures. Imipramine may serve as a promising therapeutic strategy for epilepsy-associated neuronal damage and cognitive deficits. Further studies should delineate the molecular mechanisms of ASMase inhibition and evaluate its long-term efficacy in addressing epilepsy-related neurodegeneration and functional impairments.

Modulating Gut Microbiota: The Mechanism of Electroacupuncture at the "Siguan" Acupoints in Alleviating Post-Stroke Depression

Purpose

To explore the related mechanisms of electroacupuncture at the "Siguan" acupoints in treating post-stroke depression (PSD).

Methods

Fifty male SD rats were randomly divided into the blank group, stroke group, PSD group, Siguan group and Bifidobacterium group, with 10 rats in each group. The Siguan group was given electroacupuncture at the bilateral "Hegu" (LI4) and "Taichong" (LR3), using the disperse-dense wave with a frequency of 2Hz/10Hz for 30 minutes each time. The changes in depressive behaviors of rats were observed according to the sucrose consumption and the scores of the open field test of rats in each group. The gene data of the intestinal flora of rats in each group were extracted to analyze the differences in the diversity, composition structure and function of the intestinal flora among different groups.

Results

The scores of the depression behavior indexes of the PSD rats in the Siguan group were higher than those in the PSD group. Meanwhile, there were disorders in the structure and function of the intestinal flora of the PSD rats. Compared with the PSD group, both the Siguan group and the Bifidobacterium group had increased contents of beneficial bacteria (Firmicutes and Clostridia) and decreased contents of pathogenic bacteria (Bacteroidetes and Bacteroidia). Compared with the PSD group, the intestinal flora structures of the Siguan group and the Bifidobacterium group were closer to those of normal rats. The abundance of the "Metabolism of Cofactors and Vitamins" functional pathway of the intestinal flora in the Siguan group was lower than that in the PSD group.

Conclusion

Electroacupuncture at the "Siguan" acupoints can improve the depression-like behaviors of PSD rats by up-regulating intestinal probiotics, down-regulating pathogenic bacteria, restoring the physiological structure of the intestinal flora and regulating the function of the intestinal flora.

Chronic treatment of mixture of two iridoids proportional to prescriptional dose of Yueju improves hippocampal PACAP-related neuroinflammation and neuroplasticity signaling in the LPS-induced depression model

ETHNOPHARMACOLOGICAL RELEVANCE

Geniposide (GP) and shanzhiside methyl ester (SM) are the two important bioactive compounds in the classical traditional Chinese herbal medicine Yueju Pill, which is currently used as an over-the-counter (OTC) medicine in China. Yueju has been demonstrated with antidepressant-like effects with the prescriptional dose. As GP and SM both have antidepressant potential, the synergism of them could be crucial to the function of Yueju.

OBJECTIVES

The neuropeptide pituitary adenylyl cyclase-activating polypeptide (PACAP) has been implicated in the onset of antidepressant-like response. Here we investigated the synergism of the chronic treatment with GP and SM, at proportional doses to Yueju, on antidepressant-like effects, and underlying mechanism of PACAP-related signaling in a neuroinflammation-based depression model.

MATERIALS AND METHODS

Depression-related behaviors were tested in the lipopolysaccharide (LPS)-induced depression model. The molecular signaling of neuroinflammation and neuroplasticity was investigated using Western blot analysis, immunofluorescence and pharmacological inhibition of mTOR signaling.

RESULTS

Chronic treatment of GP and SM (GS) at the dose which is proportional to the prescriptional dose of Yueju synergistically elicited antidepressant-like effects. Chronic treatment of the GS or the conventional antidepressant fluoxetine (FLX) showed antidepressant-like effects in LPS-injected mice. In vitro analysis indicated the synergism of GS on PACAP expression. In the hippocampus of LPS-injected mice, both GS and FLX enhanced PACAP expression, downregulated the inflammatory signaling of Iba-1/NF-кB/IL-1β and NLRP3, and upregulated the neuroplasticity signaling of mTOR-BDNF/PSD95. Additionally, both treatments reduced microglia activation indicated by Iba-1 immunofluorescent staining. Rapamycin, an mTOR inhibitor, blunted the antidepressant-like effects and the upregulation of BDNF expression induced by chronic GS.

CONCLUSION

The antidepressant-like effects elicited by chronic fluoxetine or by synergistic doses of GS were involved in the upregulation of hippocampal PACAP levels, in association with ameliorated neuroinflammation and neuroplasticity signaling in LPS-injected mice. GS synergism may play a key part in the antidepressant-like effects of the prescriptional dose of Yueju.

Infantile Amnesia can be Operationalized as a Psychological Meta Norm in the Development of Memory

This paper offers a syncretic synthesis of the highlights of the scientific knowledge accumulated to date on the mechanisms of infantile amnesia (IA). IA can be conceptualized as a meta-norm of memory development. The review shows that the neurobiological and neuropsychological evidence for IA converges within a common metacognitive framework of inquiry. The involvement of consciousness in the conditioning of memory traces and the association between infantile knowledge and implicit memory allow IA to be analyzed as a phenomenon with complex, universal neuropsychic regulation of a higher order. This approach overcomes the paradox of understanding IA.

Behavioral Animal Models and Neural-Circuit Framework of Depressive Disorder

Depressive disorder is a chronic, recurring, and potentially life-endangering neuropsychiatric disease. According to a report by the World Health Organization, the global population suffering from depression is experiencing a significant annual increase. Despite its prevalence and considerable impact on people, little is known about its pathogenesis. One major reason is the scarcity of reliable animal models due to the absence of consensus on the pathology and etiology of depression. Furthermore, the neural circuit mechanism of depression induced by various factors is particularly complex. Considering the variability in depressive behavior patterns and neurobiological mechanisms among different animal models of depression, a comparison between the neural circuits of depression induced by various factors is essential for its treatment. In this review, we mainly summarize the most widely used behavioral animal models and neural circuits under different triggers of depression, aiming to provide a theoretical basis for depression prevention.

Exogenous L-fucose attenuates depression induced by chronic unpredictable stress: Implicating core fucosylation has an antidepressant potential

Core fucosylation is one of the most essential modifications of the N-glycans, catalyzed by α1,6-fucosyltransferase (Fut8), which transfers fucose from guanosine 5'-diphosphate (GDP)-fucose to the innermost N-acetylglucosamine residue of N-glycans in an α1-6 linkage. Our previous studies demonstrated that lipopolysaccharide (LPS) can induce a more robust neuroinflammatory response in Fut8 homozygous knockout (KO) (Fut8-/-) and heterozygous KO (Fut8+/-) mice contrasted to the wild-type (Fut8+/+) mice. Exogenous administration of L-fucose suppressed LPS-induced neuroinflammation. Numerous studies indicate that neuroinflammation plays a vital role in the development of depression. Here, we investigated whether core fucosylation regulates depression induced by chronic unpredictable stress (CUS), a well-established model for depression. Our results showed that Fut8+/- mice exhibited depressive-like behaviors and increased neuroinflammation earlier than Fut8+/+ mice. Administration of L-fucose significantly reduced CUS-induced depressive-like behaviors and pro-inflammatory cytokine levels in Fut8+/- mice. The L-fucose treatment produced antidepressant effects by attenuating the complex formation between gp130 and the interleukin-6 (IL-6) receptor and the JAK2/STAT3 signaling pathway. Notably, L-fucose treatment increased dendritic spine density and postsynaptic density protein 95 (PSD-95) expression, which were suppressed in CUS-induced depression. Furthermore, the effects of L-fucose on the CUS-induced depression were also observed in Fut8+/+ mice. Our results clearly demonstrate that L-fucose ameliorates neuroinflammation and synaptic defects in CUS-induced depression, implicating that core fucosylation has significant anti-neuroinflammatory activity and an antidepressant potential.

The immunological perspective of major depressive disorder: unveiling the interactions between central and peripheral immune mechanisms

Major depressive disorder is a prevalent mental disorder, yet its pathogenesis remains poorly understood. Accumulating evidence implicates dysregulated immune mechanisms as key contributors to depressive disorders. This review elucidates the complex interplay between peripheral and central immune components underlying depressive disorder pathology. Peripherally, systemic inflammation, gut immune dysregulation, and immune dysfunction in organs including gut, liver, spleen and adipose tissue influence brain function through neural and molecular pathways. Within the central nervous system, aberrant microglial and astrocytes activation, cytokine imbalances, and compromised blood-brain barrier integrity propagate neuroinflammation, disrupting neurotransmission, impairing neuroplasticity, and promoting neuronal injury. The crosstalk between peripheral and central immunity creates a vicious cycle exacerbating depressive neuropathology. Unraveling these multifaceted immune-mediated mechanisms provides insights into major depressive disorder's pathogenic basis and potential biomarkers and targets. Modulating both peripheral and central immune responses represent a promising multidimensional therapeutic strategy.

From air to mind: unraveling the impact of indoor pollutants on psychiatric disorders

Epidemiological evidence from the past 20 years indicates that environmental chemicals brought into the air by the vaporization of volatile organic compounds and other anthropogenic pollutants might be involved, at least in part, in the development or progression of psychiatric disorders. This evidence comes primarily from occupational work studies in humans, with indoor occupations being the most important sources of airborne pollutants affecting neural circuits implicated in mood disorders (e.g., major depressive disorder and bipolar disorder). The current mini review brings together recent findings of indoor airborne pollution from different fields of research, including genetics, neuropathology, and neuroimaging, for gauging underlying physiological mechanisms leading to emotional disturbances that impact nearly all aspects of human behavior. A better understanding of how indoor airborne pollutants affect brain neurons to augment clinical symptoms associated with psychiatric disorders will undoubtedly be useful in the subsequent treatment of patients with major depressive and/or bipolar disorders. This article is part of the themed issue, "Understanding the Link Between Environmental Pollutants, Brain & Behavior."

Ascorbic acid Mitigates behavioural disturbances associated with letrozole-induced PCOS via switching-off JAK2/STAT5 and JAK2/ERK1/2 pathways in rat hippocampus

PURPOSE

Polycystic ovary syndrome (PCOS) is an endocrine disorder with the highest prevalence among other disorders in sexually-active women. It is associated with broad-spectrum hormonal and metabolic disturbances with behavioural difficulties. Experimentally, letrozole administration causes similar findings. Ascorbic acid is powerful anti-oxidant; and its cellular levels decrease with "hyperglycemic and poor anti-oxidative" status, which is, a main hallmark of PCOS. Thus, ascorbic acid administration may prevent the induction of PCOS and its consequences.

BASIC PROCEDURES

Forty female rats were divided into four groups (n = 10 in each): normal control (CTRL), ascorbic acid (ASC), letrozole (LTZ), and ascorbic acid + letrozole (ASC + LTZ) group. Behavioural tests (Y-maze spontaneous alteration, tail suspension test, forced swimming test) were performed. In serum, hormones (testosterone, estradiol, progesterone), glycemia (blood glucose, insulin and HOMA-IR) and oxidative stress (SOD activity, GSH) markers were measured. In hippocampus, inflammation and apoptosis indicators (p-JAK2, p-STAT5, p-ERK1/2, NF-κB, BAX, Bcl2, BAX/Bcl2 ratio) and neurotransmitters (DA, 5-HT, NE, BDNF) were determined. Lastly, ovary histopathological investigation was conducted to confirm PCOS induction.

PRINCIPAL RESULTS

Letrozole induced PCOS with subsequent disturbances. Testosterone levels were augmented while estradiol and progesterone were declined. Fasting blood glucose, insulin, HOMA-IR and oxidative stress markers were elevated. The expression of p-JAK2, p-STAT5, p-ERK1/2, BAX and the levels of NF-κB were increased, but Bcl2 expression, monoamines and BDNF levels were lowered. Importantly, ASC restored the last mentioned parameters markedly.

MAJOR CONCLUSIONS

Ascorbic acid mitigated the behavioural difficulties of PCOS possibly by switching-off JAK2/STAT5 and JAK2/ERK1/2 pathways in hippocampus along with its neurotransmission-improving, hormonal-normalizing, anti-hyperglycemic and anti-oxidative effects.

Corticosterone-induced postpartum depression induces depression-like behavior and impairs hippocampal neurogenesis in adolescent offspring via HPA axis and BDNF-mTOR pathway

Postpartum depression (PPD) adversely affects the growth and development of the offspring, increasing the risk of various internalizing behaviorsduring adolescence. Studies have shown that corticosterone (CORT)-induced PPD affects neurogenesis in the offspring, which is closely related to the onset of depression. However, the underlying mechanisms of these changes in the offspring of PPD mothers remain unexplored. In this study, we demonstrated postpartum mice treated with high CORT experienced activation of the hypothalamic-pituitary-adrenal (HPA) axis, which induced depressive-like behavior and impaired maternal caring behavior. Furthermore, adolescent offspring of PPD mice exhibited depression-like behavior, and learning and memory deficits. These offspring also showed diminished levels of DCX+, decreased levels of synaptic proteins, and reduced dendritic spine density and length in hippocampus. Additionally, we detected increased serum stressed hormones and decreased hippocampal glucocorticoid receptor (GR) protein level in the offspring. We also found the offspring exhibited reduced expression of brain-derived neurotrophic factor (BDNF) and the phosphorylation tyrosine kinase receptor B (TrkB), protein kinase B (AKT), and mammalian target of rapamycin (mTOR) proteins in hippocampus. These results indicated that the behavioral deficits and neuronal damage observed in the offspring of PPD mice may be related to HPA axis dysfunction and inhibition of the BDNF-mTOR pathway. In conclusion, our findings confirm that CORT induces depression-like behavior and impairs maternal caring behavior in maternal mice, which in turn affects their offspring's emotion and cognitive behavior. This impact is characterized by the activation of the HPA axis and inhibition of the BDNF-mTOR pathway.

Beyond metabolic messengers: Bile acids and TGR5 as pharmacotherapeutic intervention for psychiatric disorders

Psychiatric disorders pose a significant global health challenge, exacerbated by the COVID-19 pandemic and insufficiently addressed by the current treatments. This review explores the emerging role of bile acids and the TGR5 receptor in the pathophysiology of psychiatric conditions, emphasizing their signaling within the gut-brain axis. We detail the synthesis and systemic functions of bile acids, their transformation by gut microbiota, and their impact across various neuropsychiatric disorders, including major depressive disorder, general anxiety disorder, schizophrenia, autism spectrum disorder, and bipolar disorder. The review highlights how dysbiosis and altered bile acid metabolism contribute to the development and exacerbation of these neuropsychiatric disorders through mechanisms involving inflammation, oxidative stress, and neurotransmitter dysregulation. Importantly, we detail both pharmacological and non-pharmacological interventions that modulate TGR5 signaling, offering potential breakthroughs in treatment strategies. These include dietary adjustments to enhance beneficial bile acids production and the use of specific TGR5 agonists that have shown promise in preclinical and clinical settings for their regulatory effects on critical pathways such as cAMP-PKA, NRF2-mediated antioxidant responses, and neuroinflammation. By integrating findings from the dynamics of gut microbiota, bile acids metabolism, and TGR5 receptor related signaling events, this review underscores cutting-edge therapeutic approaches poised to revolutionize the management and treatment of psychiatric disorders.

Neuroprotective effects of gypenosides on LPS-induced anxiety and depression-like behaviors

AIM

Depression, a prevalent mental disorder, significantly impairs the quality of life and social functioning. Targeting neuroinflammation is a promising therapeutic approach, highlighting the need for natural neuroprotective agents. Gypenosides (Gyp) from Gynostemma pentaphyllum exhibit anxiolytic and antidepressant effects, yet the underlying mechanisms remain unclear. We investigated whether Gyp, isolated and purified by our laboratory, can exert neuroprotective effects by modulating neuroinflammation in the hippocampus and prefrontal cortex (PFC) of mice with LPS-induced anxiety and depression, thereby ameliorating behavioral phenotypes.

METHODS

LPS (1 mg/kg, i.p.) was used to induce anxiety and depression-like behaviors. Gyp was administered at 50, 100, or 200 mg/kg in pretreatment, with fluoxetine hydrochloride (Flu) as a positive control, for 10 consecutive days.

RESULTS

Gyp, especially at 100 mg/kg, significantly ameliorated LPS-induced anxiety and depression in mice, normalizing cytokine expression in the hippocampus and PFC, with IL-1β showing the most pronounced regulation (Hippocampus: RatioGyp-100/LPS = 30.73 %, PFC: RatioGyp-100/LPS = 55.89 %). Gyp also reversed LPS-induced neuronal loss and necrosis, reduced glial cell activation, and prevented the transition of microglia to the M1 phenotype. Mechanistically, Gyp suppressed the activation of the NLRP3 inflammasome in the PFC, and modulated hippocampal synaptic protein loss, thereby mediating neuroinflammation.

CONCLUSIONS

Gyp improved anxiety and depression in LPS-induced mice, which may be achieved by balancing systemic inflammatory levels, regulating glial cell activation and phenotypic polarization, regulating hippocampal synaptic plasticity, and suppressing the NLRP3/Caspase-1/ASC signaling pathway in the PFC.

The BDNF-Interactive Model for Sustainable Hippocampal Neurogenesis in Humans: Synergistic Effects of Environmentally-Mediated Physical Activity, Cognitive Stimulation, and Mindfulness

This paper bridges critical gaps through proposing a novel, environmentally mediated brain-derived neurotrophic factor (BDNF)-interactive model that promises to sustain adult hippocampal neurogenesis in humans. It explains how three environmental enrichment mechanisms (physical activity, cognitive stimulation, and mindfulness) can integratively regulate BDNF and other growth factors and neurotransmitters to support neurogenesis at various stages, and how those mechanisms can be promoted by the physical environment. The approach enables the isolation of specific environmental factors and their molecular effects to promote sustainable BDNF regulation by testing the environment's ability to increase BDNF immediately or shortly before it is consumed for muscle repair or brain update. This model offers a novel, feasible method to research environment enrichment and neurogenesis dynamics in real-world human contexts at the immediate molecular level, overcoming the confounds of complex environment settings and challenges of long-term exposure and structural plasticity changes. The model promises to advance understanding of environmental influences on the hippocampus to enhance brain health and cognition. This work bridges fundamental gaps in methodology and knowledge to facilitate more research on the enrichment-neuroplasticity interplay for humans without methodological limitations.

Pleiotrophin modulates acute and long-term LPS-induced neuroinflammatory responses and hippocampal neurogenesis

The hippocampus is one of the most vulnerable regions affected in disorders characterized by overt neuroinflammation such as neurodegenerative diseases. Pleiotrophin (PTN) is a neurotrophic factor that modulates acute neuroinflammation in different contexts. PTN is found highly upregulated in the brain in different chronic disorders characterized by neuroinflammation, suggesting an important role in the modulation of sustained neuroinflammation. To test this hypothesis, we studied the acute and long-term effects of a single lipopolysaccharide (LPS; 5 mg/kg) administration in Ptn+/+ and Ptn-/- mice, and in mice with Ptn-overexpression (Ptn-Tg). Endogenous PTN levels proportionally modulate LPS-induced increase in TNF-α plasma levels one hour after treatment. In the dentate gyrus (DG) of the hippocampus, a lower percentage of DCX+ cells were detected in saline-treated Ptn-/- mice compared to Ptn+/+ mice, suggesting a crucial role of PTN in the maintenance of hippocampal neuronal progenitors. The data show that PTN overexpression tends to potentiate acute microglial responses in the DG 16 hours after LPS treatment. Remarkably, a significant increase in the number of neuronal progenitors together with astrogliosis was detected 10 months after a single injection of LPS treatment in wild type mice. However, these LPS-induced long-term effects were prevented in Ptn-/- and Ptn-Tg mice, suggesting that PTN modulates LPS-induced long-term neurogenesis changes and astrocytic response in the hippocampus. The data presented here suggest that endogenous PTN levels are crucial in the regulation of acute LPS-induced systemic and hippocampal microglial responses in young mice. Furthermore, our findings provide evidence of the key role of PTN in the regulation of long-term LPS effects on astrocytic response and neurogenesis in the hippocampus.

A comprehensive analysis of the differential expression in the hippocampus of depression induced by gut microbiota compared to traditional stress

Depression, which is a disease of heterogeneous etiology, is characterized by high disability and mortality rates. Gut microbiota are associated with the development of depression. To further explore any differences in the mechanisms of depression induced by gut microbiota and traditional stresses, as well as facilitate the development of microbiota-based interventions, a fecal microbiota transplantation (FMT) depression model was made. This was achieved by transplanting feces from major depressive disorder (MDD) patients into germ-free mice. Second, the mechanisms of the depression induced by gut microbiota were analyzed in comparison with those of the depression caused by different forms of stress. It turned out that mice exhibited depressive-like behavior after FMT. Then, PCR array analysis was performed on the hippocampus of the depressed mice to identify differentially expressed genes (DEGs). The KEGG analysis revealed that the pathways of depression induced by gut microbes are closely associated with immuno-inflammation. To determine the pathogenic pathways of physiological stress and psychological stress-induced depression, raw data was extracted from several databases and KEGG analysis was performed. The results from the analysis revealed that the mechanisms of depression induced by physiological and psychological stress are closely related to the regulation of neurotransmitters and energy metabolism. Interestingly, the immunoinflammatory response was distinct across different etiologies that induced depression. The findings showed that gut microbiota dysbiosis-induced depression was mainly associated with adaptive immunity, while physiological stress-induced depression was more linked to innate immunity. This study compared the pathogenesis of depression caused by gut microbiota dysbiosis, and physiological and psychological stress. We explored new intervention methods for depression and laid the foundation for precise treatment.

Bmal1 haploinsufficiency impairs fear memory and modulates neuroinflammation via the 5-HT2C receptor

Background

BMAL1, a key regulator of circadian rhythms, plays a multifaceted role in brain function. However, the complex interplay between BMAL1, memory, neuroinflammation, and neurotransmitter regulation remains poorly understood. To investigate these interactions, we conducted a study using BMAL1-haplodeficient mice (BMAL1+/-).

Methods

We exposed BMAL1+/- mice to behavioral assessments including cued fear conditioning, new objection recognition (NOR) test, and Y-maze test to evaluate BMAL1+/- haplodeficiency impact on memory. Furthermore, biochemical changes were analyzed through western blotting, and ELISA to explore further the mechanism of BMAL1+/- in memory, and neuroinflammation.

Results

We found that BMAL1 haploinsufficiency led to deficits in cued fear learning and memory, while spatial memory and object recognition remained intact. Further analysis revealed dysregulated neurotransmitter levels and alterations in neurotransmitter-related proteins in the prefrontal cortex of BMAL1+/- mice. Pharmacological interventions targeting dopamine uptake or the 5-HT2C receptor demonstrated that inhibiting the 5-HT2C receptor could rescue fear learning and memory impairments in BMAL1+/- mice. Additionally, we observed downregulation of the inflammasome and neuroinflammation pathways in BMAL1+/- mice, which is validated by inflammation mediator lipopolysaccharide (LPS) administration.

Conclusion

These findings highlight that BMAL1 haploinsufficiency leads to deficits in fear learning and memory, which are linked to alterations in neurotransmitters and receptors, particularly the 5-HT2C receptor. Targeting the 5-HT2C receptor may offer a potential therapeutic strategy for mitigating cognitive impairments associated with BMAL1 dysfunction.

Prefrontal cortex astrocytes in major depressive disorder: exploring pathogenic mechanisms and potential therapeutic targets

Major depressive disorder (MDD) is a prevalent mental health condition characterized by persistent feelings of sadness and hopelessness, affecting millions globally. The precise molecular mechanisms underlying MDD remain elusive, necessitating comprehensive investigations. Our study integrates transcriptomic analysis, functional assays, and computational modeling to explore the molecular landscape of MDD, focusing on the DLPFC. We identify key genomic alterations and co-expression modules associated with MDD, highlighting potential therapeutic targets. Functional enrichment and protein-protein interaction analyses emphasize the role of astrocytes in MDD progression. Machine learning is employed to develop a predictive model for MDD risk assessment. Single-cell and spatial transcriptomic analyses provide insights into cell type-specific expression patterns, particularly regarding astrocytes. We have identified significant genomic alterations and co-expression modules associated with MDD in the DLPFC. Key genes involved in neuroactive ligand-receptor interaction pathways, notably in astrocytes, have been highlighted. Additionally, we developed a predictive model for MDD risk assessment based on selected key genes. Single-cell and spatial transcriptomic analyses underscored the role of astrocytes in MDD. Virtual screening of compounds targeting GPR37L1, KCNJ10, and PPP1R3C proteins has identified potential therapeutic candidates. In summary, our comprehensive approach enhances the understanding of MDD's molecular underpinnings and offers promising opportunities for advancing therapeutic interventions, ultimately aiming to alleviate the burden of this debilitating mental health condition. KEY MESSAGES: Our investigation furnishes insightful revelations concerning the dysregulation of astrocyte-associated processes in MDD. We have pinpointed specific genes, namely KCNJ10, PPP1R3C, and GPR37L1, as potential candidates warranting further exploration and therapeutic intervention. We incorporate a virtual screening of small molecule compounds targeting KCNJ10, PPP1R3C, and GPR37L1, presenting a promising trajectory for drug discovery in MDD.

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.

Serum glial cell line-derived neurotrophic factor: a potential biomarker for white matter alteration in Parkinson's disease with mild cognitive impairment

Objective

Mild cognitive impairment (MCI) is a common non-motor manifestation of Parkinson's disease, commonly referred to as PD-MCI. However, there is a lack of comprehensive data regarding the role of glial cell line-derived neurotrophic factor (GDNF) and cerebral white matter damage in the pathogenesis of PD-MCI. The objective of this study is to investigate the association between alterations in GDNF levels and cerebral white matter damage in individuals diagnosed with PD-MCI, as well as to explore their potential involvement in cognitive progression.

Methods

Neuropsychological assessments were conducted on 105 patients with Parkinson's disease and 45 healthy volunteers to examine various cognitive domains. An enzyme-linked immunosorbent assay (ELISA) was employed to measure serum levels of GDNF. Additionally, all participants underwent 3.0T magnetic resonance imaging (MRI) to acquire diffusion tensor images (DTI), and a voxel-based analysis (VBA) approach was utilized to compare the fractional anisotropy (FA) values of white matter in the brain.

Results

There was a significant correlation between the right corpus callosum, right cingulate gyrus, and the Digit Span Backward Test (DSB-T) as well as the Trail Making Test A (TMT-A), both of which assess attention and working memory functions. The left internal capsule exhibited a significant correlation with the Trail Making Test B (TMT-B) and the Clock Drawing Test (CDT), which evaluate executive function. Additionally, the right cingulate gyrus showed a significant association with scores on the Auditory Verbal Learning Test-HuaShan (AVLT-H), assessing memory function. Abnormal fiber structures that demonstrated significant correlations with serum GDNF levels included the left internal capsule, left corticospinal tract, right corpus callosum, and right cingulate gyrus.

Conclusion

The decrease in serum GDNF levels among PD-MCI patients exhibiting impairments in attention and working memory function was significantly correlated with alterations in the corpus callosum (knee) and posterior cingulate gyrus. Furthermore, the reduction of serum GDNF levels in PD-MCI patients with impaired executive function is associated with changes in the internal capsule (forelimb) projection fibers. Additionally, the decline of serum GDNF levels in PD-MCI patients experiencing memory function impairment is related to alterations in the right cingulate gyrus.

The Protective Effects of Polygala tenuifolia and Tenuifolin on Corticosterone-Evoked Ferroptosis, Oxidative Stress, and Neuroinflammation: Insights from Molecular Dynamics Simulations and In Vitro Experiments

Excessive stress is a well-established contributor to neurological damage, insomnia, and depression, imposing a significant burden on individuals and society. This underscores the urgent need for effective stress-relief strategies. The main purpose of this study was to explore the protective effects of Polygala tenuifolia (PT) and its bioactive compound, tenuifolin, against corticosterone-induced neurotoxicity, with a focus on ferroptosis, oxidative stress, and neuroinflammation. Both PT extracts and tenuifolin mitigated corticosterone-induced cellular damage. Tenuifolin reversed the corticosterone-induced dysregulation of ferroptosis-associated proteins, such as SLC7A11, GPX4, and Nrf2, leading to a marked reduction in ferroptosis levels. Molecular dynamics simulations revealed that corticosterone significantly altered the conformation and binding energy of the SLC7A11/SLC3A2 complex, critical for ferroptosis regulation. These changes were reversed by tenuifolin. Additionally, tenuifolin alleviated corticosterone-induced oxidative stress and neuroinflammation, both of which accelerated ferroptosis. In conclusion, these results indicate that tenuifolin attenuates corticosterone-induced neurotoxicity by modulating ferroptosis, oxidative stress, and neuroinflammation. This study provides a theoretical foundation for the application of PT and tenuifolin in stress-induced nerve damage.

Ketamine Prevents Inflammation-Induced Reduction of Human Hippocampal Neurogenesis via Inhibiting the Production of Neurotoxic Metabolites of the Kynurenine Pathway

BACKGROUND

Understanding the precise mechanisms of ketamine is crucial for replicating its rapid antidepressant effects without inducing psychomimetic changes. Here, we explore whether the antidepressant-like effects of ketamine enantiomers are underscored by protection against cytokine-induced reductions in hippocampal neurogenesis and activation of the neurotoxic kynurenine pathway in our well-established in vitro model of depression in a dish.

METHODS

We used the fetal hippocampal progenitor cell line (HPC0A07/03C) to investigate ketamine's impact on cytokine-induced reductions in neurogenesis in vitro. Cells were treated with interleukin- 1beta (IL-1b) (10 ng/mL) or IL-6 (50 pg/mL), alone or in combination with ketamine enantiomers arketamine (R-ketamine, 400 nM) or esketamine (S-ketamine, 400 nM) or antidepressants sertraline (1 mM) or venlafaxine (1 mM).

RESULTS

Resembling the effect of antidepressants, both ketamine enantiomers prevented IL-1b- and IL-6-induced reduction in neurogenesis and increase in apoptosis. This was mediated by inhibition of IL-1b-induced production of IL-2 and IL-13 by R-ketamine and of IL-1b-induced tumor necrosis factor-alpha by S-ketamine. Likewise, R-ketamine inhibited IL-6-induced production of IL-13, whereas S-ketamine inhibited IL-6-induced IL-1b and IL-8. Moreover, both R- and S-ketamine prevented IL-1b-induced increases in indoleamine 2,3-dioxygenase expression as well as kynurenine production, which in turn was shown to mediate the detrimental effects of IL-1b on neurogenesis and apoptosis. In contrast, neither R- nor S-ketamine prevented IL-6-induced kynurenine pathway activation.

CONCLUSIONS

Results suggest that R- and S-ketamine have pro-neurogenic and anti-inflammatory properties; however, this is mediated by inhibition of the kynurenine pathway only in the context of IL-1b. Overall, this study enhances our understanding of the mechanisms underlying ketamine's antidepressant effects in the context of different inflammatory phenotypes, ultimately leading to the development of more effective, personalized therapeutic approaches for patients suffering from depression.

Causal role of immune cells in major depressive disorder and bipolar disorder: Mendelian randomization (MR) study

BACKGROUND

Major depressive disorder (MDD) and bipolar disorder (BD) are prevalent psychiatric conditions linked to inflammatory processes. However, it is unclear whether associations of immune cells with these disorders are likely to be causal.

METHODS

We used two-sample Mendelian randomization (MR) approach to investigate the relationship between 731 immune cells and the risk of MDD and BD. Rigorous sensitivity analyses are conducted to assess the reliability, heterogeneity, and horizontal pleiotropy of the findings.

RESULTS

Genetically-predicted CD27 on IgD+ CD38- unswitched memory B cell (inverse variance weighting (IVW): odds ratio (OR) [95 %]: 1.017 [1.007 to 1.027], p = 0.001), CD27 on IgD+ CD24+ B cell (IVW: OR [95 %]: 1.021 [1.011 to 1.031], p = 4.821E-05) and other 12 immune cells were associated with increased risk of MDD in MR, while HLA DR++ monocyte %leukocyte (IVW: OR [95 %]: 0.973 [0.948 to 0.998], p = 0.038), CD4 on Central Memory CD4+ T cell (IVW: OR [95 %]: 0.979 [0.963 to 0.995], p = 0.011) and other 13 immune cells were associated with decreased risk of MDD in MR. Additionally, CD33+ HLA DR+ Absolute Count (IVW: OR [95 %]: 1.022[1.007 to 1.036], p = 0.007), CD28+ CD45RA- CD8+ T cell %T cell (IVW: OR [95 %]: 1.024 [1.008 to 1.041], p = 0.004) and other 18 immune cells were associated with increased risk of BD in MR, while CD62L on CD62L+ myeloid Dendritic Cell (IVW: OR [95 %]: 0.926 [0.871 to 0.985], p = 0.014), IgD- CD27- B cell %lymphocyte (IVW: OR [95 %]: 0.918 [0.880 to 0.956], p = 4.654E-05) and other 13 immune cells were associated with decreased risk of BD in MR.

CONCLUSIONS

This MR study provides robust evidence supporting a causal relationship between immune cells and the susceptibility to MDD and BD, offering valuable insights for future clinical investigations. Experimental studies are also required to further examine causality, mechanisms, and treatment potential for these immune cells for MDD and BD.

Apoptosis-induced decline in hippocampal microglia mediates the development of depression-like behaviors in adult mice triggered by unpredictable stress during adolescence

Depression triggered by harmful stress during adolescence is a common problem that can affect mental health. To date, the mechanisms underlying this type of depression remain unclear. One mechanism for the promotion of depression by chronic stress in adulthood is the loss of hippocampal microglia. Since deleterious stress in adolescence also activates microglia, we investigated the dynamic changes of microglia in the hippocampus in mice exposed to chronic unpredictable stress (CUS) in adolescence. Our results showed that 12 days of CUS stimulation in adolescence induced typical depression-like behaviors in adult mice, which were accompanied by a significant decrease and dystrophy of microglia in the dentate gyrus of the hippocampus. Further analysis showed that this decrease in microglia was mediated by the initial response of microglia to unpredictable stress in the dentate gyrus of the hippocampus and their subsequent apoptosis. Blocking the initial response of microglia to unpredictable stress by pretreatment with minocycline was able to prevent apoptosis and microglial decline as well as the development of depression-like behaviors in adult mice induced by adolescent CUS. Moreover, administration of lipopolysaccharide (LPS) or macrophage-colony stimulatory factor (M-CSF), two drugs that reversed microglia decline in the dentate gyrus, ameliorated the depression-like behaviors induced by CUS stimulation in adolescence. These findings reveal a novel mechanism for the development of depression-like behaviors in animals triggered by deleterious stress in adolescence and suggest that reversing microglial decline in the hippocampus may be a hopeful strategy for the treatment of depression triggered by deleterious stress in adolescence.

"Inflamed" depression: A review of the interactions between depression and inflammation and current anti-inflammatory strategies for depression

Depression is a common mental disorder, the effective treatment of which remains a challenging issue worldwide. The clinical pathogenesis of depression has been deeply explored, leading to the formulation of various pathogenic hypotheses. Among these, the monoamine neurotransmitter hypothesis holds a prominent position, yet it has significant limitations as more than one-third of patients do not respond to conventional treatments targeting monoamine transmission disturbances. Over the past few decades, a growing body of research has highlighted the link between inflammation and depression as a potential key factor in the pathophysiology of depression. In this review, we first summarize the relationship between inflammation and depression, with a focus on the pathophysiological changes mediated by inflammation in depression. The mechanisms linking inflammation to depression as well as multiple anti-inflammatory strategies are also discussed, and their efficacy and safety are assessed. This review broadens the perspective on specific aspects of using anti-inflammatory strategies for treating depression, laying the groundwork for advancing precision medicine for individuals suffering from "inflamed" depression.

AMPA receptor potentiation alleviates NLRP3 knockout-induced fear generalization in mice

Genetic knockout and pharmaceutical inhibition of the NLRP3 inflammasome enhances the extinction of contextual fear memory, which is attributed to its role in neuronal and synaptic dysregulation, concurrent with neurotransmitter function disturbances. This study aimed to determine whether NLRP3 plays a role in generalizing fear via the inflammatory axis. We established the NLRP3 KO mice model, followed by behavioral and biochemical analyses. The NLRP3 KO mice displayed impaired fear generalization, lower neuroinflammation levels, and dysregulated neurotransmitter function. Additionally, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, but not the inhibition of NMDA or 5-HT2C receptors, resulted in fear generalization in NLRP3 KO mice because TAT-GluA2 3Y, but not SB242084 and D-cycloserine, treated blocked NLRP3 deprivation effects on fear generalization. Thus, global knockout of NLRP3 is associated with aberrant fear generalization, possibly through AMPA receptor signaling.

A high-fat diet induced depression-like phenotype via hypocretin-HCRTR1 mediated inflammation activation

Background: A high-fat diet (HFD) is generally associated with an increased risk of mental disorders that constitute a sizeable worldwide health. A HFD results in the gut microbiota-brain axis being altered and linked to mental disorders. Hypocretin-1, which can promote appetite, has been previously confirmed to be associated with depression. However, no exact relationship has been found for hypocretin between depression and HFDs. Methods: Adult male SD rats were randomly assigned to either a HFD or a normal diet for eight weeks, followed by behavioral tests and plasma biochemical analyses. Then, we investigated the protein and mRNA levels of inflammation-related factors in the hippocampus. We also observed morphological changes in brain microglia and lipid accumulation. Additionally, metagenomic and metabolomic analyses of gut microbiomes were performed. 3T3-L1 cells were utilized in vitro to investigate the impact of hypocretin receptor 1 antagonists (SB334867) on lipid accumulation. To consider the connection between the brain and adipose tissue, we used a conditioned medium (CM) treated with 3T3-L1 cells to observe the activation and phagocytosis of BV2 cells. Following a 12-week period of feeding a HFD to C57BL/6 mice, a three-week intervention period was initiated during which the administration of SB334867 was observed. This was followed by a series of assessments, including monitoring of body weight changes and emotional problems, as well as attention to plasma biochemical levels and microglial cell phenotypes in the brain. Results: The HFD rats displayed anxiety and depressive-like behaviors. HFD rats exhibited increased plasma HDL, LDL, and TC levels. A HFD also causes an increase in hypocretin-1 and hypocretin-2 in the hypothalamus. Metagenomics and metabolomics revealed that the HFD caused an increase in the relative abundance of associated inflammatory bacteria and decreased the abundance of anti-inflammatory and bile acid metabolites. Compared with the CTR group, hippocampal microglia in the HFD group were significantly activated and accompanied by lipid deposition. At the same time, protein and mRNA expression levels of inflammation-related factors were increased. We found that SB334867 could significantly reduce lipid accumulation in 3T3-L1 cells after differentiation. The expression of inflammatory factors decreased in the SB334867 group. The administration of SB334867 was found to reverse the adverse effects of the HFD on body weight, depressive-like behaviour and anxiety-like mood. Furthermore, this treatment was associated with improvements in plasma biochemical levels and a reduction in the number of microglia in the brain. Conclusions: In summary, our results demonstrated that a HFD induced anxiety and depressive-like behaviors, which may be linked to the increased hypocretin-1 level and lipid accumulation. Supplementation with SB334867 improved the above. These observations highlight the possibility of hypocretin-1 inducing the risk of HFD-associated emotional dysfunctions.

From Perspective of Hippocampal Plasticity: Function of Antidepressant Chinese Medicine Xiaoyaosan

The hippocampus is one of the most commonly studied brain regions in the context of depression. The volume of the hippocampus is significantly reduced in patients with depression, which severely disrupts hippocampal neuroplasticity. However, antidepressant therapies that target hippocampal neuroplasticity have not been identified as yet. Chinese medicine (CM) can slow the progression of depression, potentially by modulating hippocampal neuroplasticity. Xiaoyaosan (XYS) is a CM formula that has been clinically used for the treatment of depression. It is known to protect Gan (Liver) and Pi (Spleen) function, and may exert its antidepressant effects by regulating hippocampal neuroplasticity. In this review, we have summarized the association between depression and aberrant hippocampal neuroplasticity. Furthermore, we have discussed the researches published in the last 30 years on the effects of XYS on hippocampal neuroplasticity in order to elucidate the possible mechanisms underlying its therapeutic action against depression. The results of this review can aid future research on XYS for the treatment of depression.

GDF11 improves hippocampal neurogenesis and cognitive abilities in diabetic mice by reducing neural inflammation

BACKGROUND

The cognitive decline associated with type 2 diabetes (T2D) is often attributed to compromised hippocampal neurogenesis and exacerbated neural inflammation. This study investigates the therapeutic potential of growth differentiation factor 11 (GDF11) in reversing these neurodegenerative processes in diabetic mice.

RESULT

We utilized a murine model of T2D and examined the effects of GDF11 on learning, memory, neurogenesis, and neuroinflammatory markers. Our results indicate that diabetic mice exhibit significant deficits in cognitive function, mirrored by reduced hippocampal neurogenesis and increased neuroinflammation. Chronic administration of GDF11 was observed to significantly enhance cognitive abilities, as evidenced by improved performance in learning and memory tasks. Concurrently, GDF11 treatment restored neural activity and promoted the regeneration of new neurons within the hippocampus. Inflammatory profiling revealed a reduction in neuroinflammatory markers, which was further supported by reduced microglia numbers. To delineate the role of neuroinflammation, we pharmacologically depleted microglia, leading to a restoration of neurogenesis and cognitive functions in diabetic mice.

CONCLUSION

These findings endorse the hypothesis that GDF11 exerts its beneficial effects by modulating neuroinflammatory pathways. Consequently, GDF11 represents a promising intervention to ameliorate diabetes-induced cognitive impairments and neural degeneration through its anti-inflammatory properties.

Can exercise benefits be harnessed with drugs? A new way to combat neurodegenerative diseases by boosting neurogenesis

Adult hippocampal neurogenesis (AHN) is affected by multiple factors, such as enriched environment, exercise, ageing, and neurodegenerative disorders. Neurodegenerative disorders can impair AHN, leading to progressive neuronal loss and cognitive decline. Compelling evidence suggests that individuals engaged in regular exercise exhibit higher production of proteins that are essential for AHN and memory. Interestingly, specific molecules that mediate the effects of exercise have shown effectiveness in promoting AHN and cognition in different transgenic animal models. Despite these advancements, the precise mechanisms by which exercise mimetics induce AHN remain partially understood. Recently, some novel exercise molecules have been tested and the underlying mechanisms have been proposed, involving intercommunications between multiple organs such as muscle-brain crosstalk, liver-brain crosstalk, and gut-brain crosstalk. In this review, we will discuss the current evidence regarding the effects and potential mechanisms of exercise mimetics on AHN and cognition in various neurological disorders. Opportunities, challenges, and future directions in this research field are also discussed.

Estrogen-immuno-neuromodulation disorders in menopausal depression

A significant decrease in estrogen levels puts menopausal women at high risk for major depression, which remains difficult to cure despite its relatively clear etiology. With the discovery of abnormally elevated inflammation in menopausal depressed women, immune imbalance has become a novel focus in the study of menopausal depression. In this paper, we examined the characteristics and possible mechanisms of immune imbalance caused by decreased estrogen levels during menopause and found that estrogen deficiency disrupted immune homeostasis, especially the levels of inflammatory cytokines through the ERα/ERβ/GPER-associated NLRP3/NF-κB signaling pathways. We also analyzed the destruction of the blood-brain barrier, dysfunction of neurotransmitters, blockade of BDNF synthesis, and attenuation of neuroplasticity caused by inflammatory cytokine activity, and investigated estrogen-immuno-neuromodulation disorders in menopausal depression. Current research suggests that drugs targeting inflammatory cytokines and NLRP3/NF-κB signaling molecules are promising for restoring homeostasis of the estrogen-immuno-neuromodulation system and may play a positive role in the intervention and treatment of menopausal depression.