The Impact of Microbiota-Gut-Brain Axis on Diabetic Cognition Impairment

Polysaccharide extracted from Sarcandra glabra residue attenuate cognitive impairment by regulating gut microbiota in diabetic mice

Diabetic encephalopathy (DE), characterized by cognitive impairment, currently lacks targeted treatment. Previous studies have shown that Sarcandra glabra extracted residue polysaccharide (SERP) exhibited hypoglycemic effects either in vitro or in streptozotocin-induced diabetes mice. However, the therapeutic effect of SERP on DE was not elucidated. This study investigated the therapeutic effect of SERP on DE and its underlying mechanism. Our results revealed that SERP regulates glucose and lipid metabolism, improves cognitive function, and exhibits diminished activity post-antibiotic intervention. Importantly, we discovered a novel mechanism by which SERP modulates the gut microbiota, specifically enriching Bacteroidales S24-7, resulting in elevated levels of butyric acid in the intestine. This regulation modulates the intestinal endocrine cell lipid metabolism level, restores damaged intestinal barriers and neural epithelial circuits, thus exhibiting cure effects. Our findings suggest that SERP could become a candidate for treating DE, potentially involving the regulation mechanism of the "microbiota-gut-brain axis". This study underscores the unique therapeutic efficacy of SERP in managing DE, offering fresh drug candidates and innovative treatment strategies for this challenging condition.

Pinctada martensii Hydrolysate Modulates the Brain Neuropeptidome and Proteome in Diabetic (db/db) Mice via the Gut-Brain Axis

Pinctada martensii hydrolysate (PMH) has been proved to have the effect of ameliorating disorders of glucose and lipid metabolism in db/db mice, but the mechanism of its hyperglycemia effect is still unclear. Bacterial communities in fecal samples from a normal control group, a diabetic control group, and a PMH-treated diabetes mellitus type 2 (T2DM) group were analyzed by 16S gene sequencing. Nano LC-MS/MS was used to analyze mice neuropeptides and proteomes. The 16S rDNA sequencing results showed that PMH modulated the structure and composition of the gut microbiota and improved the structure and composition of Firmicutes and Bacteroidetes at the phylum level and Desulfovibrionaceae and Erysipelatoclostridiaceae at the family level. Furthermore, the expressions of functional proteins of the central nervous system, immune response-related protein, and proteins related to fatty acid oxidation in the brain disrupted by an abnormal diet were recovered by PMH. PMH regulates the brain neuropeptidome and proteome and further regulates blood glucose in diabetic mice through the gut-brain axis. PMH may be used as a prebiotic agent to attenuate T2DM, and target-specific microbial species may have unique therapeutic promise for metabolic diseases.

Modulation of gut microbiota with probiotics as a strategy to counteract endogenous and exogenous neurotoxicity

The existing data demonstrate that probiotic supplementation affords protective effects against neurotoxicity of exogenous (e.g., metals, ethanol, propionic acid, aflatoxin B1, organic pollutants) and endogenous (e.g., LPS, glucose, Aβ, phospho-tau, α-synuclein) agents. Although the protective mechanisms of probiotic treatments differ between various neurotoxic agents, several key mechanisms at both the intestinal and brain levels seem inherent to all of them. Specifically, probiotic-induced improvement in gut microbiota diversity and taxonomic characteristics results in modulation of gut-derived metabolite production with increased secretion of SFCA. Moreover, modulation of gut microbiota results in inhibition of intestinal absorption of neurotoxic agents and their deposition in brain. Probiotics also maintain gut wall integrity and inhibit intestinal inflammation, thus reducing systemic levels of LPS. Centrally, probiotics ameliorate neurotoxin-induced neuroinflammation by decreasing LPS-induced TLR4/MyD88/NF-κB signaling and prevention of microglia activation. Neuroprotective mechanisms of probiotics also include inhibition of apoptosis and oxidative stress, at least partially by up-regulation of SIRT1 signaling. Moreover, probiotics reduce inhibitory effect of neurotoxic agents on BDNF expression, on neurogenesis, and on synaptic function. They can also reverse altered neurotransmitter metabolism and exert an antiamyloidogenic effect. The latter may be due to up-regulation of ADAM10 activity and down-regulation of presenilin 1 expression. Therefore, in view of the multiple mechanisms invoked for the neuroprotective effect of probiotics, as well as their high tolerance and safety, the use of probiotics should be considered as a therapeutic strategy for ameliorating adverse brain effects of various endogenous and exogenous agents.

Cognitive protection of sinomenine in type 2 diabetes mellitus through regulating the EGF/Nrf2/HO-1 signaling, the microbiota-gut-brain axis, and hippocampal neuron ferroptosis

Recent years have witnessed a growing research interest in traditional Chinese medicine as a neuroprotective nutrient in the management of diabetic cognitive dysfunction. However, the underlying molecular mechanisms of sinomenine in mediating ferroptosis of hippocampal neurons have been poorly understood. This study sought to decipher the potential effect and molecular mechanism of sinomenine in the cognitive dysfunction following type 2 diabetes mellitus (T2DM). Multi-omics analysis was conducted to identify the microbiota-gut-brain axis in T2DM patient samples obtained from the publicly available database. In HT-22 cells, erastin was utilized to create a ferroptosis model, and streptozotocin was injected intraperitoneally to create a rat model of DM. It was noted that intestinal flora imbalance occurred in patients with T2DM-associated cognitive dysfunction. Sinomenine could reduce Erastin-induced hippocampus neuronal ferroptosis by increasing EGF expression. EGF protected hippocampal neurons against ferroptosis by activating the Nrf2/HO-1 signaling pathway. Furthermore, in vivo results confirmed that sinomenine blocked ferroptosis of hippocampal neurons and alleviated cognitive dysfunction in T2DM rats. Collectively, these results suggest that sinomenine confers neuroprotective effects by curtailing hippocampal neuron ferroptosis via the EGF/Nrf2/HO-1 signaling and microbiota-gut-brain axis. It may be a candidate for the treatment of diabetic cognitive dysfunction.

A State-of-Art Review of the Vicious Circle of Sleep Disorders, Diabetes and Neurodegeneration Involving Metabolism and Microbiota Alterations

In the context of neurodegenerative disorders, cognitive decline is frequently reported in older population. Recently, numerous metabolic pathways have been implicated in neurodegeneration, including signaling disruption of insulin and other glucose-regulating hormones. In fact, Alzheimer's disease has now been considered as "type-3 diabetes". In this review, we tried to clarify the role of sleep impairment as the third major player in the complex relationship between metabolic and neurodegenerative diseases. Altered sleep may trigger or perpetuate these vicious mechanisms, leading to the development of both dementia and type 2 diabetes mellitus. Finally, we analyzed these reciprocal interactions considering the emerging role of the gut microbiota in modulating the same processes. Conditions of dysbiosis have been linked to circadian rhythm disruption, metabolic alterations, and release of neurotoxic products, all contributing to neurodegeneration. In a future prospective, gut microbiota could provide a major contribution in explaining the tangled relationship between sleep disorders, dementia and diabetes.

Association of skin autofluorescence with depressive symptoms and the severity of depressive symptoms: The prospective REACTION study

AIM

Millions of people are afflicted by depression, a highly prevalent mental illness with increased morbidity and mortality. Advanced glycation end-products (AGEs) are potential risk factors for depression. We aimed to investigate the correlation of AGEs with depressive symptoms and the severity of depressive symptoms.

METHODS

This study was nested in the prospective REACTION (Risk Evaluation of cAncers in Chinese diabeTic Individuals) study and included 4420 eligible participants. skin autofluorescence (SAF) was used to measure skin AGEs. Depressive symptoms were evaluated by the Self-Rating Depression Scale (SDS). Multiple logistic regression analysis was used to assess the association of AGEs with depressive symptoms and the severity of depressive symptoms.

RESULTS

Logistic analysis showed a significantly positive relationship between quartiles of SAF-AGEs and the risk of depressive symptoms with the OR [95% confidence interval (CI), p value] of 1.24 (95% CI: 1.03-1.50, p = 0.022), 1.39 (95% CI: 1.15-1.68, p = 0.001) and 1.57 (95% CI: 1.28-1.91, p < 0.001) for multivariable-adjusted model respectively. And SAF-AGEs were associated with the severity of depressive symptoms with the multivariable-adjusted OR (95% CI, p value) of 1.06 (95% CI:0.79-1.43, p = 0.681), 1.47 (95% CI: 1.08-1.99, p = 0.014), and 1.54 (95% CI: 1.12-2.11, p = 0.008) respectively. Stratified analyses showed that SAF-AGEs were significantly associated with the severity of depressive symptoms only in females, overweight people, individuals with hypertension, and those without diabetes and insomnia.

CONCLUSIONS

The present study showed that a higher SAF-AGEs level was associated with depressive symptoms and the severity of depressive symptoms.

Gut microbiota composition is altered in a preclinical model of type 1 diabetes mellitus: Influence on gut steroids, permeability, and cognitive abilities

Sex steroid hormones are not only synthesized from the gonads but also by other tissues, such as the brain (i.e., neurosteroids) and colon (i.e., gut steroids). Gut microbiota can be shaped from sex steroid hormones synthesized from the gonads and locally interacts with gut steroids as in turn modulates neurosteroids. Type 1 diabetes mellitus (T1DM) is characterized by dysbiosis and also by diabetic encephalopathy. However, the interactions of players of gut-brain axis, such as gut steroids, gut permeability markers and microbiota, have been poorly explored in this pathology and, particularly in females. On this basis, we have explored, in streptozotocin (STZ)-induced adult female rats, whether one month of T1DM may alter (I) gut microbiome composition and diversity by 16S next-generation sequencing, (II) gut steroid levels by liquid chromatography-tandem mass spectrometry, (III) gut permeability markers by gene expression analysis, (IV) cognitive behavior by the novel object recognition (NOR) test and whether correlations among these aspects may occur. Results obtained reveal that T1DM alters gut β-, but not α-diversity. The pathology is also associated with a decrease and an increase in colonic pregnenolone and allopregnanolone levels, respectively. Additionally, diabetes alters gut permeability and worsens cognitive behavior. Finally, we reported a significant correlation of pregnenolone with Blautia, claudin-1 and the NOR index and of allopregnanolone with Parasutterella, Gammaproteobacteria and claudin-1. Altogether, these results suggest new putative roles of these two gut steroids related to cognitive deficit and dysbiosis in T1DM female experimental model. This article is part of the Special Issue on "Microbiome & the Brain: Mechanisms & Maladies".

Sex-Related Effects of Gut Microbiota in Metabolic Syndrome-Related Diabetic Retinopathy

The metabolic syndrome (MetS) is a complex disease of metabolic abnormalities, including obesity, insulin resistance, hypertension and dyslipidaemia, and it is associated with an increased risk of cardiovascular disease (CVD). Diabetic retinopathy (DR) is the leading cause of vision loss among working-aged adults around the world and is the most frequent complication in type 2 diabetic (T2D) patients. The gut microbiota are a complex ecosystem made up of more than 100 trillion of microbial cells and their composition and diversity have been identified as potential risk factors for the development of several metabolic disorders, including MetS, T2D, DR and CVD. Biomarkers are used to monitor or analyse biological processes, therapeutic responses, as well as for the early detection of pathogenic disorders. Here, we discuss molecular mechanisms underlying MetS, the effects of biological sex in MetS-related DR and gut microbiota, as well as the latest advances in biomarker research in the field. We conclude that sex may play an important role in gut microbiota influencing MetS-related DR.

Neuroprotective Effect of Ponicidin Alleviating the Diabetic Cognitive Impairment: Regulation of Gut Microbiota

Cognitive impairment is a major complication of diabetes mellitus, which is caused by constitutive hyperglycaemia. Ponicidin is a diterpenoid isolated from a Chinese traditional herb (Rabdosia rubescens) and demonstrates the various pharmacological effects. The goal of this study was to scrutinise the neuroprotective effect of ponicidin against diabetic nephropathy (DN) induced by streptozotocin (STZ). Intraperitoneal administration of STZ (55 mg/kg) was used for the induction of diabetes and rats were received oral administration of ponicidin (5, 10 and 15 mg/kg) until 28 days. The body weight, food intake, water intake and blood glucose level were assessed at regular time interval. Plasma insulin level, antioxidant, inflammatory cytokines, apoptosis marker and faecal gut microbiota compositions were estimated. DN-induced group rats revealed the augmented glucose level, water intake, food intake and reduced body weight. Ponicidin significantly (P < 0.001) repressed the glucose level and water food intake and improved the body weight and plasma insulin. Ponicidin significantly (P < 0.001) repressed the malonaldehyde (MDA) level and boosted the level of glutathione (GSH), glutathione reductase (GR) and superoxide dismutase (SOD) in the brain and serum level. Ponicidin significantly (P < 0.001) repressed the level of interleukin-1β (IL-1β), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) and enhanced the level of interleukin-4 (IL-4), interleukin-10 (IL-10) in the brain and serum level. DN group rats exhibited the enhanced relative abundance of Firmicutes, along with enhancing the Firmicutes/Bacteroidetes ratio and repressing the Bacteroidetes relative abundance. Ponicidin effectually restored the relative abundance of Allobaculum, Lactobacillus and Ruminococcus genera. Our findings clearly demonstrated that ponicidin has a neuroprotective effect against diabetic cognitive impairment through modulating the gut microbiome.

Protective Effect of Flavonoids against Methylglyoxal-Induced Oxidative Stress in PC-12 Neuroblastoma Cells and Its Structure-Activity Relationships

Methylglyoxal-induced oxidative stress and cytotoxicity are the main factors causing neuronal death-related, diabetically induced memory impairment. Antioxidant and anti-apoptotic therapy are potential intervention strategies. In this study, 25 flavonoids with different substructures were assayed for protecting PC-12 cells from methylglyoxal-induced damage. A structure-activity relationship (SAR) analysis indicated that the absence of the double bond at C-2 and C-3, substitutions of the gallate group at the 3 position, the pyrogallol group at the B-ring, and the R configuration of the 3 position enhanced the protection of flavan-3-ols, and a hydroxyl substitution at the 4' and meta-positions were important for the protection of flavonol. These SARs were further confirmed by molecular docking using the active site of the Keap1-Nrf2 complex as the receptor. The mechanistic study demonstrated that EGCG with the lowest EC₅₀ protected the PC-12 cells from methylglyoxal-induced damage by reducing oxidative stress via the Nrf2/Keap1/HO-1 and Bcl-2/Bax signaling pathways. These results suggested that flavan-3-ols might be a potential dietary supplement for protection against diabetic encephalopathy.

Insights on dental care management and prevention in children with autism spectrum disorder (ASD). What is new?

Autistic subjects represent a severe concern to dentistry due to the considerable difficulty in managing their oral health, maintaining routine toothbrushing, and preventing dental and periodontal problems. The social and economic burden of managing dental care in autism spectrum disorder (ASD) children is particularly cumbersome for families and public and private health expenditure, especially when children reach the dentist following a late diagnosis with evident oral health problems. An early diagnosis of ASD helps dentists better address these children's oral health. Unfortunately, insufficient attention is paid to the training and education of general pediatricians, dentists, and dental hygienists, allowing them to get to approach the different clinical aspects of ASD. Usually, children diagnosed with ASD are scheduled for dental appointments like their neurotypical peers, whereas their needs are typically complex and personalized. Scant attention is also devoted to these patients by commercial manufacturers of dental products and devices for oral hygiene and prevention of caries and periodontal diseases, leaving parents without the support and often failing when they address the oral health of autistic children. The difficulties of oral care do not derive simply from the behavior of ASD patients, as is commonly assumed, and therefore cannot be overcome solely by the patience and attention of parents and dentists. Genetics, dietary habits, sensory impairments, and cognition disorders are other causes contributing in various degrees to the impact on the mood and psychological reactions of autistic children towards dentists. How can we prevent teeth caries, periodontal disorders, and other oral health impairments by properly managing ASD children? This manuscript gives an up-to-date overview of these problems and helps to provide good remarks.

Association of gut microbiota with sort-chain fatty acids and inflammatory cytokines in diabetic patients with cognitive impairment: A cross-sectional, non-controlled study

Emerging evidence suggests that gut microbiota, short-chain fatty acids (SCFAs), and inflammatory cytokines play important roles in the pathogenesis of diabetic cognitive impairment (DCI). However, little is known about alterations of gut microbiota and SCFA levels as well as the relationships between inflammatory cytokines and cognitive function in Chinese DCI patients. Herein, the differences in the gut microbiota, plasma SCFAs, and inflammatory cytokines in DCI patients and type 2 diabetes mellitus (T2DM) patients were explored. A cross-sectional study of 30 DCI patients and 30 T2DM patients without mild cognitive impairment (MCI) was conducted in Tianjin city, China. The gut microbiota, plasma SCFAs, and inflammatory cytokines were determined using 16S ribosomal RNA (rRNA) gene sequencing, gas chromatography-mass spectrometry (GC-MS), and Luminex immunofluorescence assays, respectively. In addition, the correlation between gut microbiota and DCI clinical characteristics, SCFAs, and inflammatory cytokines was investigated. According to the results, at the genus level, DCI patients presented a greater abundance of Gemmiger, Bacteroides, Roseburia, Prevotella, and Bifidobacterium and a poorer abundance of Escherichia and Akkermansia than T2DM patients. The plasma concentrations of acetic acid, propionic acid, isobutyric acid, and butyric acid plummeted in DCI patients compared to those in T2DM patients. TNF-α and IL-8 concentrations in plasma were significantly higher in DCI patients than in T2DM patients. Moreover, the concentrations of acetic acid, propionic acid, butyric acid, and isovaleric acid in plasma were negatively correlated with TNF-α, while those of acetic acid and butyric acid were negatively correlated with IL-8. Furthermore, the abundance of the genus Alloprevotella was negatively correlated with butyric acid, while that of Holdemanella was negatively correlated with propanoic acid and isobutyric acid. Fusobacterium abundance was negatively correlated with propanoic acid. Clostridium XlVb abundance was negatively correlated with TNF-α, while Shuttleworthia abundance was positively correlated with TNF-α. It was demonstrated that the gut microbiota alterations were accompanied by a change in SCFAs and inflammatory cytokines in DCI in Chinese patients, potentially causing DCI development. These findings might help to identify more effective microbiota-based therapies for DCI in the future.

Zi Shen Wan Fang Attenuates Neuroinflammation and Cognitive Function Via Remodeling the Gut Microbiota in Diabetes-Induced Cognitive Impairment Mice

Background: Cognitive dysfunction is a critical complication of diabetes mellitus, and there are still no clinically approved drugs. Zi Shen Wan Fang (ZSWF) is an optimized prescription composed of Anemarrhenae Rhizoma, Phellodendri Chinensis Cortex, and Cistanches Herba. The purpose of this study is to investigate the effect of ZSWF on DCI and explore its mechanism from the perspective of maintaining intestinal microbial homeostasis in order to find an effective prescription for treating DCI.

Methods: The diabetes model was established by a high-fat diet combined with intraperitoneal injections of streptozotocin (STZ, 120 mg/kg) and the DCI model was screened by Morris water maze (MWM) after 8 weeks of continuous hyperglycemic stimulation. The DCI mice were randomly divided into the model group (DCI), the low- and high-ZSWF–dose groups (9.63 g/kg, 18.72 g/kg), the mixed antibiotic group (ABs), and the ZSWF combined with mixed antibiotic group (ZSWF + ABs). ZSWF was administered orally once a day for 8 weeks. Then, cognitive function was assessed using MWM, neuroinflammation and systemic inflammation were analyzed by enzyme-linked immunosorbent assay kits, intestinal barrier integrity was assessed by hematoxylin-eosin (HE) staining and Western blot and high performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Furthermore, the alteration to intestinal flora was monitored by 16S rDNA sequencing.

Results: ZSWF restored cognitive function in DCI mice and reduced levels of proinflammatory cytokines such as IL-1β, IL-6, and TNF-α. Moreover, ZSWF protected the integrity of the intestinal barrier by increasing intestinal ZO-1 and occludin protein expression and decreasing urinary lactulose to mannitol ratio. In addition, ZSWF reshaped the imbalanced gut microbiota in DCI mice by reversing the abundance changes of a wide range of intestinal bacteria at the phyla and genus levels. In contrast, removing gut microbiota with antibiotics partially eliminated the effects of ZSWF on improving cognitive function and reducing inflammation, confirming the essential role of gut microbiota in the improvement of DCI by ZSWF.

Conclusion: ZSWF can reverse cognitive impairment in DCI mice by remolding the structure of destructed gut microbiota community, which is a potential Chinese medicine prescription for DCI treatment.

Effect of Tanshinone IIA on Gut Microbiome in Diabetes-Induced Cognitive Impairment

Diabetes-induced cognitive impairment (DCI) presents a major public health risk among the aging population. Previous clinical attempts on known therapeutic targets for DCI, such as depleted insulin secretion, insulin resistance, and hyperglycaemia have delivered poor patient outcomes. However, recent evidence has demonstrated that the gut microbiome plays an important role in DCI by modulating cognitive function through the gut–brain crosstalk. The bioactive compound tanshinone IIA (TAN) has shown to improve cognitive and memory function in diabetes mellitus models, though the pharmacological actions are not fully understood. This study aims to investigate the effect and underlying mechanism of TAN in attenuating DCI in relation to regulating the gut microbiome. Metagenomic sequencing analyses were performed on a group of control rats, rats with diabetes induced by a high-fat/high-glucose diet (HFD) and streptozotocin (STZ) (model group) and TAN-treated diabetic rats (TAN group). Cognitive and memory function were assessed by the Morris water maze test, histopathological assessment of brain tissues, and immunoblotting of neurological biomarkers. The fasting blood glucose (FBG) level was monitored throughout the experiments. The levels of serum lipopolysaccharide (LPS) and tumor necrosis factor-α (TNF-α) were measured by enzyme-linked immunoassays to reflect the circulatory inflammation level. The morphology of the colon barrier was observed by histopathological staining. Our study confirmed that TAN reduced the FBG level and improved the cognitive and memory function against HFD- and STZ-induced diabetes. TAN protected the endothelial tight junction in the hippocampus and colon, regulated neuronal biomarkers, and lowered the serum levels of LPS and TNF-α. TAN corrected the reduced abundance of Bacteroidetes in diabetic rats. At the species level, TAN regulated the abundance of B. dorei, Lachnoclostridium sp. YL32 and Clostridiodes difficile. TAN modulated the lipid metabolism and biosynthesis of fatty acids in related pathways as the main functional components. TAN significantly restored the reduced levels of isobutyric acid and butyric acid. Our results supported the use of TAN as a promising therapeutic agent for DCI, in which the underlying mechanism may be associated with gut microbiome regulation.

Dietary Supplement of Anoectochilus roxburghii (Wall.) Lindl. Polysaccharides Ameliorates Cognitive Dysfunction Induced by High Fat Diet via “Gut-Brain” Axis

Purpose

Anoectochilus roxburghii (Wall.) Lindl. polysaccharides (ARPs) have been reported to exhibit multiple pharmacological activities including anti-inflammatory and anti-hyperglycemia. This study aims to investigate the effect of ARPs on cognitive dysfunction induced by high fat diet (HFD).

Methods

Six-week-old male mice were treated with ARPs by dietary supplementation for 14 weeks. The effect of ARPs on cognitive function was determined by assessing the changes in spatial learning and memory ability, neurotrophic factors in hippocampus, inflammatory parameters, intestinal barrier integrity, and gut microbiota.

Results

ARPs supplementation can effectively ameliorate cognitive dysfunction, decrease the phosphorylation levels of Tau protein in hippocampus. Meanwhile, the increased body weight, plasma glucose, total cholesterol, inflammatory factors induced by HFD were abolished by ARPs treatment. Furthermore, ARPs treatment restored the intestinal epithelial barrier as evidenced by upregulation of intestinal tight junction proteins. Additionally, ARPs supplementation significantly decreased the relative abundance of several bacteria genus such as Parabacteroides, which may play regulatory roles in cognitive function.

Conclusion

These results suggest that ARPs might be a promising strategy for the treatment of cognitive dysfunction induced by HFD. Mechanistically, alleviation of cognitive dysfunction by ARPs might be associated with the “gut-brain” axis.

Type 2 diabetes mellitus-associated cognitive dysfunction: Advances in potential mechanisms and therapies

Type 2 diabetes (T2D) and its target organ injuries cause distressing impacts on personal health and put an enormous burden on the healthcare system, and increasing attention has been paid to T2D-associated cognitive dysfunction (TDACD). TDACD is characterized by cognitive dysfunction, delayed executive ability, and impeded information-processing speed. Brain imaging data suggest that extensive brain regions are affected in patients with T2D. Based on current findings, a wide spectrum of non-specific neurodegenerative mechanisms that partially overlap with the mechanisms of neurodegenerative diseases is hypothesized to be associated with TDACD. However, it remains unclear whether TDACD is a consequence of T2D or a complication that co-occurs with T2D. Theoretically, anti-diabetes methods are promising neuromodulatory approaches to reduce brain injury in patients with T2D. In this review, we summarize potential mechanisms underlying TDACD and promising neurotropic effects of anti-diabetes methods and some neuroprotective natural compounds. Constructing screening or diagnostic tools and developing targeted treatment and preventive strategies would be expected to reduce the burden of TDACD.

Effect of dendrobium mixture in alleviating diabetic cognitive impairment associated with regulating gut microbiota

Dendrobium mixture (DM) is a patent Chinese herbal formulation consisting of Dendrobii Caulis, Astragali Radix, Rehmanniae Radix as the main ingredients. DM has been shown to alleviate diabetic related symptoms attributed to its anti-hyperglycaemic and anti-inflammatory activities. However, the effect on diabetic induced cognitive dysfunction has not been investigated. This study aims to investigate the effect of DM in improving diabetic cognitive impairment and associated mechanisms. Our study confirmed the anti-hyperglycaemic effect of DM and showed its capacity to restore the cognitive and memory function in high fat/high glucose and streptozotocin-induced diabetic rats. The neuroprotective effect was manifested as improved learning and memory behaviours, restored blood-brain barrier tight junction, and enhanced expressions of neuronal survival related biomarkers. DM protected the colon tight junction, and effectively lowered the circulated proinflammatory mediators including tumour necrosis factor-α, interleukin-6 and lipopolysaccharides. In the gut microbiota, DM corrected the increase in the abundance of Firmicutes, the increase in the ratio of Firmicutes/Bacteroidetes, and the decrease in the abundance of Bacteroidetes in diabetic rats. It also reversed the abundance of Lactobacillus, Ruminococcus and Allobaculum genera. Short chain fatty acids, isobutyric acid and ethylmethylacetic acid, were negatively and significantly correlated to Ruminococcus and Allobaculum. Isovaleric acid was positively and significantly correlated with Lactobacillus, which all contributing to the improvement in glucose level, systemic inflammation and cognitive function in diabetic rats. Our results demonstrated the potential of DM as a promising therapeutic agent in treating diabetic cognitive impairment and the underlying mechanism may be associated with regulating gut microbiota.

Intake of flavonoids from Astragalus membranaceus ameliorated brain impairment in diabetic mice via modulating brain-gut axis

Background

Brain impairment is one of a major complication of diabetes. Dietary flavonoids have been recommended to prevent brain damage. Astragalus membranaceus is a herbal medicine commonly used to relieve the complications of diabetes. Flavonoids is one of the major ingredients of Astragalus membranaceus, but its function and mechanism on diabetic encepholopathy is still unknown.

Methods

Type 2 diabetes mellitus (T2DM) model was induced by high fat diet and STZ in C57BL/6J mice, and BEnd.3 and HT22 cell lines were applied in the in vitro study. Quality of flavonoids was evaluated by LC–MS/MS. Differential expressed proteins in the hippocampus were evaluated by proteomics; influence of the flavonoids on composition of gut microbiota was analyzed by metagenomics. Mechanism of the flavonoids on diabetic encepholopathy was analyzed by Q-PCR, Western Blot, and multi-immunological methods et al.

Results

We found that flavonoids from Astragalus membranaceus (TFA) significantly ameliorated brain damage by modulating gut-microbiota-brain axis: TFA oral administration decreased fasting blood glucose and food intake, repaired blood brain barrier, protected hippocampus synaptic function; improved hippocampus mitochondrial biosynthesis and energy metabolism; and enriched the intestinal microbiome in high fat diet/STZ-induced diabetic mice. In the in vitro study, we found TFA increased viability of HT22 cells and preserved gut barrier integrity in CaCO₂ monocellular layer, and PGC1α/AMPK pathway participated in this process.

Conclusion

Our findings demonstrated that flavonoids from Astragalus membranaceus ameliorated brain impairment, and its modulation on gut-brain axis plays a pivotal role. Our present study provided an alternative solution on preventing and treating diabetic cognition impairment.

Liraglutide ameliorates diabetes-associated cognitive dysfunction via rescuing autophagic flux

The incidence of diabetes-associated cognitive dysfunction is increasing. However, few clinical interventions are available to prevent the disorder. Several researches have shown that liraglutide, as a glucagon-like peptide-1 analog, has protective effects on various neurodegenerative diseases, but its roles in diabetic cognitive dysfunction are rarely reported. This study aims to investigate the protective effects of liraglutide on diabetic cognitive dysfunction and its underlying mechanisms. In vivo, the effects of liraglutide treatment were investigated in a mouse model of type 2 diabetes mellitus (T2DM). In vitro, we investigated the effects of liraglutide on the high-glucose-induced rat primary neurons. The results showed that liraglutide reduced the escape latency and increased the time in effective area in the Morris water maze test, improved the damage of hippocampal and synaptic ultrastructure, and decreased the accumulation of amyloid β protein in hippocampus of T2DM mice. Furthermore, liraglutide increased the ratio of microtubule-associated protein light 1 chain Ⅱ/Ⅰ, the expression of Beclin1 protein and Lysosome-associated membrane protein 2 in vivo and vitro. Additionally, Bafilomycin A1 which can inhibit the fusion of autophagosome and lysosome partially abolished the effects of liraglutide. These findings indicate liraglutide ameliorates diabetes-associated cognitive dysfunction by rescuing autophagic flux.

Impact of Gut Microbiome Lactobacillus spp. in Brain Function and its Medicament towards Alzheimer’s Disease Pathogenesis

Alzheimer’s disease is neurodegenerative dementia which has significant health complications in the old age group. An imbalance in gut microbiota can influence to cause several diseases like chronic disorders, depression, type II diabetics, and neurological disorders like AD. Aging is one of the major causes of the development of neurodegenerative disease due to the decreasing levels of neurotransmitters, oxidative stress, chronic inflammation, and apoptosis. These harmful effects of aging can be prevented by probiotics usage. The gut-microbiota is capable to control the brain function through the gut-brain axis. Lactobacillus strains are considered as beneficial microorganism because of its importance of the maintenance in healthy intestinal microflora, immunomodulation, and intestinal pathogenic intervention. They have diverse applications in the medical field with properties like antioxidant, anticancer, anti-inflammatory, anti-proliferative, anti-obesity, and anti-diabetic activities. Probiotic supplementation with Lactobacillus strains shows an optimistic trend to use it as a significant therapy for cognitive symptoms. This review article put forwards the significance of the gut-brain axis and the contribution of Lactobacillus strains as a probiotic supplement and its therapeutic innovations for future aspects and the limitation to treat AD-related pathogenesis are briefly elucidated.

Acupuncture therapy and cognitive dysfunction in patients with type 2 diabetes: A protocol for systematic review

BACKGROUND

With the aging of society, the incidence of type 2 diabetes (T2DM) is increasing every year, and there is a clear correlation between T2DM and cognitive dysfunction. Acupuncture therapy has been widely used in the treatment of T2DM, but there is no systematic review on the treatment of T2DM associated with cognitive impairment. Therefore, this study aimed to conduct a meta-analysis of acupuncture in the treatment of T2DM with cognitive impairment to clarify its efficacy.

METHODS

A structured and systematic literature search will be conducted in the following databases up to April 26, 2021: PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science (WOS), China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM), Chinese Scientific and Journal Database (VIP), and Wan Fang database (Wanfang). We will use the Review Manager 5.4 software provided by the Cochrane Collaborative Network for statistical analysis. We then assessed the quality and risk of the included studies and observed the outcome measures.

RESULTS

This meta-analysis further determined the beneficial effects of acupuncture on T2DM with cognitive impairment.

CONCLUSION

The purpose of this meta-analysis was to explore the effect of acupuncture on patients T2DM with and cognitive impairment patients, and provide more options for clinicians and patients to treat T2DM with cognitive impairment.

ETHICS AND DISSEMINATION

This systematics review will evaluate the efficacy and safety of acupuncture in the treatment of T2DM with cognitive impairment. Since all the data included were published, the systematic review did not require ethical approval.

REGISTRATION NUMBER

CRD42021245681.

Neuritin inhibits astrogliosis to ameliorate diabetic cognitive dysfunction

Earlier, it was shown that reversing the downregulation of neuritin expression in the brain improves central neuropathy in diabetic rats. We investigated the protective mechanism of neuritin in diabetic cognitive dysfunction via astrocytes. Further, the impact of the overexpression of neuritin in the cortex and the hippocampus on diabetic cognitive dysfunction and astrogliosis in type 2 diabetic (db/db) mice was assessed. Antagonists were used to inhibit the JAK2/STAT3 signaling pathway in U-118MG, an astrocyte cell line. Immunofluorescence, Western blotting, and real-time PCR were performed. Neuritin overexpression in the hippocampus of db/db mice significantly ameliorated cognitive dysfunction, hippocampal neuronal impairment, and synaptic plasticity deterioration, and inhibited astrogliosis and the JAK2/STAT3 signaling pathway in the hippocampus. Neuritin suppressed the JAK2/STAT3 signaling pathway to inhibit lipopolysaccharide-induced gliosis in U-118MG cells. It was observed that neuritin regulates the JAK2/STAT3 signaling pathway in astrocytes to inhibit astrogliosis and improve diabetic cognitive dysfunction.

The diversity of gut microbiota in type 2 diabetes with or without cognitive impairment

BACKGROUND

Diabetes is associated with a high risk of developing cognitive impairment, but the underlying mechanism remains unclear. Recent studies have found that gut microbiota may be involved in the progression of diabetes-associated cognitive impairment.

AIMS

To analyze the diversity of gut microbiota in type 2 diabetes with or without cognitive impairment METHODS: 16S rRNA sequencing was used to detect the gut microbiota composition in 154 type 2 diabetes (T2DM) subjects RESULTS: Among 154 elderly T2DM participants included in our study, 73 with normal and 81 with impaired cognition. Lower levels of hemoglobin and HDL were observed in subjects with cognitive impairment. Patients with cognitive impairment had a lower abundance of Tenericutes. Comparison at the genus level revealed that T2DM patients with cognitive impairment had a decreased abundance of Bifidobacterium and unranked-RF39 and an increased abundance of Peptococcus and unranked-Leuconostocaceae. Additionally, the relative abundance of Veillonella and Pediococcus were decreased in subjects with cognitive impairment. Furthermore, the relative abundance of 7 sub-functions was significantly changed in the group with cognitive impairment. Calcium signaling pathways and the Renin-angiotensin system were upregulated in the cognitive impairment group while GnRH signaling, Fc gamma R-mediated phagocytosis, endocytosis, isoflavonoid biosynthesis, and cytochrome P450 were deregulated.

CONCLUSION

Bifidobacterium may be associated with cognition in T2DM. Calcium signaling and renin-angiotensin system were shown to be associated with diabetes-associated cognitive impairment through gut microbiota.

Oxidative Stress-Mediated Blood-Brain Barrier (BBB) Disruption in Neurological Diseases

The blood-brain barrier (BBB), as a crucial gate of brain-blood molecular exchange, is involved in the pathogenesis of multiple neurological diseases. Oxidative stress is caused by an imbalance between the production of reactive oxygen species (ROS) and the scavenger system. Since oxidative stress plays a significant role in the production and maintenance of the BBB, the cerebrovascular system is especially vulnerable to it. The pathways that initiate BBB dysfunction include, but are not limited to, mitochondrial dysfunction, excitotoxicity, iron metabolism, cytokines, pyroptosis, and necroptosis, all converging on the generation of ROS. Interestingly, ROS also provide common triggers that directly regulate BBB damage, parameters including tight junction (TJ) modifications, transporters, matrix metalloproteinase (MMP) activation, inflammatory responses, and autophagy. We will discuss the role of oxidative stress-mediated BBB disruption in neurological diseases, such as hemorrhagic stroke, ischemic stroke (IS), Alzheimer’s disease (AD), Parkinson’s disease (PD), traumatic brain injury (TBI), amyotrophic lateral sclerosis (ALS), and cerebral small vessel disease (CSVD). This review will also discuss the latest clinical evidence of potential biomarkers and antioxidant drugs towards oxidative stress in neurological diseases. A deeper understanding of how oxidative stress damages BBB may open up more therapeutic options for the treatment of neurological diseases.

The relationship between Helicobacter pylori infection and depressive symptoms in the general population in China: The TCLSIH cohort study

BACKGROUND

Depressive symptoms are a common, debilitating, and costly public health issue. Helicobacter pylori (H pylori) infection cause changes in the normal physiological state of the gastrointestinal (GI) flora. Although the physiological state of the GI tract is closely related to mental disorders, few population studies have examined the relationship between H pylori infection and depressive symptoms in the general population. The aim of this study was to examine whether H pylori infection is related to depressive symptoms among the general adult population.

MATERIALS AND METHODS

This cross-sectional study included 5558 inhabitants of Tianjin, China. H pylori infection was diagnosed with the carbon 13 breath test. Depressive symptoms were assessed using the Chinese version of 20-item Self-rating Depression Scale (SDS) with three cutoffs (45, 48, and 50) to indicate elevated depressive symptoms. Multiple logistic regression analysis were conducted to assess the association between H pylori infection and depressive symptoms.

RESULTS

The prevalence of depressive symptoms (SDS ≥ 45) was 12.7% in men and 17.4% in women. In multivariable models, the odds ratios and 95% confidence interval of having depressive symptoms by H pylori infection were 1.25 (1.01-1.56), 1.46 (1.11-1.91), and 1.46 (1.05-2.06) for three cutoffs: 45, 48, and 50 in women. However, no significant difference was found between H pylori infection and depressive symptoms in men.

CONCLUSIONS

This study firstly suggested that H pylori infection was related to depressive symptoms in women in the general adult population. Further prospective studies or randomized trials are required to clarify the causality.

Sodium Butyrate Improves Liver Glycogen Metabolism in Type 2 Diabetes Mellitus

Liver plays a central role in modulating blood glucose level. Our most recent findings suggested that supplementation with microbiota metabolite sodium butyrate (NaB) could ameliorate progression of type 2 diabetes mellitus (T2DM) and decrease blood HbA1c in db/db mice. To further investigate the role of butyrate in homeostasis of blood glucose and glycogen metabolism, we carried out the present study. In db/db mice, we found significant hypertrophy and steatosis in hepatic lobules accompanied by reduced glycogen storage, and expression of GPR43 was significantly decreased by 59.38 ± 3.33%; NaB administration significantly increased NaB receptor G-protein coupled receptor 43 (GPR43) level and increased glycogen storage in both mice and HepG2 cells. Glucose transporter 2 (GLUT2) and sodium-glucose cotransporter 1 (SGLT1) on cell membrane were upregulated by NaB. The activation of intracellular signaling Protein kinase B (PKB), also known as AKT, was inhibited while glycogen synthase kinase 3 (GSK3) was activated by NaB in both in vivo and in vitro studies. The present study demonstrated that microbiota metabolite NaB possessed beneficial effects on preserving blood glucose homeostasis by promoting glycogen metabolism in liver cells, and the GPR43-AKT-GSK3 signaling pathway should contribute to this effect.

Gut Microbiota in Alzheimer's Disease, Depression, and Type 2 Diabetes Mellitus: The Role of Oxidative Stress

Gut microbiota consists of over 100 trillion microorganisms including at least 1000 different species of bacteria and is crucially involved in physiological and pathophysiological processes occurring in the host. An imbalanced gastrointestinal ecosystem (dysbiosis) seems to be a contributor to the development and maintenance of several diseases, such as Alzheimer's disease, depression, and type 2 diabetes mellitus. Interestingly, the three disorders are frequently associated as demonstrated by the high comorbidity rates. In this review, we introduce gut microbiota and its role in both normal and pathological processes; then, we discuss the importance of the gut-brain axis as well as the role of oxidative stress and inflammation as mediators of the pathological processes in which dysbiosis is involved. Specific sections pertain the role of the altered gut microbiota in the pathogenesis of Alzheimer's disease, depression, and type 2 diabetes mellitus. The therapeutic implications of microbiota manipulation are briefly discussed. Finally, a conclusion comments on the possible role of dysbiosis as a common pathogenetic contributor (via oxidative stress and inflammation) shared by the three disorders.

Gut microbiota, cognitive frailty and dementia in older individuals: a systematic review

Cognitive frailty, defined as the coexistence of mild cognitive impairment symptoms and physical frailty phenotype in older persons, is increasingly considered the main geriatric condition predisposing to dementia. Recent studies have demonstrated that gut microbiota may be involved in frailty physiopathology by promoting chronic inflammation and anabolic resistance. The contribution of gut microbiota to the development of cognitive impairment and dementia is less defined, even though the concept of "gut-brain axis" has been well demonstrated for other neuropsychiatric disorders. The aim of this systematic review was to summarize the current state-of-the-art literature on the gut microbiota alterations associated with cognitive frailty, mild cognitive impairment and dementia and elucidate the effects of pre- or probiotic administration on cognitive symptom modulation in animal models of aging and human beings. We identified 47 papers with original data (31 from animal studies and 16 from human studies) suitable for inclusion according to our aims. We concluded that several observational and intervention studies performed in animal models of dementia (mainly Alzheimer's disease) support the concept of a gut-brain regulation of cognitive symptoms. Modulation of vagal activity and bacterial synthesis of substances active on host neural metabolism, inflammation and amyloid deposition are the main mechanisms involved in this physiopathologic link. Conversely, there is a substantial lack of human data, both from observational and intervention studies, preventing to formulate any clinical recommendation on this topic. Gut microbiota modulation of cognitive function represents, however, a promising area of research for identifying novel preventive and treatment strategies against dementia.

Factors Influencing Individual Variation in Farm Animal Cognition and How to Account for These Statistically

For farmed species, good health and welfare is a win-win situation: both the animals and producers can benefit. In recent years, animal welfare scientists have embraced cognitive sciences to rise to the challenge of determining an animal's internal state in order to better understand its welfare needs and by extension, the needs of larger groups of animals. A wide range of cognitive tests have been developed that can be applied in farmed species to assess a range of cognitive traits. However, this has also presented challenges. Whilst it may be expected to see cognitive variation at the species level, differences in cognitive ability between and within individuals of the same species have frequently been noted but left largely unexplained. Not accounting for individual variation may result in misleading conclusions when the results are applied both at an individual level and at higher levels of scale. This has implications both for our fundamental understanding of an individual's welfare needs, but also more broadly for experimental design and the justification for sample sizes in studies using animals. We urgently need to address this issue. In this review, we will consider the latest developments on the causes of individual variation in cognitive outcomes, such as the choice of cognitive test, sex, breed, age, early life environment, rearing conditions, personality, diet, and the animal's microbiome. We discuss the impact of each of these factors specifically in relation to recent work in farmed species, and explore the future directions for cognitive research in this field, particularly in relation to experimental design and analytical techniques that allow individual variation to be accounted for appropriately.

Longitudinal Analysis of Fecal Microbiome and Pathologic Processes in a Rotenone Induced Mice Model of Parkinson's Disease

Recent studies reported an association between gut microbiota composition and Parkinson’s disease (PD). However, we know little about the relationship between microbiome dysbiosis and the pathogenesis of PD. The objective of this study was to describe the evolution of fecal microbiota using an oral rotenone model of PD from a longitudinal study over a period of 4 weeks. Gastrointestinal function was assessed by measuring fecal pellet output, motor functions was assessed by open-field and pole tests every week. α-synuclein pathology, inflammation and tyrosine hydroxylase (TH) neuron loss from the middle brain were also analyzed. Fecal samples were collected every week followed by 16S rRNA sequencing and bioinformatics analysis. We reported that chronically oral administered rotenone caused gastrointestinal dysfunction and microbiome dysbiosis prior to motor dysfunction and central nervous system (CNS) pathology. 16S rRNA sequencing of fecal microbiome showed rotenone-treated mice exhibited fecal microbiota dysbiosis characterized by an overall decrease in bacterial diversity and a significant change of microbiota composition, notably members of the phyla Firmicutes and Bacteroidetes, with an increase in Firmicutes/Bacteroidetes ratio after 3 weeks of rotenone treatment. Moreover, rotenone-induced gastrointestinal and motor dysfunctions were observed to be robustly correlated with changes in the composition of fecal microbiota. Our results demonstrated that gut microbiome perturbation might contribute to rotenone toxicity in the initiation of PD and brought a new insight in the pathogenesis of PD. Novel therapeutic options aimed at modifying the gut microbiota composition might postpone the onset and following cascade of neurodegeneration.