Lactobacillus fermentum PS150 showed psychotropic properties by altering serotonergic pathway during stress

The new science of sleep: From cells to large-scale societies

In the past 20 years, more remarkable revelations about sleep and its varied functions have arguably been made than in the previous 200. Building on this swell of recent findings, this essay provides a broad sampling of selected research highlights across genetic, molecular, cellular, and physiological systems within the body, networks within the brain, and large-scale social dynamics. Based on this raft of exciting new discoveries, we have come to realize that sleep, in this moment of its evolution, is very much polyfunctional (rather than monofunctional), yet polyfunctional for reasons we had never previously considered. Moreover, these new polyfunctional insights powerfully reaffirm sleep as a critical biological, and thus health-sustaining, requisite. Indeed, perhaps the only thing more impressive than the unanticipated nature of these newly emerging sleep functions is their striking divergence, from operations of molecular mechanisms inside cells to entire group societal dynamics.

Gut microbiota: Candidates for a novel strategy for ameliorating sleep disorders

The aim of this review was to evaluate the feasibility of treating sleep disorders using novel gut microbiota intervention strategies. Multiple factors can cause sleep disorders, including an imbalance in the gut microbiota. Studies of the microbiome-gut-brain axis have revealed bidirectional communication between the central nervous system and gut microbes, providing a more comprehensive understanding of mood and behavioral regulatory patterns. Changes in the gut microbiota and its metabolites can stimulate the endocrine, nervous, and immune systems, which regulate the release of neurotransmitters and alter the activity of the central nervous system, ultimately leading to sleep disorders. Here, we review the main factors affecting sleep, discuss possible pathways and molecular mechanisms of the interaction between sleep and the gut microbiota, and compare common gut microbiota intervention strategies aimed at improving sleep physiology.

Exopolysaccharide is the potential effector of Lactobacillus fermentum PS150, a hypnotic psychobiotic strain

Psychobiotics are a class of probiotics that confer beneficial effects on the mental health of the host. We have previously reported hypnotic effects of a psychobiotic strain, Lactobacillus fermentum PS150 (PS150), which significantly shortens sleep latency in experimental mice, and effectively ameliorate sleep disturbances caused by either caffeine consumption or a novel environment. In the present study, we discovered a L. fermentum strain, GR1009, isolated from the same source of PS150, and found that GR1009 is phenotypically distinct but genetically similar to PS150. Compared with PS150, GR1009 have no significant hypnotic effects in the pentobarbital-induced sleep test in mice. In addition, we found that heat-killed PS150 exhibited hypnotic effects and altered the gut microbiota in a manner similar to live bacteria, suggesting that a heat-stable effector, such as exopolysaccharide (EPS), could be responsible for these effects. Our comparative genomics analysis also revealed distinct genetic characteristics in EPS biosynthesis between GR1009 and PS150. Furthermore, scanning electron microscopy imaging showed a sheet-like EPS structure in PS150, while GR1009 displayed no apparent EPS structure. Using the phenol-sulfate assay, we found that the sugar content value of the crude extract containing EPS (C-EPS) from PS150 was approximately five times higher than that of GR1009, indicating that GR1009 has a lower EPS production activity than PS150. Through the pentobarbital-induced sleep test, we confirmed the hypnotic effects of the C-EPS isolated from PS150, as evidenced by a significant reduction in sleep latency and recovery time following oral administration in mice. In summary, we utilized a comparative approach to delineate differences between PS150 and GR1009 and proposed that EPS may serve as a key factor that mediates the observed hypnotic effect.

Guts Imbalance Imbalances the Brain: A Review of Gut Microbiota Association With Neurological and Psychiatric Disorders

Over the last 10 years, there has been a growing interest in the relationship between gut microbiota, the brain, and neurologic-associated affections. As multiple preclinical and clinical research studies highlight gut microbiota’s potential to modulate the general state of health state, it goes without saying that gut microbiota plays a significant role in neurogenesis, mental and cognitive development, emotions, and behaviors, and in the progression of neuropsychiatric illnesses. Gut microbiota produces important biologic products that, through the gut-brain axis, are directly connected with the appearance and evolution of neurological and psychiatric disorders such as depression, anxiety, bipolar disorder, autism, schizophrenia, Parkinson’s disease, Alzheimer’s disease, dementia, multiple sclerosis, and epilepsy. This study reviews recent research on the link between gut microbiota and the brain, and microbiome’s role in shaping the development of the most common neurological and psychiatric illnesses. Moreover, special attention is paid to the use of probiotic formulations as a potential non-invasive therapeutic opportunity for prevention and management of neuropsychiatric-associated affections.

Lactobacillus paracasei CCFM1229 and Lactobacillus rhamnosus CCFM1228 Alleviated Depression- and Anxiety-Related Symptoms of Chronic Stress-Induced Depression in Mice by Regulating Xanthine Oxidase Activity in the Brain

Depression is a common mood disorder that affects around 350 million people worldwide. We studied the effect of supplementation with Lactobacillus strains for the treatment of depression. Except for control group (n = 8), C57BL/6J mice were treated with Lactobacillus during six weeks of chronic unpredictable stress (depression group: n = 9, Lactobacillus intervention group: n = 7). L. paracasei CCFM1229 and L. rhamnosus CCFM1228 significantly reduced depressive behaviour in the forced swimming test and tail suspension test, significantly reduced anxiety behaviour in the open field test, and reduced anxiety behaviour in the marble burying test and light/dark box test. L. paracasei CCFM1229 and L. rhamnosus CCFM1228 significantly increased the brain serotonin and brain-derived neurotrophic factor concentrations, and CCFM1229 significantly decreased the serum corticosterone concentration, all of which are closely associated with the relief of depressive symptoms. Furthermore, CCFM1229 and CCFM1228 were shown to regulate purine metabolism in mice, as indicated by decreases in brain xanthine oxidase activity and an increase in liver adenosine deaminase activity. Anxiety- and depression-related indicators were significantly associated with xanthine oxidase activity in the cerebral cortex. The strains CCFM1229 and CCFM1228 reduced anxiety- and depression-related behaviour in a mouse model of chronic stress-induced depression, which may be achieved by regulating the activity of brain xanthine oxidase.

The role of serotonin within the microbiota-gut-brain axis in the development of Alzheimer's disease: A narrative review

Alzheimer's disease (AD) is the most common cause of dementia, accounting for more than 50 million patients worldwide. Current evidence suggests the exact mechanism behind this devastating disease to be of multifactorial origin, which seriously complicates the quest for an effective disease-modifying therapy, as well as impedes the search for strategic preventative measures. Of interest, preclinical studies point to serotonergic alterations, either induced via selective serotonin reuptake inhibitors or serotonin receptor (ant)agonists, in mitigating AD brain neuropathology next to its clinical symptoms, the latter being supported by a handful of human intervention trials. Additionally, a substantial amount of preclinical trials highlight the potential of diet, fecal microbiota transplantations, as well as pre- and probiotics in modulating the brain's serotonergic neurotransmitter system, starting from the gut. Whether such interventions could truly prevent, reverse or slow down AD progression likewise, should be initially tested in preclinical studies with AD mouse models, including sufficient analytical measurements both in gut and brain. Thereafter, its potential therapeutic effect could be confirmed in rigorously randomized controlled trials in humans, preferentially across the Alzheimer's continuum, but especially from the prodromal up to the mild stages, where both high adherence to such therapies, as well as sufficient room for noticeable enhancement are feasible still. In the end, such studies might aid in the development of a comprehensive approach to tackle this complex multifactorial disease, since serotonin and its derivatives across the microbiota-gut-brain axis might serve as possible biomarkers of disease progression, next to forming a valuable target in AD drug development. In this narrative review, the available evidence concerning the orchestrating role of serotonin within the microbiota-gut-brain axis in the development of AD is summarized and discussed, and general considerations for future studies are highlighted.

Lactobacillus fermentum PS150 promotes non-rapid eye movement sleep in the first night effect of mice

The first night effect (FNE) is a type of sleep disturbance caused by an unfamiliar environment, which leads to difficulty falling asleep and reduced sleep duration. Previously, we reported that Lactobacillus fermentum PS150 (PS150) improves sleep conditions in a pentobarbital-induced sleep mouse model. In this study, we aimed to evaluate the effect of PS150 on the FNE in mice. Briefly, mice were implanted with electrodes and orally administered PS150 for four weeks, and then the FNE was induced by cage changing. Analysis of polysomnographic signals revealed that intervention with PS150 restored non-rapid eye movement (NREM) sleep length under the FNE. Compared to diphenhydramine, a commonly used sleep aid, PS150 had no unwanted side effects, such as rapid eye movement (REM) sleep deprivation and fragmented sleep. Moreover, temporal analysis revealed that PS150 efficiently reduced both sleep latency and time spent restoring normal levels of REM sleep. Taken together, these results suggest that PS150 efficiently ameliorates sleep disturbance caused by the FNE. Additionally, V3–V4 16S rRNA sequencing revealed significant increases in Erysipelotrichia, Actinobacteria, and Coriobacteriia in fecal specimens of the PS150-treated group, indicating that PS150 induces gut microbiota remodeling.

Lactobacillus-Based Probiotics Reduce the Adverse Effects of Stress in Rodents: A Meta-analysis

Lactobacillus species play a critical role in the bidirectional communication between the gut and the brain. Consequently, they have the potential to aid in the treatment of psychological disorders. The impact of Lactobacillus supplementation on the stress responses triggering psychological disorders has not been systematically reviewed. Therefore, the aim of this meta-analysis is to summarize the body of research assessing the effects of Lactobacillus-based probiotics in rodents that underwent an experimental stress treatment or not. The duration of immobility in a Forced Swim Test (FST) was the outcome used to measure changes induced by various treatments. Four online databases were systematically searched for relevant studies published in English. Fourteen studies meeting the criteria were included in the meta-analysis. The effects of probiotic supplementation and stress treatment on the duration of immobility in the FST were analyzed using a generalized linear mixed model. Publication bias was evaluated by funnel plots. Our analysis shows that Lactobacillus-based probiotic supplements significantly reduce immobility in the FST (P < 0.001) in stressed rodents. However, probiotics did not affect the rodents that did not undergo the stress treatment (P = 0.168). These findings provide a better understanding of the potential of Lactobacillus-based probiotics for the management of stress-induced behavior.

Molecular evolutionary and 3D protein structural analyses of Lactobacillus fermentum elongation factor Tu, a novel brain health promoting factor

The role of microbiota in gut-brain communication has led to the development of probiotics promoting brain health. Here we report a genomic study of a Lactobacillus fermentum PS150 and its patented bioactive protein, elongation factor Tu (EF-Tu), which is associated with cognitive improvement in rats. The L. fermentum PS150 circular chromosome is 2,238,401 bp and it consists of 2281 genes. Chromosome comparisons with other L. fermentum strains highlighted a cluster of glycosyltransferases as potential candidate probiotic factors besides EF-Tu. Molecular evolutionary analyses on EF-Tu genes (tuf) in 235 bacteria species revealed one to three copies of the gene per genome. Seven tuf pseudogenes were found and three species only possessed pseudogenes, which is an unprecedented finding. Protein variability analysis of EF-Tu showed five highly variable residues (40 K, 41G, 42 L, 44 K, and 46E) on the protein surface, which warrant further investigation regarding their potential roles as binding sites.

Oral treatment with Lactobacillus reuteri attenuates depressive-like behaviors and serotonin metabolism alterations induced by chronic social defeat stress

BACKGROUND

Alterations in bidirectional gut-brain interactions are believed to be involved in the pathogenesis of neuropsychiatric diseases. Considering the putative connections among gut microbiota, neural function, and behavior, this study investigated the potential of microbe-induced gut-to-brain signaling to modulate the impact of stress on depressive-like behaviors and serotonin metabolism.

METHODS

Depression-susceptible mice induced by chronic social defeat stress received oral treatment of either Lactobacillus reuteri 3 (L. reuteri 3) or vehicle for 28 days, and alterations in behavior and serotonin metabolism were assessed. 16S rRNA sequencing and gas chromatograph were employed to analyze the gut microbiota community and short-chain fatty acids (SCFAs).

RESULTS

Treatment with L. reuteri 3 ameliorated depressive-like behaviors, suppressed the increase in the relative abundances of Clostridiales and Adlercreutzia, improved the decrease in abundances of Lactobacillus, Allobaculum, and Sutterella induced by stress, and significantly increased the proportion of Bifidobacterium. L. reuteri 3 reduced the acetate and total SCFAs levels in the depression group. Blood and colon 5-HT were decreased in depressive-like mice but were significantly ameliorated after L. reuteri 3 treatment. Moreover, L. reuteri 3 administration increased the expression of enzymes involved in serotonin biosynthesis but suppressed that of the enzymes involved in tryptophan metabolism along the kynurenine pathway in colon and prefrontal cortex.

CONCLUSIONS

Despite the complexity of the gut microbiota, exposure to a single microbial strain L. reuteri 3 can protect against depressive-like behaviors induced by chronic social defeat stress. The anti-depressive effects of L. reuteri 3 were associated with improved gut microbiota and serotonin metabolism.