Neurotransmitters: The Critical Modulators Regulating Gut-Brain Axis

Norepinephrine may promote the progression of Fusobacterium nucleatum related colorectal cancer via quorum sensing signalling

Fusobacterium nucleatum (F. nucleatum) is closely correlated with tumorigenesis in colorectal cancer (CRC). We aimed to investigate the effects of host norepinephrine on the carcinogenicity of F. nucleatum in CRC and reveal the underlying mechanism. The results revealed that both norepinephrine and bacterial quorum sensing (QS) molecule auto-inducer-2 (AI-2) were positively associated with the progression of F. nucleatum related CRC (p < 0.01). In vitro studies, norepinephrine induced upregulation of QS-associated genes and promoted the virulence and proliferation of F. nucleatum. Moreover, chronic stress significantly increased the colon tumour burden of ApcMin/+ mice infected with F. nucleatum (p < 0.01), which was decreased by a catecholamine inhibitor (p < 0.001). Our findings suggest that stress-induced norepinephrine may promote the progression of F. nucleatum related CRC via bacterial QS signalling. These preliminary data provide a novel strategy for the management of pathogenic bacteria by targeting host hormones-bacterial QS inter-kingdom signalling.

Is the enteric nervous system a lost piece of the gut-kidney axis puzzle linked to chronic kidney disease?

The enteric nervous system (ENS) regulates numerous functional and immunological attributes of the gastrointestinal tract. Alterations in ENS cell function have been linked to intestinal outcomes in various metabolic, intestinal, and neurological disorders. Chronic kidney disease (CKD) is associated with a challenging intestinal environment due to gut dysbiosis, which further affects patient quality of life. Although the gut-related repercussions of CKD have been thoroughly investigated, the involvement of the ENS in this puzzle remains unclear. ENS cell dysfunction, such as glial reactivity and alterations in cholinergic signaling in the small intestine and colon, in CKD are associated with a wide range of intestinal pathways and responses in affected patients. This review discusses how the ENS is affected in CKD and how it is involved in gut-related outcomes, including intestinal permeability, inflammation, oxidative stress, and dysmotility.

Recombinant Interleukin - 2 2 Immunotherapy Ameliorates Inflammation and Promotes the Release of Monoamine Neurotransmitters in the Gut-Brain Axis of Schistosoma mansoni-Infected Mice

Recombinant interleukin-22 (rIL-22) has been reported as a protective agent in murine models of diseases driven by epithelial injury. Parasites have a circadian rhythm and their sensitivity to a certain drug may vary during the day. Therefore, this work aimed to investigate the effect of rIL-22 administration at different times of the day on the inflammation, oxidative status, and neurotransmitter release in the gut-brain axis of the Schistosoma mansoni-infected mice. Sixty male BALB/c mice aged six weeks weighing 25-30 g were divided into a control group (injected intraperitoneally with PBS), mice infected with 80 ± 10 cercariae of S. mansoni (infected group) then injected intraperitoneally with PBS, and rIL-22 treated groups. rIL-22 was administrated intraperitoneally (400 ng/kg) either at the onset or offset of the light phase for 14 days. IL-22 administration reduced the levels of IL-1β, tumor necrosis factor-alpha (TNF-α), nuclear factor kappa beta (NF-κβ), and enhanced the production of IL-22 and IL-17. The treatment with IL-22 increased glutathione (GSH) and reduced malondialdehyde (MDA) and nitric oxide (NO) levels both in the ileum and brain. The B-cell lymphoma 2 (BCL2) protein level in the ileum was diminished after IL-22 administration. Brain-derived neurotrophic factor (BDNF) and neurotransmitter release (serotonin, 5HT, norepinephrine, NE, dopamine, DA, Glutamate, Glu, and -amino butyric acid, GABA) were improved by rIL-22. In conclusion, rIL-22 showed promising immunotherapy for inflammation, oxidative damage, and neuropathological signs associated with schistosomiasis. The efficacy of IL-22 increased significantly upon its administration at the time of light offset.

Acute Response of Different High-Intensity Interval Training Protocols on Cardiac Auto-Regulation Using Wearable Device

The purpose of this study was to compare different high-intensity interval training (HIIT) protocols with different lengths of work and rest times for a single session (all three had identical work-to-rest ratios and exercise intensities) for cardiac auto-regulation using a wearable device. With a randomized counter-balanced crossover, 13 physically active young male adults (age: 19.4 years, BMI: 21.9 kg/m2) were included. The HIIT included a warm-up of at least 5 min and three protocols of 10 s/50 s (20 sets), 20 s/100 s (10 sets), and 40 s/200 s (5 sets), with intensities ranging from 115 to 130% Wattmax. Cardiac auto-regulation was measured using a non-invasive method and a wearable device, including HRV and vascular function. Immediately after the HIIT session, the 40 s/200 s protocol produced the most intense stimulation in R-R interval (Δ-33.5%), ln low-frequency domain (Δ-42.6%), ln high-frequency domain (Δ-73.4%), and ln LF/HF ratio (Δ416.7%, all p < 0.05) compared to other protocols of 10 s/50 s and 20 s/100 s. The post-exercise hypotension in the bilateral ankle area was observed in the 40 s/200 s protocol only at 5 min after HIIT (right: Δ-12.2%, left: Δ-12.6%, all p < 0.05). This study confirmed that a longer work time might be more effective in stimulating cardiac auto-regulation using a wearable device, despite identical work-to-rest ratios and exercise intensity. Additional studies with 24 h measurements of cardiac autoregulation using wearable devices in response to various HIIT protocols are warranted.

The Relationship between Canine Behavioral Disorders and Gut Microbiome and Future Therapeutic Perspectives

Canine behavioral disorders have become one of the most common concerns and challenging issues among dog owners. Thus, there is a great demand for knowledge about various factors affecting dogs' emotions and well-being. Among them, the gut-brain axis seems to be particularly interesting, especially since in many instances the standard treatment or behavioral therapies insufficiently improve animal behavior. Therefore, to face this challenge, the search for novel therapeutic methods is highly required. Existing data show that mammals' gut microbiome, immune system, and nervous system are in continuous communication and influence animal physiology and behavior. This review aimed to summarize and discuss the most important scientific evidence on the relationship between mental disorders and gut microbiota in dogs, simultaneously presenting comparable outcomes in humans and rodent models. A comprehensive overview of crucial mechanisms of the gut-brain axis is included. This refers especially to the neurotransmitters crucial for animal behavior, which are regulated by the gut microbiome, and to the main microbial metabolites-short-chain fatty acids (SCFAs). This review presents summarized data on gut dysbiosis in relation to the inflammation process within the organism, as well as the activation of the hypothalamic-pituitary-adrenal (HPA) axis. All of the above mechanisms are presented in this review in strict correlation with brain and/or behavioral changes in the animal. Additionally, according to human and laboratory animal studies, the gut microbiome appears to be altered in individuals with mental disorders; thus, various strategies to manipulate the gut microbiota are implemented. This refers also to the fecal microbiome transplantation (FMT) method, based on transferring the fecal matter from a donor into the gastrointestinal tract of a recipient in order to modulate the gut microbiota. In this review, the possible effects of the FMT procedure on animal behavioral disorders are discussed.

Cognition and gut microbiota in schizophrenia spectrum and mood disorders: A systematic review

FRILEUX, M., BOLTRI M. and al. Cognition and Gut microbiota in schizophrenia spectrum and mood disorders: a Systematic Review. NEUROSCI BIOBEHAV REV (1) 2024 Schizophrenia spectrum disorders and major mood disorders are associated with cognitive impairments. Recent studies suggest a link between gut microbiota composition and cognitive functioning. Here, we review the relationship between gut microbiota and cognition in these disorders. To do this, we conducted a systematic review, searching Cochrane Central Register of Controlled Trials, EBSCOhost, Embase, Pubmed, Scopus, and Web of Science. Studies were included if they investigated the relationship between gut microbiota composition and cognitive function through neuropsychological assessments in patients with bipolar, depressive, schizophrenia spectrum, and other psychotic disorders. Ten studies were identified. Findings underscore a link between gut dysbiosis and cognitive impairment. This relationship identified specific taxa (Haemophilus, Bacteroides, and Alistipes) as potential contributors to bolstered cognitive performance. Conversely, Candida albicans, Toxoplasma gondii, Streptococcus and Deinococcus were associated with diminished performance on cognitive assessments. Prebiotics and probiotics interventions were associated with cognitive enhancements, particularly executive functions. These results emphasize the role of gut microbiota in cognition, prompting further exploration of the underlying mechanisms paving the way toward precision psychiatry.

Gut Microbiota Metabolite Messengers in Brain Function and Pathology at a View of Cell Type-Based Receptor and Enzyme Reaction

The human gastrointestinal (GI) tract houses a diverse microbial community, known as the gut microbiome comprising bacteria, viruses, fungi, and protozoa. The gut microbiome plays a crucial role in maintaining the body's equilibrium and has recently been discovered to influence the functioning of the central nervous system (CNS). The communication between the nervous system and the GI tract occurs through a two-way network called the gut-brain axis. The nervous system and the GI tract can modulate each other through activated neuronal cells, the immune system, and metabolites produced by the gut microbiome. Extensive research both in preclinical and clinical realms, has highlighted the complex relationship between the gut and diseases associated with the CNS, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. This review aims to delineate receptor and target enzymes linked with gut microbiota metabolites and explore their specific roles within the brain, particularly their impact on CNS-related diseases.

Alleviating effect of vagus nerve cutting in Salmonella-induced gut infections and anxiety-like behavior via enhancing microbiota-derived GABA

The vagus nerve, a pivotal link within the gut-brain axis, plays a critical role in maintaining homeostasis and mediating communication between the gastrointestinal tract and the brain. It has been reported that gastrointestinal infection by Salmonella typhimurium (S. typhimurium) triggers gut inflammation and manifests as anxiety-like behaviors, yet the mechanistic involvement of the vagus nerve remains to be elucidated. In this study, we demonstrated that unilateral cervical vagotomy markedly attenuated anxiety-like behaviors induced by S. typhimurium SL1344 infection in C57BL/6 mice, as evidenced by the open field test and marble burying experiment. Furthermore, vagotomy significantly diminished neuronal activation within the nucleus of the solitary tract and amygdala, alongside mitigating aberrant glial cell activation in the hippocampus and amygdala. Additionally, vagotomy notably decreases serum endotoxin levels, counters the increase in splenic Salmonella concentration, and modulates the expression of inflammatory cytokines-including IL-6, IL-1β, and TNF-α-in both the gastrointestinal tract and brain, with a concurrent reduction in IL-22 and CXCL1 expression. This intervention also fostered the enrichment of beneficial gut microbiota, including Alistipes and Lactobacillus species, and augmented the production of gamma-aminobutyric acid (GABA) in the gut. Administration of GABA replicated the vagotomy's beneficial effects on reducing gut inflammation and anxiety-like behavior in infected mice. However, blockade of GABA receptors with picrotoxin abrogated the vagotomy's protective effects against gut inflammation, without influencing its impact on anxiety-like behaviors. Collectively, these findings suggest that vagotomy exerts a protective effect against infection by promoting GABA synthesis in the colon and alleviating anxiety-like behavior. This study underscores the critical role of the vagus nerve in relaying signals of gut infection to the brain and posits that targeting the gut-brain axis may offer a novel and efficacious approach to preventing gastrointestinal infections and associated behavioral abnormalities.

Stroke and Distal Organ Damage: Exploring Brain-Kidney Crosstalk

Stroke and kidney dysfunction represent significant public health challenges, yet the precise mechanisms connecting these conditions and their severe consequences remain unclear. Individuals experiencing chronic kidney disease (CKD) and acute kidney injury (AKI) are at heightened susceptibility to experiencing repeated strokes. Similarly, a reduced glomerular filtration rate is associated with an elevated risk of suffering a stroke. Prior strokes independently contribute to mortality, end-stage kidney disease, and cardiovascular complications, underscoring the pathological connection between the brain and the kidneys. In cases of AKI, various mechanisms, such as cytokine signaling, leukocyte infiltration, and oxidative stress, establish communication between the brain and the kidneys. The bidirectional relationship between stroke and kidney pathologies involves key factors such as uremic toxins, proteinuria, inflammatory responses, decreased glomerular filtration, impairment of the blood-brain barrier (BBB), oxidative stress, and metabolites produced by the gut microbiota. This review examines potential mechanisms of brain-kidney crosstalk underlying stroke and kidney diseases. It holds significance for comprehending multi-organ dysfunction associated with stroke and for formulating therapeutic strategies to address stroke-induced kidney dysfunction and the bidirectional pathological connection between the kidney and stroke.

Therapeutic potential of CBD in Autism Spectrum Disorder

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition characterized by persistent deficits in social communication and interaction, as well as restricted and repetitive patterns of behavior. Despite extensive research, effective pharmacological interventions for ASD remain limited. Cannabidiol (CBD), a non-psychotomimetic compound of the Cannabis sativa plant, has potential therapeutic effects on several neurological and psychiatric disorders. CBD interacts with the endocannabinoid system, a complex cell-signaling system that plays a crucial role in regulating various physiological processes, maintaining homeostasis, participating in social and behavioral processing, and neuronal development and maturation with great relevance to ASD. Furthermore, preliminary findings from clinical trials indicate that CBD may have a modulatory effect on specific ASD symptoms and comorbidities in humans. Interestingly, emerging evidence suggests that CBD may influence the gut microbiota, with implications for the bidirectional communication between the gut and the central nervous system. CBD is a safe drug with low induction of side effects. As it has a multi-target pharmacological profile, it becomes a candidate compound for treating the central symptoms and comorbidities of ASD.

Intestinal toxicity of Pb: Structural and functional damages, effects on distal organs and preventive strategies

Lead (Pb) is one of the most common heavy metal pollutants that possesses multi-organ toxicity. For decades, great efforts have been devoted to investigate the damage of Pb to kidney, liver, bone, blood cells and the central nervous system (CNS). For the common, dietary exposure is the main avenue of Pb, but our knowledge of Pb toxicity in gastrointestinal tract (GIT) remains quite insufficient. Importantly, emerging evidence has documented that gastrointestinal disorders affect other distal organs like brain and liver though gut-brain axis or gut-liver axis, respectively. This review focuses on the recent understanding of intestinal toxicity of Pb exposure, including structural and functional damages. We also review the influence and mechanism of intestinal toxicity on other distal organs, mainly concentrated on brain and liver. At last, we summarize the bioactive substances that reported to alleviate Pb toxicity, providing potential dietary intervention strategies to prevent or attenuate Pb toxicity.

Single-Cell Chromatin Accessibility Analysis Reveals Subgroup-Specific TF-NTR Regulatory Circuits in Medulloblastoma

Medulloblastoma (MB) stands as one of the prevalent malignant brain tumors among pediatric patients. Despite its prevalence, the intricate interplay between the regulatory program driving malignancy in MB cells and their interactions with the microenvironment remains insufficiently understood. Leveraging the capabilities of single-cell Assay for Transposase-Accessible Chromatin sequencing (scATAC-seq), the chromatin accessibility landscape is unveiled across 59,015 distinct MB cells. This expansive dataset encompasses cells belonging to discrete molecular subgroups, namely SHH, WNT, Group3, and Group4. Within these chromatin accessibility profiles, specific regulatory elements tied to individual subgroups are uncovered, shedding light on the distinct activities of transcription factors (TFs) that likely orchestrate the tumorigenesis process. Moreover, it is found that certain neurotransmitter receptors (NTRs) are subgroup-specific and can predict MB subgroup classification when combined with their associated transcription factors. Notably, targeting essential NTRs within tumors influences both the in vitro sphere-forming capability and the in vivo tumorigenic capacity of MB cells. These findings collectively provide fresh insights into comprehending the regulatory networks and cellular dynamics within MBs. Furthermore, the significance of the TF-NTR regulatory circuits is underscored as prospective biomarkers and viable therapeutic targets.

Gut microbial β-glucuronidases influence endobiotic homeostasis and are modulated by diverse therapeutics

Hormones and neurotransmitters are essential to homeostasis, and their disruptions are connected to diseases ranging from cancer to anxiety. The differential reactivation of endobiotic glucuronides by gut microbial β-glucuronidase (GUS) enzymes may influence interindividual differences in the onset and treatment of disease. Using multi-omic, in vitro, and in vivo approaches, we show that germ-free mice have reduced levels of active endobiotics and that distinct gut microbial Loop 1 and FMN GUS enzymes drive hormone and neurotransmitter reactivation. We demonstrate that a range of FDA-approved drugs prevent this reactivation by intercepting the catalytic cycle of the enzymes in a conserved fashion. Finally, we find that inhibiting GUS in conventional mice reduces free serotonin and increases its inactive glucuronide in the serum and intestines. Our results illuminate the indispensability of gut microbial enzymes in sustaining endobiotic homeostasis and indicate that therapeutic disruptions of this metabolism promote interindividual response variabilities.

Imaging Neurotransmitters with Small-Molecule Fluorescent Probes

Neurotransmitters play a crucial role in regulating communication between neurons within the brain and central nervous system. Thus, imaging neurotransmitters has become a high priority in neuroscience. This minireview focuses on recent advancements in the development of fluorescent small-molecule fluorescent probes for neurotransmitter imaging and applications of these probes in neuroscience. Innovative approaches for probe design are highlighted as well as attributes which are necessary for practical utility, with a view to inspiring new probe development capable of visualizing neurotransmitters.

How Diet and Lifestyle Can Fine-Tune Gut Microbiomes for Healthy Aging

Many physical, social, and psychological changes occur during aging that raise the risk of developing chronic diseases, frailty, and dependency. These changes adversely affect the gut microbiota, a phenomenon known as microbe-aging. Those microbiota alterations are, in turn, associated with the development of age-related diseases. The gut microbiota is highly responsive to lifestyle and dietary changes, displaying a flexibility that also provides anactionable tool by which healthy aging can be promoted. This review covers, firstly, the main lifestyle and socioeconomic factors that modify the gut microbiota composition and function during healthy or unhealthy aging and, secondly, the advances being made in defining and promoting healthy aging, including microbiome-informed artificial intelligence tools, personalized dietary patterns, and food probiotic systems.

Enteric Nervous System Alterations in Inflammatory Bowel Disease: Perspectives and Implications

The enteric nervous system (ENS), consisting of neurons and glial cells, is situated along the gastrointestinal (GI) tract's wall and plays a crucial role in coordinating digestive processes. Recent research suggests that the optimal functioning of the GI system relies on intricate connections between the ENS, the intestinal epithelium, the immune system, the intestinal microbiome, and the central nervous system (CNS). Inflammatory bowel disease (IBD) encompasses a group of chronic inflammatory disorders, such as Crohn's disease (CD) and ulcerative colitis (UC), characterized by recurring inflammation and damage to the GI tract. This review explores emerging research in the dynamic field of IBD and sheds light on the potential role of ENS alterations in both the etiology and management of IBD. Specifically, we delve into IBD-induced enteric glial cell (EGC) activation and its implications for persistent enteric gliosis, elucidating how this activation disrupts GI function through alterations in the gut-brain axis (GBA). Additionally, we examine IBD-associated ENS alterations, focusing on EGC senescence and the acquisition of the senescence-associated secretory phenotype (SASP). We highlight the pivotal role of these changes in persistent GI inflammation and the recurrence of IBD. Finally, we discuss potential therapeutic interventions involving senotherapeutic agents, providing insights into potential avenues for managing IBD by targeting ENS-related mechanisms. This approach might represent a potential alternative to managing IBD and advance treatment of this multifaceted disease.

Protein Kinase C (PKC) in Neurological Health: Implications for Alzheimer's Disease and Chronic Alcohol Consumption

Protein kinase C (PKC) is a diverse enzyme family crucial for cell signalling in various organs. Its dysregulation is linked to numerous diseases, including cancer, cardiovascular disorders, and neurological problems. In the brain, PKC plays pivotal roles in synaptic plasticity, learning, memory, and neuronal survival. Specifically, PKC's involvement in Alzheimer's Disease (AD) pathogenesis is of significant interest. The dysregulation of PKC signalling has been linked to neurological disorders, including AD. This review elucidates PKC's pivotal role in neurological health, particularly its implications in AD pathogenesis and chronic alcohol addiction. AD, characterised by neurodegeneration, implicates PKC dysregulation in synaptic dysfunction and cognitive decline. Conversely, chronic alcohol consumption elicits neural adaptations intertwined with PKC signalling, exacerbating addictive behaviours. By unravelling PKC's involvement in these afflictions, potential therapeutic avenues emerge, offering promise for ameliorating their debilitating effects. This review navigates the complex interplay between PKC, AD pathology, and alcohol addiction, illuminating pathways for future neurotherapeutic interventions.

The Improvement and Related Mechanism of Microecologics on the Sports Performance and Post-Exercise Recovery of Athletes: A Narrative Review

The diversity and functionality of gut microbiota may play a crucial role in the function of human motor-related systems. In addition to traditional nutritional supplements, there is growing interest in microecologics due to their potential to enhance sports performance and facilitate post-exercise recovery by modulating the gut microecological environment. However, there is a lack of relevant reviews on this topic. This review provides a comprehensive overview of studies investigating the effects of various types of microecologics, such as probiotics, prebiotics, synbiotics, and postbiotics, on enhancing sports performance and facilitating post-exercise recovery by regulating energy metabolism, mitigating oxidative-stress-induced damage, modulating immune responses, and attenuating bone loss. Although further investigations are warranted to elucidate the underlying mechanisms through which microecologics exert their effects. In summary, this study aims to provide scientific evidence for the future development of microecologics in athletics.

Neuromodulation and the Gut-Brain Axis: Therapeutic Mechanisms and Implications for Gastrointestinal and Neurological Disorders

The gut-brain axis (GBA) represents a complex, bidirectional communication network that intricately connects the gastrointestinal tract with the central nervous system (CNS). Understanding and intervening in this axis opens a pathway for therapeutic advancements for neurological and gastrointestinal diseases where the GBA has been proposed to play a role in the pathophysiology. In light of this, the current review assesses the effectiveness of neuromodulation techniques in treating neurological and gastrointestinal disorders by modulating the GBA, involving key elements such as gut microbiota, neurotrophic factors, and proinflammatory cytokines. Through a comprehensive literature review encompassing PubMed, Google Scholar, Web of Science, and the Cochrane Library, this research highlights the role played by the GBA in neurological and gastrointestinal diseases, in addition to the impact of neuromodulation on the management of these conditions which include both gastrointestinal (irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and gastroesophageal reflux disease (GERD)) and neurological disorders (Parkinson's disease (PD), Alzheimer's disease (AD), autism spectrum disorder (ASD), and neuropsychiatric disorders). Despite existing challenges, the ability of neuromodulation to adjust disrupted neural pathways, alleviate pain, and mitigate inflammation is significant in improving the quality of life for patients, thereby offering exciting prospects for future advancements in patient care.

Importance of good hosting: reviewing the bi-directionality of the microbiome-gut-brain-axis

Gut microorganisms have been shown to significantly impact on central function and studies that have associated brain disorders with specific bacterial genera have advocated an anomalous gut microbiome as the pathophysiological basis of several psychiatric and neurological conditions. Thus, our knowledge of brain-to-gut-to microbiome communication in this bidirectional axis seems to have been overlooked. This review examines the known mechanisms of the microbiome-to-gut-to-brain axis, highlighting how brain-to-gut-to-microbiome signaling may be key to understanding the cause of disrupted gut microbial communities. We show that brain disorders can alter the function of the brain-to-gut-to-microbiome axis, which will in turn contribute to disease progression, while the microbiome-to gut-to brain direction presents as a more versatile therapeutic axis, since current psychotropic/neurosurgical interventions may have unwanted side effects that further cause disruption to the gut microbiome. A consideration of the brain-to-gut-to-microbiome axis is imperative to better understand how the microbiome-gut-brain axis overall is involved in brain illnesses, and how it may be utilized as a preventive and therapeutic tool.

Dysregulated brain-gut axis in the setting of traumatic brain injury: review of mechanisms and anti-inflammatory pharmacotherapies

Traumatic brain injury (TBI) is a chronic and debilitating disease, associated with a high risk of psychiatric and neurodegenerative diseases. Despite significant advancements in improving outcomes, the lack of effective treatments underscore the urgent need for innovative therapeutic strategies. The brain-gut axis has emerged as a crucial bidirectional pathway connecting the brain and the gastrointestinal (GI) system through an intricate network of neuronal, hormonal, and immunological pathways. Four main pathways are primarily implicated in this crosstalk, including the systemic immune system, autonomic and enteric nervous systems, neuroendocrine system, and microbiome. TBI induces profound changes in the gut, initiating an unrestrained vicious cycle that exacerbates brain injury through the brain-gut axis. Alterations in the gut include mucosal damage associated with the malabsorption of nutrients/electrolytes, disintegration of the intestinal barrier, increased infiltration of systemic immune cells, dysmotility, dysbiosis, enteroendocrine cell (EEC) dysfunction and disruption in the enteric nervous system (ENS) and autonomic nervous system (ANS). Collectively, these changes further contribute to brain neuroinflammation and neurodegeneration via the gut-brain axis. In this review article, we elucidate the roles of various anti-inflammatory pharmacotherapies capable of attenuating the dysregulated inflammatory response along the brain-gut axis in TBI. These agents include hormones such as serotonin, ghrelin, and progesterone, ANS regulators such as beta-blockers, lipid-lowering drugs like statins, and intestinal flora modulators such as probiotics and antibiotics. They attenuate neuroinflammation by targeting distinct inflammatory pathways in both the brain and the gut post-TBI. These therapeutic agents exhibit promising potential in mitigating inflammation along the brain-gut axis and enhancing neurocognitive outcomes for TBI patients.

Effect of gut microbiome on serotonin metabolism: a personalized treatment approach

Several factors including diet, exercise, and medications influence the makeup of the resilient but adaptable gut microbiome. Bacteria in the gut have a significant role in the homeostasis of the neurotransmitter serotonin, also known as 5-hydroxytryptamine, involved in mood and behavior. The goal of the current work is to review the effect of the gut microbiome on serotonin metabolism, and how it can potentially contribute to the development of a personalized treatment approach for depression and anxiety. Bacterial strains provide innovative therapeutic targets that can be used for disorders, such as depression, that involve dysregulation of serotonin. Advances in bacterial genomic sequencing have increased the accessibility and affordability of microbiome testing, which unlocks a new targeted pathway to modulate serotonin metabolism by targeting the gut-brain axis. Microbiome testing can facilitate the recommendation of strain-specific probiotic supplements based on patient-specific microbial profiles. Several studies have shown that supplementation with probiotics containing specific species of bacteria, such as Bifidobacterium and Lactobacillus, can improve symptoms of depression. Further research is needed to improve the process and interpretation of microbiome testing and how to successfully incorporate testing results into guiding clinical decision-making. This targeted approach centered around the gut-brain axis can provide a novel way to personalize therapy for mental health disorders.

Inhibition of calcium-sensing receptor by its antagonist promotes gastrointestinal motility in a Parkinson's disease mouse model

BACKGROUND

The Calcium-sensing receptor (CaSR) participates in the regulation of gastrointestinal (GI) motility under normal conditions and might be involved in the regulation of GI dysmotility in patients with Parkinson's disease (PD).

METHODS

CaSR antagonist-NPS-2143 was applied in in vivo and ex vivo experiments to study the effect and underlying mechanisms of CaSR inhibition on GI dysmotility in the MPTP-induced PD mouse model.

FINDINGS

Oral intake of NPS-2143 promoted GI motility in PD mice as shown by the increased gastric emptying rate and shortened whole gut transit time together with improved weight and water content in the feces of PD mice, and the lack of influence on normal mice. Meanwhile, the number of cholinergic neurons, the proportion of serotonergic neurons, as well as the levels of acetylcholine and serotonin increased, but the numbers of nitrergic and tyrosine hydroxylase immunoreactive neurons, and the levels of nitric oxide synthase and dopamine decreased in the myenteric plexus in the gastric antrum and colon of PD mice in response to NPS-2143 treatment. Furthermore, the numbers of c-fos positive neurons in the nucleus tractus solitarius (NTS) and cholinergic neurons in the dorsal motor nucleus of the vagus (DMV) increased in NPS-2143 treated PD mice, suggesting the involvement of both the enteric (ENS) and central (CNS) nervous systems. However, ex vivo results showed that NPS-2143 directly inhibited the contractility of antral and colonic strips in PD mice via a non-ENS mediated mechanism. Further studies revealed that NPS-2143 directly inhibited the voltage gated Ca2+ channels, which might, at least in part, explain its direct inhibitory effects on the GI muscle strips.

INTERPRETATION

CaSR inhibition by its antagonist ameliorated GI dysmotility in PD mice via coordinated neuronal regulation by both ENS and CNS in vivo, although the direct effects of CaSR inhibition on GI muscle strips were suppressive.

The major histocompatibility complex participates in Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disease characterized by progressive loss of dopaminergic neurons in the substantia nigra and the aggregation of alpha-synuclein (α-syn). The central nervous system (CNS) has previously been considered as an immune-privileged area. However, studies have shown that the immune responses are involved in PD. The major histocompatibility complex (MHC) presents antigens from antigen-presenting cells (APCs) to T lymphocytes, immune responses will be induced. MHCs are expressed in microglia, astrocytes, and dopaminergic neurons. Single nucleotide polymorphisms in MHC are related to the risk of PD. The aggregated α-syn triggers the expression of MHCs by activating glia cells. CD4+ and CD8+ T lymphocytes responses and microglia activation are detected in brains of PD patients. In addiction immune responses further increase blood-brain barrier (BBB) permeability and T cell infiltration in PD. Thus, MHCs are involved in PD through participating in immune and inflammatory responses.

The Microbiome and Irritable Bowel Syndrome: An Emerging Hope for Treatment

Irritable bowel syndrome is a gastrointestinal disorder that affects 15%-20% of the US population. Its symptoms can have negative effects on a person's quality of life, and its treatment can be associated with high medical costs. An emerging area of irritable bowel syndrome research concerns the relationship between this condition and the gut microbiome. The purpose of this article is not only to review irritable bowel syndrome, and the role that the microbiome can play in its symptoms, but also to examine new emerging pathways that could blaze the trail for more individualized treatments. If equipped with this knowledge, gastrointestinal nurses and providers of care can be better prepared to help patients with irritable bowel syndrome in order to manage symptoms and improve their quality of life.

Long-term use of etomidate disrupts the intestinal homeostasis and nervous system in mice

Etomidate (ETO) is used as an anesthetic in surgery, but it is being abused in some populations. The damage caused by long-term intake of ETO to intestinal and brain functions is not yet clear, and it remains to be determined whether the drug affects the central nervous system through the gut-brain axis. This study aimed to investigate the neurotoxic and gastrointestinal effects of ETO at doses of 1 mg/kg and 3 mg/kg in mice over 14 consecutive days. The results showed that long-term injection of ETO led to drug resistance in mice, affecting their innate preference for darkness and possibly inducing dependence on ETO. The levels of 5-hydroxytryptamine in the brain, serum, and colon decreased by 37%, 51%, and 42% respectively, while the levels of γ-aminobutyric acid reduced by 38%, 52%, and 41% respectively. H&E staining revealed that ETO reduced goblet cells in the colon and damaged the intestinal barrier. The expression of tight junction-related genes Claudin4 and ZO-1 was downregulated. The intestinal flora changed, the abundance of Akkermansia and Lactobacillus decreased by 33% and 14%, respectively, while Klebsiella increased by 18%. TUNEL results showed that high-dose ETO increased apoptotic cells in the brain. The expression of Claudin1 in the brain was downregulated. Untargeted metabolomics analysis of the colon and brain indicated that ETO caused abnormalities in glycerophospholipid metabolism. Abnormal lipid metabolism might lead to the production or accumulation of lipotoxic metabolites, causing central nervous system diseases. ETO induced changes in the intestinal flora and metabolism, further affecting the central nervous system through the gut-brain axis. The study unveiled the detrimental effects on the brain and gastrointestinal system resulting from long-term intake of ETO, which holds significant implications for comprehending the adverse impact of ETO abuse on human health.

A microfluidic-based gut-on-a-chip model containing the gut microbiota of patients with depression reveals physiological characteristics similar to depression

The diverse commensal microbiome of the human intestine has been considered to play a central role in depression. However, no host-microbiota co-culture system has been developed for depression, which hinders the controlled study of the interaction between depression and gut microbiota. We designed and manufactured a microfluidic-based gut-on-a-chip model containing the gut microbiota of patients with depression (depression-on-gut-chip, DoGC), which enables the extended co-culture of viable aerobic human intestinal epithelial cells and anaerobic gut microbiota, and allows the direct study of interactions between human gut microbiota and depression. We introduced representative gut microbiota from individuals with depression into our constructed DoGC model, successfully recapitulating the gut microbiota structure of depressed patients. This further led to the manifestation of physiological characteristics resembling depression, such as reduced gut barrier function, chronic low-grade inflammatory responses and decreased neurotransmitter 5-HT levels. Metabolome analysis of substances in the DoGC revealed a significant increase in lipopolysaccharides and tyrosine, while hyodeoxycholic acid, L-proline and L-threonine were significantly reduced, indicating the occurrence of depression. The proposed DoGC can serve as an effective platform for studying the gut microbiota of patients with depression, providing important cues for their roles in the pathology of this condition and acting as a powerful tool for personalized medicine.

Roseburia intestinalis Supplementation Could Reverse the Learning and Memory Impairment and m6A Methylation Modification Decrease Caused by 27-Hydroxycholesterol in Mice

The abnormality in N6-methyladenosine (m6A) methylation is involved in the course of Alzheimer's disease (AD), while the intervention of 27-Hydroxycholesterol (27-OHC) can affect the m6A methylation modification in the brain cortex. Disordered gut microbiota is a key link in 27-OHC leading to cognitive impairment, and further studies have found that the abundance of Roseburia intestinalis in the gut is significantly reduced under the intervention of 27-OHC. This study aims to investigate the association of 27-OHC, Roseburia intestinalis in the gut, and brain m6A modification in the learning and memory ability injury. In this study, 9-month-old male C57BL/6J mice were treated with antibiotic cocktails for 6 weeks to sweep the intestinal flora, followed by 27-OHC or normal saline subcutaneous injection, and then Roseburia intestinalis or normal saline gavage were applied to the mouse. The 27-OHC level in the brain, the gut barrier function, the m6A modification in the brain, and the memory ability were measured. From the results, we observed that 27-OHC impairs the gut barrier function, causing a disturbance in the expression of m6A methylation-related enzymes and reducing the m6A methylation modification level in the brain cortex, and finally leads to learning and memory impairment. However, Roseburia intestinalis supplementation could reverse the negative effects mentioned above. This study suggests that 27-OHC-induced learning and memory impairment might be linked to brain m6A methylation modification disturbance, while Roseburia intestinalis, as a probiotic with great potential, could reverse the damage caused by 27-OHC. This research could help reveal the mechanism of 27-OHC-induced neural damage and provide important scientific evidence for the future use of Roseburia intestinalis in neuroprotection.

Peripheral neuronal activation shapes the microbiome and alters gut physiology

The gastrointestinal (GI) tract is innervated by intrinsic neurons of the enteric nervous system (ENS) and extrinsic neurons of the central nervous system and peripheral ganglia. The GI tract also harbors a diverse microbiome, but interactions between the ENS and the microbiome remain poorly understood. Here, we activate choline acetyltransferase (ChAT)-expressing or tyrosine hydroxylase (TH)-expressing gut-associated neurons in mice to determine effects on intestinal microbial communities and their metabolites as well as on host physiology. The resulting multi-omics datasets support broad roles for discrete peripheral neuronal subtypes in shaping microbiome structure, including modulating bile acid profiles and fungal colonization. Physiologically, activation of either ChAT+ or TH+ neurons increases fecal output, while only ChAT+ activation results in increased colonic contractility and diarrhea-like fluid secretion. These findings suggest that specific subsets of peripherally activated neurons differentially regulate the gut microbiome and GI physiology in mice without involvement of signals from the brain.

The emerging roles of microbiota-derived extracellular vesicles in psychiatric disorders

Major depressive disorder, schizophrenia, and bipolar disorder are three major psychiatric disorders that significantly impact the well-being and overall health of patients. Some researches indicate that abnormalities in the gut microbiota can trigger certain psychiatric diseases. Microbiota-derived extracellular vesicles have the ability to transfer bioactive compounds into host cells, altering signaling and biological processes, ultimately influencing the mental health and illness of the host. This review aims to investigate the emerging roles of microbiota-derived extracellular vesicles in these three major psychiatric disorders and discusses their roles as diagnostic biomarkers and therapies for these psychiatric disorders.

Novel LC-MS/MS Method for Simultaneous Determination of Monoamine Neurotransmitters and Metabolites in Human Samples

For the simultaneous determination of monoamine neurotransmitters (NTs) like dopamine, serotonin, noradrenaline, and epinephrine, and their metabolites (metanephrine, normetanephrine, 3-methoxytyramine, vanillylmandelic acid, 3,4-dihydroxyphenylacetic acid, homovanillic acid, and 5-hydroxyindoleacetic acid), a robust liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) was introduced as the analytical method. This analytical method proved to be accurate for the simultaneous measurement of the amounts of 11 NTs and their metabolites in biological samples. The method proved to be more efficient and better than the previously reported method in terms of precision, recovery, sample requirement, and extraction procedure. The reported method requires only 100 μL of blood and 200 μL of urine, and the extraction procedure requires acetonitrile precipitation, filtration, drying, and reconstitution in water. The separation of all analytes was performed on an C18 column (4.6 mm × 150 mm and 1.8 μm). A 10 min gradient elution program with a mobile phase consisting of phase A (0.2% formic acid in water) and phase B (methanol) was used. The positive ionization mode was used for the detection of all analytes in multiple reaction monitoring (MRM). The proposed method was validated with an internal standard and yielded lower limits of detection and quantification ranges of 0.0182-0.0797 ng/mL and 0.0553-0.2415 ng/mL, respectively, with a good linearity (R2) between 0.9959 and 0.9994. The recoveries ranged from 73.37% to 116.63% in blood and from 80.9% to 115.33% in urine. For the NTs and metabolites, the intra- and interday % CV were 0.24-9.36 and 0.85-9.67, respectively. The developed LC-MS/MS method was successfully used for the determination of trace amounts of endogenous compounds in human blood and urine samples.

The cancer-immune dialogue in the context of stress

Although there is little direct evidence supporting that stress affects cancer incidence, it does influence the evolution, dissemination and therapeutic outcomes of neoplasia, as shown in human epidemiological analyses and mouse models. The experience of and response to physiological and psychological stressors can trigger neurological and endocrine alterations, which subsequently influence malignant (stem) cells, stromal cells and immune cells in the tumour microenvironment, as well as systemic factors in the tumour macroenvironment. Importantly, stress-induced neuroendocrine changes that can regulate immune responses have been gradually uncovered. Numerous stress-associated immunomodulatory molecules (SAIMs) can reshape natural or therapy-induced antitumour responses by engaging their corresponding receptors on immune cells. Moreover, stress can cause systemic or local metabolic reprogramming and change the composition of the gastrointestinal microbiota which can indirectly modulate antitumour immunity. Here, we explore the complex circuitries that link stress to perturbations in the cancer-immune dialogue and their implications for therapeutic approaches to cancer.

A pro-inflammatory diet is associated with long-term depression and anxiety levels but not fatigue in people with multiple sclerosis

BACKGROUND

Multiple sclerosis is characterised by acute and chronic inflammation in the CNS. Diet may influence inflammation, and therefore MS outcomes.

OBJECTIVE

To determine whether the Dietary Inflammatory Index (DII®)) is associated with depression, anxiety, and fatigue in a prospective cohort of people with MS.

METHODS

People with a first clinical diagnosis of demyelination were followed over 10 years (n=223). DII and energy-adjusted DII (E-DIITM) scores were calculated from the dietary intake in the preceding 12 months measured by food frequency questionnaire. Depression and anxiety were assessed by the Hospital Anxiety and Depression Scale (HADS-A and HADS-D, respectively), and fatigue by the Fatigue Severity Scale.

RESULTS

A higher E-DII score was associated with higher levels of depression and anxiety five years later (e.g., highest vs lowest E-DII quartile, HADS-D score: β=2.23, 95%CI=0.98,3.48, p<0.001; HADS-A score: β=1.90, 95%CI=0.59,3.21, p<0.001). A cumulative E-DII score was associated with depression (p<0.01) and anxiety (p=0.05) at the 10-year review. No associations were seen for fatigue.

CONCLUSION

Our findings suggest that, in people with MS, a more pro-inflammatory diet may long-term adverse impact on depression and anxiety, but not fatigue.

A microfluidic chip for sustained oxygen gradient formation in the intestine ex vivo

The oxygen gradient across the intestine influences intestinal physiology and the microbial environment of the microbiome. The microbiome releases metabolites that communicate with enterochromaffin cells, neuronal cells, and resident immune cells to facilitate the bidirectional communication across the gut-brain axis. Measuring communication between various cell types within the intestine could provide essential information about key regulators of gut and brain health; however, the microbial environment of the intestine is heavily dependent on the physiological oxygen gradient that exists across the intestinal wall. Likewise, there exist a need for methods which enable real-time monitoring of intestinal signaling ex vivo yet this remains challenging due to the inability to adequately culture intestinal tissue ex vivo while also exposing the appropriate locations of the intestine for probe insertion and monitoring. Here, we designed and fabricated a 3D printed microfluidic device to maintain the oxygen gradient across precision cut murine intestinal slices with the capability to couple to external neurochemical recording techniques. The gradient is maintained from outlets below while allowing access to the slice from above for detection with fast scan cyclic voltammetry (FSCV) and carbon-fiber microelectrodes. A series of 11 outlet ports were designed to lay underneath the slice which were connected to channels to deliver oxygenated vs. deoxygenated media. Outlet ports were designed in an oval shape where deoxygenated media was delivered to the center of the slice and oxygenated media is delivered to the outer portion of the slice to mimic the location of oxygen across the intestine. An oxygen sensitive fluorescent dye, tris(2,2'-bipyridyl)dichlororuthenium(II), was used to characterize the tunability of the gradient. Viability of the tissue was confirmed by both fluorescence microscopy and FSCV. Additionally, we measured simultaneous serotonin and melatonin signaling with FSCV in the intestine for the first time. Overall, this chip provides a significant advance in our ability to culture intestinal slices ex vivo with the added benefit of direct access for measurements and imaging.

Gut bacteria-derived serotonin promotes immune tolerance in early life

The gut microbiota promotes immune system development in early life, but the interactions between the gut metabolome and immune cells in the neonatal gut remain largely undefined. Here, we demonstrate that the neonatal gut is uniquely enriched with neurotransmitters, including serotonin, and that specific gut bacteria directly produce serotonin while down-regulating monoamine oxidase A to limit serotonin breakdown. We found that serotonin directly signals to T cells to increase intracellular indole-3-acetaldehdye and inhibit mTOR activation, thereby promoting the differentiation of regulatory T cells, both ex vivo and in vivo in the neonatal intestine. Oral gavage of serotonin into neonatal mice resulted in long-term T cell-mediated antigen-specific immune tolerance toward both dietary antigens and commensal bacteria. Together, our study has uncovered an important role for specific gut bacteria to increase serotonin availability in the neonatal gut and identified a function of gut serotonin in shaping T cell response to dietary antigens and commensal bacteria to promote immune tolerance in early life.

Pathophysiology of acute lung injury in patients with acute brain injury: the triple-hit hypothesis

It has been convincingly demonstrated in recent years that isolated acute brain injury (ABI) may cause severe dysfunction of peripheral extracranial organs and systems. Of all potential target organs and systems, the lung appears to be the most vulnerable to damage after ABI. The pathophysiology of the bidirectional brain-lung interactions is multifactorial and involves inflammatory cascades, immune suppression, and dysfunction of the autonomic system. Indeed, the systemic effects of inflammatory mediators in patients with ABI create a systemic inflammatory environment ("first hit") that makes extracranial organs vulnerable to secondary procedures that enhance inflammation, such as mechanical ventilation (MV), surgery, and infections ("second hit"). Moreover, accumulating evidence supports the knowledge that gut microbiota constitutes a critical superorganism and an organ on its own, potentially modifying various physiological functions of the host. Furthermore, experimental and clinical data suggest the existence of a communication network among the brain, gastrointestinal tract, and its microbiome, which appears to regulate immune responses, gastrointestinal function, brain function, behavior, and stress responses, also named the "gut-microbiome-brain axis." Additionally, recent research evidence has highlighted a crucial interplay between the intestinal microbiota and the lungs, referred to as the "gut-lung axis," in which alterations during critical illness could result in bacterial translocation, sustained inflammation, lung injury, and pulmonary fibrosis. In the present work, we aimed to further elucidate the pathophysiology of acute lung injury (ALI) in patients with ABI by attempting to develop the "double-hit" theory, proposing the "triple-hit" hypothesis, focused on the influence of the gut-lung axis on the lung. Particularly, we propose, in addition to sympathetic hyperactivity, blast theory, and double-hit theory, that dysbiosis and intestinal dysfunction in the context of ABI alter the gut-lung axis, resulting in the development or further aggravation of existing ALI, which constitutes the "third hit."

Effects of continuous and pulse lead exposure on the swimming behavior of tadpoles revealed by brain-gut axis analysis

Lead (Pb) is present in aquatic environments with a continuous or pulse form due to the regular or irregular discharge of wastewater. These two modes of exposure result in different toxicological effects on aquatic animals. To compare the effects of Pb exposure mode on the swimming behavior of amphibian larvae, this study proposed a combination method to examine the brain-gut axis (gut bacteria, histopathology, metabolomics, and ethology) in order to evaluate the ecotoxic differences in Pelophylax nigromaculatus tadpoles (Gs 21-28) when exposed to continuous (CE100) versus pulse exposure (PE100) of environmental concentrations of Pb (100 μg/L). The results showed that: 1) CE100 significantly decreased the movement distance and swimming activity of the tadpoles compared to PE100 and the control, while there were no significant differences between the control group and PE100. 2) At the phyla level, compared to PE100, CE100 treatment significantly decreased the abundance of Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes and increased the abundance of Fusobacteria in the gut. At the genus level, compared to PE100, CE100 significantly increased the abundance of U114 and decreased the abundance of Anaerorhabdus, Exiguobacterium and Microbacterium. 3) Compared to PE100, CE100 changed the metabolites of the brain-gut axis pathway, such as quinolinic acid, L-valine, L-dopa, L-histidine, urocanic acid, L-threonine, γ-aminobutyric acid (GABA), L-glutamate (Glu), acetylcholine (Ach), L-tyrosine (Tyr), L-tryptophan (Trp), and levodopa (DOPA). 4) CE100 and PE100 played a repressive role in the histidine metabolism and tyrosine metabolism pathways and played a promoting role in the purine metabolism and pyrimidine metabolism pathways. This study provides a method for evaluating the toxic effects of heavy metal exposure via two different exposure modes (pulse versus continuous) which tadpoles may encounter in the natural environment from a combined study examining the brain-gut axis.

Role of the Gut Microbiome and Bacterial Amyloids in the Development of Synucleinopathies

Less than ten years ago, evidence began to accumulate about association between the changes in the composition of gut microbiota and development of human synucleinopathies, in particular sporadic form of Parkinson's disease. We collected data from more than one hundred and thirty experimental studies that reported similar results and summarized the frequencies of detection of different groups of bacteria in these studies. It is important to note that it is extremely rare that a unidirectional change in the population of one or another group of microorganisms (only an elevation or only a reduction) was detected in the patients with Parkinson's disease. However, we were able to identify several groups of bacteria that were overrepresented in the patients with Parkinson's disease in the analyzed studies. There are various hypotheses about the molecular mechanisms that explain such relationships. Usually, α-synuclein aggregation is associated with the development of inflammatory processes that occur in response to the changes in the microbiome. However, experimental evidence is accumulating on the influence of bacterial proteins, including amyloids (curli), as well as various metabolites, on the α-synuclein aggregation. In the review, we provided up-to-date information about such examples.

Neural, Anti-Inflammatory, and Clinical Effects of Transauricular Vagus Nerve Stimulation in Major Depressive Disorder: A Systematic Review

BACKGROUND

The discovery of effective treatments for major depressive disorder (MDD) may help target different brain pathways. Invasive vagus nerve stimulation (VNS) is an effective neuromodulation technique for the treatment of MDD; however, the effectiveness of the noninvasive technique, transauricular VNS (taVNS), remains unknown. Moreover, a mechanistic understanding of the neural effects behind its biological and therapeutic effects is lacking. This review aimed to evaluate the clinical evidence and the neural and anti-inflammatory effects of taVNS in MDD.

METHODS

Two searches were conducted using a systematic search strategy reviewed the clinical efficacy and neural connectivity of taVNS in MDD in humans and evaluated the changes in inflammatory markers after taVNS in humans or animal models of depression. A risk of bias assessment was performed in all human studies.

RESULTS

Only 5 studies evaluated the effects of taVNS in patients with depression. Although the studies demonstrated the efficacy of taVNS in treating depression, they used heterogeneous methodologies and limited data, thus preventing the conduct of pooled quantitative analyses. Pooled analysis could not be performed for studies that investigated the modulation of connectivity between brain areas; of the 6 publications, 5 were based on the same experiment. The animal studies that analyzed the presence of inflammatory markers showed a reduction in the level of pro-inflammatory cytokines or receptor expression.

CONCLUSIONS

Data on the clinical efficacy of taVNS in the treatment of MDD are limited. Although these studies showed positive results, no conclusions can be drawn regarding this topic considering the heterogeneity of these studies, as in the case of functional connectivity studies. Based on animal studies, the application of taVNS causes a decrease in the level of inflammatory factors in different parts of the brain, which also regulate the immune system. Therefore, further studies are needed to understand the effects of taVNS in patients with MDD.

Chemical structures, biological activities, and medicinal potentials of amine compounds detected from Aloe species

Unrestricted interest in Aloe species has grown rapidly, and a lot of research is currently being done to learn more about the properties of the various Aloe constituents. Organic compounds containing amine as functional group are present in a vivid variety of compounds, namely, amino acids, hormones, neurotransmitters, DNA, alkaloids, dyes, etc. These compounds have amine functional groups that have various biological activities, which make them responsible for medicinal potential in the form of pharmaceutical, nutraceutical, and cosmeceutical applications. Consequently, the present review work provides an indication of the amines investigated in Aloe species and their therapeutic uses. Various amine compounds of the Aloe species have effective biological properties to treat diseases. Generally, the genus Aloe has various active amine-containing compounds to combat diseases when humans use them in various forms.

Pharmacogenetics of selective serotonin reuptake inhibitors (SSRI): A serotonin reuptake transporter (SERT)-based approach

Neuropsychiatric disorders are considered to be the most common cause of disability worldwide. Serotonin and its transporter is a prominent paradigm in mood disorders. Response to selective serotonin reuptake inhibitors (SSRI) is altered due to heterogeneity in the serotonin transporter gene, SLC6A4 (solute carrier family 6 member 4). The reported polymorphisms are found to be in different regions of the transporter gene: promoter region (5-HTTLPR and various single nucleotide polymorphisms within it), intron (STin2), and exon 9 (I425V). The long and short alleles of the 5-HTTLPR gene, which are prevalent among variations, may mediate differential effects. In long allelic variant carriers, an increased response to SSRI and timely recovery is due to increased availability of SERT. Whereas, SERT availability is significantly decreased in short allelic carriers, necessitating a reduction in SSRI dosage due to the increased risk of adverse drug reactions. Thus, pharmacogenetic investigations are required to understand the impact of functional variations on the efficacy and tolerability of SSRI. Identifying the carrier variants may aid in clear-decision making of the treatment regimen, aiding the approach of personalized medication.

Does gut brain axis has an impact on Parkinson's disease (PD)?

Parkinson's Disease (PD) is becoming a growing global concern by being the second most prevalent disease next to Alzheimer's Disease (AD). Henceforth new exploration is needed in search of new aspects towards the disease mechanism and origin. Evidence from recent studies has clearly stated the role of Gut Microbiota (GM) in the maintenance of the brain and as a root cause of various diseases and disorders including other neurological conditions. In the case of PD, with an unknown etiology, the GM is said to have a larger impact on the disease pathophysiology. Although GM and its metabolites are crucial for maintaining the normal physiology of the host, it is an undeniable fact that there is an influence of GM in the pathophysiology of PD. As such the Enteroendocrine Cells (EECs) in the epithelium of the intestine are one of the significant regulators of the gut-brain axis and act as a communication mediator between the gut and the brain. The communication is established via the molecules of neuroendocrine which are said to have a crucial part in neurological diseases such as AD, PD, and other psychiatry-related disorders. This review is focused on understanding the proper role of GM and EECs in PD. Here, we also focus on some of the metabolites and compounds that can interact with the PD genes causing various dysfunctions in the cell and facilitating the disease conditions using bioinformatical tools. Various mechanisms concerning EECs and PD, their identification, the latest studies, and available current therapies have also been discussed.

Cellular and Molecular Roles of Immune Cells in the Gut-Brain Axis in Migraine

Migraine is a complex and multi-system dysfunction. The realization of its pathophysiology and diagnosis is developing rapidly. Migraine has been linked to gastrointestinal disorders such as irritable bowel syndrome and celiac disease. There is also direct and indirect evidence for a relationship between migraine and the gut-brain axis, but the exact mechanism is not yet explained. Studies have shown that this interaction appears to be influenced by a variety of factors, such as inflammatory mediators, gut microbiota, neuropeptides, and serotonin pathways. Recent studies suggest that immune cells can be the potential tertiary structure between migraine and gut-brain axis. As the hot interdisciplinary subject, the relationship between immunology and gastrointestinal tract is now gradually clear. Inflammatory signals are involved in cellular and molecular responses that link central and peripheral systems. The gastrointestinal symptoms associated with migraine and experiments associated with antibiotics have shown that the intestinal microbiota is abnormal during the attacks. In this review, we focus on the mechanism of migraine and gut-brain axis, and summarize the tertiary structure between immune cells, neural network, and gastrointestinal tract.

Intestinal mucosal microbiota mediate amino acid metabolism involved in the gastrointestinal adaptability to cold and humid environmental stress in mice

Growing evidence has demonstrated that cold and humid environmental stress triggers gastrointestinal (GI) disorders. In this study, we explored the effects of intestinal microbiota homeostasis on the intestinal mucus barrier and GI disorders by cold and humid environmental stress. Moreover, the inner link between the intestinal mucosal microbiota and metabolites in mice with cold and humid environmental stress was interpreted by integrative analysis of PacBio HiFi sequencing microbial genomics and targeted metabolomics. In the current study, we found (1) after the cold and wet cold and humid environmental stress intervened in the intestinal microbiota disorder and homeostasis mice respectively, the bacterial culturing and fluorescein diacetate (FDA) microbial activity detection of intestinal microbiota including feces, intestinal contents, and intestinal mucosa suggested that the cold and humid environmental stress decreased the colony of culturable bacteria and microbial activity, in which intestinal microbiota disorder aggravated the injury of the intestinal mucus barrier and the GI symptoms related to cold and humid environmental stress; (2) the serum amino acid transferases such as glutamate pyruvic transa (GPT), and glutamic oxaloacetic transaminase (GOT) in cold and humid environmental stressed mice increased significantly, indicating that the intestinal microbiota adapted to cold and humid environmental stress by regulating the host's amino acid metabolism; (3) the integrative analysis of multi-omics illustrated a prediction model based on the microbiota Lactobacillus reuteri abundance and host amino acid level that can predict intestinal mucoprotein Muc2 with an adjusted R2 of 75.0%. In conclusion, the cold and humid environmental stress regulates the neurotransmitter amino acids metabolic function both in intestinal mucosal microbiota and host serum by adjusting the composition of the dominant bacterial population Lactobacillus reuteri, which contributes to the intestinal mucus barrier injury and GI disorders caused by cold and humid environmental stress.

Comprehensive analysis of the gut microbiome and post-translational modifications elucidates the route involved in microbiota-host interactions

The gut microbiome interacts with the host to maintain body homeostasis, with gut microbial dysbiosis implicated in many diseases. However, the underlying mechanisms of gut microbe regulation of host behavior and brain functions remain unclear. This study aimed to elucidate the influence of gut microbiota on brain functions via post-translational modification mechanisms in the presence or absence of bacteria without any stimulation. We conducted succinylome analysis of hippocampal proteins in germ-free (GF) and specific pathogen-free (SPF) mice and metagenomic analysis of feces from SPF mice. These results were integrated with previously reported hippocampal acetylome and phosphorylome data from the same batch of mice. Subsequent bioinformatics analyses revealed 584 succinylation sites on 455 proteins, including 54 up-regulated succinylation sites on 91 proteins and 99 down-regulated sites on 51 proteins in the GF mice compared to the SPF mice. We constructed a panoramic map of gut microbiota-regulated succinylation, acetylation, and phosphorylation, and identified cross-talk and relative independence between the different types of post-translational modifications in modulating complicated intracellular pathways. Pearson correlation analysis indicated that 13 taxa, predominantly belonging to the Bacteroidetes phylum, were correlated with the biological functions of post-translational modifications. Positive correlations between these taxa and succinylation and negative correlations between these taxa and acetylation were identified in the modulation of intracellular pathways. This study highlights the hippocampal physiological changes induced by the absence of gut microbiota, and proteomic quantification of succinylation, phosphorylation, and acetylation, contributing to our understanding of the role of the gut microbiome in brain function and behavioral phenotypes.

Probiotic Lactobacillus rhamnosus alleviates the neurotoxicity of microcystin-LR in zebrafish (Danio rerio) through the gut-brain axis

Microcystin-LR (MCLR) is one of the most toxic cyanobacterial toxins and is harmful to the central nervous system of fish. Probiotic additives can improve neuroendocrine function in fish. Although both MCLR and probiotics aim at the nervous system, whether they interact with each other and the mechanisms remain unexplored. In the present study, 4-month-old zebrafish were exposed to 0, 2.2, and 22 μg/L of MCLR for 28 days with or without the probiotic L. rhamnosus. We found that MCLR exposure could inhibit the swimming speed of zebrafish, while the presence of L. rhamnosus mitigated this abnormality. To elucidate the mechanism of how L. rhamnosus alleviates MCLR-induced neurotoxicity, we examined the bioaccumulation of MCLR, changes in neurotransmitters, immune biochemical indicators, and hormone content of the hypothalamic-pituitary-interrenal (HPI) axis in zebrafish along the gut-brain axis. Our results showed L. rhamnosus could reverse the abnormal swimming behavior and eventually alleviate neurotoxicity in zebrafish by modulating intestinal and brain neural signaling, neuroinflammation, and HPI axis responses. This study provides implications for the application of probiotics in the aquaculture industry.

Polybrominated diphenyl ether (PBDE) exposure and adverse maternal and infant health outcomes: Systematic review

Polybrominated diphenyl ethers (PBDEs) are flame retardants found in ambient environment and are measured in humans. There are reports on general PBDE toxicity, including endocrine disrupting properties. Studies on adverse maternal and infant outcomes and underlying toxicity mechanisms needs to be understood. The objective of this study was to conduct a systematic review to examine the state of science on the relationship between PBDE and adverse maternal/infant health outcomes and related maternal biomarker changes. This literature review was conducted using PubMed, Scopus, Embase and Web of Science for published articles from January 2005-February 2022. Article quality was assessed using Newcastle-Ottawa Scale. Of the 1518 articles, only 54 human observational studies were screened in for this review. A second reviewer examined the validity of these articles. Reports on associations between PBDE and maternal health outcomes included gestational hypertension/preeclampsia (N = 2) and gestational diabetes mellitus/glycemic index (N = 6). Meanwhile, reports on PBDE and infant outcomes (N=32) included effects on infant birth weight, birth length and cephalic perimeter, preterm birth, fetal growth restriction and APGAR scores. Although findings on PBDE exposure and adverse infant outcomes showed inconsistencies across studies, in general, negative correlations between maternal PBDEs and infant birth weight, birth length and cephalic perimeter were seen, in few cases, after stratification by sex. Association between maternal PBDE and maternal biomarkers (N=18) suggested negative impact of PBDE exposure on markers relevant to neuro-endocrine system and inflammatory processes. The review findings identified potential associations between maternal PBDE and adverse maternal/infant health outcomes. Furthermore, PBDE-related biomarker changes suggest disturbances in maternal mechanisms relevant to endocrine disrupting properties of PBDEs. The observed study heterogeneity can be attributed to factors namely, sample size, study design and statistical analysis. Overall review findings imply the necessity for further research to validate PBDE exposure-related adverse maternal/infant health effects and to validate underlying toxicity mechanisms.

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.

Effect of lairage time prior to slaughter on stress in pigs: a path analysis

BACKGROUND

Pre-slaughter process during transportation, handling, and lairage causes stress in pigs, affecting animal welfare and meat quality. Therefore, lairage factors are important for relieving stress. A total of 24 LYD (Landrace × Yorkshire × Duroc) barrows were used to investigate the effect of 6 and 20 h lairage time (LT) on cortisol, serotonin, and catecholamine in blood and physiological factors in muscle, and to verify the causal relationship between these factors.

RESULTS

The results revealed that cortisol was increased (0.064 ± 0.007 µg/ml), and epinephrine (0.020 ± 0.002 µg/ml) and norepinephrine (1.518 ± 0.071 µg/ml) were lower at a LT of 20 h than those at 6 h, and there was no significant effect on the muscle and carcass characteristic factors. In addition, cortisol and norepinephrine showed a negative correlation (r = -50,346, p = 0.0121), epinephrine and glycogen had a positive correlation (r = 0.4417, p = 0.0307), and serotonin and heat shock protein 70 (HSP70) were positively correlated (r = 0.4715, p = 0.0200). Path analysis indicated that the increase in LT had a direct effect on cortisol, epinephrine, and norepinephrine, and an indirect effect on muscle glycogen.

CONCLUSION

This study confirmed the effect of the increase in LT from 6 to 20 h in the lairage room on the stress response of pigs. These findings support the legal requirements that advocate for shorter lairage times, in alignment with enhanced animal welfare standards.

Gut microbiota and traumatic central nervous system injuries: Insights into pathophysiology and therapeutic approaches

Traumatic brain injury and spinal cord injury are two distinct but fundamentally similar types of acute insults to the central nervous system (CNS) that often culminate in death or cognitive and motor impairment. Over the past decade, researchers have tapped into research to discover the potential role being played by gut bacteria in CNS. After an acute CNS injury, the altered composition of the gut microbiota disturbs the balance of the bidirectional gut-brain axis, aggravating secondary CNS injury, motor dysfunctions, and cognitive deficits, which worsens the patient's prognosis. Some of the well-known therapeutic interventions which can also be used as adjuvant therapy for alleviating CNS injuries include, the use of pro and prebiotics, fecal microbiota transplantation, and microbial engineering. In this review, we aim to discuss the importance of gut microbes in our nervous system, anatomy, and signaling pathways involved in regulating the gut-brain axis, the alteration of the gut microbiome in CNS injuries, and the therapeutic strategies to target gut microbiomes in traumatic CNS injuries.