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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

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

Anxiety and depression are growing global burdens with limited drug options. Traditional Chinese medicine (TCM) offers unique advantages, including Roudoukou-Suanzaoren (RS), an ancient TCM-derived beverage with the potential for treating these conditions. This study aims to explore whether this combination improves the outcomes. The results show that the main constituents of RS include flavonoids, terpenoids, alkaloids, and phenylpropanoids. Behavioral and histopathological analyses demonstrate that RS alleviates chronic restraint stress (CRS)-induced anxiety- and depression-like behaviors and attenuates neuropathological damage in relevant brain regions; the underlying mechanism is likely mediated by the CREB/BDNF/TrkB signaling pathway. Meanwhile, RS reduces proinflammatory cytokines in tissues, decreases hippocampal microglial numbers, and increases astrocytes. Additionally, RS attenuates colonic injury, restores intestinal permeability, upregulates tight-junction proteins, and improves gut microbiota dysbiosis. This study highlights that RS exerts antianxiety and antidepression effects by modulating the gut microbiota, controlling inflammatory responses, and increasing BDNF levels through the "gut-brain axis" pathway. Show less

The global rise in mental health conditions has prompted interest in interventions that act beyond conventional psychopharmacology. Psychobiotics, broadly understood as live microorganisms or microbe-derived products that interact with the microbiota-gut-brain axis, have been suggested to exert neuroactive effects through neural, immune, endocrine and metabolic routes. This narrative review synthesizes recent preclinical, mechanistic and early clinical observations. Experimental studies show that selected strains can modulate cytokine signalling, influence stress-responsive systems such as the hypothalamic-pituitary-adrenal axis, and support synaptic plasticity via factors such as brain-derived neurotrophic factor. A limited number of human trials using well-characterized Lactobacillus and Bifidobacterium strains have reported improvements in affective and stress-related outcomes, but these effects are generally small to moderate, more apparent in adjunctive than stand-alone use, and dependent on strain, dose, population and intervention length (typically 4-12 weeks). Evidence on neurodevelopmental conditions (e.g., autism spectrum disorder, attention-deficit/hyperactivity disorder) remains preliminary, based on small and heterogeneous samples. Across studies, key constraints include methodological heterogeneity, incomplete strain-level reporting, and gaps in mechanistic resolution that make it difficult to link microbial shifts to psychiatric benefit. Emerging microbiome- and metabolomics-informed approaches may help identify likely responders and improve translational precision, but they are not yet ready for routine clinical application. Overall, psychobiotics should currently be viewed as a promising adjunct within integrative mental health care, warranting larger, standardized trials with clearly defined strains, doses and mechanistic 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

Tianwang Buxin Dan (TWBXD) is a classical Chinese formula traditionally prescribed to "nourish Yin, calm the mind and relieve bowel stagnation" in disorders characterized by heart-kidney disharmony, insomnia, anxiety, and constipation. However, the mechanistic basis associating its gut-regulating and emotion-modulating effects along the gut-brain axis remains unclear. To investigate whether TWBXD ameliorates functional constipation comorbid with emotional disturbances by modulating mitogen-activated protein kinase/Extracellular Signal-Regulated Kinase/c-Jun N-terminal Kinase (MAPK/ERK/JNK) signaling, hypothalamic-pituitary-adrenal (HPA)-axis activity, and autophagy-related mitochondrial integrity in the colon and hippocampus. A diphenoxylate-induced rat model of functional constipation with anxiety/depression-like behavior was treated with low, medium, or high doses of TWBXD. Intestinal transit, fecal parameters, and distal colonic transit were also assessed. Emotional behaviors were evaluated using open-field and elevated plus-maze tests. Colonic and hippocampal histopathology and ultrastructure were examined using hematoxylin and eosin staining, Nissl staining, and transmission electron microscopy. Serum corticotropin-releasing factor (CRF), adrenocorticotropic hormone (ACTH), and corticosterone (CORT) levels were measured using enzyme-linked immunosorbent assay. MAPK/ERK/JNK-related proteins and brain-derived neurotrophic factor (BDNF) were analyzed by Western blotting. The major chemical constituents of TWBXD were characterized using ultra-high-performance liquid chromatography-tandem mass spectrometry(UHPLC-MS/MS). TWBXD dose-dependently improved intestinal transit, fecal moisture, and body weight gain, and alleviated anxiety-/depression-like behaviors. TWBXD preserved colonic mucosal architecture and hippocampal neuronal integrity, mitigated mitochondrial swelling and excessive autophagic vacuole formation, downregulated colonic phosphorylated ERK (p-ERK), phosphorylated JNK, and phosphorylated p38, restored hippocampal BDNF expression while normalizing p-ERK levels, and reduced serum CRF, ACTH, and CORT levels. TWBXD exerts multi-target therapeutic effects on functional constipation with emotional disturbances by suppressing MAPK/ERK/JNK overactivation, normalizing HPA-axis hyperactivity, and protecting mitochondrial structure and autophagy along the gut-brain axis, providing mechanistic support for its traditional use in gut-brain-related disorders. 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

Post-cardiac surgery anxiety or depression (PCPAD) is a common neuropsychiatric complication following cardiovascular interventional procedures, which significantly increases the risk of adverse cardiovascular events and long-term mortality. Existing treatment strategies have limitations, and clinical needs remain unmet. The gut-brain axis (GBA) serves as a core network regulating neuroimmune and endocrine responses, and its imbalance involves key links such as intestinal flora dysbiosis and neuroimmune crosstalk disorders. It is closely related to the pathogenesis of this complication, providing a novel perspective for targeted interventions. This review aims to systematically clarify the mechanism of GBA in PCPAD, comprehensively explore therapeutic strategies targeting this axis, and focus on the intervention value and application potential of natural products. The study was designed and conducted in strict accordance with the PRISMA 2020 guidelines. Relevant literatures were searched from PubMed, Web of Science Core Collection, ScienceDirect, Embase, Cochrane Library, and CNKI databases from their inception to December 2025. Literatures focusing on GBA-related mechanisms of PCPAD or investigating the mechanisms and clinical applications of natural products targeting GBA for PCPAD treatment were included. Conference abstracts, case reports, duplicate publications, and other ineligible literatures were excluded. Through quality control strategies including double independent screening and verification, priority inclusion of high-credibility evidence, and data cross-validation, 168 eligible literatures were finally included. The composition and functions of GBA, its imbalance mechanisms, and the basic and clinical evidence of natural product-based interventions were systematically analyzed. Studies have shown that GBA imbalance is the core pathogenesis of PCPAD, among which the inflammatory cascade initiated by intestinal flora dysbiosis, abnormal activation of the neuroendocrine axis, disorder of immune-nerve crosstalk, and abnormal gene and epigenetic regulation are key pathological links. In summary, GBA imbalance, especially gut microbiota dysbiosis and neuroimmune interactions, plays a critical role in the pathogenesis of PCPAD. Natural products (including traditional Chinese medicine (TCM) monomers, TCM compound prescriptions, patented TCM drugs, and natural products from other plant sources worldwide) can exert therapeutic effects by synergistically regulating GBA homeostasis through multiple targets. Specifically, they include increasing the abundance of beneficial bacteria such as Bifidobacterium and Lactobacillus, promoting the production of anti-inflammatory metabolites such as short-chain fatty acids, repairing intestinal barrier function, inhibiting pro-inflammatory pathways such as NF-κB and NLRP3 inflammasome, and regulating the levels of neurotransmitters and neurotrophic factors such as 5-HT and BDNF. Basic and clinical studies have confirmed that these natural products have high biocompatibility and low toxic side effects, and are compatible with the safe medication needs of patients during the organ function recovery period after cardiac surgery. Several natural products have been proven to modulate GBA dysfunction, with potential for clinical therapeutic application. This review systematically elucidates a new paradigm of precise intervention for PCPAD via natural products that regulate GBA through multiple targets, addressing the limitation of traditional single-target therapies and providing a low-cost, easily promotable solution for clinical translation. Additionally, natural product-based interventions offer a novel approach for treating post-cardiac surgery complications. In the future, it is necessary to further conduct large-sample, multicenter clinical trials to clarify their mechanisms of action and standardized dosage regimens, strengthen toxicological research, facilitate the translation from basic research to clinical practice, and provide more precise therapeutic strategies for patients. Show less

Obesity is closely associated with cognitive dysfunction, and markedly increases the risk of developing neurodegenerative diseases. Currently, obesity-related cognitive impairment lacks effective therapeutic interventions. Shenling Baizhu Powder (SLBZ) is a classical formula used to strengthen the spleen and promote the ascent of clear qi in traditional Chinese medicine (TCM). According to the TCM, this formula has great potential for the treatment of obesity-related cognitive impairment. However, research on SLBZ has focused primarily on its gastrointestinal effects, leaving its neurocognitive mechanisms largely unexplored. This study aimed to elucidate the therapeutic mechanisms of SLBZ in obesity-related cognitive impairment. Obese mice were obtained by subjecting male mice to a 16-week high-fat diet (HFD, 60 kcal % fat). During the final four weeks of the study, a SLBZ decoction (10 and 20 g/kg/day) was administered orally. The mice were then subjected to two behavioral tests and a glucose tolerance test. To evaluate the therapeutic effects of HFD on metabolic dysregulation, neuroinflammation, and intestinal barrier impairment, a range of analytical techniques, including biochemical analysis, immunofluorescence, RT-qPCR, and Western blotting, were used. Subsequently, 16S rRNA gene sequencing and metabolomic profiling were used to detect changes in the gut microbes and metabolite levels. Finally, fecal microbiota transplantation was performed to assess the functional link between SLBZ remodeling of the gut microbiota, metabolic alterations, and hippocampal cognitive function. Our study demonstrated that HFD-fed mice developed significant cognitive impairment, supporting the notion that obesity adversely affects cognitive function. In the Morris water maze and open-field tests, SLBZ administration effectively ameliorated HFD-induced cognitive dysfunction. This improvement was accompanied by the restoration of the hippocampal synaptic ultrastructure and the recovery of the key synaptic proteins BDNF and PSD95. In agreement with this, SLBZ suppressed microglial activation and associated neuroinflammatory responses in HFD-fed mice. In the colon, SLBZ administration markedly alleviated HFD-induced gut barrier impairment, as evidenced by increased colonic mucus thickness and elevated expression of tight junction proteins, ZO-1, Occludin, and Claudin-1. Furthermore, SLBZ reduced endotoxin translocation and downregulated the expression of pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. Notably, HFD-induced gut microbiota dysbiosis was remodeled by the SLBZ treatment, which was characterized by an increased capacity for microbial vitamin B6 synthesis. SLBZ increased the serum levels of vitamin B6 in HFD-fed mice. Intriguingly, fecal microbiota transplantation from SLBZ-treated HFD-fed mice facilitated the amelioration of cognitive deficits, including superior performance in behavioral tests and synaptic repair in the hippocampus compared to recipients of HFD-microbiota. Our findings highlight that SLBZ is a promising therapeutic agent mitigating obesity-related cognitive impairment via the "gut microbiota-vitamin B6-neuroprotection" axis. Show less

The gut-brain axis represents a highly integrated communication network, connecting the gastrointestinal tract and the central nervous system via neural, immune, endocrine, and metabolic pathways. Steroid hormones, such as estrogens, androgens, and glucocorticoids, play a pivotal role in modulating these interactions across the lifespan. These hormones influence the composition of microbiota, intestinal permeability, and neuroimmune responses, thereby shaping brain function and behavior. Emerging evidence suggests a correlation between disruptions in the gut-brain axis and the onset and progression of neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, and multiple sclerosis. The diseases exhibit distinct sex-specific patterns in terms of prevalence, symptomatology, and progression. These patterns are often the consequence of differences in steroid hormone levels, receptor distribution, and immune responses. Despite these differences, the role of sex as a biological variable remains underrepresented in experimental and clinical research. This review synthesizes current evidence on how steroid hormones modulate gut-brain axis interactions and how these mechanisms contribute to neurodegeneration in a sex-specific manner. We highlight recent findings on hormonal regulation of the gut microbiome and its impact on neuroinflammation and neuronal vulnerability. This overview focuses not only on Parkinson's disease, in which genetic variations in the gene for brain-derived neurotrophic factor have been observed among others as triggers for dopaminergic neurodegeneration. In addition, Alzheimer's disease and multiple sclerosis are also considered, in which the prevalence of intestinal dysbiosis and impaired intestinal barrier function have been identified as significant influencing factors. This review provides a comprehensive framework for understanding the gender-specific neurobiology of gut-brain axis by integrating perspectives from the fields of endocrinology, neuroimmunology, and microbiome research. It is argued that a targeted investigation of the interactions between hormones and gut-brain axis is essential for the development of sex-specific therapeutic strategies for neurodegenerative diseases. Show less