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Chronic ketamine exposure results in psychotic and cognitive symptoms that resemble those found in patients with schizophrenia. Emerging evidence suggests that patients with schizophrenia exhibit gut microbiota dysbiosis and decreased levels of short-chain fatty acids (SCFAs) and BDNF, which are related to the severity of psychotic and cognitive symptoms. Dietary inulin can regulate gut microbiota, SCFAs, and BDNF. However, the role of gut microbiota, SCFAs, and BDNF in chronic ketamine-induced schizophrenia-like behaviors is unclear. In this study, we found that chronic ketamine exposure for 28 days caused gut microbiota dysregulation, reduced the expression of SCFAs in serum, hippocampus, and feces, elevated gut permeability, downregulated the BDNF-TrkB-ERK1/2-CREB signaling pathway, caused neuronal damage, and decreased the expression of synaptic proteins Syn and PSD-95, which may lead to anxiety-like behaviors, prepulse inhibition (PPI) deficits, and spatial learning and memory deficits. In addition, inulin intervention reversed gut microbiota dysbiosis by decreasing the abundance of Show less

Quercetin is a flavonoid bioactive compound with potential anti-depression effect. Dietary advanced glycation end products (AGEs) might be critically associated with depression. We aimed to explore whether quercetin ameliorates dietary AGEs-induced anxiety and depression-like behaviors in female mice, with a focus on hypothalamic-pituitary-adrenal axis (HPA) regulation and gut microbiota composition. Mice were divided into three groups: control, dietary AGEs, and AGEs plus quercetin. Dietary AGEs induced anxiety and depression-like behavioral effects, reduced BDNF, P-CREB, PSD95, doublecortin, and synaptophysin protein expression. Dietary AGEs induced HPA axis overactivation has been confirmed by decreased hippocampal GR, P-GR S211, and arginase-1, and elevated FKBP51, NLRP3, caspase-1, and p65 protein expression. Dietary AGEs resulted in gut microbiota disorder and correlation analysis revealed significant associations between Proteobacteria, the [Eubacterium] coprostanoligenes group, Klebsiella and Lachnospiraceae_NK4A136_group with behavioral parameters. Quercetin intervention improved dietary AGEs associated anxiety and depression-like behavioral effects via restoring HPA axis and gut microbiota. Show less

Resveratrol (RSV), a dietary polyphenol widely present in traditional medicinal plants and foods, exhibits antioxidant and anti-inflammatory properties that are relevant to ethnopharmacological strategies for protecting against environmental neurotoxicants. Given increasing real-world co-exposure to lead (Pb) and cadmium (Cd), elucidating RSV's capacity to preserve gut-brain axis (GBA) homeostasis has direct translational relevance for populations relying on phytochemical interventions. Sprague-Dawley rats were randomized into control, Pb-Cd model, and RSV treatment groups (10, 20, or 40 mg/kg). For 4 weeks, rats received Pb (300 mg/L) and Cd (50 mg/L) in drinking water with daily RSV. Cognitive function was assessed by Morris water maze; barrier integrity by Evans blue assay, histology, and Western blot for ZO-1/Occludin; synaptic ultrastructure by TEM; microbiota composition by 16S rRNA sequencing; and short-chain fatty acids (SCFAs) by GC-MS. Neurotransmitters (5-HT, GABA, SP, VIP) and cytokines (IL-6, IL-1β, TNF-α) were measured by ELISA. RSV improved spatial learning, reduced EB extravasation, preserved synaptic ultrastructure and proteins (BDNF, SYN, PSD-95), and restored intestinal architecture with increased ZO-1/Occludin. RSV attenuated cytokine release, normalized goblet cells, reversed dysbiosis by restoring Lactobacillaceae/Prevotellaceae, and increased acetate, propionate, and butyrate. It reinstated 5-HT and GABA while reducing SP and restoring VIP across serum, colon, and hippocampus. RSV attenuated Pb-Cd-associated neurotoxicity and was accompanied by improved intestinal and BBB-related readouts, partial normalization of gut microbiota features and SCFA levels, and preservation of synaptic and neurotransmitter-related markers, consistent with a link to gut-brain axis function. This study is among the first to test RSV in a Pb-Cd co-exposure model using a multi-dose regimen with integrated behavioral, barrier, microbial, and neurochemical endpoints. Show less

Substance use disorders (SUDs) present a global health challenge with high relapse rates. Emerging evidence implicates gut microbiota dysbiosis in SUD pathophysiology via the gut-brain axis. This 24-week randomized controlled trial investigated whether precision exercise interventions could modulate the gut microbiota-emotion axis to improve psychological outcomes in individuals undergoing compulsory drug rehabilitation. Thirty male participants were randomized to a precision exercise group (n = 15; individualized aerobic + resistance training, 4-5 sessions/week) or control group (n = 15; standard rehabilitation activities). Multi-dimensional assessments included weekly fecal (16S rRNA sequencing), urine (SCFAs via GC-MS), and saliva samples (cortisol, serotonin, BDNF via ELISA), alongside psychological evaluations (SCL-90-R, POMS) and physiological measures. The exercise group exhibited significant increases in gut microbial diversity (Shannon index: +18.2%, p < 0.001; Cohen's d = 2.14) and enrichment of beneficial taxa (e.g., Faecalibacterium, Bifidobacterium; LDA >3.5). Urinary SCFAs increased markedly (butyrate: 3.12-fold, p < 0.001), correlating with elevated salivary BDNF (+82%, p < 0.001) and reduced cortisol (-41.1%, p < 0.001). Psychological outcomes improved substantially: SCL-90-R Global Severity Index decreased by 43.3% (p < 0.001), and 78.6% of exercise participants achieved clinically meaningful improvement. Machine learning models predicted treatment response (AUC = 0.91) using baseline microbiome features. Precision exercise restores gut microbiota homeostasis, enhances neuroactive metabolite production, and improves emotional regulation in SUD recovery. The gut microbiota-emotion axis represents a viable target for non-pharmacological interventions, with microbiome profiles enabling personalized treatment strategies. Show less

Alzheimer's disease (AD) is increasingly recognized as a multisystem disorder shaped not only by central neurodegeneration but also by peripheral metabolic and immune dysregulation. Growing evidence highlights the gut microbiota and its metabolites as key modulators of amyloid accumulation, tau phosphorylation, neuroinflammation, and microglial dysfunction. This review aims to synthesize current advances on how plant-derived bioactive compounds modulate AD pathophysiology through microbiota-dependent metabolic and neuroimmune mechanisms, and to establish a systems-level framework linking botanical interventions to gut microbiota remodeling and metabolite signaling. A comprehensive literature survey was conducted using PubMed, Web of Science, ScienceDirect, and Google Scholar, covering publications from 2010 to 2026. Studies investigating gut microbiota, microbial metabolites, and plant-derived bioactive compounds in AD-related metabolic, immune, and neurodegenerative pathways were systematically reviewed and integrated. Plant-derived bioactive compounds, including phytochemicals, polysaccharides, and multi-herb formulations, interact extensively with the gut microbiota, undergoing microbial biotransformation to yield more active metabolites while simultaneously reshaping microbial community structure and metabolite profiles. These bidirectional interactions position the microbiota as a central mediator of plant-derived therapeutic activity. We summarize current evidence on how plant-derived compounds influence AD pathophysiology through microbiota-dependent metabolic and neuroimmune pathways. Major microbial metabolites, including short-chain fatty acids (SCFAs), trimethylamine N-oxide (TMAO), bile acids (BAs), and indole derivatives, are discussed, together with their regulatory roles in signaling networks such as nuclear factor κB (NF-κB), phosphatidylinositol 3-kinase/Akt (PI3K/Akt), cAMP response element-binding protein/brain-derived neurotrophic factor (CREB/BDNF), and triggering receptor expressed on myeloid cells 2 (TREM2)-associated microglial states. We further summarize evidence for synergistic strategies combining plant bioactives with probiotics and highlight advances in microbial biotransformation, precision metabolite modulation, and engineered microbial systems. Finally, future directions integrating multi-omics, personalized microbiota-guided interventions, and synthetic biology are outlined to support the development of targeted, mechanism-based therapies. By framing AD through a gut microbiota-centered perspective, this review provides a unified mechanistic foundation for the development of next-generation interventions based on plant-derived compounds and microbiota regulation. Show less

Semaglutide (SEM) is a glucagon-like peptide-1 (GLP-1) receptor agonist formulated for oral delivery with the absorption enhancer salcaprozate sodium (SNAC). Although oral SEM achieves 0.4-1% bioavailability through gastric epithelial uptake, gastrointestinal (GI) adverse events remain a major cause of therapy discontinuation. This study examined the effects of SEM (0.74 mg/kg/day), SNAC (22 mg/kg/day), and combined SEM-SNAC (1:33 w/w) treatments on microbiota and metabolic function, in healthy Sprague Dawley rats over 21 days. Whilst microbial α-diversity remained stable, SNAC significantly altered β-diversity (PERMANOVA, p < 0.05) and depleted primary fermenters in Muribaculaceae (-62%) and Bacteroidaceae (-77%) compared to the control group. These compositional changes correlated with reduced predicted saccharolytic enzyme abundance and fecal butyrate concentrations (-77% SNAC, -75% SEM-SNAC). Plasma cytokine analysis showed elevated tumor necrosis factor-α (TNF-α, 70%) and suppressed brain-derived neurotrophic factor (BDNF, 85%), consistent with changes in circulating inflammatory and neurotrophic markers from SNAC monotherapy. SNAC-treated animals also exhibited increased liver weight and reduced caecum mass, occurring alongside microbiota compositional changes and altered fermentation-associated markers. Spearman correlations linked Muribaculaceae and Bacteroidaceae loss with decreased saccharolytic enzyme abundance, lower SCFA levels, and increased TNF-α. While these findings are associative and require mechanistic validation, they indicate that chronic SNAC exposure is linked to concurrent microbial, metabolic, and inflammatory marker changes in healthy rats, highlighting the potential need for alternative, microbiota-safe strategies for oral peptide delivery. Show less

Aging triggers gut microbiota dysbiosis that disrupts the gut-brain axis (GBA), promoting neuroinflammation and neurodegeneration. Elderly exhibit reduced microbial diversity, depleted beneficial bacteria, and expanded pathobionts, elevating neurotoxic metabolites-lipopolysaccharides (LPS), trimethylamine-N-oxide, kynurenine derivatives, and secondary bile acids. These drive "inflammaging," blood-brain barrier breakdown, microglial activation, mitochondrial impairment, and proteinopathies in Alzheimer's and Parkinson's disease. Conversely, neuroprotective metabolites from commensals-short-chain fatty acids, indole-3-propionic acid, and urolithins-preserve gut integrity, suppress inflammation, upregulate BDNF for synaptic plasticity, and enhance mitophagy. Postbiotics, stable probiotic-derived bioactives (butyrate, polyphenol metabolites, and lactate derivatives), surpass live probiotics in safety and precision. They modulate GBA via histone deacetylase inhibition, GPR41/43 signaling, NF-κB blockade, and microglial M2 shift, blocking LPS translocation and bolstering neuronal resilience. Preclinical rodent studies demonstrate robust neuroprotection, but human translation reveals challenges: inter-individual microbiota variability (diet/genetics/comorbidities), inconsistent metabolite absorption/brain penetration between species, methodological limitations (16S rRNA vs. functional metagenomics), postbiotic standardization barriers, and sparse Phase I/II trials showing biomarker benefits without cognitive endpoints. This review synthesizes gut dysbiosis-metabolite-brain aging mechanisms, positioning postbiotics as precision therapeutics. Multi-omics stratified controlled trials are essential to validate long-term efficacy for delaying neurodegeneration and extending cognitive health. Show less

Type 2 diabetes has been linked to oxidative stress, inflammation, and an imbalance in the gut microbiota, all of which contribute to neuroinflammation and cognitive decline. Gut microbiota influence inflammation and produce various substances, including butyrate, a short-chain fatty acid that promotes brain-derived neurotrophic factor (BDNF), which is essential for memory. This study investigated whether prebiotics, probiotics, or a combination of both (symbiotics) could improve memory in diabetic rats. Male Wistar rats were divided into five groups: control; diabetic and obese (induced by a high-fat diet and streptozotocin); diabetic and obese with prebiotics (inulin); diabetic and obese with probiotics (Lactobacillus acidophilus); and diabetic and obese with symbiotics (inulin + L. acidophilus). Treatments lasted 42 d. Memory performance was evaluated using the Morris water maze (spatial memory) and the Eight-arm radial maze (working memory). After testing, hippocampal tissue was analyzed for inflammatory markers (TNF-α, IL-10), BDNF, and butyric acid. Diabetes impaired memory and increased neuroinflammatory markers. All supplemented groups showed improved memory. The symbiotic group exhibited the most pronounced benefits, with higher levels of BDNF, IL-10, and butyric acid, and reduced TNF-α. Electrophysiological recordings revealed that diabetes reduced the firing frequency of CA1 pyramidal cells and decreased the synaptic strength in the hippocampus. Symbiotic supplementation preserved these neuronal and synaptic functions. Symbiotic treatment effectively countered diabetes-induced cognitive deficits by reducing neuroinflammation, increasing neurotrophic support, and maintaining synaptic plasticity. These results imply that altering the gut microbiota through symbiotic supplementation may be an effective approach to prevent or mitigate diabetes-associated cognitive decline. Show less

Schisandrin C (SCC), a bioactive lignan compound derived from Schisandra chinensis (S. chinensis), has been demonstrated to promote intestinal health. However, the antidepressant activity of SCC and its impact on the gut‒brain axis have not been reported. This study aimed to investigate the antidepressant effects of SCC and elucidate its molecular mechanisms through modulation of the microbiota‒gut‒brain axis. Artificial intelligence (AI)-based target protein prediction, network pharmacology analysis, and experimental validation using intestinal cells, Caenorhabditis elegans, and mice models were conducted. Targeted metabolomics, gut microbiota analyses, and molecular biology techniques were employed for mechanistic elucidation. SCC treatment effectively suppressed depressive-like behaviors in mice subjected to chronic unpredictable mild stress (CUMS). SCC upregulated brain-derived neurotrophic factor (BDNF) expression in the brain by regulating the AKT/CREB/BDNF signaling pathway. Additionally, integrated network pharmacology, molecular docking, and metabolomics analyses revealed that SCC significantly increased brain serotonin levels by inhibiting monoamine oxidase (MAO) activity. Furthermore, SCC increased the abundance of Akkermansia and Bifidobacterium, as observed both in the synthetic microbial community in vitro and in the gut microbiota in vivo. Additionally, SCC effectively alleviated intestinal barrier dysfunction and reduced intestinal inflammation in vitro in intestinal cells, in vivo in C. elegans infected with Bacteroides fragilis, and in vivo in the CUMS-induced mice model. SCC improves depressive-like behaviors by modulating the microbiota‒gut‒brain axis. These findings underscore the potential of SCC as an effective therapeutic agent for depression. Show less

Electroconvulsive therapy (ECT) stands as the most effective intervention for treatment-resistant depression; however, its interaction with dietary regulation of the gut-brain axis has not been thoroughly explored. This study aimed to elucidate the mechanistic link between ECT, gut microbiota remodeling, short-chain fatty acid (SCFA) production, and neural plasticity. In this study, mice were subjected to chronic restraint stress (6 h/d for 28 consecutive days) to establish a depression-like model. Utilizing a translational approach that incorporated behavioral assessments, multimodal neuroimaging techniques such as PET-CT and laser speckle contrast imaging, along with multiomics analyses including metagenomics, metabolomics, and transcriptomics in rodent models, we demonstrated that ECT induced significant gut microbiota remodeling, characterized by an enrichment of SCFA-producing genera like Lactobacillus and Bifidobacterium. This remodeling was associated with restored intestinal barrier integrity and elevated plasma SCFA levels. Mechanistically, these microbial metabolites activated hippocampal Wnt/β-catenin signaling pathways, enhancing synaptic plasticity restoration, while concurrent probiotic supplementation further amplified brain-derived neurotrophic factor (BDNF) expression via SCFA-dependent epigenetic mechanisms. Neuroimaging corroborated the normalization of cerebral glucose metabolism and hemodynamic function post-ECT. In conclusion, our findings unveil a novel gut-brain communication pathway by which ECT exerts its antidepressant effects, positioning SCFAs as vital mediators connecting microbial metabolic alterations to neural plasticity. This research not only redefines the role of nutritional biochemistry in neuromodulation but also suggests the potential of microbial metabolite monitoring to tailor antidepressant therapies for enhanced efficacy. Show less

The gut microbiota plays a pivotal role in maintaining host health and has increasingly been linked to the pathogenesis of neurodegenerative diseases through the microbiota-gut-brain axis. Parkinson's disease (PD), characterized by dopaminergic dysfunction, neuro inflammation, and pathological alpha-synuclein (α-synuclein) aggregation, is frequently accompanied by gut microbial dysbiosis. Probiotics isolated from human infants could offer distinct neuroprotective and immunomodulatory benefits, yet their effects on integrated gut-brain axis models remain underexplored. In this study, we investigated the therapeutic potential of Lactobacillus acidophilus SLAM_LAA02 (L. acidophilus SLAM_LAA02), a novel infant-derived strain, in modulating PD-related behavioral and neuropathological features via modulation of the gut-brain axis. Following comprehensive safety and functional assessments, we first assessed L. acidophilus SLAM_LAA02 in Caenorhabditis elegans, where supplementation extended lifespan, enhanced antimicrobial defense, improved behavioral responses, and reduced α-synuclein expression in transgenic worms. We then evaluated its effects in a rotenone-induced mouse model that reflects early-stage PD-like features. L. acidophilus SLAM_LAA02 administration ameliorated motor dysfunction, modulated neuroinflammatory signaling, restored gut microbial diversity, and improved intestinal barrier-associated outcomes. These changes were accompanied by a notable reduction in α-synuclein expression and upregulated neuroprotective gene expression, including brain-derived neurotrophic factor (BDNF). Together, these findings suggest that L. acidophilus SLAM_LAA02 exhibits neuroprotective and gut-modulating properties across complementary model systems, supporting its potential as a promising probiotic candidate for alleviating early PD-related dysfunctions through the gut-brain axis. Show less

With the rapid progression of global population aging, the incidence of cognitive dysfunction-related disorders is steadily increasing. In recent years, growing attention has been directed toward the interaction between the gut microbiota and the central nervous system (CNS). The gut-brain axis (GBA), as a bidirectional communication pathway, plays an increasingly recognized role in regulating cognitive functions. Ganoderma lucidum polysaccharides (GLP), a traditional medicinal and edible substance, can regulate gut microbiota homeostasis and short-chain fatty acid (SCFAs) levels through the GBA. GLP reduces the Firmicutes/Bacteroidetes ratio, significantly increases the abundance of Lactobacillus, and further suppresses oxidative stress and inflammatory responses by controlling microglial overactivation and neuroinflammation, thereby enhancing the expression of synapse-associated proteins and brain-derived neurotrophic factor (BDNF). Consequently, GLP shows potential for improving cognitive dysfunction. This review systematically summarizes the bioactivities of GLP, explores the neurodegenerative mechanisms of aging, and proposes the possibility that GLP mitigates aging-induced inflammation and improves cognitive function via modulation of the gut microbiota. Show less