Gut Microbiota-Induced Changes in β-Hydroxybutyrate Metabolism Are Linked to Altered Sociability and Depression in Alcohol Use Disorder

Ellagic acid ameliorates alcohol-induced cognitive and social dysfunction through the gut microbiota-mediated CCL21-CCR7 axis

Chronic alcohol consumption disrupts the balance of the gut microbiome, resulting in alcohol-induced cognitive and social dysfunction (AICSD), and serves as a primary etiological factor for early-onset dementia. Ellagic acid (EA) is a polyphenolic compound belonging to the ellagitannin family, showing potential as a dietary intervention for alleviating cognitive impairments. Nonetheless, the protective effects and underlying mechanisms of EA on AICSD remain unclear. In our study, we employed a multi-omics approach to elucidate the microbiome-mediated mechanism underlying the beneficial effects of EA on AICSD. Firstly, our findings demonstrate that EA significantly ameliorated cognitive and social behavioral deficits as well as neuroinflammation induced by alcohol. Moreover, RNA-seq analysis of hippocampi indicates that EA regulated the KEGG pathway of cytokine-cytokine receptor interaction signaling by downregulating the CCL21-CCR7 axis. Furthermore, we observed that EA effectively restored the dysbiosis of gut microbiota and their derived metabolites induced by chronic alcohol consumption. Strong connections were observed between EA-regulated genes, microbiota and metabolites. Finally, the causal relationship between the microbiome and behavioral changes was further confirmed through antibiotic treatment and fecal microbiota transplantation experiments. Overall, our study provides innovative evidence supporting the role of EA in improving AICSD via regulation of the cytokine-cytokine receptor interaction signaling pathway through the microbiota-mediated CCl21-CCR7 axis. These findings offer valuable insights into both EA-based interventions as well as microbial interventions against AICSD.

Interoception mediates the association between social support and sociability in patients with major depressive disorder

BACKGROUND

Interoception dysfunction has an important impact on the onset and development of major depressive disorder (MDD). Social support serves as a protective factor against MDD, and sociability also plays a significant role in this condition. These interconnected constructs-social support and sociability-play pivotal roles in MDD. However, no research on the mechanisms underlying the associations between social support and sociability, particularly the potential role of interoception, have been reported.

AIM

To investigate the mediating effect of interoception between social support and social ability and to explore the independent role of social support in sociability.

METHODS

The participants included 292 patients with MDD and 257 healthy controls (HCs). The patient health questionnaire 9, the multidimensional assessment of interoception awareness, version 2 (MAIA-2), the social support rating scale (SSRS), and the Texas social behavior inventory (TSBI) were used to assess depression, interoception, social support, and sociability, respectively. A mediation analysis model for the eight dimensions of interoception (noticing, not distracting, not worrying, attention regulation, emotional awareness, self-regulation, body listening, and trust), social support, and sociability were established to evaluate the mediating effects.

RESULTS

A partial correlation analysis of eight dimensions of the MAIA-2, SSRS, and TSBI scores, with demographic data as control variables, revealed pairwise correlations between the SSRS score and both the MAIA-2 score and TSBI score. In the major depression (MD) group, the SSRS score had a positive direct effect on the TSBI score, while the scores for body listening, emotional awareness, self-regulation, and trust in the MAIA-2C had indirect effects on the TSBI score. In the HC group, the SSRS score had a positive direct effect on the TSBI score, and the scores for attention regulation, emotional awareness, self-regulation, and trust in the MAIA-2C had indirect effects on the TSBI score. The proportion of mediators in the MD group was lower than that in the HC group.

CONCLUSION

Interoceptive awareness is a mediating factor in the association between social support and sociability in both HCs and depressed patients. Training in interoceptive awareness might not only help improve emotional regulation in depressed patients but also enhance their social skills and support networks.

The gut microbiota-oligodendrocyte axis: A promising pathway for modulating oligodendrocyte homeostasis and demyelination-associated disorders

The bidirectional regulation between the gut microbiota and brain, known as gut-brain axis, has received significant attention. The myelin sheath, produced by oligodendrocytes or Schwann cells, is essential for efficient nervous signal transmission and the maintenance of brain function. Growing evidence shows that both oligodendrogenesis and myelination are modulated by gut microbiota and its metabolites, and when dysbiosis occurs, changes in the microbiota composition and/or associated metabolites may impact developmental myelination and the occurrence of neurodevelopmental disabilities. Although the link between the microbiota and demyelinating disease such as multiple sclerosis has been extensively studied, our knowledge about the role of the microbiota in other myelin-related disorders, such as neurodegenerative diseases, is limited. Mechanistically, the microbiota-oligodendrocyte axis is primarily mediated by factors such as inflammation, the vagus nerve, endocrine hormones, and microbiota metabolites as evidenced by metagenomics, metabolomics, vagotomy, and morphological and molecular approaches. Treatments targeting this axis include probiotics, prebiotics, microbial metabolites, herbal bioactive compounds, and specific dietary management. In addition to the commonly used approaches, viral vector-mediated tracing and gene manipulation, integrated multiomics and multicenter clinical trials will greatly promote the mechanistic and interventional studies and ultimately, the development of new preventive and therapeutic strategies against gut-oligodendrocyte axis-mediated brain impairments. Interestingly, recent findings showed that microbiota dysbiosis can be induced by hippocampal myelin damage and is reversible by myelin-targeted drugs, which provides new insights into understanding how hippocampus-based functional impairment (such as in neurodegenerative Alzheimer's disease) regulates the peripheral homeostasis of microbiota and associated systemic disorders.

Effect of Lacticaseibacillus rhamnosus IDCC 3201 on irritable bowel syndrome with constipation: a randomized, double-blind, and placebo-controlled trial

Irritable bowel syndrome is a chronic disorder affecting the gastrointestinal tract, negatively impacting patients' quality of life. Here, we aimed to evaluate the effects of Lacticaseibacillus rhamnosus IDCC 3201 (RH 3201) on irritable bowel syndrome with constipation (IBS-C). In this randomised, double-blind, placebo-controlled trial, a total of 30 subjects with IBS-C were randomly assigned (1:1) to receive 8 weeks of probiotics administration or placebo. Concerning bowel activities, both irritant bowel movements and discomfort caused by constipation showed significant improvement with RH 3201 at 8 weeks. Symptoms including severity of abdominal bloating, frequency of abdominal bloating, and satisfaction of bowel habits based on the irritable bowel syndrome-severity scoring system also ameliorated in the probiotic group. Analysis of the fecal microbiome revealed that the abundance of Bacteroides cellulosilyticus and Akkermansia muciniphila was higher during the period of RH 3201 administration compared to the placebo. Untargeted metabolome analysis further suggested a correlation between specific metabolites, such as N-acetylornithine, xanthine, and 3-phenylpropionic acid, and the improvement of clinical symptoms. These results indicate that RH 3201 was effective in ameliorating IBS-C, potentially by enriching beneficial microbes and associated metabolites in the gut environment.

Phlorizin ameliorates cognitive and behavioral impairments via the microbiota-gut-brain axis in high-fat and high-fructose diet-induced obese male mice

The long-term high-fat, high-sugar diet exacerbates type 2 diabetes mellitus (T2DM)-related cognitive impairments. Phlorizin, a well-studied natural compound found in apples and other plants, is recognized for its bioactive properties, including modulation of glucose and lipid metabolism. Despite its established role in mitigating metabolic disorders, the neuroprotective effects of phlorizin, particularly against diabetes-related cognitive dysfunction, have not been fully elucidated. Therefore, the present study aimed to investigate the effect of dietary supplementation of phlorizin on high-fat and high-fructose diet (HFFD)-induced cognitive dysfunction and evaluate the crucial role of the microbiota-gut-brain axis. We found that dietary supplementation of phlorizin for 14 weeks effectively prevented glucolipid metabolism disorder, spatial learning impairment, and memory impairment in HFFD mice. In addition, phlorizin improved the HFFD-induced decrease in synaptic plasticity, neuroinflammation, and excessive activation of microglia in the hippocampus. Transcriptomics analysis shows that the protective effect of phlorizin on cognitive impairment was associated with increased expression of neurotransmitters and synapse-related genes in the hippocampus. Phlorizin treatment alleviated colon microbiota disturbance, mainly manifested by an increase in gut microbiota diversity and the abundance of short-chain fatty acid (SCFA)-producing bacteria. The level of microbial metabolites, including SCFA, inosine 5'-monophosphate (IMP), and D (-)-beta-hydroxybutyric acid (BHB) were also significantly increased after phlorizin treatment. Integrating multiomics analysis observed tight connections between phlorizin-regulated genes, microbiota, and metabolites. Furthermore, removal of the gut microbiota via antibiotics treatment diminished the protective effect of phlorizin against HFFD-induced cognitive impairment, underscoring the critical role of the gut microbiota in mediating cognitive behavior. Importantly, supplementation with SCFA and BHB alone mimicked the regulatory effects of phlorizin on cognitive function. Therefore, phlorizin shows promise as a potential nutritional therapy for addressing cognitive impairment associated with metabolic disorders. Further research is needed to explore its effectiveness in preventing and alleviating neurodegenerative diseases.

Prenatal Stress and Ethanol Exposure: Microbiota-Induced Immune Dysregulation and Psychiatric Risks

Changes in maternal gut microbiota due to stress and/or ethanol exposure can have lasting effects on offspring's health, particularly regarding immunity, inflammation response, and susceptibility to psychiatric disorders. The literature search for this review was conducted using PubMed and Scopus, employing keywords and phrases related to maternal stress, ethanol exposure, gut microbiota, microbiome, gut-brain axis, diet, dysbiosis, progesterone, placenta, prenatal development, immunity, inflammation, and depression to identify relevant studies in both preclinical and human research. Only a limited number of reviews were included to support the arguments. The search encompassed studies from the 1990s to the present. This review begins by exploring the role of microbiota in modulating host health and disease. It then examines how disturbances in maternal microbiota can affect the offspring's immune system. The analysis continues by investigating the interplay between stress and dysbiosis, focusing on how prenatal maternal stress influences both maternal and offspring microbiota and its implications for susceptibility to depression. The review also considers the impact of ethanol consumption on gut dysbiosis, with an emphasis on the effects of prenatal ethanol exposure on both maternal and offspring microbiota. Finally, it is suggested that maternal gut microbiota dysbiosis may be significantly exacerbated by the combined effects of stress and ethanol exposure, leading to immune system dysfunction and chronic inflammation, which could increase the risk of depression in the offspring. These interactions underscore the potential for novel mental health interventions that address the gut-brain axis, especially in relation to maternal and offspring health.

Zebrafish (Danio rerio) behavioral phenotypes are not underscored by different gut microbiomes

Although bold and shy behavioral phenotypes in zebrafish (Danio rerio) have been selectively bred and maintained over multiple generations, it is unclear if they are underscored by different gut microbiota. Using the microbiota-gut-brain concept, we examined the relationship between gut microbiota and the behavioral phenotypes within this model animal system to assess possible gut microbe-mediated effects on host behavior. To this end, we amplified and sequenced 16S rRNA gene amplicons from the guts of bold and shy zebrafish individuals using the Illumina Miseq platform. We did not record any significant differences in within-group microbial diversity nor between-group community composition of the two behavioral phenotypes. Interestingly, though not statistically different, we determined that the gut microbial community of the bold phenotype was dominated by Burkholderiaceae, Micropepsaceae, and Propionibacteriaceae. In contrast, the shy phenotype was dominated by Beijerinckaceae, Pirelullacaeae, Rhizobiales_Incertis_Sedis, and Rubinishaeraceae. The absence of any significant difference in gut microbiome profiles between the two phenotypes would suggest that in this species, there might exist a stable core gut microbiome, regardless of behavioral phenotypes, and possibly, a limited role for the gut microbiota in modulating this selected-for host behavior. This study characterized the gut microbiomes of distinct innate behavioral phenotypes of the zebrafish (that are not considered dysbiotic states) and did not rely on antibiotic or probiotic treatments to induce changes in behavior. Such studies are crucial to our understanding of the modulating impacts of the gut microbiome on normative animal behavior.

Associations Between Gut Microbiota and Alcohol Abuse: A Mendelian Randomisation and Bioinformatics Study

Alcohol abuse, also known as Alcohol Use Disorder (AUD), is a substance dependency psychiatric disorder. We aimed to establish a causal relationship between specific gut microbiota and alcohol abuse using Mendelian Randomisation (MR) and bioinformatics methods. We acquired summary data of genome-wide association studies (GWAS) for gut microbiota and alcohol abuse from the Mibiogen and Finngen databases, respectively. We conducted MR analyses using various methodologies and mapped the single nucleotide polymorphisms (SNPs) to genes via the FUMA GWAS platform. We further performed multiple enrichment analyses and a Multi-variable Mendelian Randomisation (MVMR) approach to examine whether gut microbiota influences alcohol abuse by modulating neurotransmitter-related amino acids. The MR analysis revealed an inverse relationship between the genus Eubacterium ventriosum group and the Porphyromonadaceae family with alcohol abuse. Gene enrichment analysis showed that these genes are expressed in brain tissue and are involved in addictive disorders, psychiatric conditions, immunological processes, neurotransmitter synthesis and synaptic regulation. MVMR analysis suggested that the Porphyromonadaceae family as well as genus Eubacterium ventriosum group may suppress alcohol abuse through the metabolism of neurotransmitter-related amino acids, especially Tryptophan. The MR analysis and bioinformatics investigations indicate that the genus Eubacterium ventriosum group and Porphyromonadaceae family confer a protective effect against alcohol abuse, potentially through the modulation of synaptic function.

Involvement of the gut microbiome-brain axis in alcohol use disorder

The human intestine is colonized by a variety of microorganisms that influence the immune system, the metabolic response, and the nervous system, with consequences for brain function and behavior. Unbalance in this microbial ecosystem has been shown to be associated with psychiatric disorders, and altered gut microbiome composition related to bacteria, viruses, and fungi has been well established in patients with alcohol use disorder. This review describes the gut microbiome-brain communication pathways, including the ones related to the vagus nerve, the inflammatory cytokines, and the gut-derived metabolites. Finally, the potential benefits of microbiota-based therapies for the management of alcohol use disorder, such as probiotics, prebiotics, and fecal microbiota transplantation, are also discussed.

The gut microbiome in alcohol use disorder and alcohol-associated liver disease: A systematic review of clinical studies

Evidence suggests that a relationship exists between the gut microbiome and the pathogenesis of alcohol use disorder (AUD) and alcohol-associated liver disease (AALD). This systematic review identified studies that investigated the gut microbiome in individuals with an AUD or an AALD. A search was conducted on October 27, 2022, in PubMed, Web of Science, and Embase databases. Fifty studies satisfied eligibility criteria. Most studies found evidence for gut dysbiosis in individuals with AUD and AALD. Microbiome intervention studies have mostly been conducted in AALD patients; fecal microbial transplant interventions show the most promise. Because most studies were conducted cross-sectionally, the causal relationship between the gut microbiome and alcohol use is unknown. Furthermore, almost all studies have been conducted in predominantly male populations, leaving critical questions regarding sex differences and generalizability of the findings. The study summaries and recommendations provided in this review seek to identify areas for further research and to highlight potential gut microbial interventions for treating AUD and AALD.

Role of the Microbiome and the Gut-Brain Axis in Alcohol Use Disorder: Potential Implication for Treatment Development

The gut microbiota is constituted by trillions of microorganisms colonizing the human intestine. Studies conducted in patients with alcohol use disorder (AUD) have shown altered microbial composition related to bacteria, viruses, and fungi.This review describes the communication pathways between the gut and the brain, including the ones related to the bacterial metabolites, the inflammatory cytokines, and the vagus nerve. We described in more detail the gut-derived metabolites that have been shown to be implicated in AUD or that could potentially be involved in the development of AUD due to their immune and/or neuroactive properties, including tryptophan-derivatives, tyrosine-derivatives, short chain fatty acids.Finally, we discussed the potential beneficial effects of microbiome-based therapies for AUD such as probiotics, prebiotics, postbiotic, and phage therapy.

Butyrate- and Beta-Hydroxybutyrate-Mediated Effects of Interventions with Pro- and Prebiotics, Fasting, and Caloric Restrictions on Depression: A Systematic Review and Meta-Analysis

To examine the butyrate- and beta-hydroxybutyrate (BHB)-modulated effects of pre- and probiotic interventions, fasting, and caloric restriction interventions, a systematic literature review was carried out with a subsequent meta-analysis. Three pre-and probiotic intervention randomized control trials (RCTs) were included in the meta-analysis. A significant increase in butyrate (standardized mean difference (SMD) [confidence interval (CI)] 0.34; [0.02-0.67]) and an improvement in depression scores (SMD [CI] 0.15, [-0.35-0.70]) through pre- and probiotic interventions were shown in the meta-analysis. The intervention duration of the included studies ranged from three days to four weeks, with the examined population being healthy adults. Butyrate was measured in either plasma or feces, and the depression score was obtained under the Swedish core affect scale, the hospital anxiety and depression scale (HADS), or the depression, anxiety, and stress scale-21 items (DASS-21). In addition to butyrate, the total SCFA concentration also seems to be positively associated with pre- and probiotic administration (SMD [CI] 0.55 [0.15-0.95]). Despite the significant short-chain fatty acid (SCFA) and butyrate concentration changes, no significant correlation between butyrate and depression or between SCFAs and depression could be shown through linear regression models. Nevertheless, the regression coefficient b1 = 1.57 (p = 0.17) for butyrate suggests a strong, positive connection between butyrate and depression. Additionally, three studies were qualitatively analyzed, examining fasting as an intervention and revealing a connection between fasting, BHB, and depression. The association between fasting, BHB, and depression or mood elevation appeared to be related to BHB concentrations, which may be due to the similar biochemical properties of BHB and butyrate. Furthermore, caloric restrictions as alternatives to fasting were proposed as potential long-term interventions.

Zebrafish (Danio rerio) behavioral phenotypes not underscored by different gut microbiota

Different animal behavioral phenotypes maintained and selectively bred over multiple generations may be underscored by dissimilar gut microbial community compositions or not have any significant dissimilarity in community composition. Operating within the microbiota-gut-brain axis framework, we anticipated differences in gut microbiome profiles between zebrafish (Danio rerio) selectively bred to display the bold and shy personality types. This would highlight gut microbe-mediated effects on host behavior. To this end, we amplified and sequenced a fragment of the 16S rRNA gene from the guts of bold and shy zebrafish individuals (n=10) via Miseq. We uncovered no significant difference in within-group microbial diversity nor between-group microbial community composition of the two behavioral phenotypes. Interestingly, though not statistically different, we determined that the gut microbial community of the bold phenotype was dominated by Burkholderiaceae, Micropepsaceae, and Propionibacteriaceae. In contrast, the shy phenotype was dominated by Beijerinckaceae, Pirelullacaeae, Rhizobiales_Incertis_Sedis, and Rubinishaeraceae. The absence of any significant difference in gut microbiota profiles between the two phenotypes would suggest that in this species, there might exist a stable "core" gut microbiome, regardless of behavioral phenotypes, and or possibly, a limited role for the gut microbiota in modulating this selected-for host behavior. This is the first study to characterize the gut microbial community of distinct innate behavioral phenotypes of the zebrafish (that are not considered dysbiotic states) and not rely on antibiotic or probiotic treatments to induce changes in behavior. Such studies are crucial to our understanding of the modulating impacts of the gut microbiome on normative animal behavior.

Modeling social cognition in alcohol use disorder: lessons from schizophrenia

A better understanding of social deficits in alcohol use disorder (AUD) has the potential to improve our understanding of the disorder. Clinical research shows that AUD is associated with interpersonal problems and the loss of a social network which impedes response to treatment. Translational research between animal models and clinical research may benefit from a discussion of the models and methods that currently guide research into social cognition in AUD. We propose that research in AUD should harness recent technological developments to improve ecological validity while maintaining experimental control. Novel methods allow us to parse naturalistic social cognition into tangible components, and to investigate previously neglected aspects of social cognition. Furthermore, to incorporate social cognition as a defining element of AUD, it is critical to clarify the timing of these social disturbances. Currently, there is limited evidence to distinguish factors that influence social cognition as a consequence of AUD, and those that precede the onset of the disorder. Both increasing the focus on operationalization of social cognition into objective components and adopting a perspective that spans the clinical spectrum will improve our understanding in humans, but also possibly increase methodological consistency and translational dialogue across species. This commentary underscores current challenges and perspectives in this area of research.

Standard rodent diets differentially impact alcohol consumption, preference, and gut microbiome diversity

Alcohol use disorder (AUD) is a complex and widespread disease with limited pharmacotherapies. Preclinical animal models of AUD use a variety of voluntary alcohol consumption procedures to recapitulate different phases of AUD, including binge alcohol consumption and dependence. However, voluntary alcohol consumption in mice is widely variable, making it difficult to reproduce results across labs. Accumulating evidence indicates that different brands of commercially available rodent chow can profoundly influence alcohol intake. In this study, we investigated the effects of three commercially available and widely used rodent diet formulations on alcohol consumption and preference in C57BL/6 J mice using the 24 h intermittent access procedure. The three brands of chow tested were LabDiet 5,001 (LD5001), LabDiet 5,053 (LD5053), and Teklad 2019S (TL2019S) from two companies (Research Diets and Envigo, respectively). Mice fed LD5001 and LD5053 displayed higher levels of alcohol consumption and preference compared to mice fed TL2019S. We also found that alcohol consumption and preference could be rapidly switched by changing the diet 48 h prior to alcohol administration. Sucrose, saccharin, and quinine preferences were not altered, suggesting that the diets did not alter sweet and bitter taste perception. We also found that mice fed LD5001 displayed increased quinine-resistant alcohol intake compared to mice fed TL2019S, suggesting that diets could influence the development of compulsive behaviors such as alcohol consumption. We profiled the gut microbiome of water- and alcohol-drinking mice that were maintained on different diets and found significant differences in bacterial alpha- and beta-diversities, which could impact the gut-brain axis signaling and alcohol consumption.

Impact of the gut microbiome composition on social decision-making

There is increasing evidence for the role of the gut microbiome in the regulation of socio-affective behavior in animals and clinical conditions. However, whether and how the composition of the gut microbiome may influence social decision-making in health remains unknown. Here, we tested the causal effects of a 7-week synbiotic (vs. placebo) dietary intervention on altruistic social punishment behavior in an ultimatum game. Results showed that the intervention increased participants' willingness to forgo a monetary payoff when treated unfairly. This change in social decision-making was related to changes in fasting-state serum levels of the dopamine-precursor tyrosine proposing a potential mechanistic link along the gut-microbiota-brain-behavior axis. These results improve our understanding of the bidirectional role body-brain interactions play in social decision-making and why humans at times act "irrationally" according to standard economic theory.

A gut (microbiome) feeling about addiction: Interactions with stress and social systems

In recent years, an increasing attention has given to the intricate and diverse connection of microorganisms residing in our gut and their impact on brain health and central nervous system disease. There has been a shift in mindset to understand that drug addiction is not merely a condition that affects the brain, it is now being recognized as a disorder that also involves external factors such as the intestinal microbiota, which could influence vulnerability and the development of addictive behaviors. Furthermore, stress and social interactions, which are closely linked to the intestinal microbiota, are powerful modulators of addiction. This review delves into the mechanisms through which the microbiota-stress-immune axis may shape drug addiction and social behaviors. This work integrates preclinical and clinical evidence that demonstrate the bidirectional communication between stress, social behaviors, substance use disorders and the gut microbiota, suggesting that gut microbes might modulate social stress having a significance in drug addiction.

Depression and hepatobiliary diseases: a bidirectional Mendelian randomization study

Background

More and more evidence suggests a close association between depression and hepatobiliary diseases, but its causal relationship is not yet clear.

Method

Using genome-wide association studies (GWAS) to summarize data, independent genetic variations associated with depression were selected as instrumental variables. Firstly, we designed a univariate Mendelian randomization (UVMR) analysis with two samples and simultaneously conducted reverse validation to evaluate the potential bidirectional causal relationship between depression and various hepatobiliary diseases. Secondly, we conducted a multivariate Mendelian randomization (MVMR) analysis on diseases closely related to depression, exploring the mediating effects of waist to hip ratio, hypertension, and daytime nap. The mediating effects were obtained through MVMR. For UVMR and MVMR, inverse variance weighted method (IVW) is considered the most important analytical method. Sensitivity analysis was conducted using Cochran'Q, MR Egger, and Leave-one-out methods.

Results

UVMR analysis showed that depression may increase the risk of non-alcoholic fatty liver disease (OR, 1.22; 95% CI, 1.03-1.46; p=0.0248) in liver diseases, while depression does not increase the risk of other liver diseases; In biliary and pancreatic related diseases, depression may increase the risk of cholelithiasis (OR, 1.26; 95% CI, 1.05-1.50; p=0.0120), chronic pancreatitis (OR, 1.61; 95% CI, 1.10-2.35; p=0.0140), and cholecystitis (OR, 1.23; 95% CI, 1.03-1.48; p=0.0250). In addition, through reverse validation, we found that non-alcoholic fatty liver disease, cholelithiasis, chronic pancreatitis, cholecystitis, or the inability to increase the risk of depression (p>0.05). The waist to hip ratio, hypertension, and daytime nap play a certain role in the process of depression leading to non-alcoholic fatty liver disease, with a mediating effect of 35.8%.

Conclusion

Depression is a susceptibility factor for non-alcoholic fatty liver disease, and the causal effect of genetic susceptibility to depression on non-alcoholic fatty liver disease is mediated by waist-hip ratio, hypertension, and daytime nap.

Artificial intelligence significantly facilitates development in the mental health of college students: a bibliometric analysis

Objective

College students are currently grappling with severe mental health challenges, and research on artificial intelligence (AI) related to college students mental health, as a crucial catalyst for promoting psychological well-being, is rapidly advancing. Employing bibliometric methods, this study aim to analyze and discuss the research on AI in college student mental health.

Methods

Publications pertaining to AI and college student mental health were retrieved from the Web of Science core database. The distribution of publications were analyzed to gage the predominant productivity. Data on countries, authors, journal, and keywords were analyzed using VOSViewer, exploring collaboration patterns, disciplinary composition, research hotspots and trends.

Results

Spanning 2003 to 2023, the study encompassed 1722 publications, revealing notable insights: (1) a gradual rise in annual publications, reaching its zenith in 2022; (2) Journal of Affective Disorders and Psychiatry Research emerged were the most productive and influential sources in this field, with significant contributions from China, the United States, and their affiliated higher education institutions; (3) the primary mental health issues were depression and anxiety, with machine learning and AI having the widest range of applications; (4) an imperative for enhanced international and interdisciplinary collaboration; (5) research hotspots exploring factors influencing college student mental health and AI applications.

Conclusion

This study provides a succinct yet comprehensive overview of this field, facilitating a nuanced understanding of prospective applications of AI in college student mental health. Professionals can leverage this research to discern the advantages, risks, and potential impacts of AI in this critical field.

Novel Techniques and Models for Studying the Role of the Gut Microbiota in Drug Metabolism

The gut microbiota, known as the second human genome, plays a vital role in modulating drug metabolism, significantly impacting therapeutic outcomes and adverse effects. Emerging research has elucidated that the microbiota mediates a range of modifications of drugs, leading to their activation, inactivation, or even toxication. In diverse individuals, variations in the gut microbiota can result in differences in microbe-drug interactions, underscoring the importance of personalized approaches in pharmacotherapy. However, previous studies on drug metabolism in the gut microbiota have been hampered by technical limitations. Nowadays, advances in biotechnological tools, such as microbially derived metabolism screening and microbial gene editing, have provided a deeper insight into the mechanism of drug metabolism by gut microbiota, moving us toward personalized therapeutic interventions. Given this situation, our review summarizes recent advances in the study of gut-microbiota-mediated drug metabolism and showcases techniques and models developed to navigate the challenges posed by the microbial involvement in drug action. Therefore, we not only aim at understanding the complex interaction between the gut microbiota and drugs and outline the development of research techniques and models, but we also summarize the specific applications of new techniques and models in researching gut-microbiota-mediated drug metabolism, with the expectation of providing new insights on how to study drug metabolism by gut microbiota.

Study of the Interactions between Muscle Fatty Acid Composition, Meat Quality-Related Genes and the Ileum Microbiota in Tibetan Sheep at Different Ages

The intestinal microbiota of ruminants is an important factor affecting animal production and health. Research on the association mechanism between the intestinal microbiota and meat quality of ruminants will play a positive role in understanding the formation mechanism of meat quality in ruminants and improving production efficiency. In this study, the fatty acid composition and content, expression of related genes, and structural characteristics of the ileum microbiota of ewes of Tibetan sheep at different ages (4 months, 1.5 years, 3.5 years, and 6 years) were detected and analyzed. The results revealed significant differences in fatty acid composition and content in the muscle of Tibetan sheep at different ages (p < 0.05); in addition, the content of MUFAs in the longissimus dorsi muscle and leg muscle was higher. Similarly, the expressions of muscle-related genes differed among the different age groups, and the expression of the LPL, SCD, and FABP4 genes was higher in the 1.5-year-old group. The ileum microbiota diversity was higher in the 1.5-year-old group, the Romboutsia abundance ratio was significantly higher in the 1.5-year-old group (p < 0.05), and there was a significant positive correlation with oleic acid (C18:1n9c) (p < 0.05). In conclusion, the content of beneficial fatty acids in the longissimus dorsi muscle and leg muscle of Tibetan sheep was higher at 1.5 years of age, and the best slaughter age was 1.5 years. This study provides a reference for in-depth research on the mechanism of the influence of the gut microbiota on meat quality and related regulation.

Gut microbiota-derived short-chain fatty acids and depression: deep insight into biological mechanisms and potential applications

The gut microbiota is a complex and dynamic ecosystem known as the 'second brain'. Composing the microbiota-gut-brain axis, the gut microbiota and its metabolites regulate the central nervous system through neural, endocrine and immune pathways to ensure the normal functioning of the organism, tuning individuals' health and disease status. Short-chain fatty acids (SCFAs), the main bioactive metabolites of the gut microbiota, are involved in several neuropsychiatric disorders, including depression. SCFAs have essential effects on each component of the microbiota-gut-brain axis in depression. In the present review, the roles of major SCFAs (acetate, propionate and butyrate) in the pathophysiology of depression are summarised with respect to chronic cerebral hypoperfusion, neuroinflammation, host epigenome and neuroendocrine alterations. Concluding remarks on the biological mechanisms related to gut microbiota will hopefully address the clinical value of microbiota-related treatments for depression.

Adolescence, the Microbiota-Gut-Brain Axis, and the Emergence of Psychiatric Disorders

Second only to early life, adolescence is a period of dramatic change and growth. For the developing young adult, this occurs against a backdrop of distinct environmental challenges and stressors. A significant body of work has identified an important role for the microbiota-gut-brain (MGB) axis in the development and function of the brain. Given that the MGB axis is both highly plastic during the teenage years and vulnerable to environmental stressors, more attention needs to be drawn to its potential role in the emergence of psychiatric illnesses, many of which first manifest during adolescence. Here, we review the current literature surrounding the developing microbiome, enteric nervous system, vagus nerve, and brain during the adolescent period. We also examine preclinical and clinical research involving the MGB axis during this dynamic developmental window and argue that more research is needed to further understand the role of the MGB in the pathogenesis of brain disorders. Greater understanding of the adolescent MGB axis will open up the exciting potential for new microbial-based therapeutics for the treatment of these often-refractory psychiatric illnesses.

Clinical and Preclinical Evidence for Gut Microbiome Mechanisms in Substance Use Disorders

Substance use disorders are a set of recalcitrant neuropsychiatric conditions that cause tremendous morbidity and mortality and are among the leading causes of loss of disability-adjusted life years worldwide. While each specific substance use disorder is driven by problematic use of a different substance, they all share a similar pattern of escalating and out-of-control substance use, continued use despite negative consequences, and a remitting/relapsing pattern over time. Despite significant advances in our understanding of the neurobiology of these conditions, current treatment options remain few and are ineffective for too many individuals. In recent years, there has been a rapidly growing body of literature demonstrating that the resident population of microbes in the gastrointestinal tract, collectively called the gut microbiome, plays an important role in modulating brain and behavior in preclinical and clinical studies of psychiatric disease. While these findings have not yet been translated into clinical practice, this remains an important and exciting avenue for translational research. In this review, we highlight the current state of microbiome-brain research within the substance use field with a focus on both clinical and preclinical studies. We also discuss potential neurobiological mechanisms underlying microbiome effects on models of substance use disorder and propose future directions to bring these findings from bench to bedside.

Fecal microbiota transplantation unveils sex-specific differences in a controlled cortical impact injury mouse model

Introduction

Contusion type of traumatic brain injury (TBI) is a major cause of locomotor disability and mortality worldwide. While post-TBI deleterious consequences are influenced by gender and gut dysbiosis, the sex-specific importance of commensal gut microbiota is underexplored after TBI. In this study, we investigated the impact of controlled cortical impact (CCI) injury on gut microbiota signature in a sex-specific manner in mice.

Methods

We depleted the gut microflora of male and female C57BL/6 mice using antibiotic treatment. Thereafter, male mice were colonized by the gut microbiota of female mice and vice versa, employing the fecal microbiota transplantation (FMT) method. CCI surgery was executed using a stereotaxic impactor (Impact One™). For the 16S rRNA gene amplicon study, fecal boli of mice were collected at 3 days post-CCI (dpi).

Results and discussion

CCI-operated male and female mice exhibited a significant alteration in the genera of Akkermansia, Alistipes, Bacteroides, Clostridium, Lactobacillus, Prevotella, and Ruminococcus. At the species level, less abundance of Lactobacillus helveticus and Lactobacillus hamsteri was observed in female mice, implicating the importance of sex-specific bacteriotherapy in CCI-induced neurological deficits. FMT from female donor mice to male mice displayed an increase in genera of Alistipes, Lactobacillus, and Ruminococcus and species of Bacteroides acidifaciens and Ruminococcus gnavus. Female FMT-recipient mice from male donors showed an upsurge in the genus Lactobacillus and species of Lactobacillus helveticus, Lactobacillus hamsteri, and Prevotella copri. These results suggest that the post-CCI neurological complications may be influenced by the differential gut microbiota perturbation in male and female mice.

Standard rodent diets differentially impact alcohol consumption and preference and gut microbiome diversity

Alcohol Use Disorder (AUD) is a complex and widespread disease with limited pharmacotherapies. Preclinical animal models of AUD use a variety of voluntary alcohol consumption procedures to recapitulate different phases of AUD including binge alcohol consumption and dependence. However, voluntary alcohol consumption in mice is widely variable rendering it difficult to reproduce results across labs. Accumulating evidence indicates that different brands of commercially available rodent chow can profoundly influence alcohol intake. In this study, we investigated the effects of three commercially available and widely used rodent diet formulations on alcohol consumption and preference in C57BL/6J mice using the 24h intermittent access procedure. The three brands of chow tested were LabDiet 5001 (LD 5001), LabDiet 5053 (LD 5053), and Teklad 2019S (TL2019S) from two companies (Research Diets and Envigo respectively). Mice fed LD5001 displayed the highest levels of alcohol consumption and preference followed by LD5053 and TL2019S. We also found that alcohol consumption and preference could be rapidly switched by changing the diet 48h prior to alcohol administration. Sucrose, saccharin, and quinine preference were not altered suggesting that the diets did not alter taste perception. We also found that mice fed LD5001 displayed increased quinine-resistant alcohol intake compared to mice fed TL2019S, suggesting that diets could influence the development of "compulsive" like alcohol consumption. We profiled the gut microbiome of water and alcohol drinking mice that were maintained on different diets and found significant differences in bacterial alpha and beta diversity, which could impact gut-brain axis signaling and alcohol consumption.

Gut-Liver-Brain Axis and Alcohol Use Disorder: Treatment Potential of Fecal Microbiota Transplantation

PURPOSE

Chronic alcohol use is a major cause of liver damage and death. In the United States, multiple factors have led to low utilization of pharmacotherapy for alcohol use disorder (AUD), including lack of provider knowledge and comfort in prescribing medications for AUD. Alcohol consumption has direct effects on the gut microbiota, altering the diversity of bacteria and leading to bacterial overgrowth. Growing evidence suggests that alcohol's effects on the gut microbiome may contribute to increased alcohol consumption and progression of alcohol-associated liver disease (ALD). This article reviews human and preclinical studies investigating the role of fecal microbiota transplantation (FMT) in ameliorating alcohol-associated alterations to the liver, gut, and brain resulting in altered behavior; it also discusses the therapeutic potential of FMT.

SEARCH METHODS

For this narrative review, a literature search was conducted in September 2022 of PubMed, Web of Science Core Collection, and Google Scholar to identify studies published between January 2012 and September 2022. Search terms used included "fecal microbiota transplantation" and "alcohol."

SEARCH RESULTS

Most results of the literature search were review articles or articles on nonalcoholic fatty liver disease; these were excluded. Of the remaining empirical manuscripts, very few described clinical or preclinical studies that were directly investigating the effects of FMT on alcohol drinking or related behaviors. Ultimately, 16 studies were included in the review.

DISCUSSION AND CONCLUSIONS

The literature search identified only a few studies that were directly investigating the effect of FMT on ALD or alcohol drinking and related behaviors. Largely proof-of-concept studies, these findings demonstrate that alcohol can alter the gut microbiome and that the microbiome can be transferred between humans and rodents to alter affective behaviors frequently associated with increased alcohol use. Other studies have shown promise of FMT or other probiotic supplementation in alleviating some of the symptoms associated with ALD and drinking. These results show that the implementation of FMT as a therapeutic approach is still in the investigatory stages.

Akkermansia muciniphila Improves Depressive-Like Symptoms by Modulating the Level of 5-HT Neurotransmitters in the Gut and Brain of Mice

Accumulating evidence has suggested that the gut microbiome plays an important role in depression. Akkermansia muciniphila (AKK), a next-generation probiotic, shows a beneficial effect on immune and metabolic homeostasis. The relative abundance of AKK was found negatively correlated with depressive symptoms in both clinical and pre-clinical studies. To evaluate the potential antidepressant effect of AKK and explore the possible mechanism, we used chronic alcohol exposure and chronic unpredictable mild stress (CUMS) to induce depressive-like behaviors in mice. We found that oral AKK administration significantly reduced the immobility time in the force swimming test (FST) and tail suspension test (TST) in the mice with chronic alcohol exposure and the CUMS mice. The sucrose preference in the mice receiving AKK was significantly increased in the sucrose preference test (SPT). More importantly, AKK implantation significantly increased the level of 5-HT in the gut and PFC of both the alcohol exposure mice and the CUMS mice. Furthermore, AKK had inhibited the expression of SERT in the gut but not in the brain for both NIAAA and the CUMS model mice. Interestingly, the expression of cFos in enteric nerves in the gut significantly decreased after AKK administration. In conclusion, our study demonstrated the antidepressant effect of AKK in mice exposed to alcohol exposure and CUMS, with the potential mechanism that AKK implantation might lead to an increased level of 5-HT and inhibited SERT expression in the gut, and might alter the gut-to-brain signal through suppression of enteric nerves activation.

Psychobiotics Regulate Purine Metabolism to Influence Host Emotional Behavior

Purine metabolism plays a pivotal role in numerous biological processes with potential implications for brain function and emotional regulation. This study utilizes gene-edited probiotics and pseudo-germ-free mice to unravel this intricate interplay. Transcriptomic analysis identified a ribonucleoside-diphosphate reductase β chain (nrdB) as a pivotal gene in purine metabolism within Bifidobacterium breve CCFM1025. Comparative evaluation between the wild-type and nrdB mutant strains revealed CCFM1025's effective reduction of xanthine and xanthosine levels in the serum and brain of stressed mice. Concomitantly, it downregulated the expression of the adenosine receptor gene (Adora2b) and inhibited the overactivation of microglia. These findings emphasize the potential of psychobiotics in modulating emotional responses by regulating purine metabolites and adenosine receptors. This study sheds light on novel pathways that influence emotional well-being through gut microbiota interactions and purine metabolic processes.

MUP1 mediates urolithin A alleviation of chronic alcohol-related liver disease via gut-microbiota-liver axis

Alcohol-related liver disease (ALD) is recognized as a global health crisis, contributing to approximately 20% of liver cancer-associated fatalities. Dysbiosis of the gut microbiome is associated with the development of ALD, with the gut microbial metabolite urolithin A (UA) exhibiting a potential for alleviating liver symptoms. However, the protective efficacy of UA against ALD and its underlying mechanism mediated by microbiota remain elusive. In this study, we provide evidence demonstrating that UA effectively ameliorates alcohol-induced metabolic disorders and hepatic endoplasmic reticulum (ER) stress through a specific gut-microbiota-liver axis mediated by major urinary protein 1 (MUP1). Moreover, UA exhibited the potential to restore alcohol-induced dysbiosis of the intestinal microbiota by enriching the abundance of Bacteroides sartorii (B. sartorii), Parabacteroides distasonis (P. distasonis), and Akkermansia muciniphila (A. muciniphila), along with their derived metabolite propionic acid. Partial attenuation of the hepatoprotective effects exerted by UA was observed upon depletion of gut microbiota using antibiotics. Subsequently, a fecal microbiota transplantation (FMT) experiment was conducted to evaluate the microbiota-dependent effects of UA in ALD. FMT derived from mice treated with UA exhibited comparable efficacy to direct UA treatment, as it effectively attenuated ER stress through modulation of MUP1. It was noteworthy that strong associations were observed among the hepatic MUP1, gut microbiome, and metabolome profiles affected by UA. Intriguingly, oral administration of UA-enriched B. sartorii, P. distasonis, and A. muciniphila can enhance propionic acid production to effectively suppress ER stress via MUP1, mimicking UA treatment. Collectively, these findings elucidate the causal mechanism that UA alleviated ALD through the gut-microbiota-liver axis. This unique mechanism sheds light on developing novel microbiome-targeted therapeutic strategies against ALD.

Intestinal microbiome dysbiosis in alcohol-dependent patients and its effect on rat behaviors

IMPORTANCE

Intestinal microbiome dysbiosis is associated with psychiatric disease through the "microbiota-gut-brain" axis. Here, we revealed that there was obvious intestinal microbiome (including bacterial and fungal) dysbiosis in alcohol-dependent patients. Alcohol consumption seriously disturbs the gut equilibrium between bacteria and fungi, reduces the interactions among bacterial-fungal trans-kingdom, and increases intestinal permeability. Gut microbiota should be considered as a whole to study the development of alcohol dependence. The gut microbiome of alcohol-dependent patients increased the anxiety- and depression-like behavior in rats. The gut microbiota dysbiosis may promote the development of alcohol dependence by regulating the endogenous cholecystokinin (CCK) and related receptors. Hence, regulating the balance of gut microbiota and the endogenous CCK may be a potential strategy for reducing the risk of relapse in alcohol addiction patients.

Microbiota-Induced Epigenetic Alterations in Depressive Disorders Are Targets for Nutritional and Probiotic Therapies

Major depressive disorder (MDD) is a complex disorder and a leading cause of disability in 280 million people worldwide. Many environmental factors, such as microbes, drugs, and diet, are involved in the pathogenesis of depressive disorders. However, the underlying mechanisms of depression are complex and include the interaction of genetics with epigenetics and the host immune system. Modifications of the gut microbiome and its metabolites influence stress-related responses and social behavior in patients with depressive disorders by modulating the maturation of immune cells and neurogenesis in the brain mediated by epigenetic modifications. Here, we discuss the potential roles of a leaky gut in the development of depressive disorders via changes in gut microbiota-derived metabolites with epigenetic effects. Next, we will deliberate how altering the gut microbiome composition contributes to the development of depressive disorders via epigenetic alterations. In particular, we focus on how microbiota-derived metabolites such as butyrate as an epigenetic modifier, probiotics, maternal diet, polyphenols, drugs (e.g., antipsychotics, antidepressants, and antibiotics), and fecal microbiota transplantation could positively alleviate depressive-like behaviors by modulating the epigenetic landscape. Finally, we will discuss challenges associated with recent therapeutic approaches for depressive disorders via microbiome-related epigenetic shifts, as well as opportunities to tackle such problems.

Research protocol of the efficacy of probiotics for the treatment of alcohol use disorder among adult males: A comparison with placebo and acceptance and commitment therapy in a randomized controlled trial

BACKGROUND AND AIM

Primarily, this study compares the efficacy of probiotic and acceptance and commitment therapy (ACT) in alleviating the severity of alcohol craving and alcohol use disorder (AUD) among patients who had undergo two weeks of in-patient detoxification. Secondarily, this study compares the efficacy of probiotic and ACT in mitigating the severity of comorbid depression and anxiety symptoms; decreasing serum level of pro-inflammatory cytokines, such as interleukin 1β (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor α (TNF-α); changing the event-related potential in electroencephalogram (EEG) and restoring microbiota flora in the gut of AUD patients.

METHODS AND ANALYSIS

Initially, during Phase I of the study, the serum level of IL-1β, IL-6 and TNF-α; ERP changes in the EEG and fecal microbiota content will be compared between 120 AUD patients and 120 healthy controls. Subsequently in Phase II of the study, 120 AUD patients will be randomized by stratified permuted block randomization into the probiotic, ACT and placebo groups in a 1:1:1 ratio. Participants in the probiotic and placebo groups will be administered one sachet per day of Lactobacillus spp. probiotic and placebo, respectively for 12 weeks. While those in the ACT group will receive one session per week of ACT for 8 weeks. Outcome measures will be administered at four timepoints, such as t0 = baseline assessment prior to intervention, t1 = 8 weeks after intervention began, t2 = 12 weeks after intervention and t3 = 24 weeks after intervention. Primary outcomes are the degrees of alcohol craving, alcohol withdrawal during abstinence and AUD. Secondary outcomes to be assessed are the severity of co-morbid depression and anxiety symptoms; the serum levels of IL-1β, IL-6 and TNF-α; changes in ERP and fecal microbiota content.

TRIAL REGISTRATION NUMBER

NCT05830708 (ClinicalTrials.gov). Registered on April 25, 2023.

Gut microbiota regulates circadian oscillation in hepatic ischemia-reperfusion injury-induced cognitive impairment by interfering with hippocampal lipid metabolism in mice

BACKGROUND

Hepatic ischemia-reperfusion injury (HIRI) is a common complication of liver surgery, which can lead to extrahepatic metabolic disorders, such as cognitive impairment. Recent observations have emphasized the critical effects of gut microbial metabolites in regulating the development of liver injury. Herein, we investigated the potential contribution of gut microbiota to HIRI-related cognitive impairment.

METHODS

HIRI murine models were established by ischemia-reperfusion surgery in the morning (ZT0, 08:00) and evening (ZT12, 20:00), respectively. Antibiotic-induced pseudo-germ-free mice were gavaged with fecal bacteria of the HIRI models. Behavioral test was used to assess cognitive function. 16S rRNA gene sequencing and metabolomics were used for microbial and hippocampal analysis.

RESULTS

Our results established that cognitive impairment caused by HIRI underwent diurnal oscillations; HIRI mice performed poorly on the Y-maze test and the novel object preference test when surgery occurred in the evening compared with the morning. In addition, fecal microbiota transplantation (FMT) from the ZT12-HIRI was demonstrated to induce cognitive impairment behavior. The specific composition and metabolites of gut microbiota were analyzed between the ZT0-HIRI and ZT12-HIRI, and bioinformatic analysis showed that the differential fecal metabolites were significantly enriched in lipid metabolism pathways. After FMT, the hippocampal lipid metabolome between the P-ZT0-HIRI and P-ZT12-HIRI groups was analyzed to reveal a series of lipid molecules with significant differences.

CONCLUSIONS

Our findings indicate that gut microbiota are involved in circadian differences of HIRI-related cognitive impairment by affecting hippocampal lipid metabolism.

Alcohol degradation, learning, and memory-enhancing effect of Acetobacter pasteurianus BP2201 in Caenorhabditis elegans model

AIMS

This study aimed to investigate the probiotic effects of Acetobacter pasteurianus BP2201, isolated from brewing mass, for the treatment of alcohol-induced learning and memory ability impairments in a Caenorhabditis elegans model.

METHODS AND RESULTS

Acetobacter pasteurianus BP2201 was examined for probiotic properties, including acid and bile salt resistance, ethanol degradation, antioxidant efficacy, hemolytic activity, and susceptibility to antibiotics. The strain displayed robust acid and bile salt tolerance, efficient ethanol degradation, potent antioxidant activity, and susceptibility to specific antibiotics. Additionally, in the C. elegans model, administering A. pasteurianus BP2201 significantly improved alcohol-induced learning and memory impairments.

CONCLUSIONS

Acetobacter pasteurianus BP2201 proves to be a promising candidate strain for the treatment of learning and memory impairments induced by alcohol intake.

Dissecting the Relationship Between Neuropsychiatric and Neurodegenerative Disorders

Neurodegenerative diseases (NDDs) and neuropsychiatric disorders (NPDs) are two common causes of death in elderly people, which includes progressive neuronal cell death and behavioral changes. NDDs include Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, and motor neuron disease, characterized by cognitive defects and memory impairment, whereas NPDs include depression, seizures, migraine headaches, eating disorders, addictions, palsies, major depressive disorders, anxiety, and schizophrenia, characterized by behavioral changes. Mounting evidence demonstrated that NDDs and NPDs share an overlapping mechanism, which includes post-translational modifications, the microbiota-gut-brain axis, and signaling events. Mounting evidence demonstrated that various drug molecules, namely, natural compounds, repurposed drugs, multitarget directed ligands, and RNAs, have been potentially implemented as therapeutic agents against NDDs and NPDs. Herein, we highlighted the overlapping mechanism, the role of anxiety/stress-releasing factors, cytosol-to-nucleus signaling, and the microbiota-gut-brain axis in the pathophysiology of NDDs and NPDs. We summarize the therapeutic application of natural compounds, repurposed drugs, and multitarget-directed ligands as therapeutic agents. Lastly, we briefly described the application of RNA interferences as therapeutic agents in the pathogenesis of NDDs and NPDs. Neurodegenerative diseases and neuropsychiatric diseases both share a common signaling molecule and molecular phenomenon, namely, pro-inflammatory cytokines, γCaMKII and MAPK/ERK, chemokine receptors, BBB permeability, and the gut-microbiota-brain axis. Studies have demonstrated that any alterations in the signaling mentioned above molecules and molecular phenomena lead to the pathophysiology of neurodegenerative diseases, namely, Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, and neuropsychiatric disorders, such as bipolar disorder, schizophrenia, depression, anxiety, autism spectrum disorder, and post-traumatic stress disorder.

Antidepressant-like Effects of Representative Types of Food and Their Possible Mechanisms

Depression is a mental disorder characterized by low mood, lack of motivation, negative cognitive outlook, and sleep problems. Suicide may occur in severe cases, although suicidal thoughts are not seen in all cases. Globally, an estimated 350 million individuals grapple with depression, as reported by the World Health Organization. At present, drug and psychological treatments are the main treatments, but they produce insufficient responses in many patients and fail to work at all in many others. Consequently, treating depression has long been an important topic in society. Given the escalating prevalence of depression, a comprehensive strategy for managing its symptoms and impacts has garnered significant attention. In this context, nutritional psychiatry emerges as a promising avenue. Extensive research has underscored the potential benefits of a well-rounded diet rich in fruits, vegetables, fish, and meat in alleviating depressive symptoms. However, the intricate mechanisms linking dietary interventions to brain function alterations remain largely unexplored. This review delves into the intricate relationship between dietary patterns and depression, while exploring the plausible mechanisms underlying the impact of dietary interventions on depression management. As we endeavor to unveil the pathways through which nutrition influences mental well-being, a holistic perspective that encompasses multidisciplinary strategies gains prominence, potentially reshaping how we approach and address depression.

Can we manage gut microbiome imbalances in patients with bipolar disorder with pharmacotherapy?

INTRODUCTION

A novel new area of exploration in the treatment of bipolar disorder is the gut brain axis. Studies have shown significant differences between the gut microbiome in those with bipolar disorder and those without the illness, as well as documented microbiome changes associated with the effects of bipolar pharmacotherapy and targeted microbial interventions. Although we have evidence suggesting the bi-directional relationship between the gut microbiome and psychiatric disorders, we are still unable to utilize this understanding clinically.

AREAS COVERED

We need to better understand the factors that impact the microbiome in this illness and vice versa.

EXPERT OPINION

Additionally, changes in gut microbiome in bipolar disorder might be used for biomarker identification with a potential to help in diagnosis and monitoring of the condition. It is an important area for further research and may provide improved therapeutic outcomes.

Alcohol, the gut microbiome, and liver disease

The microorganisms inhabiting our gastrointestinal tract are critical for human health. Chronic heavy alcohol use can modulate the composition and function of the gut microbiota, thereby exacerbating end-organ damage via the gut-brain axis and the gut-liver axis. In this review, we summarize the bacterial, fungal, and viral gut microbial compositional changes associated with alcohol use and alcohol-associated liver disease and discuss the mechanisms of action by which gut dysbiosis reinforces alcohol use behavior and liver inflammation and injury. We also highlight important pre-clinical and clinical trials that target gut microbial-specific mechanisms for the treatment of alcohol use disorder and alcohol-associated liver disease.

Ketogenic diet: a potential adjunctive treatment for substance use disorders

Substance use disorders (SUD) can lead to serious health problems, and there is a great interest in developing new treatment methods to alleviate the impact of substance abuse. In recent years, the ketogenic diet (KD) has shown therapeutic benefits as a dietary therapy in a variety of neurological disorders. Recent studies suggest that KD can compensate for the glucose metabolism disorders caused by alcohol use disorder by increasing ketone metabolism, thereby reducing withdrawal symptoms and indicating the therapeutic potential of KD in SUD. Additionally, SUD often accompanies increased sugar intake, involving neural circuits and altered neuroplasticity similar to substance addiction, which may induce cross-sensitization and increased use of other abused substances. Reducing carbohydrate intake through KD may have a positive effect on this. Finally, SUD is often associated with mitochondrial damage, oxidative stress, inflammation, glia dysfunction, and gut microbial disorders, while KD may potentially reverse these abnormalities and serve a therapeutic role. Although there is much indirect evidence that KD has a positive effect on SUD, the small number of relevant studies and the fact that KD leads to side effects such as metabolic abnormalities, increased risk of malnutrition and gastrointestinal symptoms have led to the limitation of KD in the treatment of SUD. Here, we described the organismal disorders caused by SUD and the possible positive effects of KD, aiming to provide potential therapeutic directions for SUD.

Epigenetic Aberrations in Major Psychiatric Diseases Related to Diet and Gut Microbiome Alterations

Nutrition and metabolism modify epigenetic signatures like histone acetylation and DNA methylation. Histone acetylation and DNA methylation in the central nervous system (CNS) can be altered by bioactive nutrients and gut microbiome via the gut-brain axis, which in turn modulate neuronal activity and behavior. Notably, the gut microbiome, with more than 1000 bacterial species, collectively contains almost three million functional genes whose products interact with millions of human epigenetic marks and 30,000 genes in a dynamic manner. However, genetic makeup shapes gut microbiome composition, food/nutrient metabolism, and epigenetic landscape, as well. Here, we first discuss the effect of changes in the microbial structure and composition in shaping specific epigenetic alterations in the brain and their role in the onset and progression of major mental disorders. Afterward, potential interactions among maternal diet/environmental factors, nutrition, and gastrointestinal microbiome, and their roles in accelerating or delaying the onset of severe mental illnesses via epigenetic changes will be discussed. We also provide an overview of the association between the gut microbiome, oxidative stress, and inflammation through epigenetic mechanisms. Finally, we present some underlying mechanisms involved in mediating the influence of the gut microbiome and probiotics on mental health via epigenetic modifications.

DNA Methylation in Alcohol Use Disorder

Excessive drinking damages the central nervous system of individuals and can even cause alcohol use disorder (AUD). AUD is regulated by both genetic and environmental factors. Genes determine susceptibility to alcohol, and the dysregulation of epigenome drives the abnormal transcription program and promotes the occurrence and development of AUD. DNA methylation is one of the earliest and most widely studied epigenetic mechanisms that can be inherited stably. In ontogeny, DNA methylation pattern is a dynamic process, showing differences and characteristics at different stages. DNA dysmethylation is prevalent in human cancer and alcohol-related psychiatric disorders, resulting in local hypermethylation and transcriptional silencing of related genes. Here, we summarize recent findings on the roles and regulatory mechanisms of DNA methylation, the development of methyltransferase inhibitors, methylation alteration during alcohol exposure at different stages of life, and possible therapeutic options for targeting methylation in human and animal studies.

Therapeutic strategies of small molecules in the microbiota-gut-brain axis for alcohol use disorder

The microbiota-gut-brain axis (MGBA) is important in maintaining the structure and function of the central nervous system (CNS) and is regulated by the CNS environment and signals from the peripheral tissues. However, the mechanism and function of the MGBA in alcohol use disorder (AUD) are still not completely understood. In this review, we investigate the underlying mechanisms involved in the onset of AUD and/or associated neuronal deficits and create a foundation for better treatment (and prevention) strategies. We summarize recent reports focusing on the alteration of the MGBA in AUD. Importantly, we highlight the properties of small-molecule short-chain fatty acids (SCFAs), neurotransmitters, hormones, and peptides in the MGBA and discusses their usage as therapeutic agents against AUD.

Detection and Quantification of Some Ethanol-Producing Bacterial Strains in the Gut of Mouse Model of Non-Alcoholic Fatty Liver Disease: Role of Metformin

Ethanol-producing dysbiotic gut microbiota could accelerate the progress of non-alcoholic fatty liver disease (NAFLD). Metformin demonstrated some benefits in NAFLD. In the present study, we tested the ability of metformin to modify ethanol-producing gut bacterial strains and, consequently, retard the progress of NAFLD. This 12-week study included forty mice divided into four groups (n = 10); normal diet, Western diet, Western diet with intraperitoneal metformin, and Western diet with oral metformin. Oral metformin has a slight advantage over intraperitoneal metformin in ameliorating the Western diet-induced changes in liver function tests and serum levels of different cytokines (IL-1β, IL-6, IL-17, and TNF-α). Changes in liver histology, fibrosis, lipid content, Ki67, and TNF-α were all corrected as well. Faecal ethanol contents were increased by the Western diet but did not improve after treatment with metformin although the numbers of ethanol-producing Klebsiella pneumoniae (K. pneumoniae) and Escherichia coli (E. coli) were decreased by oral metformin. Metformin did not affect bacterial ethanol production. It does not seem that modification of ethanol-producing K. pneumoniae and E. coli bacterial strains by metformin could have a significant impact on the therapeutic potentials of metformin in this experimental model of NAFLD.

Seeking the Psilocybiome: Psychedelics meet the microbiota-gut-brain axis

Moving towards a systems psychiatry paradigm embraces the inherent complex interactions across all levels from micro to macro and necessitates an integrated approach to treatment. Cortical 5-HT2A receptors are key primary targets for the effects of serotonergic psychedelics. However, the therapeutic mechanisms underlying psychedelic therapy are complex and traverse molecular, cellular, and network levels, under the influence of biofeedback signals from the periphery and the environment. At the interface between the individual and the environment, the gut microbiome, via the gut-brain axis, plays an important role in the unconscious parallel processing systems regulating host neurophysiology. While psychedelic and microbial signalling systems operate over different timescales, the microbiota-gut-brain (MGB) axis, as a convergence hub between multiple biofeedback systems may play a role in the preparatory phase, the acute administration phase, and the integration phase of psychedelic therapy. In keeping with an interconnected systems-based approach, this review will discuss the gut microbiome and mycobiome and pathways of the MGB axis, and then explore the potential interaction between psychedelic therapy and the MGB axis and how this might influence mechanism of action and treatment response. Finally, we will discuss the possible implications for a precision medicine-based psychedelic therapy paradigm.

Antioxidant and Anti-Inflammatory Effects of Carotenoids in Mood Disorders: An Overview

Depression has a multifactorial etiology comprising family history and unemployment. This review aims to summarize the evidence available for the antioxidant and anti-inflammatory effects of carotenoids in mood disorders. This review article’s methodologies were based on a search of the PubMed database for all linked published papers. Epidemiological studies indicate that a diet rich in vegetables, fruits, nuts, fish, and olive oil may prevent the development of depression. Antioxidant supplementation has been found to combat various stress-induced psychiatric disorders, including depression and anxiety. A growing body of evidence indicates that carotenoids have both antioxidant and anti-inflammatory. Studies also suggest that poor dietary intake, particularly low intakes of fruit and vegetables and high intakes of fast food and other convenience foods, may increase the risk of developing depression. Thus, dietary interventions have the potential to help mitigate the risk of mental health decline in both the general population and those with mood disorders. Considering that carotenoids have both antioxidant and anti-inflammatory effects, it is expected that they might exert a promising antidepressant effect. Nevertheless, further studies (including interventional and mechanistic studies) assessing the effect of carotenoids on preventing and alleviating depression symptoms are needed.

Gut microbiome is linked to functions of peripheral immune cells in transition cows during excessive lipolysis

BACKGROUND

Postpartum dairy cows experiencing excessive lipolysis are prone to severe immunosuppression. Despite the extensive understanding of the gut microbial regulation of host immunity and metabolism, its role during excessive lipolysis in cows is largely unknown. Herein, we investigated the potential links between the gut microbiome and postpartum immunosuppression in periparturient dairy cows with excessive lipolysis using single immune cell transcriptome, 16S amplicon sequencing, metagenomics, and targeted metabolomics.

RESULTS

The use of single-cell RNA sequencing identified 26 clusters that were annotated to 10 different immune cell types. Enrichment of functions of these clusters revealed a downregulation of functions in immune cells isolated from a cow with excessive lipolysis compared to a cow with low/normal lipolysis. The results of metagenomic sequencing and targeted metabolome analysis together revealed that secondary bile acid (SBA) biosynthesis was significantly activated in the cows with excessive lipolysis. Moreover, the relative abundance of gut Bacteroides sp. OF04 - 15BH, Paraprevotella clara, Paraprevotella xylaniphila, and Treponema sp. JC4 was mainly associated with SBA synthesis. The use of an integrated analysis showed that the reduction of plasma glycolithocholic acid and taurolithocholic acid could contribute to the immunosuppression of monocytes (CD14⁺MON) during excessive lipolysis by decreasing the expression of GPBAR1.

CONCLUSIONS

Our results suggest that alterations in the gut microbiota and their functions related to SBA synthesis suppressed the functions of monocytes during excessive lipolysis in transition dairy cows. Therefore, we concluded that altered microbial SBA synthesis during excessive lipolysis could lead to postpartum immunosuppression in transition cows. Video Abstract.

The Microbiome-Gut-Brain axis regulates social cognition & craving in young binge drinkers

BACKGROUND

Binge drinking is the consumption of an excessive amount of alcohol in a short period of time. This pattern of consumption is highly prevalent during the crucial developmental period of adolescence. Recently, the severity of alcohol use disorders (AUDs) has been linked with microbiome alterations suggesting a role for the gut microbiome in its development. Furthermore, a strong link has emerged too between microbiome composition and socio-emotional functioning across different disorders including AUD. The aim of this study was to investigate the potential link (and its predictive value) between alcohol-related altered microbial profile, social cognition, impulsivity and craving.

METHODS

Young people (N = 71) aged 18-25 reported their alcohol use and underwent a neuropsychological evaluation. Craving was measured at baseline and three months later. Diet was controlled for. Blood, saliva and hair samples were taken for inflammatory, kynurenine and cortisol analysis. Stool samples were provided for shotgun metagenomic sequencing and short-chain fatty acids (SCFAs) were measured.

FINDINGS

Binge drinking was associated with distinct microbiome alterations and emotional recognition difficulties. Associations were found for several microbiome species with emotional processing and impulsivity. Craving showed a strong link with alterations in microbiome composition and neuroactive potential over time.

INTERPRETATION

In conclusion, this research demonstrates alterations in the gut microbiome of young binge drinkers (BDs) and identifies early biomarkers of craving. Associations between emotional processing and microbiome composition further support the growing literature on the gut microbiome as a regulator of social cognition. These findings are of relevance for new gut-derived interventions directed at improving early alcohol-related alterations during the vulnerability period of adolescence.

FUNDING

C.C. and R.G-C. received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 754535. APC Microbiome Ireland is a research centre funded by Science Foundation Ireland (SFI), through the Irish Government's National Development Plan [grant no. SFI/12/RC/2273_P2]. J.F.C has research support from Cremo, Pharmavite, DuPont and Nutricia. He has spoken at meetings sponsored by food and pharmaceutical companies. G.C. has received honoraria from Janssen, Probi, and Apsen as an invited speaker; is in receipt of research funding from Pharmavite, Fonterra, Nestle and Reckitt; and is a paid consultant for Yakult, Zentiva and Heel pharmaceuticals. All the authors declare no competing interests.

Exploring the links between gut microbiota and excitatory and inhibitory brain processes in alcohol use disorder: A TMS study

While the impact of the gut microbiota on brain and behavior is increasingly recognized, human studies examining this question are still scarce. The primary objective of the current study was to explore the potential relationships between the gut microbiota composition, motor cortical excitability at rest and during inhibitory control, as well as behavioral inhibition, in healthy volunteers and in patients suffering from alcohol use disorder. Motor cortical excitability was examined using a range of transcranial magnetic stimulation (TMS) measures probed at rest, including the recruitment curve, short and long intracortical inhibition, and intracortical facilitation within the primary motor cortex. Moreover, TMS was applied during a choice reaction time task to assess changes in motor excitability associated with inhibitory control. Finally, behavioral inhibition was investigated using a neuropsychological task (anti-saccade). Overall, our results highlight several interesting correlations between microbial composition and brain measures. Hence, higher bacterial diversity, as well as higher relative abundances of UGC-002 and Christensenellaceae R-7 group were correlated with stronger changes in motor excitability associated with inhibitory control. Also, higher abundance of Anaerostipes was associated with higher level of corticospinal excitability. Finally, relative abundances of Bifidobacterium and Faecalibacterium were positively related to performance in the neuropsychological task, suggesting that they might have a positive impact on behavioral inhibition. Although correlation is not causation, the present study suggests that excitatory and inhibitory brain processes might be related to gut microbiota composition. This article is part of the Special Issue on 'Microbiome & the Brain: Mechanisms & Maladies'.