Role of DPP-4 and SGLT2 Inhibitors Connected to Alzheimer Disease in Type 2 Diabetes Mellitus

Neuroprotective roles of SGLT2 and DPP4 inhibitors: Modulating ketone metabolism and suppressing NLRP3 inflammasome in T2D induced Alzheimer's disease

Sodium-glucose cotransporter 2 inhibitor (SGLT2-i) and dipeptidyl peptidase-4 inhibitor (DPP4-i) are known to ameliorate Alzheimer's disease (AD)-like pathology and cognitive decline through distinct mechanisms. In this study, we investigated how these antidiabetic drugs elevate ketone levels and subsequently reduce amyloid-β (Aβ) and tau pathology via the NLR family pyrin domain containing 3 (NLRP3) inflammasome pathway in microglia, using a type 2 diabetes (T2D)-AD mouse model. Male C57BL/6 mice were fed a high-fat diet and injected with low doses of streptozotocin to establish a T2D-AD model. The mice were then treated with either SGLT2-i or DPP4-i. Our results revealed that both the inhibitors markedly enhanced brain ketone metabolism by upregulating key metabolic enzymes and transporters. They also reduced neuroinflammation by suppressing the expression of pro-inflammatory cytokines, such as IL-1β, and increasing the expression of the anti-inflammatory cytokine IL-4. A critical mechanism for this anti-inflammatory effect involved the inhibition of the expression of the NLRP3 inflammasome, a key driver of neuroinflammation. Notably, SGLT2-i appeared to inhibit NLRP3 inflammasome expression by disrupting the pTau-CX3C1 interaction, whereas DPP4-i exerted its effects through the Aβ-TLR4-NF-κB pathway. Moreover, our results showed that both the inhibitors promoted a shift in microglial activation from the pro-inflammatory M1 phenotype to the anti-inflammatory M2 phenotype, as indicated by the changes in CD206 and CD86 expression. These findings suggest that SGLT2-i and DPP4-i provide neuroprotective benefits through multiple mechanisms, including enhanced ketone metabolism, reduced neuroinflammation, and modulation of microglial activity in T2D-AD mouse model. This research offers a scientific basis for considering these inhibitors as potential therapeutic agents for neurodegenerative diseases, particularly in cognitive impairment patients with metabolic dysfunction.

Neuropathological links between T2DM and LOAD: systematic review and meta-analysis

Recent decades have described parallel neuropathological mechanisms increasing the risk for developing late-onset Alzheimer's dementia (LOAD) in type 2 diabetes mellitus (T2DM); however, still little is known of the role of diabetic encephalopathy and brain atrophy in LOAD. The aim of this systematic review is to provide a comprehensive view on diabetic encephalopathy/cerebral atrophy, taking into account neuroimaging data, neuropathology, metabolic and endocrine mechanisms, amyloid formation, brain perfusion impairments, neuroimmunology, and inflammasome activation. Key switches were identified, to further meta-analyze genomic candidate loci and epigenetic modifications. For the qualitative meta-analysis of genomic bases extracted, human linkage studies were examined; for epigenetic mechanisms, data from both human and animal studies are described. For the systematic review of pathophysiological mechanisms, 1,259 publications were evaluated and 93 gene loci extracted for candidate risk linkages. Sixty-six publications were evaluated for genomic association and descriptions of epigenomic modifications. Overall accumulated results highlight the insulin signaling system, vascular markers, inflammation and inflammasome pathways, amylin interactions, and glycosylation mechanisms. The protocol was registered with PROSPERO (ID: CRD42023440535).

Cardiovascular therapeutic targets of sodium-glucose co-transporter 2 (SGLT2) inhibitors beyond heart failure

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are oral antidiabetic agents that have shown significant improvements in cardiovascular and renal outcomes among patients with heart failure (HF), regardless of diabetic status, establishing them as a cornerstone therapy. In addition to glycemic control and the osmotic diuretic effect, the inhibition of SGLT2 improves endothelial function and vasodilation, optimizing myocardial energy metabolism and preserving cardiac contractility. Moreover, SGLT2 inhibitors may exhibit anti-inflammatory properties and attenuate acute myocardial ischemia/reperfusion injury, thereby reducing cardiac infarct size, enhancing left ventricular function, and mitigating arrhythmias. These pleiotropic effects have demonstrated efficacy across various cardiovascular conditions, ranging from acute to chronic coronary syndromes and extending to arrhythmias, valvular heart disease, cardiomyopathies, cardio-oncology, and cerebrovascular disease. This review provides an overview of the current literature on the potential mechanisms underlying the effectiveness of SGLT2 inhibitors across a wide range of cardiovascular diseases beyond HF.

Reducing Alzheimer's disease risk with SGLT2 inhibitors: From glycemic control to neuroprotection

Recent research has established a strong link between metabolic abnormalities and an increased risk of dementia. In parallel, there is growing epidemiological evidence supporting the neuroprotective effects of antidiabetic medications against cognitive impairments. Among these, sodium-glucose co-transporter (SGLT2) inhibitors have emerged as pharmacological candidates with promising potential in alleviating the burden of age-related diseases, particularly neurodegenerative diseases (NDD). SGLT2 inhibitor therapies are FDA-approved medications routinely prescribed to manage diabetes. This novel class was initially developed to address cardiovascular disorders and to reduce the risk of hypoglycemia associated with insulin-secretagogue agents. It subsequently attracted growing interest for its beneficial effects on central nervous system (CNS) disorders. However, the molecular mechanisms through which these glucose-lowering therapies mitigate cognitive decline and limit the progression of certain brain degenerative diseases remain largely unexplored. Consequently, the neuroscientific community needs further studies that gather, analyze, and critically discuss the available mechanistic evidence regarding the neuroprotective effects of SGLT2 inhibitors. This review aims to critically examine the most relevant published findings, both in vitro and in vivo, as well as human studies evaluating the impact of SGLT2 inhibitors exposure on Alzheimer's disease (AD). It seeks to integrate the current understanding of their beneficial effects at the molecular level and their role in addressing the pathophysiology and neuropathology of AD. These insights will help extend our knowledge of how SGLT2 inhibitor therapies are associated with reduced risk of dementia and thus shed light on the link between diabetes and AD.

Comparative study of SGLT2 inhibitors and metformin: Evaluating first-line therapies for dementia prevention in type 2 diabetes

BACKGROUND

- Type 2 diabetes (T2D) increases the risk of dementia by 1.5 to 2.5 times. Sodium-glucose cotransporter 2 inhibitors (SGLT2is) and metformin, widely used antidiabetic therapies, have demonstrated potential neuroprotective effects. Their comparative effectiveness in dementia prevention remains unknown.

METHODS

- This retrospective cohort study used the TriNetX global federated network, analyzing de-identified records from over 98 healthcare organizations. Adults with T2D initiating SGLT2i or metformin as first-line therapy were propensity score-matched (1:1). The primary outcome was overall dementia incidence, including vascular dementia, Alzheimer's disease, and other subtypes. Secondary outcomes included all-cause mortality. Time-to-event outcomes were assessed using Kaplan-Meier curves and Cox models.

RESULTS

- Among 74,975 matched patients in each cohort, SGLT2i use was associated with a lower incidence of overall dementia: 2.7 % vs. 6.9 %: adjusted hazard ratio (aHR) 0.80 [95 % CI 0.76;0.84]. Reductions were observed in vascular dementia (0.8 % vs. 2.0 %; aHR 0.87), Alzheimer's dementia (1.1 % vs. 3.2 %; aHR, 0.76), and all-cause mortality (6.8 % vs. 15.4 %; aHR, 0.92). Benefits were pronounced in older adults, particularly those aged ≥80 years.

CONCLUSIONS

- SGLT2is significantly reduced dementia risk and mortality compared to metformin in T2D patients. These findings suggest SGLT2is may offer superior neuroprotective benefits, underscoring their potential as a first-line therapy for T2D. Further randomized trials are needed to confirm these results.

Translational research on cognitive impairment in chronic kidney disease

Cognitive decline is common in patients with acute or chronic kidney disease. Several areas of brain function can be affected, including short- and long-term memory, attention and inhibitory control, sleep, mood, eating control and motor function. Cognitive decline in kidney disease shares risk factors with cognitive dysfunction in people without kidney disease, such as diabetes, high blood pressure, sedentary lifestyle and unhealthy diet. However, additional kidney-specific risk factors may contribute, such as uremic toxins, electrolyte imbalances, chronic inflammation, acid-base disorders or endocrine dysregulation. Traditional and kidney-specific risk factors may interact to cause damage to the blood-brain barrier, induce vascular damage in the brain and cause neurotoxicity or neuroinflammation. Here, we discuss recent insights into the pathomechanisms of cognitive decline from animal models and novel avenues for prevention and therapy. We focus on a several areas that influence cognition: blood-brain barrier disruption, the role of skeletal muscle, physical activity and the endocrine factor irisin, and the emerging therapeutic role of sodium-glucose cotransporter 2 (SGLT2) inhibitors and glucagon-like peptide 1 (GLP-1) receptor agonists. Taken together, these studies demonstrate the importance of animal models in providing a mechanistic understanding of this complex condition and their potential to explain the mechanisms of novel therapies.

Comparative effectiveness of SGLT2 inhibitors and GLP-1 receptor agonists in preventing Alzheimer's disease, vascular dementia, and other dementia types among patients with type 2 diabetes

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with an elevated risk of dementia, including Alzheimer's disease (AD) and vascular dementia (VaD). While sodium-glucose cotransporter-2 (SGLT2) inhibitors and glucagon-like peptide-1 (GLP-1) receptor agonists have shown neuroprotective potential, comparative data on their efficacy in dementia prevention remain scarce.

METHODS

- We conducted a retrospective cohort study using the TriNetX database, including 307,103 SGLT2 inhibitor users and 348,686 GLP-1 receptor agonist users with T2DM. Propensity score matching yielded 221,883 pairs with balanced baseline characteristics. The primary outcome was overall dementia incidence, with secondary outcomes including AD, VaD, and all-cause mortality. Hazard ratios (HRs) were calculated using Cox proportional hazards models.

RESULTS

SGLT2 inhibitors were associated with a significantly lower incidence of overall dementia compared to GLP-1 receptor agonists (2.7 % vs. 3.6 %; HR, 0.92; 95 % CI, 0.89-0.95). The risk of VaD (HR, 0.89; 95 % CI, 0.84-0.95) and AD (HR, 0.90; 95 % CI, 0.86-0.94) was also reduced with SGLT2 inhibitors. All-cause mortality was lower in the SGLT2 group (3.6 % vs. 4.6 %; HR, 0.95; 95 % CI, 0.92-0.98). No significant difference was observed in other dementia subtypes (HR, 0.96; 95 % CI, 0.91-1.01).

CONCLUSIONS

In this large, real-world cohort, SGLT2 inhibitors demonstrated superior efficacy over GLP-1 receptor agonists in reducing the risks of overall dementia, VaD, and AD among patients with T2DM. These findings support the preferential use of SGLT2 inhibitors in mitigating dementia risk in this population, though randomized controlled trials are warranted for confirmation.

Unveiling the mTOR pathway modulation by SGLT2 inhibitors: a novel approach to Alzheimer's disease in type 2 diabetes

Alzheimer's disease (AD) is a neurological condition causing cognitive deterioration, leading to severe consequences. As the global prevalence of AD increases, new treatment approaches are needed to supplement current conventional therapies, as traditional treatments are not meeting the increasing demand for alternative treatments. It is increasingly evident that treating metabolic disorders like diabetes mellitus, obesity, and AD by blocking mechanistic target of rapamycin (mTOR) signalling is advantageous. Chronic mTOR activation may cause AD's metabolic, lysosomal, and mitochondrial dysfunction, tau hyperphosphorylation, amyloid plaque development, and disruption of the blood-brain barrier through endothelial cell malfunction. Chronic glucose loss through sodium-glucose transporter 2 (SGLT2) inhibitions can restore mTOR cycling, potentially halting or slowing AD pathogenesis. Chronic activation of mTOR is implicated in pathophysiological aspects of AD, such as metabolic dysfunction, tau hyperphosphorylation, amyloid plaque formation, and disruption of the blood-brain barrier. SGLT-2 inhibitors, commonly used in treating Type 2 Diabetes, have been shown to reduce mTOR activation and restore circadian regularity, a new finding in cognitive decline and metabolic disorders. Conversely, SGLT2 inhibitors decrease oxidative damage, inflammation, insulin signaling pathways, and proliferation of endothelial cells to enhance vascular tone, flexibility, and contractility. Along with reducing the formation of plaque containing amyloid and improving brain function, neural plasticity, acetylcholinesterase (AChE) activity, damage to the brain, and cognitive decline, they also regulate the mTOR pathway in the brain. Thus, repurposing SGLT-2 inhibitors, primarily used in diabetes treatment, presents a promising avenue for changing the way that AD is managed. The purpose of this review was to focus on the mTOR signalling cascade of SGLT 2 inhibitors to AD management in Type 2 Diabetes mellitus.

Integrative Study of Plantago lanceolata L.: Phytochemical Properties and Therapeutic Effects on Cancer, Diabetes, and Alzheimer's Disease

Alzheimer's disease is linked with diabetes and cancer, emphasising the need for effective treatments. Plantago lanceolata, recognised as safe by various pharmacopeias, was investigated in this study for therapeutic potential. We examined the effects of its leaf extracts and sub-extracts (methanol, hexane, dichloromethane, ethyl acetate, butanol, aqueous) on AChE, BChE, α-amylase, α-glucosidase enzymes, as well as their impact on HDF-a and U87-MG cancer cells. The phytochemical characterisation was performed using ICP-MS and LC-MS/MS. Cytotoxic effects were evaluated on HDF-a and U87-MG cell lines, along with assessments for nuclear abnormalities. Na and K were detected in extracts, with isoleucine and cyanidin-3-O-glucoside being the most concentrated compounds. Extracts at concentrations exceeding 25 µg/mL significantly increased cytotoxicity in HDF-a cell lines compared to the control group, without inducing nuclear abnormalities. Methanol extract demonstrated moderate inhibition against AChE and BChE at concentrations of 100 µg/mL and 500 µg/mL, respectively. These findings suggest that extracts exhibit potential therapeutic effects.

Restoring Brain Pathways Involved in Diabetes-Associated Neurocognitive Disorders: The Potential of Dipeptidyl Peptidase 4 Inhibitors as a Therapeutic Strategy

BACKGROUND

Diabetes, a widespread chronic metabolic disease, is projected to affect 783 million people globally by 2045. Recent studies emphasize the neuroprotective potential of dipeptidyl peptidase 4 (DPP4i) inhibitors, pointing toward a promising avenue for intervention in addressing cognitive challenges associated with diabetes. Due to limited data on the effect of DPP4i on brain pathways involvedin diabetes-related neurocognitive disorders, the decision was made to conduct this study to fill existing knowledge gaps on this topic.

METHODS

The primary aim of our study was to evaluate the potential of DPP4 inhibitors (DPP4i) in preventing cognitive decline in mice with type 2 diabetes (T2D), placing special emphasis on gaining insight into the complex molecular mechanisms underlying this action.

RESULTS

We examined drug efficacy in modulating neurotrophic factors, calcium levels, and the expression of key genes (HIF1α, APP, Arc) crucial for neural plasticity. Conducting cognitive assessments with the hole board and passive avoidance tests, we discerned a remarkable influence of shortterm gliptin usage on the limiting progress of cognitive dysfunction in diabetic mice. The administration of DPP4 inhibitors ledto heightened neurotrophin levels, increased HIF1α in the prefrontal cortex, and a significant elevation in Arc mRNA levels.

CONCLUSION

Our findings reveal that DPP4 inhibitors effectively limit the progression of diabetesrelated cognitive disorders. This breakthrough discovery not only opens new research avenues but also constitutes a potential starting point for creating innovative strategies for the treatment of central nervous system disorders focused on improving cognitive abilities.

The Promising Potency of Sodium-Glucose Cotransporter 2 Inhibitors in the Prevention of and as Treatment for Cognitive Impairment Among Type 2 Diabetes Patients

Type 2 diabetes mellitus (T2DM), accounting for the majority of diabetes mellitus prevalence, is associated with an increased risk of cognition decline and deterioration of cognition function in diabetic patients. The sodium-glucose cotransporter 2 (SGLT2), located in the renal proximal tubule, plays a role in urine glucose reabsorption. SGLT2 inhibitors (SGLT2i), have shown potential benefits beyond cardiac and renal improvement in preventing and treating cognitive impairment (CI), including mild cognitive impairment, Alzheimer's disease and vascular dementia in T2DM patients. Studies suggest that SGLT2i may ameliorate diabetic CI through metabolism pathways, inflammation, oxidative stress, neurotrophic factors and AChE inhibition. Clinical trials and meta-analyses have reported significant and insignificant results. Given their vascular effects, SGLT2i may offer unique protection against vascular CI. This review compiles mechanisms and clinical evidence, emphasizing the need for future analysis, evaluation, trials and meta-analyses to verify and recommend optimal SGLT2i selection and dosage for specific patients.

Empagliflozin Attenuates High-Glucose-Induced Astrocyte Activation and Inflammation via NF-κB Pathway

Sodium-glucose cotransporter-2 (SGLT2) inhibitors regulate blood glucose levels in patients with type 2 diabetes mellitus and may also exert anti-inflammatory and anti-atherosclerotic effects by promoting M2 macrophage polarization. Although SGLT2 is expressed in brain regions that influence glucose balance and cognitive function, its roles in the central nervous system are unclear. This study investigated the effects of empagliflozin (EMPA), an SGLT2 inhibitor, on hypothalamic inflammation associated with metabolic diseases. Mice were subjected to a high-fat diet (HFD) for varying durations (3 d, 3 weeks, and 16 weeks) and treated with EMPA for 3 weeks (NFD, NFD + EMPA, HFD, HFD + EMPA; n = 5/group). EMPA regulated the expression of astrocyte markers and pro-inflammatory cytokine mRNA in the hypothalamus of HFD-induced mice, which was linked to regulation of the NF-κB pathway. Under hyperglycemic conditions, EMPA may mitigate hypothalamic inflammation by modulating astrocyte activation via the NF-κB pathway. Our findings demonstrated that EMPA possesses therapeutic potential beyond merely lowering blood glucose levels, opening new avenues for addressing inflammation and providing neuroprotection in metabolic disease management.

A Comprehensive Review of Membrane Transporters and MicroRNA Regulation in Alzheimer's Disease

Alzheimer's disease (AD) is a distressing neurodegenerative condition characterized by the accumulation of amyloid-beta (Aβ) plaques and tau tangles within the brain. The interconnectedness between membrane transporters (SLCs) and microRNAs (miRNAs) in AD pathogenesis has gained increasing attention. This review explores the localization, substrates, and functions of SLC transporters in the brain, emphasizing the roles of transporters for glutamate, glucose, nucleosides, and other essential compounds. The examination delves into the significance of SLCs in AD, their potential for drug development, and the intricate realm of miRNAs, encompassing their transcription, processing, functions, and regulation. MiRNAs have emerged as significant players in AD, including those associated with mitochondria and synapses. Furthermore, this review discusses the intriguing nexus of miRNAs targeting SLC transporters and their potential as therapeutic targets in AD. Finally, the review underscores the interaction between SLC transporters and miRNA regulation within the context of Alzheimer's disease, underscoring the need for further research in this area. This comprehensive review aims to shed light on the complex mechanisms underlying the causation of AD and provides insights into potential therapeutic approaches.

The neuroprotective role of celastrol on hippocampus in diabetic rats by inflammation restraint, insulin signaling adjustment, Aβ reduction and synaptic plasticity alternation

Celastrol, the primary constituent of Tripterygium wilfordii, has demonstrated neuroprotective properties in rats with dementia by reducing inflammation. A high-fat diet and streptozotocin injection were utilized to establish a diabetic rat model, which was then employed to investigate the possible protective effect of celastrol against the development of diabetes-induced learning and memory deficits. Afterwards, the experimental animals received a dose of celastrol by gavage (4 mg/kg/d). An animal study showed that celastrol enhanced insulin sensitivity and glucose tolerance in diabetic rats. In the Morris water maze test, rats with diabetes performed poorly in terms of spatial learning and memory; treatment with celastrol improved these outcomes. Additionally, administration of celastrol downregulated the expression of inflammatory-related proteins (NF-κB, IKKα, TNF-α, IL-1β, and IL-6) and greatly reduced the generation of Aβ in the diabetic hippocampus tissue. Moreover, the insulin signaling pathway-related proteins PI3K, AKT, and GSK-3β were significantly upregulated in diabetic rats after celastrol was administered. Also, celastrol prevented damage to the brain structures and increased the synthesis of synaptic proteins like PSD-95 and SYT1. In conclusion, celastrol exerts a neuroprotective effect by modulating the insulin signaling system and reducing inflammatory responses, which helps to ameliorate the cognitive impairment associated with diabetes.

Risk of Dementia and Alzheimer's Disease Associated With Antidiabetics: A Bayesian Network Meta-Analysis

INTRODUCTION

Dementia risk is substantially elevated in patients with diabetes. However, evidence on dementia risk associated with various antidiabetic regimens is still limited. This study aims to comprehensively investigate the risk of dementia and Alzheimer's disease (AD) associated with various antidiabetic classes.

METHODS

Cochrane Central Register of Controlled Trials, Embase, MEDLINE (PubMed), and Scopus were searched from inception to March 2024 (PROSPERO CRD 42022365927). Observational studies investigating dementia and AD incidences after antidiabetic initiation were identified. Bayesian network meta-analysis was performed to determine dementia and AD risks associated with antidiabetics. Preferred Reporting Items for Systematic Reviews-Network Meta-Analyses (PRISMA-NMA) guidelines were followed. Statistical analysis was performed and updated in November 2023 and March 2024, respectively.

RESULTS

A total of 1,565,245 patients from 16 studies were included. Dementia and AD risks were significantly lower with metformin and sodium glucose co-transporter-2 inhibitors (SGLT2i). Metformin displayed the lowest risk of dementia across diverse antidiabetics, whereas α-glucosidase inhibitors demonstrated the highest risk. SGLT2i exhibited the lowest dementia risk across second-line antidiabetics. Dementia risk was significantly higher with dipeptidyl peptidase-4 inhibitor (DPP4i), metformin, sulfonylureas, and thiazolidinediones (TZD) compared to SGLT2i in the elderly (≥75 years). Dementia risk associated with metformin was substantially lower, regardless of diabetic complication status or baseline A1C.

DISCUSSION

Metformin and SGLT2i demonstrated lower dementia risk than other antidiabetic classes. Patient-specific factors may affect this relationship and cautious interpretation is warranted as metformin is typically initiated at an earlier stage with fewer complications. Hence, further large-scaled clinical trials are required.

Improving insulin resistance by sulforaphane via activating the Bacteroides and Lactobacillus SCFAs-GPR-GLP1 signal axis

Background: Insulin resistance (IR) is closely associated with non-alcoholic fatty liver disease (NAFLD), and the gut microbiome contributes to the development of NAFLD. Sulforaphane (SFN) is a phytochemical in cruciferous vegetables that could improve lipid metabolism disorder. However, whether SFN can alleviate IR in NAFLD by regulating the intestinal flora remains unclear. Methods: SFN was administered to high fat diet (HFD)-fed Wistar rats for 10 weeks. Gut microbiota was analysed by 16S rRNA sequencing and the short chain fatty acids (SCFAs) by gas chromatography. The expression of tight junction protein and the numbers of Lactobacillus, Bacteroides and Bifidobacterium were determined by qPCR. The expression of G-protein-coupled receptor 41/43 (GPR41/43) was determined by western blot. A randomized controlled trial (RCT) was conducted in NAFLD patients with broccoli seed tablets (rich in SFN, 42 mg d-1) as intervention for 12 weeks. Thirty-six volunteers with abnormal glucose before the broccoli seed tablet treatment were selected in the intervention group to analyze their blood glucose, insulin, homeostasis model assessment-insulin resistance index (HOMA-IRI), homeostasis model assessment-insulin sensitivity index (HOMA-ISI) and glucagon-like peptide (GLP-1). Results: SFN reduced blood glucose and HOMA-IRI while increasing insulin sensitivity in HFD rats. SFN reduced glycogen synthase kinase 3 (GSK-3), phosphoenolpyruvate carboxykinase (PEPCK) activity, and phosphorylation of serine residues of IRS-2 induced by HFD. SFN reshaped the gut microbiota composition of HFD-induced rats and, especially, increased the content of Bacteroidaceae, Lactobacillaceae and Bifidobacteriaceae, which are related to the improvement from SFN of the blood glucose and HOMA-IRI. The increased numbers of Bacteroides and Lactobacillus were the targets of SFN to enhance the expression of tight junction proteins ZO-1 and occludin, thereby lowering lipopolysaccharide content to reduce inflammation, ultimately alleviating IR. Bacteroides and Lactobacillus produced SCFAs, which activated GPR41/43 to secrete GLP1. Moreover, it was also confirmed in RCT that SFN intervention increased the level of GLP1 in NAFLD patients, which was positively correlated with the reduction of blood glucose and HOMA-IR. Conclusions: SFN alleviated IR in NAFLD via the Bacteroides and Lactobacillus SCFAs-GPR41/43-GLP1 axis and protected the intestinal mucosal barrier to decrease inflammation.

SGLT2 inhibitors: a novel therapy for cognitive impairment via multifaceted effects on the nervous system

The rising prevalence of diabetes mellitus has casted a spotlight on one of its significant sequelae: cognitive impairment. Sodium-glucose cotransporter-2 (SGLT2) inhibitors, originally developed for diabetes management, are increasingly studied for their cognitive benefits. These benefits may include reduction of oxidative stress and neuroinflammation, decrease of amyloid burdens, enhancement of neuronal plasticity, and improved cerebral glucose utilization. The multifaceted effects and the relatively favorable side-effect profile of SGLT2 inhibitors render them a promising therapeutic candidate for cognitive disorders. Nonetheless, the application of SGLT2 inhibitors for cognitive impairment is not without its limitations, necessitating more comprehensive research to fully determine their therapeutic potential for cognitive treatment. In this review, we discuss the role of SGLT2 in neural function, elucidate the diabetes-cognition nexus, and synthesize current knowledge on the cognitive effects of SGLT2 inhibitors based on animal studies and clinical evidence. Research gaps are proposed to spur further investigation.

The associations between type 2 diabetes and plasma biomarkers of Alzheimer's disease in the Health and Aging Brain Study: Health Disparities (HABS-HD)

Alzheimer's disease (AD) affects Latinos disproportionately. One of the reasons underlying this disparity may be type 2 diabetes (T2D) that is a risk factor for AD. The purpose of this study was to examine the associations of T2D and AD blood biomarkers and the differences in these associations between Mexican Americans and non-Hispanic Whites. This study was a secondary analysis of baseline data from the observational Health and Aging Brain Study: Health Disparities (HABS-HD) that investigated factors underlying health disparities in AD in Mexican Americans in comparison to non-Hispanic Whites. HABS-HD participants were excluded if they had missing data or were large outliers (z-scores >|4|) on a given AD biomarker. Fasting blood glucose and glycosylated hemoglobin (HbA1c) levels were measured from clinical labs. T2D was diagnosed by licensed clinicians. Plasma amyloid-beta 42 and 40 (Aβ42/42) ratio, total tau (t-tau), and neurofilament light (NfL) were measured via ultra-sensitive Simoa assays. The sample sizes were 1,552 for Aβ42/40 ratio, 1,570 for t-tau, and 1,553 for NfL. Mexican Americans were younger (66.6±8.7 vs. 69.5±8.6) and had more female (64.9% female vs. 55.1%) and fewer years of schooling (9.5±4.6 vs. 15.6±2.5) than non-Hispanic Whites. Mexican Americans differed significantly from non-Hispanic Whites in blood glucose (113.5±36.6 vs. 99.2±17.0) and HbA1c (6.33±1.4 vs. 5.51±0.6) levels, T2D diagnosis (35.3% vs. 11.1%), as well as blood Aβ42/40 ratio (.051±.012 vs. .047±.011), t-tau (2.56±.95 vs. 2.33±.90), and NfL levels (16.3±9.5 vs. 20.3±10.3). Blood glucose, blood HbA1c, and T2D diagnosis were not related to Aβ42/40 ratio and t-tau but explained 3.7% of the variation in NfL (p < .001). Blood glucose and T2D diagnosis were not, while HbA1c was positively (b = 2.31, p < .001, β = 0.26), associated with NfL among Mexican Americans. In contrast, blood glucose, HbA1c, and T2D diagnosis were negatively (b = -0.09, p < .01, β = -0.26), not (b = 0.34, p = .71, β = 0.04), and positively (b = 3.32, p < .01, β = 0.33) associated with NfL, respectively in non-Hispanic Whites. To conclude, blood glucose and HbA1c levels and T2D diagnosis are associated with plasma NfL levels, but not plasma Aβ and t-tau levels. These associations differ in an ethnicity-specific manner and need to be further studied as a potential mechanism underlying AD disparities.

Neuroprotective effects of dipeptidyl peptidase 4 inhibitor on Alzheimer's disease: a narrative review

Insulin resistance in brain and amyloidogenesis are principal pathological features of diabetes-related cognitive decline and development of Alzheimer's disease (AD). A growing body of evidence suggests that maintaining glucose under control in diabetic patients is beneficial for preventing AD development. Dipeptidyl peptidase 4 inhibitors (DDP4is) are a class of novel glucose-lowering medications through increasing insulin excretion and decreasing glucagon levels that have shown neuroprotective potential in recent studies. This review consolidates extant evidence from earlier and new studies investigating the association between DPP4i use, AD, and other cognitive outcomes. Beyond DPP4i's benefits in alleviating insulin resistance and glucose-lowering, underlying mechanisms for the potential neuroprotection with DPP4i medications were categorized into the following sections: (Ferrari et al., Physiol Rev, 2021, 101, 1,047-1,081): the benefits of DPP4is on directly ameliorating the burden of β-amyloid plaques and reducing the formation of neurofibrillary tangles; DPP4i increasing the bioactivity of neuroprotective DPP4 substrates including glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic peptide (GIP), and stromal-derived factor-1α (SDF-1α) etc.; pleiotropic effects of DPP4is on neuronal cells and intracerebral structure including anti-inflammation, anti-oxidation, and anti-apoptosis. We further revisited recently published epidemiological studies that provided supportive data to compliment preclinical evidence. Given that there remains a lack of completed randomized trials that aim at assessing the effect of DPP4is in preventing AD development and progression, this review is expected to provide a useful insight into DPP4 inhibition as a potential therapeutic target for AD prevention and treatment. The evidence is helpful for informing the rationales of future clinical research and guiding evidence-based clinical practice.

Risks and Benefits of SGLT-2 Inhibitors for Type 1 Diabetes Patients Using Automated Insulin Delivery Systems-A Literature Review

The primary treatment for autoimmune Diabetes Mellitus (Type 1 Diabetes Mellitus-T1DM) is insulin therapy. Unfortunately, a multitude of clinical cases has demonstrated that the use of insulin as a sole therapeutic intervention fails to address all issues comprehensively. Therefore, non-insulin adjunct treatment has been investigated and shown successful results in clinical trials. Various hypoglycemia-inducing drugs such as Metformin, glucagon-like peptide 1 (GLP-1) receptor agonists, dipeptidyl peptidase-4 (DPP-4) inhibitors, amylin analogs, and Sodium-Glucose Cotransporters 2 (SGLT-2) inhibitors, developed good outcomes in patients with T1DM. Currently, SGLT-2 inhibitors have remarkably improved the treatment of patients with diabetes by preventing cardiovascular events, heart failure hospitalization, and progression of renal disease. However, their pharmacological potential has not been explored enough. Thus, the substantial interest in SGLT-2 inhibitors (SGLT-2is) underlines the present review. It begins with an overview of carrier-mediated cellular glucose uptake, evidencing the insulin-independent transport system contribution to glucose homeostasis and the essential roles of Sodium-Glucose Cotransporters 1 and 2. Then, the pharmacological properties of SGLT-2is are detailed, leading to potential applications in treating T1DM patients with automated insulin delivery (AID) systems. Results from several studies demonstrated improvements in glycemic control, an increase in Time in Range (TIR), a decrease in glycemic variability, reduced daily insulin requirements without increasing hyperglycemic events, and benefits in weight management. However, these advantages are counterbalanced by increased risks, particularly concerning Diabetic Ketoacidosis (DKA). Several clinical trials reported a higher incidence of DKA when patients with T1DM received SGLT-2 inhibitors such as Sotagliflozin and Empagliflozin. On the other hand, patients with T1DM and a body mass index (BMI) of ≥27 kg/m2 treated with Dapagliflozin showed similar reduction in hyperglycemia and body weight and insignificantly increased DKA incidence compared to the overall trial population. Additional multicenter and randomized studies are required to establish safer and more effective long-term strategies based on patient selection, education, and continuous ketone body monitoring for optimal integration of SGLT-2 inhibitors into T1DM therapeutic protocol.

Cognitive Benefits of Sodium-Glucose Co-Transporters-2 Inhibitors in the Diabetic Milieu

Patients with diabetes are at higher risk of cognitive impairment and memory loss than the normal population. Thus, using hypoglycemic agents to improve brain function is important for diabetic patients. Sodium-glucose cotransporters-2 inhibitors (SGLT2i) are a class of therapeutic agents used in the management of diabetes that has some pharmacologic effects enabling them to fight against the onset and progress of memory deficits. Although the exact mediating pathways are not well understood, emerging evidence suggests that SGLT2 inhibition is associated with improved brain function. This study reviewed the possible mechanisms and provided evidence suggesting SGLT2 inhibitors could ameliorate cognitive deficits.

A Review of the Common Neurodegenerative Disorders: Current Therapeutic Approaches and the Potential Role of Bioactive Peptides

Neurodegenerative disorders, which include Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS), represent a significant and growing global health challenge. Current therapies predominantly focus on symptom management rather than altering disease progression. In this review, we discuss the major therapeutic strategies in practice for these disorders, highlighting their limitations. For AD, the mainstay treatments are cholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists. For PD, dopamine replacement therapies, including levodopa, are commonly used. HD is managed primarily with symptomatic treatments, and reusable extends survival in ALS. However, none of these therapies halts or substantially slows the neurodegenerative process. In contrast, this review highlights emerging research into bioactive peptides as potential therapeutic agents. These naturally occurring or synthetically designed molecules can interact with specific cellular targets, potentially modulating disease processes. Preclinical studies suggest that bioactive peptides may mitigate oxidative stress, inflammation, and protein misfolding, which are common pathological features in neurodegenerative diseases. Clinical trials using bioactive peptides for neurodegeneration are limited but show promising initial results. For instance, hemiacetal, a γ-secretase inhibitor peptide, has shown potential in AD by reducing amyloid-beta production, though its development was discontinued due to side effects. Despite these advancements, many challenges remain, including identifying optimal peptides, confirming their mechanisms of action, and overcoming obstacles related to their delivery to the brain. Future research should prioritize the discovery and development of novel bioactive peptides and improve our understanding of their pharmacokinetics and pharmacodynamics. Ultimately, this approach may lead to more effective therapies for neurodegenerative disorders, moving beyond symptom management to potentially modify the course of these devastating diseases.

Diabetic Pneumopathy- A Novel Diabetes-associated Complication: Pathophysiology, the Underlying Mechanism and Combination Medication

BACKGROUND

The "diabetic lung" has been identified as a possible target organ in diabetes, with abnormalities in ventilation control, bronchomotor tone, lung volume, pulmonary diffusing capacity, and neuroadrenergic bronchial innervation.

OBJECTIVE

This review summarizes studies related to diabetic pneumopathy, pathophysiology and a number of pulmonary disorders including type 1 and type 2 diabetes.

METHODS

Electronic searches were conducted on databases such as Pub Med, Wiley Online Library (WOL), Scopus, Elsevier, ScienceDirect, and Google Scholar using standard keywords "diabetes," "diabetes Pneumopathy," "Pathophysiology," "Lung diseases," "lung infection" for review articles published between 1978 to 2023 very few previous review articles based their focus on diabetic pneumopathy and its pathophysiology.

RESULTS

Globally, the incidence of diabetes mellitus has been rising. It is a chronic, progressive metabolic disease. The "diabetic lung" may serve as a model of accelerated ageing since diabetics' rate of respiratory function deterioration is two to three-times higher than that of normal, non-smoking people.

CONCLUSION

Diabetes-induced pulmonary dysfunction has not gained the attention it deserves due to a lack of proven causality and changes in cellular properties. The mechanism underlying a particular lung illness can still only be partially activated by diabetes but there is evidence that hyperglycemia is linked to pulmonary fibrosis in diabetic people.

Exercise combined with postbiotics treatment results in synergistic improvement of mitochondrial function in the brain of male transgenic mice for Alzheimer's disease

BACKGROUND

It has been suggested that exercise training and postbiotic supplement could decelerate the progress of functional and biochemical deterioration in double transgenic mice overexpresses mutated forms of the genes for human amyloid precursor protein (APPsw) and presenilin 1 (m146L) (APP/PS1TG). Our earlier published data indicated that the mice performed better than controls on the Morris Maze Test parallel with decreased occurrence of amyloid-β plaques in the hippocampus. We investigated the neuroprotective and therapeutic effects of high-intensity training and postbiotic supplementation.

METHODS

Thirty-two adult APP/PS1TG mice were randomly divided into four groups: (1) control, (2) high-intensity training (3) postbiotic, (4) combined (training and postbiotic) treatment for 20 weeks. In this study, the whole hemibrain without hippocampus was used to find molecular traits explaining improved brain function. We applied qualitative RT-PCR for gene expression, Western blot for protein level, and Zymography for LONP1 activity. Disaggregation analysis of Aβ-40 was performed in the presence of Lactobacillus acidophilus and Bifidobacterium longum lysate.

RESULTS

We found that exercise training decreased Alzheimer's Disease (AD)-related gene expression (NF-kB) that was not affected by postbiotic treatment. The preparation used for postbiotic treatment is composed of tyndallized Bifidobacterium longum and Lactobacillus acidophilus. Both of the postbiotics effectively disaggregated amyloid-β/Aβ-40 aggregates by chelating Zn2+ and Cu2+ ions. The postbiotic treatment decreased endogenous human APPTG protein expression and mouse APP gene expression in the hemibrains. In addition, the postbiotic treatment elevated mitochondrial LONP1 activity as well.

CONCLUSION

Our findings revealed distinct mechanisms behind improved memory performance in the whole brain: while exercise training modulates NF-kB signaling pathway regulating immune response until postbiotic diminishes APP gene expression, disaggregates pre-existing amyloid-β plaques and activates mitochondrial protein quality control in the region of brain out of hippocampus. Using the above treatments complements and efficiently slows down the development of AD.

Dipeptidyl peptidase-4 inhibitors alleviate cognitive dysfunction in type 2 diabetes mellitus

BACKGROUND

Patients with type 2 diabetes mellitus (T2DM) are commonly at high risk for developing cognitive dysfunction. Antidiabetic agents might be repurposed for targeting cognitive dysfunction in addition to modulation on glucose homeostasis. This study aimed to evaluate the impact of dipeptidyl peptidase-4 inhibitors (DPP-4i) on cognitive function in T2DM.

METHODS

PubMed, Embase, Cochrane Library and Web of Science were systematically searched from inception to September 30, 2023. Weighted mean differences were calculated using the Mantel-Haenszel (M-H) fixed or random effects model based on the degree of heterogeneity among studies. Heterogeneity was evaluated using a Chi-squared test and quantified with Higgins I2. Sensitivity analysis was performed with the leave-one-out method, and publication bias was evaluated according to Begg's and Egger's tests.

RESULTS

Six clinical trials involving 5,178 participants were included in the pooled analysis. Administration of DPP-4i generally correlated with an increase of Mini-Mental State Examination (MMSE) scores (1.09, 95% CI: 0.22 to 1.96). DPP-4i alleviated cognitive impairment in the copying skill subdomain of MMSE (0.26, 95% CI: 0.12 to 0.40). Treatment with DPP-4i also resulted in an increase of Instrumental Activities of Daily Living (IADL) scores (0.82, 95% CI: 0.30 to 1.34). However, DPP-4i produced no significant effects on Barthel Activities of Daily Living (BADL) scores (0.37, 95% CI: -1.26 to 1.99) or other test scores.

CONCLUSIONS

DPP-4i treatment favourably improved cognitive function in patients with T2DM. Further trials with larger samples should be performed to confirm these estimates and investigate the association of different DPP-4i with cognitive function among diabetic patients.

TRIAL REGISTRATION IN PROSPERO

CRD42023430873.

SGLT2 and DPP4 inhibitors improve Alzheimer's disease-like pathology and cognitive function through distinct mechanisms in a T2D-AD mouse model

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2D) share common features, including insulin resistance. Brain insulin resistance has been implicated as a key factor in the pathogenesis of AD. Recent studies have demonstrated that anti-diabetic drugs sodium-glucose cotransporter-2 inhibitor (SGLT2-i) and dipeptidyl peptidase-4 inhibitor (DPP4-i) improve insulin sensitivity and provide neuroprotection. However, the effects of these two inhibitors on the brain metabolism and insulin resistance remain uninvestigated. We developed a T2D-AD mouse model using a high-fat diet (HFD) for 19 weeks along with a single dose of streptozotocin (100 mg/kg, intraperitoneally) at the fourth week of HFD initiation. Subsequently, the animals were treated with SGLT2-i (empagliflozin, 25 mg/kg/day orally [p.o.]) and DPP4-i (sitagliptin, 100 mg/kg/day p.o.) for 7 weeks. Subsequently, behavioral tests were performed, and the expression of insulin signaling, AD-related, and other signaling pathway proteins in the brain were examined. T2D-AD mice not only showed increased blood glucose levels and body weight but also insulin resistance. SGLT2-i and DPP4-i effectively ameliorated insulin sensitivity and reduced body weight in these mice. Furthermore, SGLT2-i and DPP4-i significantly improved hippocampal-dependent learning, memory, and cognitive functions in the T2D-AD mouse model. Interestingly, SGLT2-i and DPP4-i reduced the hyperphosphorylated tau (pTau) levels and amyloid β (Aβ) accumulation and enhanced brain insulin signaling. SGLT2-i reduced pTau accumulation through the angiotensin converting enzyme-2/angiotensin (1-7)/ mitochondrial assembly receptor axis, whereas DPP4-i reduced Aβ accumulation by increasing insulin-degrading enzyme levels. These findings suggest that SGLT2-i and DPP4-i prevent AD-like pathology and cognitive dysfunction in T2D mice potentially through affecting brain insulin signaling via different mechanisms.

GLP-1 Analogs, SGLT-2, and DPP-4 Inhibitors: A Triad of Hope for Alzheimer's Disease Therapy

Alzheimer's is a prevalent, progressive neurodegenerative disease marked by cognitive decline and memory loss. The disease's development involves various pathomechanisms, including amyloid-beta accumulation, neurofibrillary tangles, oxidative stress, inflammation, and mitochondrial dysfunction. Recent research suggests that antidiabetic drugs may enhance neuronal survival and cognitive function in diabetes. Given the well-documented correlation between diabetes and Alzheimer's disease and the potential shared mechanisms, this review aimed to comprehensively assess the potential of new-generation anti-diabetic drugs, such as GLP-1 analogs, SGLT-2 inhibitors, and DPP-4 inhibitors, as promising therapeutic approaches for Alzheimer's disease. This review aims to comprehensively assess the potential therapeutic applications of novel-generation antidiabetic drugs, including GLP-1 analogs, SGLT-2 inhibitors, and DPP-4 inhibitors, in the context of Alzheimer's disease. In our considered opinion, antidiabetic drugs offer a promising avenue for groundbreaking developments and have the potential to revolutionize the landscape of Alzheimer's disease treatment.

Insights from insulin resistance pathways: Therapeutic approaches against Alzheimer associated diabetes mellitus

Alzheimer Associated Diabetes Mellitus, commonly known as Type 3 Diabetes Mellitus (T3DM) is a distinct subtype of diabetes with a pronounced association with Alzheimer's disease (AD). Insulin resistance serves as a pivotal link between these two conditions, leading to diminished insulin sensitivity, hyperglycemia, and impaired glucose uptake. The brain, a vital organ in AD context, is also significantly impacted by insulin resistance, resulting in energy deficits and neuronal damage, which are hallmark features of the neurodegenerative disorder. To pave the way for potential therapeutic interventions targeting the insulin resistance pathway, it is crucial to comprehend the intricate pathophysiology of T3DM and identify the overlapped features between diabetes and AD. This comprehensive review article aims to explore various pathway such as AMPK, PPARγ, cAMP and P13K/Akt pathway as potential target for management of T3DM. Through the analysis of these complex mechanisms, our goal is to reveal their interdependencies and support the discovery of innovative therapeutic strategies. The review extensively discusses several promising pharmaceutical candidates that have demonstrated dual drug action mechanisms, addressing both peripheral and cerebral insulin resistance observed in T3DM. These candidates hold significant promise for restoring insulin function and mitigating the detrimental effects of insulin resistance on the brain. The exploration of these therapeutic options contributes to the development of innovative interventions that alleviate the burden of T3DM and enhance patient care.

Diabetes-Alzheimer's connection in older age: SGLT2 inhibitors as promising modulators of disease pathways

Late-onset Alzheimer's disease (LOAD) is the most frequent cause of dementia in older persons. Subjects affected by type 2 diabetes mellitus (T2DM) are at higher risk of vascular disease, cognitive decline, and dementia. LOAD has many characteristics shared with impaired insulin signaling pathways, and substantial evidence has demonstrated a pivotal role in dysregulated glucose metabolism in its pathogenesis. Recent studies have shown that some anti-diabetic drugs, other than regulating the metabolism of peripheral tissues, can also modulate the brain's metabolism, reduce inflammation, and have a direct neuroprotective effect. Sodium-glucose cotransporter-2 inhibitors (SGLT2i) are a newer class with many pleiotropic effects that may have strong neuroprotective potential. After a summary of the principal "anti-diabetic" drugs acting as suitable candidates in treating LOAD, this narrative review explored the potential role of SGLT2i on cognition from pre-clinical to clinical studies.

Tirzepatide ameliorates spatial learning and memory impairment through modulation of aberrant insulin resistance and inflammation response in diabetic rats

Background: One of the typical symptoms of diabetes mellitus patients was memory impairment, which was followed by gradual cognitive deterioration and for which there is no efficient treatment. The anti-diabetic incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) were demonstrated to have highly neuroprotective benefits in animal models of AD. We wanted to find out how the GLP-1/GIP dual agonist tirzepatide affected diabetes's impairment of spatial learning memory. Methods: High fat diet and streptozotocin injection-induced diabetic rats were injected intraperitoneally with Tirzepatide (1.35 mg/kg) once a week. The protective effects were assessed using the Morris water maze test, immunofluorescence, and Western blot analysis. Golgi staining was adopted for quantified dendritic spines. Results: Tirzepatide significantly improved impaired glucose tolerance, fasting blood glucose level, and insulin level in diabetic rats. Then, tirzepatide dramatically alleviated spatial learning and memory impairment, inhibited Aβ accumulation, prevented structural damage, boosted the synthesis of synaptic proteins and increased dendritic spines formation in diabetic hippocampus. Furthermore, some aberrant changes in signal molecules concerning inflammation signaling pathways were normalized after tirzepatide treatment in diabetic rats. Finally, PI3K/Akt/GSK3β signaling pathway was restored by tirzepatide. Conclusion: Tirzepatide obviously exerts a protective effect against spatial learning and memory impairment, potentially through regulating abnormal insulin resistance and inflammatory responses.

Dapagliflozin Ameliorates Cognitive Impairment in Aluminum-Chloride-Induced Alzheimer's Disease via Modulation of AMPK/mTOR, Oxidative Stress and Glucose Metabolism

Alzheimer's disease (AD) is a progressive neurological illness characterized by memory loss and cognitive deterioration. Dapagliflozin was suggested to attenuate the memory impairment associated with AD; however, its mechanisms were not fully elucidated. This study aims to examine the possible mechanisms of the neuroprotective effects of dapagliflozin against aluminum chloride (AlCl₃)-induced AD. Rats were distributed into four groups: group 1 received saline, group 2 received AlCl₃ (70 mg/kg) daily for 9 weeks, and groups 3 and 4 were administered AlCl₃ (70 mg/kg) daily for 5 weeks. Dapagliflozin (1 mg/kg) and dapagliflozin (5 mg/kg) were then given daily with AlCl₃ for another 4 weeks. Two behavioral experiments were performed: the Morris Water Maze (MWM) and the Y-maze spontaneous alternation (Y-maze) task. Histopathological alterations in the brain, as well as changes in acetylcholinesterase (AChE) and amyloid β (Aβ) peptide activities and oxidative stress (OS) markers, were all evaluated. A western blot analysis was used for the detection of phosphorylated 5' AMP-activated protein kinase (p-AMPK), phosphorylated mammalian target of Rapamycin (p-mTOR) and heme oxygenase-1 (HO-1). Tissue samples were collected for the isolation of glucose transporters (GLUTs) and glycolytic enzymes using PCR analysis, and brain glucose levels were also measured. The current data demonstrate that dapagliflozin represents a possible approach to combat AlCl₃-induced AD in rats through inhibiting oxidative stress, enhancing glucose metabolism and activating AMPK signaling.

The sodium glucose co-transporter 2 inhibitor ertugliflozin for Alzheimer's disease: Inhibition of brain insulin signaling disruption-induced tau hyperphosphorylation

An antidiabetic agent sodium glucose co-transporter 2 (SGLT2) inhibitor ertugliflozin has been revealed to bind to catalytic anionic site of acetylcholinesterase (AChE), which is considered to be associated with the cognitive decline in neurodegenerative diseases, such as Alzheimer's disease (AD). The aim of the present study was thus to probe the effect of ertugliflozin on AD. Intracerebroventricular injection of streptozotocin (STZ/i.c.v) (3 mg/kg) was done bilaterally in male Wistar rats at 7-8 weeks of age. Two treatment doses (5 mg/kg and 10 mg/kg) of ertugliflozin were given intragastrically to STZ/i.c.v-induced rats for 20 days daily for behavioral assessment. Biochemical estimations of cholinergic activity, neuronal apoptosis, mitochondrial function and synaptic plasticity were performed. Behavioral results with ertugliflozin treatment revealed attenuation of cognitive deficit. Ertugliflozin also inhibited hippocampal AChE activity, downregulated pro-apoptotic marker expression, as well as mitigated mitochondrial dysfunction and synaptic damage in STZ/i.c.v rats. Importantly, we found that the hyperphosphorylation of tau in the hippocampus of STZ/i.c.v rats was decreased after oral administration of ertugliflozin, which was accompanied by decreased Phospho.IRS-1_Ser307/Total.IRS-1 ratio and increased Phospho.Akt_Ser473/Total.Akt and Phospho.GSK3β_Ser9/Total.GSK3β ratios. Our results indicated that treatment with ertugliflozin reversed AD pathology, which may be associated with inhibition of insulin signaling disruption-induced tau hyperphosphorylation.

Molecular and neural roles of sodium-glucose cotransporter 2 inhibitors in alleviating neurocognitive impairment in diabetic mice

Diabetes causes a variety of molecular changes in the brain, making it a real risk factor for the development of cognitive dysfunction. Complex pathogenesis and clinical heterogeneity of cognitive impairment makes the efficacy of current drugs limited. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) gained our attention as drugs with potential beneficial effects on the CNS. In the present study, these drugs ameliorated the cognitive impairment associated with diabetes. Moreover, we verified whether SGLT2i can mediate the degradation of amyloid precursor protein (APP) and modulation of gene expression (Bdnf, Snca, App) involved in the control of neuronal proliferation and memory. The results of our research proved the participation of SGLT2i in the multifactorial process of neuroprotection. SGLT2i attenuate the neurocognitive impairment through the restoration of neurotrophin levels, modulation of neuroinflammatory signaling, and gene expression of Snca, Bdnf, and App in the brain of diabetic mice. The targeting of the above-mentioned genes is currently seen as one of the most promising and developed therapeutic strategies for diseases associated with cognitive dysfunction. The results of this work could form the basis of a future administration of SGLT2i in diabetics with neurocognitive impairment.

Unlocking the Full Potential of SGLT2 Inhibitors: Expanding Applications beyond Glycemic Control

The number of diabetic patients has risen dramatically in recent decades, owing mostly to the rising incidence of type 2 diabetes mellitus (T2DM). Several oral antidiabetic medications are used for the treatment of T2DM including, α-glucosidases inhibitors, biguanides, sulfonylureas, meglitinides, GLP-1 receptor agonists, PPAR-γ agonists, DDP4 inhibitors, and SGLT2 inhibitors. In this review we focus on the possible effects of SGLT2 inhibitors on different body systems. Beyond the diabetic state, SGLT2 inhibitors have revealed a demonstrable ability to ameliorate cardiac remodeling, enhance myocardial function, and lower heart failure mortality. Additionally, SGLT2 inhibitors can modify adipocytes and their production of cytokines, such as adipokines and adiponectin, which enhances insulin sensitivity and delays diabetes onset. On the other hand, SGLT2 inhibitors have been linked to decreased total hip bone mineral deposition and increased hip bone resorption in T2DM patients. More data are needed to evaluate the role of SGLT2 inhibitors on cancer. Finally, the effects of SGLT2 inhibitors on neuroprotection appear to be both direct and indirect, according to scientific investigations utilizing various experimental models. SGLT2 inhibitors improve vascular tone, elasticity, and contractility by reducing oxidative stress, inflammation, insulin signaling pathways, and endothelial cell proliferation. They also improve brain function, synaptic plasticity, acetylcholinesterase activity, and reduce amyloid plaque formation, as well as regulation of the mTOR pathway in the brain, which reduces brain damage and cognitive decline.

The many facets of CD26/dipeptidyl peptidase 4 and its inhibitors in disorders of the CNS - a critical overview

Dipeptidyl peptidase 4 is a serine protease that cleaves X-proline or X-alanine in the penultimate position. Natural substrates of the enzyme are glucagon-like peptide-1, glucagon inhibiting peptide, glucagon, neuropeptide Y, secretin, substance P, pituitary adenylate cyclase-activating polypeptide, endorphins, endomorphins, brain natriuretic peptide, beta-melanocyte stimulating hormone and amyloid peptides as well as some cytokines and chemokines. The enzyme is involved in the maintenance of blood glucose homeostasis and regulation of the immune system. It is expressed in many organs including the brain. DPP4 activity may be effectively depressed by DPP4 inhibitors. Apart from enzyme activity, DPP4 acts as a cell surface (co)receptor, associates with adeosine deaminase, interacts with extracellular matrix, and controls cell migration and differentiation. This review aims at revealing the impact of DPP4 and DPP4 inhibitors for several brain diseases (virus infections affecting the brain, tumours of the CNS, neurological and psychiatric disorders). Special emphasis is given to a possible involvement of DPP4 expressed in the brain.While prominent contributions of extracerebral DPP4 are evident for a majority of diseases discussed herein; a possible role of "brain" DPP4 is restricted to brain cancers and Alzheimer disease. For a number of diseases (Covid-19 infection, type 2 diabetes, Alzheimer disease, vascular dementia, Parkinson disease, Huntington disease, multiple sclerosis, stroke, and epilepsy), use of DPP4 inhibitors has been shown to have a disease-mitigating effect. However, these beneficial effects should mostly be attributed to the depression of "peripheral" DPP4, since currently used DPP4 inhibitors are not able to pass through the intact blood-brain barrier.

Intranasal Administration of KYCCSRK Peptide Rescues Brain Insulin Signaling Activation and Reduces Alzheimer's Disease-like Neuropathology in a Mouse Model for Down Syndrome

Down syndrome (DS) is the most frequent genetic cause of intellectual disability and is strongly associated with Alzheimer's disease (AD). Brain insulin resistance greatly contributes to AD development in the general population and previous studies from our group showed an early accumulation of insulin resistance markers in DS brain, already in childhood, and even before AD onset. Here we tested the effects promoted in Ts2Cje mice by the intranasal administration of the KYCCSRK peptide known to foster insulin signaling activation by directly interacting and activating the insulin receptor (IR) and the AKT protein. Therefore, the KYCCSRK peptide might represent a promising molecule to overcome insulin resistance. Our results show that KYCCSRK rescued insulin signaling activation, increased mitochondrial complexes levels (OXPHOS) and reduced oxidative stress levels in the brain of Ts2Cje mice. Moreover, we uncovered novel characteristics of the KYCCSRK peptide, including its efficacy in reducing DYRK1A (triplicated in DS) and BACE1 protein levels, which resulted in reduced AD-like neuropathology in Ts2Cje mice. Finally, the peptide elicited neuroprotective effects by ameliorating synaptic plasticity mechanisms that are altered in DS due to the imbalance between inhibitory vs. excitatory currents. Overall, our results represent a step forward in searching for new molecules useful to reduce intellectual disability and counteract AD development in DS.

Aberrant Energy Metabolism in Alzheimer's Disease

To maintain energy supply to the brain, a direct energy source called adenosine triphosphate (ATP) is produced by oxidative phosphorylation and aerobic glycolysis of glucose in the mitochondria and cytoplasm. Brain glucose metabolism is reduced in many neurodegenerative diseases, including Alzheimer's disease (AD), where it appears presymptomatically in a progressive and region-specific manner. Following dysregulation of energy metabolism in AD, many cellular repair/regenerative processes are activated to conserve the energy required for cell viability. Glucose metabolism plays an important role in the pathology of AD and is closely associated with the tricarboxylic acid cycle, type 2 diabetes mellitus, and insulin resistance. The glucose intake in neurons is from endothelial cells, astrocytes, and microglia. Damage to neurocentric glucose also damages the energy transport systems in AD. Gut microbiota is necessary to modulate bidirectional communication between the gastrointestinal tract and brain. Gut microbiota may influence the process of AD by regulating the immune system and maintaining the integrity of the intestinal barrier. Furthermore, some therapeutic strategies have shown promising therapeutic effects in the treatment of AD at different stages, including the use of antidiabetic drugs, rescuing mitochondrial dysfunction, and epigenetic and dietary intervention. This review discusses the underlying mechanisms of alterations in energy metabolism in AD and provides potential therapeutic strategies in the treatment of AD.

The Outcomes of Sodium-Glucose Co-transporter 2 Inhibitors (SGLT2I) on Diabetes-Associated Neuropathy: A Systematic Review and meta-Analysis

Diabetes mellitus (DM) is one of the leading causes of morbidity and mortality worldwide. DM patients with diabetic neuropathy (DN) usually present with distal pain, sensorimotor polyneuropathy, postural hypotension, or erectile dysfunction. They also may present with other nerve pathologies such as inflammatory neuropathies and carpal tunnel syndrome. We conducted a systematic review and meta-analysis to assess the benefits of using sodium–glucose co-transporter-2 inhibitors (SGLT2Is) to manage DN. An extensive systematic literature review was conducted to include all articles published up to 24 February 2022. All clinical studies included patients with DM and reported the outcomes of SGLT2I on diabetes-associated neuropathy. Six studies were identified for meta-analysis, including a total of 5312 diabetic patients. The average age of the included patients ranged from 41 to 74 years and 34–73 years in the SGLT2I treatment and control groups, respectively. SGLT2I moderately improved the manifestations of diabetic peripheral neuropathy events and nerve conduction velocity. Furthermore, the SGLT2I treatment group had a statistically significant higher mean heart-to-mediastinum ratio (MD 0.41; 95% 0.17, 0.64; p = 0.0006). However, the mean heart rates (MD −4.51; 95% −10.05, 1.04; p = 0.11) and wash out rates (MD 2.13; 95% −8.48, 12.75; p = 0.69) were not significantly different between the two groups. SGLT2Is could therefore be considered neuroprotective in patients with DN, possibly by considerably increasing the sensory and motor nerve conduction velocity, improving the clinical manifestations of DPN, and reducing sympathetic nervous system activity.

Systematic Review Registration:http://www.crd.york.ac.uk/prospero/, identifier CRD42022312828

Glucose-lowering drugs, cognition, and dementia: The clinical evidence

Type 2 diabetes mellitus (T2DM) is an important risk factor for dementia. The possibility to mitigate this risk by controlling T2DM is compelling; however, different glucose-lowering drugs have different effects on the brain by virtue of their different mechanisms of action. The clinical and epidemiological data appear mixed, warranting careful critical evaluation of the human studies. Here we examine the evidence in the context of dementia prevention and treatment, both for people with and without T2DM. We discuss the evidence on this scaffold of research directions, identifying methodological complexities in the extant literature (e.g. comparator discrepancies, changes in the therapeutic landscape), and the implications of different outcome measures (e.g. neuropsychological). We consider possible implications of cerebrovascular protection vs. effects on progression of neurodegenerative proteinopathy, and we present a research roadmap for glucose-lowering drugs in cognitive neurology, including neuroimaging, and fluid biomarkers. We conclude that there is great potential to advance personalized strategies to prevent and treat dementia with glucose-lowering drugs.

Neuroprotective Effect of SGLT2 Inhibitors

Patients with diabetes are at higher risk of cardiovascular diseases and cognitive impairment. SGLT2 inhibitors (Empagliflozin, Canagliflozin, Dapagliflozin, Ertugliflozin, Sotagliflozin) are newer hypoglycemic agents with many pleiotropic effects. In this review, we discuss their neuroprotective potential. SGLT2 inhibitors (SGLT2i) are lipid-soluble and reach the brain/serum ratio from 0.3 to 0.5. SGLT receptors are present in the central nervous system (CNS). Flozins are not fully SGLT2-selective and have an affinity for the SGLT1 receptor, which is associated with protection against ischemia/reperfusion brain damage. SGLT2i show an anti-inflammatory and anti-atherosclerotic effect, including reduction of proinflammatory cytokines, M2 macrophage polarization, JAK2/STAT1 and NLRP3 inflammasome inhibition, as well as cIMT regression. They also mitigate oxidative stress. SGLT2i improve endothelial function, prevent remodeling and exert a protective effect on the neurovascular unit, blood-brain barrier, pericytes, astrocytes, microglia, and oligodendrocytes. Flozins are also able to inhibit AChE, which contributes to cognitive improvement. Empagliflozin significantly increases the level of cerebral BDNF, which modulates neurotransmission and ensures growth, survival, and plasticity of neurons. Moreover, they may be able to restore the circadian rhythm of mTOR activation, which is quite a novel finding in the field of research on metabolic diseases and cognitive impairment. SGLT2i have a great potential to protect against atherosclerosis and cognitive impairment in patients with type 2 diabetes mellitus.