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

Exploring the effect and mechanism of action of Jinlida granules (JLD) in the treatment of diabetes-associated cognitive impairment based on network pharmacology with experimental validation

OBJECTIVES

To explore the effect and the probable mechanisms of JLD in the treatment of type 2 diabetes mellitus (T2DM) - associated cognitive impairment (TDACI).

METHODS

The effect of JLD in combating TDACI was assessed in T2DM model mice by conducting Morris water maze (MWM) behaviour testing. Active components and their putative targets, as well as TDACI-related targets, were collected from public databases. Protein-protein interactions (PPIs), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses and molecular docking were then utilized to explore potential molecular network mechanisms. Finally, the main targets were verified in animal model experiments.

RESULTS

MWM test showed that JLD improved aspects of behaviour in T2DM model mice. JLD improved glucose intolerance, tissue insulin sensitivity, lipid metabolism and enhanced synapse-associated protein expression in hippocampus tissue. Network pharmacology revealed 185 active components, 337 targets of JLD, and 7998 TDACI related targets were obtained . PPI network analyses revealed 39 core targets. GO and KEGG analyses suggested that JLD might improve TDACI by regulating gene expression, apoptotic processes and inflammatory responses mainly via PI3K-AKT and AGE-RAGE signaling pathways. Molecular docking revealed strong binding of the main components to core targets. JLD reduced hippocampus tissue expression of the inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL6), core targets of treatment of TDACI.

CONCLUSIONS

The findings suggested that JLD has the potential to improve TDACI through multiple components, multiple targets and multiple pathways. JLD may be a promising treatment for diabetic cognitive impairment.

Omega-3 polyunsaturated fatty acids attenuate cognitive impairment via the gut-brain axis in diabetes-associated cognitive dysfunction rats

Diabetes-related cognitive dysfunction (DACD) is a comorbidity of type 2 diabetes that has a negative effect on patients' quality of life. Research has indicated that disruption of the gut microbiota (GM) may be linked to dementia with altered cognitive performance. Conversely, omega-3 polyunsaturated fatty acids (n-3 PUFAs) may reverse DACD. The present study aimed to assess the effects of an n-3 PUFA intervention and fecal microbiota transplantation (FMT) on high-fat and streptozotocin-induced DACD model rats. In DACD rats, n-3 PUFA treatment restored fasting blood glucose (FBG) levels and cognitive function, increased the expression of anti-inflammatory cytokines and downregulated the expression of proinflammatory cytokines in the cortex and colon. Additionally, the expression of the postsynaptic density protein-95 mRNA and protein varied with n-3 PUFA treatment. Treatment with n-3 PUFAs also increased the expression of tight junction proteins. Beneficial and short-chain fatty acid-producing bacteria were more abundant when rats were exposed to n-3 PUFAs. After FMT from the rats with DACD symptoms that were improved by the n-3 PUFA dietary intervention into another batch of DACD rats, we observed recovery in recipient DACD rats. These results indicated that the alleviation of DACD symptoms by n-3 PUFAs was attributed to gut microbiota remodeling.

Gut microbiota mediates semaglutide attenuation of diabetes-associated cognitive decline

Diabetes-associated cognitive decline (DACD), characterized by cognitive impairment, is a serious complication of diabetes mellitus (DM). Research has shown that semaglutide, a novel glucagon-like peptide-1 receptor agonist, has neurotrophic and neuroprotective properties. However, a comprehensive understanding of the specific effects and underlying mechanisms of semaglutide treatment in patients with DACD remains lacking. In this study, we evaluated the potential of semaglutide to alleviate DACD in mice with DM. Eight-week-old mice fed a high-fat diet with streptozotocin-induced DM were subcutaneously injected with semaglutide (30 ​nmol/kg qd) for 12 weeks. Semaglutide administration significantly alleviated cognitive impairment, inhibited hippocampal neuron loss, improved the hippocampal synaptic ultrastructure, and effectively mitigated neuroinflammation. Furthermore, semaglutide treatment increased the relative abundances of g_Alistipes, g_norank_f_Eubacterium_coprostanoligenes, g_Bacteroides, and g_Parabacteroides, while decreasing the relative abundances of g_ faecalibaculum, g_Colodertribacter, g_GCA-900066575, g_Erysipelatoclostridium, and g_norank_f_Lachnospiraceae. Semaglutide also induced alterations in fecal and serum metabolites, as well as transcriptomic changes in brain tissue, with significant common enrichment in neuroactive ligand-receptor interactions. Furthermore, strong correlations were observed among semaglutide-affected genes, metabolites, and microbiota, as assessed by correlation analysis and integrative modeling. In conclusion, these findings suggest a correlation between the protective effects of semaglutide against DACD and the microbiota-gut-brain axis.

Intranasal insulin enhances resting-state functional connectivity in Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) affects cognition and resting-state functional connectivity (rsFC). Intranasal insulin (INI) has emerged as a potential treatment for T2DM-related cognitive decline. We aimed to evaluate the effect of INI treatment on rsFC with medio-prefrontal (mPFC) and left/right hippocampus (lHPC/rHPC), and their relationship with the cognition, hemoglobin A1c (HbA1c), and homeostatic model assessment of insulin resistance (HOMA-IR) and walking speed. An MRI sub-study of the MemAID trial was conducted, involving a 24-week treatment with either intranasal insulin or placebo. Blood oxygen level-dependent (BOLD) functional MRI (fMRI) images were acquired on eighteen DM subjects at baseline and eleven DM subjects (eight DM-INI patients and three DM-Placebo) at the end-of-treatment. Compared to DM-Placebo treated subjects, DM-INI patients showed increased mPFC-postcentral rsFC, lHPC-frontal rsFC, lHPC-postcentral rsFC, rHPC-frontal rsFC, and lHPC-mPFC rsFC (p < 0.05). The decreased HOMA-IR, which was observed in the MemAID trial, was associated with increased mPFC-basal ganglia rsFC (p < 0.05). This sub-study provides insights into potential mechanisms of INI effects on rsFC that require validation in a larger trial.

AIM2 mediated neuron PANoptosis plays an important role in diabetes cognitive dysfunction

The increasing global aging population has led to a rise in diabetic cognitive dysfunction (DCD), a common complication of diabetes that significantly impacts the health of elderly individuals. Neuronal death is a key factor in cognitive impairment, with studies showing interactions between cellular pyroptosis, apoptosis, and necroptosis in the development of neurodegenerative disorders. This has led to the concept of PANoptosis, where these pathways work together to cause cell death. High glucose levels can induce neuronal damage and cognitive dysfunction in rats, leading to various forms of programmed cell death. It is hypothesized that high glucose can trigger neuronal PANoptosis, resulting in cognitive dysfunction. AIM2, an upstream regulator of PANoptosis, is closely associated with the pathogenesis of DCD. In DCD, dysregulated glucose metabolism induces the release of mitochondrial DNA (mtDNA), which acts as a ligand to activate the cell membrane-bound DNA sensor AIM2. Upon activation, AIM2 oligomerizes and recruits a caspase recruit domain (ASC), forming a complex that activates caspase-1. Caspase-1 activation subsequently triggers the production of pro-inflammatory cytokines, induces pyroptosis, and mediates apoptosis, necroptosis, and PANoptosis in neurons through signaling crosstalk. Understanding the pathophysiological mechanism of AIM2-mediated neuronal PANoptosis in DCD development can aid in early diagnosis and identify new therapeutic targets.

Scientometric analysis and historical review of diabetic encephalopathy research: Trends and hotspots (2004-2023)

BACKGROUND

Diabetic encephalopathy (DE) is a common and serious complication of diabetes that can cause death in many patients and significantly affects the lives of individuals and society. Multiple studies investigating the pathogenesis of DE have been reported. However, few studies have focused on scientometric analysis of DE.

AIM

To analyze literature on DE using scientometrics to provide a comprehensive picture of research directions and progress in this field.

METHODS

We reviewed studies on DE or cognitive impairment published between 2004 and 2023. The latter were used to identify the most frequent keywords in the keyword analysis and explore the hotspots and trends of DE.

RESULTS

Scientometric analysis revealed 1308 research papers on DE, a number that increased annually over the past 20 years, and that the primary topics explored were domain distribution, knowledge structure, evolution, and emergence of research topics related to DE. The inducing factors, comorbidities, pathogenesis, treatment, and animal models of DE help clarify its occurrence, development, and treatment. An increasing number of studies on DE may be a result of the recent increase in patients with diabetes, unhealthy lifestyles, and unhealthy eating habits, which have aggravated the incidence of this disease.

CONCLUSION

We identified the main inducing factors and comorbidities of DE, though other complex factors undoubtedly increase social and economic burdens. These findings provide vital references for future studies.

Predictive value of biliverdin reductase-A and homeostasis model assessment of insulin resistance on mild cognitive impairment in patients with type 2 diabetes

AIMS/INTRODUCTION

To investigate the predictive value of the biliverdin reductase-A (BVR-A) and the homeostasis model assessment for insulin resistance (HOMA-IR) on mild cognitive impairment (MCI) in patients with type 2 diabetes mellitus, and to establish a nomogram model.

MATERIALS AND METHODS

This study included 140 patients with type 2 diabetes mellitus. Based on Montreal Cognitive Assessment (MoCA) scores, participants were categorized into the normal cognitive function (T2DM-NCF) group (65 cases) and the mild cognitive impairment (T2DM-MCI) group (75 cases). Multivariate logistic regression analysis was performed to identify the factors associated with MCI in patients with type 2 diabetes mellitus. A nomogram prediction model was developed using R software for the selected factors, and its predictability and accuracy were verified.

RESULTS

Compared with the T2DM-NCF group, subjects with MCI were older, had a longer duration of diabetes, higher HOMA-IR, lower BVR-A, lower cognitive scores, and lower education levels (all P < 0.05). Multivariate logistic regression analysis showed that duration of diabetes (OR = 1.407, 95% CI: 1.163-1.701), HOMA-IR (OR = 1.741, 95% CI: 1.197-2.53), and BVR-A (OR = 0.528, 95% CI: 0.392-0.712) were significantly associated with the development of MCI in patients with type 2 diabetes mellitus. The C-index of the nomogram was 0.863 (95% CI: 0.752-0.937).

CONCLUSIONS

Our findings suggest that BVR-A and HOMA-IR are significantly associated with the development of MCI in patients with type 2 diabetes mellitus. The nomogram incorporating BVR-A and HOMA-IR aids in predicting the risk of developing MCI in these patients.

Phospholipids and peroxisomes in ferroptosis: the therapeutic target of acupuncture regulating vascular cognitive impairment and dementia

Ferroptosis, since its conceptualization in 2012, has witnessed an exponential growth in research interest over recent years. It is regulated by various cellular metabolic pathways during chronic cerebral ischemia and hypoxia, including reactive oxygen species (ROS) generation, iron accumulation, abnormalities in glutathione metabolism, and disruptions in lipid and glucose metabolism. With the deepening and widespread research, ferroptosis has emerged as a critical pathway in the pathogenesis of vascular cognitive impairment and dementia (VCID). This unique cell death pathway caused by iron-dependent phospholipid peroxidation is strongly related to VICD. We examine the impact of phospholipid composition on neuronal susceptibility to ferroptosis, with a particular focus on the critical role of polyunsaturated fatty acids (PUFAs) in this process. Intriguingly, peroxisomes, as key regulators of lipid metabolism and oxidative stress, influence the susceptibility of neuronal cells to ferroptosis through the synthesis of plasmalogens and other lipid species. In this Review, we provide a critical analysis of the current molecular mechanisms and regulatory networks of acupuncture for ferroptosis, the potential functions of acupuncture in peroxisomal functions and phospholipid metabolism, and its neuroprotective effects in VCID, together with a potential for therapeutic targeting. As such, this highlights the theoretical basis for the application of acupuncture in VCID through multi-target regulation of ferroptosis. This review underscores the potential of acupuncture as a non-pharmacological therapeutic approach in VCID, offering new insights into its role in modulating ferroptosis and associated metabolic pathways for neuroprotection.

Investigating the Effect and Mechanism of 3-Methyladenine Against Diabetic Encephalopathy by Network Pharmacology, Molecular Docking, and Experimental Validation

Background/Objectives: Diabetic encephalopathy (DE), a severe neurological complication of diabetes mellitus (DM), is characterized by cognitive dysfunction. 3-Methyladenine (3-MA), a methylated adenine derivative, acts as a biomarker for DNA methylation and exhibits hypoglycemic and neuroprotective properties. However, the pharmacological mechanisms underlying 3-MA's therapeutic effects on diabetic microvascular complications remain incompletely understood, owing to the intricate and multifactorial pathogenesis of DE. Methods: This study employed network pharmacology and molecular docking techniques to predict potential targets and signaling pathways of 3-MA against DE, with subsequent validation through animal experiments to elucidate the molecular mechanisms of 3-MA in DE treatment. Results: Network pharmacological analysis identified two key targets of 3-MA in DE modulation: AKT and GSK3β. Molecular docking confirmed a strong binding affinity between 3-MA and AKT/GSK3β. In animal experiments, 3-MA significantly reduced blood glucose levels in diabetic mice, ameliorated learning and memory deficits, and preserved hippocampal neuronal integrity. Furthermore, we found that 3-MA inhibited apoptosis by regulating the expression of Bax and BCL-2. Notably, 3-MA also downregulated the expression of amyloid precursor protein (APP) and Tau while enhancing the expression of phosphorylated AKT and GSK-3β. Conclusions: Our findings may contribute to elucidating the therapeutic mechanisms of 3-MA in diabetic microangiopathy and provide potential therapeutic targets through activation of the AKT/GSK-3β pathway.

Associations between morphometric similarity network and brain gene expression in type 2 diabetes mellitus

Abnormal functional and structural connectivity in brain networks is commonly observed in patients with type 2 diabetes mellitus (T2DM) and is often associated with cognitive impairment. In this study, we employed the Morphometric Similarity Network (MSN) method, which is based on seven morphometric features derived from structural and diffusion magnetic resonance imaging, to investigate structural differences in the brains of T2DM patients by quantifying structural similarities between brain regions. Globally, morphometric similarity (MS) was significantly reduced in T2DM patients. Regionally, MS was decreased in the left sensorimotor network and the right salience/ventral attention network, while it was increased in the bilateral visual network. Notably, the increased MS in the bilateral visual network was negatively correlated with memory function in T2DM patients. Furthermore, using the Allen Human Brain Atlas (AHBA; http://human.brain-map.org), which provides transcriptome data from postmortem adult brains, we linked MSN changes to regional gene expression patterns. Transcription-neuroimaging association analyses identified 298 genes whose expression was significantly spatially correlated with T2DM-related MSN abnormalities. Many of these genes are involved in biological processes such as central nervous system development and neurotransmitter transmission, offering valuable molecular and cellular insights into MS abnormalities and cognitive decline in T2DM. These findings shed light on the neural and genetic mechanisms underlying T2DM-related brain changes and cognitive impairment, providing new perspectives for future research and potential therapeutic approaches.

Risk Factors, Pathological Changes, and Potential Treatment of Diabetes-Associated Cognitive Dysfunction

BACKGROUND

Diabetes is a prevalent public health issue worldwide, and the cognitive dysfunction and subsequent dementia caused by it seriously affect the quality of life of patients.

METHODS

Recent studies were reviewed to provide a comprehensive summary of the risk factors, pathogenesis, pathological changes and potential drug treatments for diabetes-related cognitive dysfunction (DACD).

RESULTS

Several risk factors contribute to DACD, including hyperglycemia, hypoglycemia, blood sugar fluctuations, hyperinsulinemia, aging, and others. Among them, modifiable risk factors for DACD include blood glucose control, physical activity, diet, smoking, and hypertension management, while non-modifiable risk factors include age, genetic predisposition, sex, and duration of diabetes. At the present, the pathogenesis of DACD mainly includes insulin resistance, neuroinflammation, vascular disorders, oxidative stress, and neurotransmitter disorders.

CONCLUSIONS

In this review, we provide a comprehensive summary of the risk factors, pathogenesis, pathological changes and potential drug treatments for DACD, providing information from multiple perspectives for its prevention and management.

Association of plasma zinc and copper levels with mild cognitive impairment in patients with type 2 diabetes

Background

Type 2 diabetes mellitus (T2DM) is a significant risk factor for cognitive impairment. Zinc deficiency contributes to T2DM development, while copper may exacerbate diabetes through prooxidant mechanisms. Higher zinc levels may protect against copper toxicity. This study investigates the association of plasma zinc and copper levels with mild cognitive impairment (MCI) in T2DM patients.

Methods

T2DM patients admitted to Tongji Hospital from 2012 to 2018 were classified into MCI (n = 136) and control (n = 136) groups, matched by age (± 3 years) and gender. Conditional logistic regression was used to assess the associations between plasma zinc, copper levels and MCI. A generalized additive model (GAM) evaluated the dose-response relationship between plasma zinc, copper levels and Mini-Mental State Examination (MMSE) scores.

Results

The median of plasma metal levels in MCI and control groups were 831.31 μg/L and 936.29 μg/L for zinc, 932.07 μg/L and 860.47 μg/L for copper, and 0.91 and 1.11 for the zinc-to-copper (Zn/Cu) ratio. Compared to participants in the lowest tertile, the multivariable-adjusted odds ratios with 95% confidence intervals (CI) for MCI in the highest tertile were 0.33 (0.13, 0.79) for zinc, 3.56 (1.42, 8.94) for copper, and 0.37 (0.15, 0.93) for the Zn/Cu ratio. Plasma Aβ40 levels were significantly lower (p = 0.009) and plasma Aβ42/40 levels were significantly higher (p = 0.008) in MCI group compared with those in control group. Zinc concentration was positively associated with Aβ42. For per SD (327.71 μg/L) increase in plasma zinc levels, the percent change (95% CI) of Aβ42 were 2.90 (0.85, 4.99).

Conclusion

Higher plasma zinc levels and higher Zn/Cu ratio were associated with lower odds of MCI in T2DM patients, while higher copper levels increased the risk of MCI. This study provides insights on plasma zinc, copper, and Zn/Cu ratio and Aβ of MCI, further studies are needed to clarify the underlying mechanisms for novel therapies that could prevent or cure multiple T2DM-related cognitive impairments.

Cognitive impairment and hippocampal degeneration in aged rat models of type 2 diabetes with induced glycemic fluctuation: A pilot study

OBJECTIVE

Effective methods for establishing an aged animal model of diabetes and glycemic fluctuation have rarely been investigated. The aim of the study was to explore the feasibility of inducing glycemic fluctuation in aged Sprague-Dawley rats and to evaluate the corresponding changes in cognitive function.

METHODS

Male rats aged 48 weeks were fed a high-fat and high-glucose diet and given streptozotocin intraperitoneally to establish a rat model of type 2 diabetes mellitus (T2DM). Then, glycemic fluctuation was induced via three different protocols: (1) intraperitoneal injection of glucose; (2) sequential fasting, insulin injection, and normal diet; and (3) intermittent intraperitoneal injections of glucose and insulin.

RESULTS

All three protocols were effective at inducing glycemic fluctuation in aged rats with T2DM, with successful modeling rates of 60 %, 90 %, and 70 %, respectively. Aged T2DM rats with glycemic fluctuation showed significant increases in glycemic variability compared with controls, including in the mean blood glucose, postprandial glycemic excursion, largest amplitude of glycemic excursion, and standard deviation of blood glucose values (all P < 0.05). Additionally, rats with glycemic fluctuation had more severe insulin resistance and dyslipidemia (P < 0.05). Morris water maze testing showed a trend of longer escape latency in the navigation test for rats in the glycemic fluctuation groups, suggesting impaired cognitive function. Pathological analysis showed degenerative changes in the CA1 hippocampal region of rats in the glycemic fluctuation groups. Finally, differential gene expression analysis revealed 1323 significantly altered genes in the GV group, with 691 upregulated and 632 downregulated. The dysregulated genes were predominantly associated with the axon guidance pathway and potassium channel regulation.

CONCLUSIONS

The proposed protocols were effective at establishing an aged T2DM rat model with glycemic fluctuation, and rats with glycemic fluctuation exhibited diminished cognitive function.

Synergistically effects of n-3 PUFA and B vitamins prevent diabetic cognitive dysfunction through promoting TET2-mediated active DNA demethylation

Diabetic cognitive dysfunction (DCD) refers to the cognitive impairment observed in individuals with diabetes. Epidemiological studies have suggested that supplementation with n-3 polyunsaturated fatty acid (PUFA) or B vitamins may prevent the development of diabetic complications. Post hoc studies indicate a potential synergistic effect of n-3 PUFA and B vitamins in preventing cognitive impairment. However, the precise effect and underlying mechanism of this combination on DCD remain unclear. In case-control study, we compared fatty acid composition of erythrocyte membrane and serum homocysteine levels between diabetic individuals with and without DCD. We found that insufficient levels of n-3 PUFA, along with elevated serum homocysteine, significantly increase the risk of developing DCD. Treatment with a combination of fish oil, folate, and vitamin B12 improved cognitive impairment and aberrant neuronal morphology in streptozotocin-induced DCD mice. Folic acid and vitamin B12 enhanced the efficiency of exogenous docosahexaenoic acid (DHA) transportation to the brain by preventing the accumulation of homocysteine and S-adenosylhomocysteine, thereby inhibiting neuronal apoptosis in diabetic brains. Furthermore, folic acid and vitamin B12 supplementation can provide sufficient 5-methylcytosine for diabetic brains by promoting DNA methylation, while increased DHA levels maintain TET-mediated active DNA demethylation in diabetic brains through enhancing TET2 function. Overall, our study provides novel insights into molecular mechanisms underlying the synergistic preventive effects of the combined supplementation with fish oil, folic acid and vitamin B12 on DCD, suggests that combining n-3 PUFA and B vitamins could be a promising strategy for preventing DCD among individuals with diabetes.

Uncovering the intricacies of O-GlcNAc modification in cognitive impairment: New insights from regulation to therapeutic targeting

O-linked β-N-acetylglucosamine (O-GlcNAc) represents a post-translational modification that occurs on serine or threonine residues on various proteins. This conserved modification interacts with vital cellular pathways. Although O-GlcNAc is widely distributed throughout the body, it is particularly enriched in the brain, where most proteins are O-GlcNAcylated. Recent studies have established a causal link between O-GlcNAc regulation in the brain and alterations in neurophysiological function. Alterations in O-GlcNAc levels in the brain are associated with the pathogenesis of several neurogenic diseases that can lead to cognitive impairment. Remarkably, manipulation of O-GlcNAc levels demonstrated a protective effect on cognitive function. Although the precise molecular mechanism of O-GlcNAc modification in the nervous system remains elusive, its regulation is fundamental to multiple neural and cognitive functions, fluctuating levels during normal and pathological cognitive processes. In this review, we highlight the significant functional importance of O-GlcNAc modification in pathological cognitive impairments and the potential application of O-GlcNAc as a promising target for the intervention or amelioration of cognitive impairments.

Study on the mechanism on Yi-guan-jian decoction alleviating cognitive dysfunction in type 2 diabetes mellitus

ETHNOPHARMACOLOGICAL RELEVANCE

Yi-guan-jian decoction (YGJ) is a traditional Chinese medicine prescription commonly used for treating syndromes associated with Yin deficiency in the liver and kidney, as well as Qi-obstructed in liver.

AIM OF THE STUDY

YGJ has shown potential alleviating cognitive dysfunction in type 2 diabetes mellitus (T2DM). However, the precise mechanisms are not yet fully understood. This study aims to reveal the mechanism by which YGJ alleviates cognitive dysfunction in T2DM.

MATERIALS AND METHODS

Various doses of YGJ were administered to T2DM rats with cognitive dysfunction for 8 weeks. The positive control group received a combination of metformin and memantine. Cognitive function was assessed in T2DM rats using the Morris water maze test during treatment. Changes in gut microbiota and bile acids in the intestine were evaluated, and their interactions analyzed. Additionally, this study also evaluated the expressions of inflammatory markers (IL-1β,TNF-α, IL-16, IL-18 and CRP protein), Tau protein, neurotransmitter (5-HT and GABA), and bile acid receptor (FXR, PXR, VDR, and TGR5).

RESULTS

YGJ significantly alleviated insulin resistance and hyperlipidemia, reduce the levels of inflammatory factors in serum and hippocampus, and decreased mortality in T2DM rats. The Morris water maze test indicated that YGJ reduced the escape latency and increased platform crossing frequency, thereby improving cognitive function in T2DM rats. Furthermore, YGJ regulated the abundance of microorganisms associated with bile acid metabolism, including Romboutsia, Bacteroides, Turicibacter, Blautia, and Ruminococcus, thus regulating bile acid metabolism in T2DM rats. Additionally, YGJ also regulated bile acid metabolism by regulating intestinal FXR, PXR, VDR and TRG5 receptors.

CONCLUSION

YGJ can alleviate glucose homeostasis, insulin sensitivity, lipid metabolism, neuroinflammation, cognitive function, as well as remodel intestinal flora and BA composition in CDT2DM rats, which is a potential complementary and alternative therapy for the prevention and treatment of CDT2DM. These effects may be associated that YGJ regulates the structure of intestinal flora and BA metabolism, and inhibits intestinal BA receptors FXR, PXR, TGR5, and VDR.

Huang-Lian-Jie-Du Decoction alleviates diabetic encephalopathy by regulating inflammation and pyroptosis via suppression of AGEs/RAGE/NF-κB pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Cognitive dysfunction associated with diabetes, known as diabetic encephalopathy (DE), is a grave neurodegenerative condition triggered by diabetes, and persistent inflammation plays a vital role in its development. The renowned traditional Chinese medicine Huang-Lian-Jie-Du Decoction (HLJDD) is clinically proven to manage diabetes mellitus and Alzheimer's disease and is famous for its heat-clearing and detoxifying effects. However, the underlying mechanisms through which HLJDD affects DE remain to be elucidated.

AIM OF THE STUDY

To explore the beneficial effects of HLJDD on improving cognitive dysfunction in DE mice.

STUDY DESIGN AND METHODS

A diabetic mouse was established through a high-fat diet and subsequent administration of streptozotocin over five consecutive days. After the animals were confirmed to have diabetes, they were treated with HLJDD. After oral administration of HLJDD or metformin for 14 weeks, behavioral tests were used to assess their cognitive capacity. Biochemical analyses were then performed to detect levels of glucose metabolism, followed by histological analyses to assess pathological damage. Furthermore, AGEs/RAGE/NF-κB axis related proteins were detected by Western blot or immunofluorescence techniques. An advanced UPLC-Q-Orbitrap HRMS/MS analytical technique utilizing a chemical derivatization strategy was employed for comprehensive metabolic profiling of carbonyl compounds in the plasma of DE mice.

RESULTS

Pharmacological assessment revealed that HLJDD effectively mitigated cognitive dysfunction, normalized glucose metabolic imbalances, and repaired neuronal damage in DE mice. It reduced neuroinflammation by attenuating carbonyl stress, deactivating astrocytes and microglia, and preserving dopaminergic neurons. Additionally, metabolomics analysis revealed 18 carbonyl compounds with marked disparities between DE and control mice, with 12 metabolites approaching normal levels post-HLJDD intervention. Further investigations showed that HLJDD regulated inflammation and pyroptosis through suppressing AGEs/RAGE/NF-κB pathways.

CONCLUSION

Our study indicated that HLJDD could ameliorate carbonyl stress via the regulation of carbonyl compound metabolism profiling, and inhibiting the AGEs/RAGE/NF-κB pathway, thereby alleviating inflammation and pyroptosis to exert beneficial effects on DE.

ZiBu PiYin recipe regulates central and peripheral Aβ metabolism and improves diabetes-associated cognitive decline in ZDF rats

ETHNOPHARMACOLOGICAL RELEVANCE

Cognitive impairment caused by central neuropathy in type 2 diabetes mellitus (T2DM), namely diabetes-associated cognitive decline (DACD), is one of the common complications in patients with T2DM. Studies have shown that brain β-amyloid (Aβ) deposition is a typical pathological change in patients with DACD, and that there is a close relationship between intestinal microorganisms and cognitive impairment. However, the specific mechanism(s) of alteration in Aβ metabolism in DACD, and of the correlation between Aβ metabolism and intestinal microorganisms remain unknown.

AIM OF THE STUDY

Revealing the mechanism of ZBPYR regulating Aβ metabolism and providing theoretical basis for clinical evaluation and diagnosis of DACD.

MATERIALS AND METHODS

We characterized Aβ metabolism in the central and peripheral tissues of Zucker diabetic fatty (ZDF) rats with DACD, and then explored the preventive and therapeutic effects of ZiBu PiYin Recipe (ZBPYR). Specifically, we assessed these animals for the formation, transport, and clearance of Aβ; the morphological structure of the blood-brain barrier (BBB); and the potential correlation between Aβ metabolism and intestinal microorganisms.

RESULTS

ZBPYR provided improvements in the structure of the BBB, attenuation of Aβ deposition in the central and peripheral tissues, and a delay in the development of DACD by improving the expression of Aβ production, transport, and clearance related protein in ZDF rats. In addition, ZBPYR improved the diversity and composition of intestinal microorganisms, decreased the abundance of Coprococcus, a bacterium closely related to Aβ production, and up regulate the abundance of Streptococcus, a bacterium closely related to Aβ clearance.

CONCLUSION

The mechanism of ZBPYR ability to ameliorate DACD may be closely related to changes in the intestinal microbiome.

Liraglutide and denatonium benzoate attenuate T2DM-induced metabolic, neurological, and testicular changes in rats: Targeting oxidative stress, inflammation, and BCRP transporter

Type 2 diabetes mellitus (T2DM) adversely affects various organs, including the brain and its blood barrier. In addition to the brain, hyperglycemia damages the testes. The testes possess blood-tissue barriers that share common characteristics and proteins with the blood-brain barrier (BBB), including breast cancer-resistant protein (BCRP). This study aimed to investigate the impact of uncontrolled DM on the brain and testes, with a specific focus on BCRP. Moreover, it examined the effects of liraglutide (Lira) and denatonium benzoate (DB), a bitter taste receptor agonist, on T2DM. Forty adult male rats were randomized into five groups: normal control, diabetic, diabetic + DB, diabetic + Lira, and diabetic + DB + Lira. T2DM was induced using fructose and streptozotocin (STZ). After eight weeks of treatment, rats were sacrificed, and samples of blood, semen, testes, and brain were collected to evaluate metabolic and semen parameters, oxidative stress, inflammatory markers, histological features of the brain and testes, and BCRP expression. DB and Lira, both individually and in combination, mitigated fructose/STZ-induced hyperglycemia and dyslipidemia. Additionally, they enhanced SOD activity and reduced MDA, TNFα, and IL-6 levels in the brain and testes, alongside improving sperm quality and serum levels of FSH, LH, and testosterone. Rats treated with DB, Lira, or DB + Lira demonstrated improved brain and testicular tissue architecture. BCRP expression was upregulated in the brains and testes of Lira- and DB + Lira-treated rats. These findings indicated that DB positively affects the metabolic profile of T2DM. Furthermore, Lira and DB provided protection against T2DM-induced brain and testicular damage.

The enlarged perivascular spaces in the hippocampus is associated with memory function in patients with type 2 diabetes mellitus

Early detection of cognitive dysfunction in patients with type 2 diabetes mellitus (T2DM) is important for preventive measures due to the lack of effective treatments. The purpose of this study is to investigate the relationship between enlarged perivascular space in the hippocampus (H-EPVS) and cognitive performance in patients with T2DM, and to determine whether it can serve as an imaging marker for cognitive dysfunction. 66 T2DM patients with cognitive impairment (T2DM-CI) and 71 T2DM patients with normal cognitive function (T2DM-NC) underwent cranial MRI scans and comprehensive neuropsychological assessments. H-EPVS counts were visually calculated on T2WI imaging according to a previous scale. The differences in the counts of H-EPVS, demographic data, laboratory test results, and cognitive assessment scores between the two groups were compared. The partial correlation analysis was used to explore the relationship between H-EPVS and glymphatic system function (indicated by the DTI-ALPS index), as well as markers of CSVD. Multiple linear regression models were conducted to explore the association between H-EPVS and cognitive functions. Compared with the T2DM-NC group, T2DM-CI exhibited significantly higher counts of H-EPVS in both the total (sum of the left and right side) and left side (P < 0.001). The T2DM-CI group had lower DTI-ALPS index and RAVLT total score. The total H-EPVS counts were significantly correlated with the DTI-ALPS index (r = - 0.240, P = 0.005), BG-EPVS (r = 0.325, P < 0.001), and CSO-EPVS (r = 0.183, P = 0.033). Multiple linear regression showed the total H-EPVS counts exhibited a negative correlation with MMSE (β = - 0.324, 95% CI: - 0.091, - 0.320), immediate memory (β = - 0.380, 95% CI: - 0.673, - 1.766) and delayed recall (β = - 0.252, 95% CI: - 0.052, - 0.463). H-EPVS may serve as a potential neuroimaging biomarker for cognitive impairment in patients with T2DM, warranting further investigation and validation in future studies.

Association Between Weight-Adjusted Waist Index and Cognitive Function in Older Adults Without Diabetes: A Cross-Sectional Study

Background

This study investigates the correlation between the weight-adjusted waist index (WWI) and cognitive performance in the senior American population, focusing on those without diabetes from 2011 to 2014.

Methods

We analyzed data from the 2011-2012 and 2013-2014 National Health and Nutrition Examination Surveys (NHANES), focusing on non-diabetic participants aged 60 and older who completed cognitive tests: Establish a Registry for Alzheimer's disease (CERAD), the Animal Fluency test (AFT), and Digit Symbol Substitution test (DSST). WWI was calculated using waist circumference divided by the square root of body weight. We employed linear univariate and multivariate analyses, along with curve fitting, we conducted subgroup and interaction analyses to elucidate the relationships under investigation.

Results

The study incorporated a cohort of 1649 participants aged 60 years and older, each with a complete set of data, enabling a thorough analysis. After adjusting for confounding factors, significant negative correlations were found between WWI and both CERAD (β: -0.48; 95% CI: -0.92 to -0.05; P=0.03) and DSST (β: -1.15; 95% CI: -2.09 to -0.21; P=0.017) scores, suggesting a link to cognitive decline. No association was found with AFT scores. The relationship between WWI and DSST was found to be nonlinear (P for non-linearity=0.022). Additionally, the association between WWI and CERAD was also observed (P for non-linearity=0.042). However, linear relationships were observed between WWI and AFT (P for non-linearity=0.418). The subgroup analysis was overall stable.

Conclusion

Our cross-sectional study indicates a strong link between a high WWI and reduced cognitive function in non-diabetic older Americans, as shown by CERAD and DSST scores. Attaining an optimal WWI may be vital for cognitive decline, highlighting its role in a potential preventative approach.

Clinical Trial Registry Number and Website Where It Was Obtained

The study design and data are publicly accessible at www.cdc.gov/nchs/nhanes/.

Type 2 diabetes mellitus: A cross-sectional analysis of glycemic controls and brain health outcomes

In this cross-sectional analysis, we explored how fluctuations in glycemic levels impact executive functions and psychosocial outcomes in patients with type 2 diabetes mellitus (T2DM). The goal was to understand the relationship between glycemic control and both neuropsychological and psychosocial health. We stratified participants into well-controlled and poorly controlled groups based on glycated hemoglobin (HbA1c) levels and variability, including a healthy control group for comparison. The study consisted of neuropsychological tests and psychosocial assessments. Results indicated that the poorly controlled T2DM group experienced significant executive dysfunction and scored lower on the Tower of London, Wisconsin Card Sorting, and Digit Span Tests, reflecting a broader impact on quality of life and resilience. These findings support the importance of maintaining stable glycemic levels for better executive and psychosocial outcomes and highlight the need for regular neuropsychological and psychosocial assessments in diabetes care.

Emerging role of adaptive immunity in diabetes-induced cognitive impairment: from the periphery to the brain

Diabetic cognitive impairment (DCI) is a central nervous system complication induced by peripheral metabolic dysfunction of diabetes mellitus. Cumulative studies have shown that neuro-immune crosstalk is involved in the pathological progression of DCI. However, current studies mostly focus on the interaction between innate immunity cells and neurons, while ignoring the role of adaptive immunity cells in DCI. Notably, recent studies have revealed adaptive immune cells are involved in cognitive development and the progression of neurodegenerative diseases. Equally important, accumulated past studies have also shown that diabetic patients experience imbalanced peripheral adaptive immune homeostasis and disrupted transmission of adaptive immune cells to the central system. Therefore, this review first updated the cognitive mechanism of adaptive immune regulation, and then summarized the contribution of adaptive immunity to DCI from the aspects of peripheral adaptive immune homeostasis, transmission pathways, and brain tissue infiltration. Furthermore, we also summarized the potential of anti-diabetic drugs to regulate adaptive immunity, and looked forward to the potential value of regulatory adaptive immunity in the prevention and treatment of DCI, to provide a new strategy for the prevention and treatment of DCI.

Antin-diabetic cognitive dysfunction effects and underpinning mechanisms of phytogenic bioactive peptides: a review

Diabetic cognitive dysfunction is one of the important comorbidities and complications of diabetes, which is mainly manifested by loss of learning ability and memory, behavioural disorders, and may even develop into dementia. While traditional anti-diabetic medications are effective in improving cognition and memory, long-term use of these medications can be accompanied by undesirable side effects. Therefore, there is an urgent need to find safe and effective alternative therapies. Accumulating evidence suggests that phytogenic bioactive peptides play an important role in the regulation of cognitive dysfunction in diabetes. In this review, we explored the relationship between diabetes mellitus and cognitive dysfunction, and the potential and underlying mechanisms of plant-derived bioactive peptides to improve diabetic cognitive dysfunction. We found that plant-derived active peptides alleviate diabetic cognitive impairment by inhibiting key enzymes (e.g., α-glucosidase, α-amylase) to improve blood glucose levels and increase antioxidant activity, modulate inflammatory mediators, and address intestinal dysbiosis. In conclusion, plant-derived active peptides show strong potential to improve diabetic cognitive impairment.

Alzheimer's disease and diabetes-associated cognitive dysfunction: the microglia link?

Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β (Aβ) plaques and the aggregation of tau protein, resulting in intense memory loss and dementia. Diabetes-associated cognitive dysfunction (DACD) is a complication of diabetes mellitus, which is associated with decreased cognitive function and impaired memory. A growing body of literature emphasize the involvement of microglia in AD and DACD. Although AD and DACD share some common features related to symptomatology and pathophysiology, the characteristics and heterogeneity of microglia remain largely unknown in these two diseases. In this study, multiple bioinformatics analyses were performed to analyze the frequency, altered genes, cell-cell communication, and subtypes of microglia in AD and DACD mouse models based on two publicly single-nucleus RNA sequencing (snRNA-Seq) datasets. The results revealed that the frequency of microglia was increased in both AD and DACD mouse models when compared with control mice. After analyzing the differentially expressed genes of microglia from the two mouse models, only six common upregulated genes were found. The CellChat analysis revealed the complex cell-cell communication network (microglia clusters with other cell types) in 5XFAD vs. control mice and db/db vs. control mice. The microglia subtypes and their transcription factor activity profile in 5XFAD mice were different from that in db/db mice. In summary, this study provided some insights into the alterations of microglia in 5XFAD and db/db mice, which might open up potential avenues for the microglial-targeted therapy in AD and DACD.

Anti-diabetic agents and the risks of dementia in patients with type 2 diabetes: a systematic review and network meta-analysis of observational studies and randomized controlled trials

OBJECTIVE

To evaluate the association between anti-diabetic agents and the risks of dementia in patients with type 2 diabetes (T2D).

METHODS

Literature retrieval was conducted in PubMed, Embase, the Cochrane Central Register of Controlled Trials and Clinicaltrial.gov between January 1995 and October 2024. Observational studies and randomized controlled trials (RCTs) in patients with T2D, which intercompared anti-diabetic agents or compared them with placebo, and reported the incidence of dementia were included. Conventional and network meta-analyses of these studies were implemented. Results were exhibited as the odds ratio (OR) or risk ratio (RR) with 95% confidence interval (CI).

RESULTS

A total of 41 observational studies (3,307,483 participants) and 23 RCTs (155,443 participants) were included. In the network meta-analysis of observational studies, compared with non-users, sodium glucose cotransporter-2 inhibitor (SGLT-2i) (OR = 0.56, 95%CI, 0.45 to 0.69), glucagon-like peptide-1 receptor agonist (GLP-1RA) (OR = 0.58, 95%CI, 0.46 to 0.73), thiazolidinedione (TZD) (OR = 0.68, 95%CI, 0.57 to 0.81) and metformin (OR = 0.89, 95%CI, 0.80 to 0.99) treatments were all associated with reduced risk of dementia in patients with T2D. The surface under the cumulative ranking curve (SUCRA) evaluation conferred a rank order as SGLT-2i > GLP-1RA > TZD > dipeptidyl peptidase-4 inhibitor (DPP-4i) > metformin > α-glucosidase inhibitor (AGI) > glucokinase activator (GKA) > sulfonylureas > glinides > insulin in terms of the cognitive benefits. Meanwhile, compared with non-users, SGLT-2i (OR = 0.43, 95%CI, 0.30 to 0.62), GLP-1RA (OR = 0.54, 95%CI, 0.30 to 0.96) and DPP-4i (OR = 0.73, 95%CI, 0.57 to 0.93) were associated with a reduced risk of Alzheimer's disease while a lower risk of vascular dementia was observed in patients receiving SGLT-2i (OR = 0.42, 95%CI, 0.22 to 0.80) and TZD (OR = 0.52, 95%CI, 0.36 to 0.75) treatment. In the network meta-analysis of RCTs, the risks of dementia were comparable among anti-diabetic agents and placebo.

CONCLUSION

Compared with non-users, SGLT-2i, GLP-1RA, TZD and metformin were associated with the reduced risk of dementia in patients with T2D. SGLT-2i, and GLP-1RA may serve as the optimal choice to improve the cognitive prognosis in patients with T2D.

Studying targeted oxidation in diabetic cognitive dysfunction based on scientometrics analysis: research progress of natural product approaches

PURPOSE

The aim is to provide new insights for researchers studying the pathogenesis of diabetic cognitive dysfunction and promoting the wider use of natural products in their treatment.

METHOD

First, the Web of Science Core Collection was selected as the data source for a computerized literature search on oxidative stress and diabetic cognitive dysfunction (DCD). Next, Biblimetrix and VOSviewer performed statistical analysis focusing on publication countries, institutions, authors, research hotspots, and emerging directions in the field. Then, through the analysis of keywords and key articles, the forefront of the field is identified. Finally, we discussed the pathogenesis of DCD, the influence of oxidative stress on DCD and the antioxidant effect of natural products on DCD.

RESULT

293 valid papers were obtained. Bibliometrics showed that oxidative stress, diabetes, Alzheimer's disease (AD), cognitive decline, insulin resistance and quercetin were the key words of the symbiotic network.

CONCLUSION

The antioxidant effects of natural products in improving DCD have been extensively studied in preclinical studies, providing potential for their treatment in DCD, but their evaluation in clinical trials is currently uncommon.

Sodium butyrate improves cognitive dysfunction in high-fat diet/ streptozotocin-induced type 2 diabetic mice by ameliorating hippocampal mitochondrial damage through regulating AMPK/PGC-1α pathway

Cognitive dysfunction is an important comorbidity of type 2 diabetes mellitus (T2DM). Sodium butyrate (NaB) is a short-chain fatty acid and has an effect improving T2DM-associated cognitive dysfunction. Using a high-fat diet (HFD)/streptozotocin (STZ)-induced T2DM mouse model, the present study investigated the mechanism involved in the beneficial effect of butyrate on diabetic cognitive dysfunction, with a focus on ameliorating mitochondrial damage through regulating the adenosine monophosphate-activated protein kinase/peroxisome proliferator-activated receptor gamma coactivator 1α (AMPK/PGC-1α) pathway considering the important role of mitochondrial impairments in the occurrence of T2DM-associated cognitive dysfunction. We found, based on reconfirmation of the improvement of NaB on cognitive impairment, that NaB treatment improved damaged synaptic structural plasticity including the decrease in dendritic spine density and downregulation in the expression of postsynaptic density protein 95 and synaptophysin in the hippocampus in the model mice. NaB treatment also ameliorated mitochondrial ultrastructural damage, increased mitochondrial membrane potential and adenosine 5'-triphosphate content, and improved mitochondrial biogenesis and dynamics in the model mice. Furthermore, the expression of phosphorylated AMPK and PGC-1α was upregulated after NaB treatment in the model mice. In particular, the above beneficial effects of NaB were blocked by the inhibition of either AMPK or PGC-1α. In conclusion, NaB treatment improved cognitive impairment and damaged synaptic structural plasticity in the hippocampus by ameliorating damage to mitochondrial morphology and function through regulating the AMPK/PGC-1α pathway in HFD/STZ-induced T2DM mice.

Ethyl gallate ameliorates diabetes-induced Alzheimer's disease-like phenotype in rats via activation of α7 nicotinic receptors and mitigation of oxidative stress

Cognitive decline, an important comorbidity of type 2 diabetes (T2D), is attributed to oxidative stress and impaired cholinergic signaling in the brain. The α7 nicotinic acetylcholine receptor (α7nAChR) is densely distributed in the hippocampus and cortex, and exerts neuroprotective and procognitive actions. Ethyl gallate (EG), a natural phenolic antioxidant compound, showed high in-silico binding affinity towards α7nAChR and brain penetrability. Therefore, the present study aimed to evaluate the involvement of α7nAChR in the potential of EG to ameliorate T2D-induced Alzheimer's disease-like condition. T2D was induced by intraperitoneal (i.p.) injection of streptozotocin (35 mg/kg) in rats on high-fat diet. Diabetic animals were treated with EG (10 and 20 mg/kg, i.p.) for four weeks, and their learning and memory performance was evaluated by the Morris water maze (MWM). Further, the brains were subjected to biochemical analysis of antioxidants like glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT), and oxidative stress marker malonaldehyde (MDA). While diabetic rats showed a significant decline in cognitive performance in the MWM, a substantial improvement was noticed following EG treatment. Further, the diabetes-associated reductions in GSH, SOD, and CAT levels, along with increased MDA contents in the brain, were effectively restored by EG. Interestingly, pre-treatment with α7nAChR antagonist methyllycaconitine (1 mg/kg, i.p.) attenuated the effects of EG on behavioral and biochemical parameters. The results suggest that EG may augment cholinergic signaling in the brain via α7nAChR to mitigate oxidative stress, consequently alleviating T2D-associated dementia. Therefore, EG could be a potential candidate for addressing cognitive impairment comorbid with T2D.

Evaluation of Cognitive and Synaptic Restoration in Diabetic Rats Treated With Emblica officinalis, Clitoria ternatea, Vitamin C, and Metformin

BACKGROUND

Diabetes is known to cause cognitive impairments and synaptic dysfunction. This study investigates the effects of Emblica officinalis (EO), Clitoria ternatea (CT), Vitamin C, and metformin on cognitive function and synaptic density (SYN) in diabetic rats. This work aims to evaluate the impact of various treatments on spatial learning, memory, and SYN in a diabetic rat model.

METHODS

The Morris water maze test was used to assess spatial learning and memory at four time points (Days 1, 3, 14, and 21). SYN was measured using optical density to assess SYN expression. Eight experimental groups were included: Non-diabetic Control, Diabetic Control, Diabetic + EO, Diabetic + CT, Diabetic + Vitamin C, Diabetic + Metformin, Non-diabetic + EO, and Non-diabetic + CT.

RESULTS

On Day 1, the Diabetic Control group exhibited significantly longer latency times, indicating cognitive impairment. Diabetic + EO and Diabetic + CT showed the most significant improvements in cognitive performance compared to other diabetic groups, while Diabetic + Vitamin C and Diabetic + Metformin were less effective. On Day 3, cognitive performance in the diabetic groups improved, but none reached the level of Non-diabetic controls. On Day 14, EO and CT were again the most effective in reducing latency times, followed by Metformin. By Day 21, EO and CT showed significant improvements in cognitive function, with Metformin outperforming Vitamin C. SYN expression was significantly higher in the Non-diabetic + CT and Non-diabetic + EO groups, and these treatments also enhanced SYN expression in diabetic rats, with Metformin showing the greatest improvement.

CONCLUSION

The results suggest that EO and CT offer significant therapeutic potential for mitigating cognitive deficits and enhancing SYN in diabetic animals. Although metformin also improved cognitive function and SYN, it exhibited the most robust restorative effects. These findings highlight the potential of herbal treatments like EO and CT for managing cognitive dysfunction in diabetes.

Proteomic analysis by 4D label-free MS-PRM identified that Nptx1, Ptpmt1, Slc25a11, and Cpt1c are involved in diabetes-associated cognitive dysfunction

BACKGROUND

Diabetes-associated cognitive dysfunction (DACD) is a chronic ailment that exerts a substantial influence on the overall well-being of individuals. The hippocampus assumes a pivotal role in the progression and sustenance of cognitive impairment. The identification of differentially expressed proteins (DEPs) in the hippocampus is crucial for understanding the mechanisms of DACD.

METHODS

A rat model of DACD was established by a high-fat diet combined with streptozotocin intraperitoneal injection. The Morris water maze (MWM), hematoxylin and eosin (H&E) staining, Nissl staining, and transmission electron microscope (TEM) were performed on the rats. The proteins expressed in the hippocampus were detected using 4D label-free quantitative proteomics. Four DEPs, namely Nptx1, Ptpmt1, Slc25a11, and Cpt1c, were validated using parallel reaction monitoring (PRM).

RESULT

Our study found that hippocampal lesions were present in the DACD rat models. There were 59 up-regulated and 98 down-regulated DEPs in the Model group compared to the Control group. We found that the levels of Nptx1, Ptpmt1, Slc25a11, and Cpt1c were elevated in the Model group, which are important for cell mitochondrial function. It should be noted that in our study, we only used PRM to validate the expression of these proteins. However, more evidence is needed to establish the relationship between these protein changes and DACD.

CONCLUSION

Our research results may provide further insight into the molecular pathology of hippocampal injury in DACD. In addition, further studies and clinical trials are required to confirm our findings and establish a more conclusive molecular mechanism for DACD.

PM2.5 Exposure as a Risk Factor for Optic Nerve Health in Type 2 Diabetes Mellitus

(1) Objective: This study investigated the relationship between long-term particulate matter (PM2.5) exposure and optic disc parameters-vertical cup-to-disc ratio (vCDR), vertical optic disc diameter (vDD), and vertical optic cup diameter (vCD)-in patients with type 2 diabetes mellitus (T2DM). (2) Methods: A cross-sectional analysis was conducted using data from 65,750 T2DM patients in the 2017-2018 Shanghai Cohort Study of Diabetic Eye Disease (SCODE). Optic disc parameters were extracted from fundus images, and PM2.5 exposure was estimated using a random forest model incorporating satellite and meteorological data. Multivariate linear regression models were applied, adjusting for confounders including age, gender, body mass index, blood pressure, glucose, time of T2DM duration, smoking, drinking, and physical exercise. (3) Results: A 10 μg/m3 increase in PM2.5 exposure was associated with significant reductions in vCDR (-0.008), vDD (-42.547 μm), and vCD (-30.517 μm) (all p-values < 0.001). These associations persisted after sensitivity analyses and adjustments for other pollutants like O3 and NO2. (4) Conclusions: Long-term PM2.5 exposure is associated with detrimental changes in optic disc parameters in patients with T2DM, suggesting possible optic nerve atrophy. Considering the close relationship between the optic nerve and the central nervous system, these findings may also reflect broader neurodegenerative processes.

From Diabetes to Dementia: Identifying Key Genes in the Progression of Cognitive Impairment

OBJECTIVES

To provide a basis for further research on the molecular mechanisms underlying type 2 diabetes-associated mild cognitive impairment (DCI) using two bioinformatics methods to screen key genes involved in the progression of mild cognitive impairment (MCI) and type 2 diabetes.

METHODS

RNA sequencing data of MCI and normal cognition groups, as well as expression profile and sample information data of clinical characteristic data of GSE63060, which contains 160 MCI samples and 104 normal samples, were downloaded from the GEO database. Hub genes were identified using weighted gene co-expression network analysis (WGCNA). Protein-protein interaction (PPI) analysis, combined with least absolute shrinkage and selection operator (LASSO) and receiver operating characteristic (ROC) curve analyses, was used to verify the genes. Moreover, RNA sequencing and clinical characteristic data for GSE166502 of 13 type 2 diabetes samples and 13 normal controls were downloaded from the GEO database, and the correlation between the screened genes and type 2 diabetes was verified by difference and ROC curve analyses. In addition, we collected clinical biopsies to validate the results.

RESULTS

Based on WGCNA, 10 modules were integrated, and six were correlated with MCI. Six hub genes associated with MCI (TOMM7, SNRPG, COX7C, UQCRQ, RPL31, and RPS24) were identified using the LASSO algorithm. The ROC curve was screened by integrating the GEO database, and revealed COX7C, SNRPG, TOMM7, and RPS24 as key genes in the progression of type 2 diabetes.

CONCLUSIONS

COX7C, SNRPG, TOMM7, and RPS24 are involved in MCI and type 2 diabetes progression. Therefore, the molecular mechanisms of these four genes in the development of type 2 diabetes-associated MCI should be studied.

Cognitive Disorders in Type 1 Diabetes: Role of Brain Glucose Variation, Insulin Activity, and Glucocorticoid Exposure

BACKGROUND

The number of patients with type 2 diabetes (T2D) and type 1 diabetes (T1D) is on the rise, partly due to a global increase in new T1D cases among children. Beyond the well-documented microvascular and macrovascular complications, there is now substantial evidence indicating that diabetes also impacts the brain, leading to neuropsychological impairments. The risk of developing neuropsychiatric symptoms is notably higher in childhood due to the ongoing maturation of the brain, which makes it more susceptible to damage. Despite this awareness, the specific effects of diabetes on cognitive function remain poorly understood.

SUMMARY

This review synthesizes literature on the impact of diabetes on cognition and its relationship with brain structural changes. It presents data and hypotheses to explain how T1D contributes to cognitive dysfunction, with a particular focus on children and adolescents. The emphasis on the pediatric population is intentional, as young diabetic patients typically have fewer comorbidities, reducing confounding factors and simplifying the investigation of cognitive alterations.

KEY MESSAGE

We examine the roles of hypo- and hyperglycemia, as well as the emerging role of glucocorticoids in the development of neuropsychological disorders. When specific mechanisms related to T1D are available, they are highlighted; otherwise, data and hypotheses applicable to both T1D and T2D are discussed.

Bioinformatics analysis of effective biomarkers and immune infiltration in type 2 diabetes with cognitive impairment and aging

With the increasing prevalence of diabetes mellitus worldwide, type 2 diabetes mellitus (T2D) combined with cognitive impairment and aging has become one of the common and important complications of diabetes mellitus, which seriously affects the quality of life of the patients, and imposes a heavy burden on the patients' families and the society. Currently, there are no special measures for the treatment of cognitive impairment and aging in type 2 diabetes mellitus. Therefore, the search for potential biological markers of type 2 diabetes mellitus combined with cognitive impairment and aging is of great significance for future precisive treatment. We downloaded three gene expression datasets from the GEO database: GSE161355 (related to T2D with cognitive impairment and aging), GSE122063, and GSE5281 (related to Alzheimer's disease). Differentially expressed genes (DEGs) were identified, followed by gene set enrichment analysis (GSEA). A protein-protein interaction (PPI) network was constructed using the STRING database, and the top 15 hub genes were identified using the CytoHubba plugin in Cytoscape. Core genes were ultimately determined using three machine learning methods: LASSO regression, Support Vector Machine Recursive Feature Elimination (SVM-RFE), and Linear Discriminant Analysis (LDA). The diagnostic performance of these genes was assessed using ROC curve analysis and validated in an independent dataset (GSE5281). Regulatory genes related to ferroptosis were screened from the FerrDb database, and their biological functions were further explored through GO and KEGG enrichment analyses. Finally, the CIBERSORT algorithm was used to analyze immune cell infiltration, and the correlation between core genes and immune cell infiltration levels was calculated, leading to the construction of an mRNA-miRNA regulatory network. In the GSE161355 and GSE122063 datasets, 217 common DEGs were identified. GSEA analysis revealed their enrichment in the PI3K-PLC-TRK signaling pathway, TP53 regulation of metabolic genes pathway, Notch signaling pathway, among others. PPI network analysis identified 15 candidate core genes, and further selection using LASSO, LDA, and SVM-RFE machine learning algorithms resulted in 6 core genes: BCL6, TP53, HSP90AA1, CRYAB, IL1B, and DNAJB1. ROC curve analysis indicated that these genes had good diagnostic performance in the GSE161355 dataset, with TP53 and IL1B achieving an AUC of 0.9, indicating the highest predictive accuracy. BCL6, HSP90AA1, CRYAB, and DNAJB1 also had AUCs greater than 0.8, demonstrating moderate predictive accuracy. Validation in the independent dataset GSE5281 showed that these core genes also had good diagnostic performance in Alzheimer's disease samples (AUC > 0.6). Ferroptosis-related analysis revealed that IL1B and TP53 play significant roles in apoptosis and immune response. Immune cell infiltration analysis showed that IL1B is significantly positively correlated with infiltration levels of monocytes and NK cells, while TP53 is significantly negatively correlated with infiltration levels of follicular helper T cells. The construction of the miRNA-mRNA regulatory network suggested that miR-150a-5p might play a key role in the regulation of T2D-associated cognitive impairment and aging by TP53. This study, by integrating bioinformatics and machine learning methods, identified BCL6, TP53, HSP90AA1, CRYAB, IL1B, and DNAJB1 as potential diagnostic biomarkers for T2D with cognitive impairment and aging, with a particular emphasis on the significance of TP53 and IL1B in immune cell infiltration. These findings not only enhance our understanding of the molecular mechanisms linking type 2 diabetes to cognitive impairment and aging, providing new targets for early diagnosis and treatment, but also offer new directions and targets for basic research.

Association of systolic blood pressure variability with cognitive decline in type 2 diabetes: A post hoc analysis of a randomized clinical trial

BACKGROUND

We aimed to explore the association between visit-to-visit systolic blood pressure variability (BPV) and cognitive function in individuals with type 2 diabetes.

METHODS

We performed a post hoc analysis of the Action to Control Cardiovascular Risk in Diabetes Memory in Diabetes (ACCORD-MIND) substudy. A total of 2867 diabetes patients with ≥3 BP measurements between the 4- and 20-month visits were included. Visit-to-visit systolic BPV was calculated. Cognitive decline was defined as a Mini-Mental State Exam (MMSE), Digit Symbol Substitution Test (DSST), or Rey Auditory Verbal Learning Test (RAVLT) score greater than 1 standard deviation (SD) below the baseline mean, or a Stroop test score more than 1 SD above the baseline mean. The associations of systolic BPV with risks of cognitive decline were examined using Cox proportional hazards models, and with changes in brain magnetic resonance imaging parameters were evaluated using mixed models.

RESULTS

The risk of cognitive decline defined by the DSST score (but not by other scores) increased significantly with systolic BPV quartiles (p for trend = 0.008), and there was a 55% increased risk for BPV quartile 4 versus quartile 1 (hazard ratio = 1.55, 95% confidence interval 1.10-2.19). Furthermore, a positive correlation was observed between systolic BPV and change in white matter lesion volume (β = 0.07, 95% CI 0.01-0.13).

CONCLUSIONS

A greater visit-to-visit systolic BPV was significantly associated with an increased risk of cognitive decline measured by DSST and an increase in white matter lesion volume in patients with type 2 diabetes.

Mechanistic Insights and Potential Therapeutic Implications of NRF2 in Diabetic Encephalopathy

Diabetic encephalopathy (DE) is a complication of diabetes, especially type 2 diabetes (T2D), characterized by damage in the central nervous system and cognitive impairment, which has gained global attention. Despite the extensive research aimed at enhancing our understanding of DE, the underlying mechanism of occurrence and development of DE has not been established. Mounting evidence has demonstrated a close correlation between DE and various factors, such as Alzheimer's disease-like pathological changes, insulin resistance, inflammation, and oxidative stress. Of interest, nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor with antioxidant properties that is crucial in maintaining redox homeostasis and regulating inflammatory responses. The activation and regulatory mechanisms of NRF2 are a relatively complex process. NRF2 is involved in the regulation of multiple metabolic pathways and confers neuroprotective functions. Multiple studies have provided evidence demonstrating the significant involvement of NRF2 as a critical transcription factor in the progression of DE. Additionally, various molecules capable of activating NRF2 expression have shown potential in ameliorating DE. Therefore, it is intriguing to consider NRF2 as a potential target for the treatment of DE. In this review, we aim to shed light on the role and the possible underlying mechanism of NRF2 in DE. Furthermore, we provide an overview of the current research landscape and address the challenges associated with using NRF2 activators as potential treatment options for DE.

Alterations in Neuronal Nicotinic Acetylcholine Receptors in the Pathogenesis of Various Cognitive Impairments

Cognitive impairment is a typical symptom of both neurodegenerative and certain other diseases. In connection with these different pathologies, the etiology and neurological and metabolic changes associated with cognitive impairment must differ. Until these characteristics and differences are understood in greater detail, pharmacological treatment of the different forms of cognitive impairment remains suboptimal. Neurotransmitter receptors, including neuronal nicotinic acetylcholine receptors (nAChRs), dopamine receptors, and glutamine receptors, play key roles in the functions and metabolisms of the brain. Among these, the role of nAChRs in the development of cognitive impairment has attracted more and more attention. The present review summarizes what is presently known concerning the structure, distribution, metabolism, and function of nAChRs, as well as their involvement in major cognitive disorders such as Alzheimer's disease, Parkinson's disease, vascular dementia, schizophrenia, and diabetes mellitus. As will be discussed, the relevant scientific literature reveals clearly that the α4β2 and α7 nAChR subtypes and/or subunits of the receptors play major roles in maintaining cognitive function and in neuroprotection of the brain. Accordingly, focusing on these as targets of drug therapy can be expected to lead to breakthroughs in the treatment of cognitive disorders such as AD and schizophrenia.

Long-term neurological dysfunction associated with COVID-19: Lessons from influenza and inflammatory diseases?

As the COVID-19 pandemic persists, SARS-CoV-2 infection is increasingly associated with long-term neurological side effects including cognitive impairment, fatigue, depression, and anxiety, colloquially known as "long-COVID." While the full extent of long-COVID neuropathology across years or even decades is not yet known, we can perhaps take direction from long-standing research into other respiratory diseases, such as influenza, that can present with similar long-term neurological consequences. In this review, we highlight commonalities in the neurological impacts of influenza and COVID-19. We first focus on the common potential mechanisms underlying neurological sequelae of long-COVID and influenza, namely (1) viral neurotropism and (2) dysregulated peripheral inflammation. The latter, namely heightened peripheral inflammation leading to central nervous system dysfunction, is emerging as a shared mechanism in various peripheral inflammatory or inflammation-associated diseases and conditions. We then discuss historical and modern examples of influenza- and COVID-19-associated cognitive impairment, depression, anxiety, and fatigue, revealing key similarities in their neurological sequelae. Although we are learning that the effects of influenza and COVID differ somewhat in terms of their influence on the brain, as the impacts of long-COVID grow, such comparisons will likely prove valuable in guiding ongoing research into long-COVID, and perhaps foreshadow what could be in store for individuals with COVID-19 and their brain health.

Abnormal resting-state functional connectivity of hippocampal subregions in type 2 diabetes mellitus-associated cognitive decline

Objective

Type 2 diabetes mellitus (T2DM) over time predisposes to inflammatory responses and abnormalities in functional brain networks that damage learning, memory, or executive function. The hippocampus is a key region often reporting connectivity abnormalities in memory disorders. Here, we investigated peripheral inflammatory responses and resting-state functional connectivity (RSFC) changes characterized of hippocampal subregions in type 2 diabetes-associated cognitive decline (T2DACD).

Methods

The study included 16 patients with T2DM, 16 patients with T2DACD and 25 healthy controls (HCs). Subjects were assessed for cognitive performance, tested for the expression of inflammatory factors IL-6, IL-10 and TNF-α in peripheral serum, underwent resting-state functional magnetic resonance imaging scans, and analyzed for RSFC using the hippocampal subregions as seeds. We also calculated the correlation between cognitive performance and RSFC of hippocampal subregion, and analyzed the significantly altered RSFC values of T2DACD for Receiver Operating Characteristic (ROC) analysis.

Results

T2DACD patients showed a decline in their ability to complete cognitive assessment scales and experimental paradigms, and T2DM did not show abnormal cognitive performance. IL-6 expression was increased in peripheral serum in both T2DACD and T2DM. Compared with HCs, T2DACD showed abnormalities RSFC of the left anterior hippocampus with left precentral gyrus and left angular gyrus. T2DM showed abnormalities RSFC of the left middle hippocampus with right medial frontal gyrus, right anterior and middle hippocampus with left precuneus, left anterior hippocampus with right precuneus and right posterior middle temporal gyrus. Compared with T2DM, T2DACD showed abnormalities RSFC of the left posterior hippocampus and right middle hippocampus with left precuneus. In addition, RSFC in the left posterior hippocampus with left precuneus of T2DACD was positively correlated with Flanker conflict response time (r=0.766, P=0.001). In the ROC analysis, the significantly altered RSFC values of T2DACD achieved significant performance.

Conclusions

T2DACD showed a significant decrease in attentional inhibition and working memory, peripheral pro-inflammatory response increased, and abnormalities RSFC of the hippocampal subregions with default mode network and sensory-motor network. T2DM did not show a significant cognitive decline, but peripheral pro-inflammatory response increased and abnormalities RSFC of the hippocampus subregions occurred in the brain. In addition, the left precuneus may be a key brain region in the conversion of T2DM to T2DACD. The results of this study may provide a basis for the preliminary diagnosis of T2DACD.

An Investigation of the Correlation Between Retinal Nerve Fiber Layer Thickness with Blood Biochemical Indices and Cognitive Dysfunction in Patients with Type 2 Diabetes Mellitus

Objective

The study aimed to explore the correlation between retinal nerve fiber layer thickness (RNFLT) with blood biochemical indicators and cognitive dysfunction in patients with type 2 diabetes mellitus (T2DM) and the possible mechanism, thereby providing more theoretical basis for the occurrence and prevention of diabetes related complications.

Methods

Eighty T2DM patients treated in our hospital from March 2022 to September 2022 were selected as the study subjects, and the clinical data of the patients were retrospectively analyzed. All patients underwent fundus fluorescein angiography (FFA) to analyze the changes in retinal blood vessels. Patients who met the inclusion criteria were divided as the diabetic retinopathy (DR) group (n=46) and simple diabetes group (n=34). The RNFLT, blood biochemical indexes and changes in cognitive functions of the patients were detected. The correlation between RNFLT with blood biochemical indexes and cognitive dysfunction was analyzed.

Results

Compared with the simple diabetes group, patients in the DR group had much lower mean, nasal, inferior and superior thicknesses (P<0.01). There existed no significant difference in blood pressure, body mass index (BMI), blood lipids (triglycerides, cholesterol, low-density lipoprotein, high-density lipoprotein) between the two groups (P>0.05). Compared with the simple diabetes group, patients in the DR group had much higher fasting blood glucose (FBG), hemoglobin A1c (HbA1c), fasting insulin (FINS), insulin resistance (HOMA-IR) index, apolipoprotein B (ApoB)/apolipoprotein A1 (ApoA1) (P<0.001). Besides, the DR group had sharply lower scores on the Mini-Mental State Examination (MMSE) scale and higher levels of the Trail Making Test-A (TMT-A) and TMT-B (P<0.001). Spearman correlation analysis confirmed that the mean RNFLT was negatively correlated with the levels of FBG, HbA1c, HOMA-IR index, TMT-A and TMT-B (P<0.05), positively correlated with the score of mini-mental state examination (MMSE) (P<0.05), and was no significant correlation with FINS and ApoB/ApoA1 (P>0.05).

Conclusion

DR patients had significantly reduced RNFLT, elevated levels of blood glucose related indicators, and cognitive dysfunction. There existed a correlation between RNFLT and FBG, HbA1c, HOMA-IR index, TMT-A, TMT-B and MMSE.

Comparing the Self-Reported Acceptability of Discrete Choice Experiment and Best-Worst Scaling: An Empirical Study in Patients with Type 2 Diabetes Mellitus

Purpose

Discrete choice experiment (DCE) and profile case (case 2) best-worst scaling (BWS) present uncertainties regarding the acceptability of quantifying individual healthcare preferences, which may adversely affect the validity of responses and impede the reflection of true healthcare preferences. This study aimed to assess the acceptability of these two methods from the perspective of patients with type 2 diabetes mellitus (T2DM) and examine their association with specific characteristics of the target population.

Patients and Methods

This cross-sectional study was based on a nationally representative survey; data were collected using a multistage stratified cluster-sampling procedure between September 2021 and January 2022. Eligible adults with confirmed T2DM voluntarily participated in this study. Participants completed both the DCE and case 2 BWS (BWS-2) choice tasks in random order and provided self-reported assessments of acceptability, including task completion difficulty, comprehension of task complexity, and response preference. Logistic regression and random forest models were used to identify variables associated with acceptability.

Results

In total, 3286 patients with T2DM were included in the study. Respondents indicated there was no statistically significant difference in completion difficulty between the DCE and BWS-2, although the DCE scores were slightly higher (3.07 ± 0.68 vs 3.03 ± 0.67, P = 0.06). However, 1979 (60.2%) respondents found the DCE easier to comprehend. No significant preferences were observed between the two methods (1638 (49.8%) vs 1648 (50.2%)). Sociodemographic factors, such as residence, monthly out-of-pocket costs, and illness duration were significantly associated with comprehension complexity and response preference.

Conclusion

This study yielded contrasting results to most of previous studies, suggesting that DCE may be less cognitively demanding and more suitable for patients with T2DM from the perspective of self-reported acceptability of DCE and BWS. This study promotes a focus on patient acceptability in quantifying individual healthcare preferences to inform tailored optimal stated-preference method for a target population.

Analysis of current situation and influencing factors of cognitive dysfunction associated with type 2 diabetes and follow-up study on treatment effectiveness

BACKGROUND

Many studies have explored the risk factors associated with cognitive impairment in patients with Type 2 diabetes mellitus (T2DM). However, research on determining the optimal threshold for these risk factors and comparative studies on the therapeutic effects of insulin and metformin is limited. This study aims to establish the optimal threshold for cognitive impairment risk factors in T2DM patients and compare the efficacy of insulin and metformin in treating mild cognitive impairment (MCI).

METHODS

A total of 308 patients with T2DM were included. The optimal threshold for cognitive impairment risk factors was determined using receiver operating characteristic curve and binary logistic regression models. MCI patients were divided into three groups: insulin, metformin, and insulin with metformin. The treatment effect was evaluated after a 6-month follow-up.

RESULTS

The study identified several factors that influenced cognitive function in T2DM patients, including female gender, duration of diabetes >13.50 years, years of education >7.50 years, and serum sodium level > 141.90 mmol/L. Metformin and insulin with metformin showed superior therapeutic effects compared to insulin alone, but no difference was observed between metformin and combination therapy.

CONCLUSION

Special attention should be given to female and those with diabetes duration >13.50 years, as well as to individuals with educational level ≤ 7.50 years and serum sodium concentration ≤ 141.90 mmol/L. Metformin and insulin with metformin effectively improve MCI in patients with T2DM and outperform insulin monotherapy. The efficacy of metformin and combination therapy was found to be comparable.

Live and pasteurized Akkermansia muciniphila ameliorates diabetic cognitive impairment by modulating gut microbiota and metabolites in db/db mice

The established role of disturbances in the microbiota-gut-brain axis in the development of diabetic cognitive impairment (DCI) has long been recognized. It has shown the potential of Akkermansia muciniphila (A. muciniphila) in improving metabolic disorders and exerting anti-inflammatory effects. However, there remains a lack of comprehensive understanding regarding the specific effects and mechanisms underlying the treatment of DCI with A. muciniphila. This study aimed to evaluate the potential of A. muciniphila in alleviating DCI in db/db mice. Eleven-week-old db/db mice were administered either live or pasteurized A. muciniphila (5 × 109 CFU/200 μL) for a duration of eight weeks. Administering live A. muciniphila significantly ameliorated cognitive impairments, improved the synaptic ultrastructure, and inhibited hippocampal neuron loss in the CA1 and CA3 subregions in db/db mice. Both live and pasteurized A. muciniphila effectively mitigated neuroinflammation. Moreover, live A. muciniphila increased the relative abundance of Lactococcus and Staphylococcus, whereas pasteurized A. muciniphila increased the relative abundance of Lactobacillus, Prevotellaceae_UCG_001, and Alistipes. Supplementation of A. muciniphila also induced alterations in serum and brain metabolites, with a particular enrichment observed in tryptophan metabolism, glyoxylate and dicarboxylate metabolism, nitrogen metabolism, and pentose and glucuronate interconversions. Correlation analysis further demonstrated a direct and substantial correlation between the altered gut microbiota and the metabolites in the serum and brain tissue. In conclusion, the results indicate that live A. muciniphila demonstrated greater efficacy compared to pasteurized A. muciniphila. The observed protective effects of A. muciniphila against DCI are likely mediated through the neuroinflammation and microbiota-metabolites-brain axis.

Protective effect of melatonin against metabolic disorders and neuropsychiatric injuries in type 2 diabetes mellitus mice

BACKGROUND

Type 2 diabetes mellitus (T2DM) is a metabolic disease characterized by hyperglycemia and progressive cognitive dysfunction, and our clinical investigation revealed that the plasma concentration of melatonin (Mlt) decreased and was closely related to cognition in T2DM patients. However, although many studies have suggested that Mlt has a certain protective effect on glucose and lipid metabolism disorders and neuropsychiatric injury, the underlying mechanism of Mlt against T2DM-related metabolic and cognitive impairments remains unclear.

PURPOSE

The aim of the present study was to investigate the therapeutic effect of Mlt on metabolic disorders and Alzheimer's disease (AD)-like neuropsychiatric injuries in T2DM mice and to explore the possible underlying molecular mechanism involved.

METHODS

A T2DM mouse model was established by a combination of a high-fat diet (HFD) and streptozotocin (STZ, 100 mg/kg, i.p.), and Mlt (5, 10 or 20 mg/kg) was intragastrically administered for six consecutive weeks. The serum levels of glycolipid metabolism indicators were measured, behavioral performance was tested, and the protein expression of key molecules involved in the regulation of synaptic plasticity, circadian rhythms, and neuroinflammation in the hippocampus was detected. Moreover, the fluorescence intensities of glial fibrillary acidic protein (GFAP), ionized calcium binding adapter molecule 1 (IBA-1), amyloid β-protein (Aβ) and phosphorylated Tau (p-Tau) in the hippocampus were also observed.

RESULTS

Treatment with Mlt not only improved T2DM-related metabolic disorders, as indicated by increased serum concentrations of fasting blood glucose (FBG), glycosylated hemoglobin (HbAlc), insulin (INS), total cholesterol (TC) and triglyceride (TG), improved glucose tolerance and liver and pancreas function but also alleviated AD-like neuropsychiatric injuries in a HFD/STZ-induced mouse model, as indicated by decreased immobility time in the tail suspension test (TST) and forced swimming test (FST), increased preference indices of novel objects or novel arms in the novel object recognition test (NOR) and Y-maze test (Y-maze), and improved platform positioning capability in the Morris water maze (MWM) test. Moreover, treatment with Mlt also improved the hyperactivation of astrocytes and microglia in the hippocampus of mice, accompanied by reduced expression of interleukin 1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor (TNF-α), Aβ, and p-Tau and increased expression of brain-derived neurotrophic factor (BDNF), Synapsin I, Synaptotagmin I, melatonin receptor 1B (MT1B), brain muscle arnt-like protein 1 (Bmal1), circadian locomotor output cycles kaput (Clock), period 2 (Per2), and cryptochrome 2 (Cry2).

CONCLUSION

Mlt alleviated T2DM-related metabolic disorders and AD-like neuropsychiatric injuries in a HFD/STZ-induced mouse model, possibly through a mechanism involving the regulation of glial activation and associated neuroinflammation and the balancing of synaptic plasticity and circadian rhythms in the hippocampus.

Microglial AKAP8L: a key mediator in diabetes-associated cognitive impairment via autophagy inhibition and neuroinflammation triggering

BACKGROUND

Diabetes-associated cognitive impairment (DACI) poses a significant challenge to the self-management of diabetes, markedly elevating the risk of adverse complications. A burgeoning body of evidence implicates microglia as a central player in the pathogenesis of DACI.

METHODS

We utilized proteomics to identify potential biomarkers in high glucose (HG)-treated microglia, followed by gene knockdown techniques for mechanistic validation in vitro and in vivo.

RESULTS

Our proteomic analysis identified a significant upregulation of AKAP8L in HG-treated microglia, with concurrent dysregulation of autophagy and inflammation markers, making AKAP8L a novel biomarker of interest. Notably, the accumulation of AKAP8L was specific to HG-treated microglia, with no observed changes in co-cultured astrocytes or neurons, a pattern that was mirrored in streptozotocin (STZ)-induced diabetic mice. Further studies through co-immunoprecipitation and proximity ligation assay indicated that the elevated AKAP8L in HG-treated microglial cells interacts with the mTORC1. In the STZ mouse model, we demonstrated that both AKAP8L knockdown and rapamycin treatment significantly enhanced cognitive function, as evidenced by improved performance in the Morris water maze, and reduced microglial activation. Moreover, these interventions effectively suppressed mTORC1 signaling, normalized autophagic flux, mitigated neuroinflammation, and decreased pyroptosis.

CONCLUSIONS

Our findings highlight the critical role of AKAP8L in the development of DACI. By interacting with mTORC1, AKAP8L appears to obstruct autophagic processes and initiate a cascade of neuroinflammatory responses. The identification of AKAP8L as a key mediator in DACI opens up new avenues for potential therapeutic interventions.

Type 2 diabetes microenvironment promotes the development of Parkinson's disease by activating microglial cell inflammation

Objective

Parkinson's disease (PD) is the second most common neurodegenerative disease in the world, and type 2 diabetes (T2DM) and PD are influenced by common genetic and environmental factors. Mitochondrial dysfunction and inflammation are common pathogenic mechanisms of both diseases. However, the close association between PD and T2DM and the specific relationship between them are not yet clear. This study aimed to reveal the specific connection between the two diseases by establishing a mouse model of comorbid PD and T2DM, as well as a Bv2 cell model.

Methods

C57BL/6 mouse were used to construct a model of PD with T2DM using streptozotocin and rotenone, while Bv2 cells were used to simulate the microenvironment of PD and T2DM using rotenone and palmitate. Behavioral tests were conducted to assess any differences in motor and cognitive functions in mouse. Immunohistochemistry was used to analyze the number of dopaminergic neurons in the substantia nigra region of mouse. Western blotting was used to detect the expression levels of TH, P-NFκB, NFκB, Cyclic GMP-AMP synthase (cGAS), and Stimulator of interferon genes (STING) proteins in the substantia nigra region of mouse and Bv2 cells. qRT-PCR was used to analyze the expression levels of IL1β, IL6, and TNF-α. Seahorse technology was used to assess mitochondrial function in Bv2 cells.

Results

T2DM exacerbated the motor and cognitive symptoms in mouse with PD. This effect may be mediated by disrupting mitochondrial function in microglial cells, leading to damaged mtDNA leakage into the cytoplasm, subsequently activating the cGAS-STING pathway and downstream P-NFκB/NFκB proteins, triggering an inflammatory response in microglial cells. Microglial cells release inflammatory factors such as IL1β, IL6, and TNF-α, exacerbating neuronal damage caused by PD.

Conclusion

Our study results suggest that T2DM may exacerbate the progression of PD by damaging mitochondrial function, and activating microglial cell inflammation. The detrimental effects on Parkinson's disease may be achieved through the activating of the cGAS-STING protein pathway.

Intermittent hypoxia exacerbates anxiety in high-fat diet-induced diabetic mice by inhibiting TREM2-regulated IFNAR1 signaling

BACKGROUND

Type 2 diabetes mellitus (T2DM) and obstructive sleep apnea (OSA) are mutual risk factors, with both conditions inducing cognitive impairment and anxiety. However, whether OSA exacerbates cognitive impairment and anxiety in patients with T2DM remains unclear. Moreover, TREM2 upregulation has been suggested to play a protective role in attenuating microglia activation and improving synaptic function in T2DM mice. The aim of this study was to explore the regulatory mechanisms of TREM2 and the cognitive and anxiety-like behavioral changes in mice with OSA combined with T2DM.

METHODS

A T2DM with OSA model was developed by treating mice with a 60% kcal high-fat diet (HFD) combined with intermittent hypoxia (IH). Spatial learning memory capacity and anxiety in mice were investigated. Neuronal damage in the brain was determined by the quantity of synapses density, the number and morphology of brain microglia, and pro-inflammatory factors. For mechanism exploration, an in vitro model of T2DM combined with OSA was generated by co-treating microglia with high glucose (HG) and IH. Regulation of TREM2 on IFNAR1-STAT1 pathway was determined by RNA sequencing and qRT-PCR.

RESULTS

Our results showed that HFD mice exhibited significant cognitive dysfunction and anxiety-like behavior, accompanied by significant synaptic loss. Furthermore, significant activation of brain microglia and enhanced microglial phagocytosis of synapses were observed. Moreover, IH was found to significantly aggravate anxiety in the HFD mice. The mechanism of HG treatment may potentially involve the promotion of TREM2 upregulation, which in turn attenuates the proinflammatory microglia by inhibiting the IFNAR1-STAT1 pathway. Conversely, a significant reduction in TREM2 in IH-co-treated HFD mice and HG-treated microglia resulted in the further activation of the IFNAR1-STAT1 pathway and consequently increased proinflammatory microglial activation.

CONCLUSIONS

HFD upregulated the IFNAR1-STAT1 pathway and induced proinflammatory microglia, leading to synaptic damage and causing anxiety and cognitive deficits. The upregulated TREM2 inT2DM mice brain exerted a negative regulation of the IFNAR1-STAT1 pathway. Mice with T2DM combined with OSA exacerbated anxiety via the downregulation of TREM2, causing heightened IFNAR1-STAT1 pathway activation and consequently increasing proinflammatory microglia.

A comparative study of urinary levels of multiple metals and neurotransmitter correlations between GDM and T2DM populations

OBJECTIVE

The pathogenesis of GDM and T2DM are closely related to various metals in vivo, and changes in the concentration of these metal exposures can lead to neuropathy through the DNA damage pathway caused by the accumulation of ROS.

METHOD

Urine samples were analyzed for heavy metals and trace elements by ICP-MS, neurotransmitter metabolites by HPLC, 8-OH-dG by HPLC-MS and metabolomics by UPLC-MS.

RESULT

Cd and Hg were risk factors for T2DM. There was a positive correlation between 8-OH-dG and neurotransmitter metabolites in both two populations. For GDM, the metabolite with the largest down-regulation effect was desloratadine and the largest up-regulation effect was D-glycine. That tyrosine and carbon metabolites were upregulated in the GDM population and downregulated in the T2DM population.

CONCLUSION

The BMI, urinary Cd and Hg endo-exposure levels correlated with elevated blood glucose, and the latter may cause changes in the DNA damage marker 8-OH-dG in both study populations and trigger common responses to neurological alterations changes in the neurotransmitter. Tyrosine, carbonin metabolites, alanine, aspartate, and glutamate were signature metabolites that were altered in both study populations. These indicators and markers have clinical implications for monitoring and prevention of neurological injury in patients with GDM and T2DM.

Bitter yet beneficial: The dual role of dietary alkaloids in managing diabetes and enhancing cognitive function

With the rising prevalence of diabetes and its association with cognitive impairment, interest in the use of dietary alkaloids and other natural products has grown significantly. Understanding how these compounds manage diabetic cognitive dysfunction (DCD) is crucial. This comprehensive review explores the etiology of DCD and the effects of alkaloids in foods and dietary supplements that have been investigated as DCD therapies. Data on how dietary alkaloids like berberine, trigonelline, caffeine, capsaicin, 1-deoxynojirimycin, nuciferine, neferine, aegeline, tetramethylpyrazine, piperine, and others regulate cognition in diabetic disorders were collected from PubMed, Research Gate, Web of Science, Science Direct, and other relevant databases. Dietary alkaloids could improve memory in behavioral models and modulate the mechanisms underlying the cognitive benefits of these compounds, including their effects on glucose metabolism, gut microbiota, vasculopathy, neuroinflammation, and oxidative stress. Evidence suggests that dietary alkaloids hold promise for improving cognition in diabetic patients and could open exciting avenues for future research in diabetes management.