Role of Insulin Resistance in the Alzheimer's Disease Progression

An acute bout of resistance exercise increases BDNF in hippocampus and restores the long-term memory of insulin-resistant rats

A sedentary lifestyle, inadequate diet, and obesity are substantial risk factors for Type 2 diabetes mellitus (T2DM) development. A major picture of T2DM is insulin resistance (IR), which causes many impairments in brain physiology, such as increased proinflammatory state and decreased brain-derived neurotrophic factor (BDNF) concentration, hence reducing cognitive function. Physical exercise is a non-pharmacological tool for managing T2DM/IR and its complications. Thus, this study investigated the effects of IR induction and the acute effects of resistance exercise (RE) on memory, neurotrophic, and inflammatory responses in the hippocampus and prefrontal cortex of insulin-resistant rats. IR was induced by a high-fat diet and fructose-rich beverage. Insulin-resistant rats performed acute resistance exercise (IR.RE; vertical ladder climb at 50-100% of the maximum load) or rest (IR.REST; 20 min). Cognitive parameters were assessed by novel object recognition (NOR) tasks, and biochemical analyses were performed to assess BDNF concentrations and inflammatory profile in the hippocampus and prefrontal cortex. Insulin-resistant rats had 20% worse long-term memory (LTM) (p < 0.01) and lower BDNF concentration in the hippocampus (-14.6%; p < 0.05) when compared to non-insulin-resistant rats (CON). An acute bout of RE restored LTM (-9.7% pre vs. post; p > 0.05) and increased BDNF concentration in the hippocampus (9.1%; p < 0.05) of insulin-resistant rats compared to REST. Thus, an acute bout of RE can attenuate the adverse effects of IR on memory and neurotrophic factors in rats, representing a therapeutic tool to alleviate the IR impact on the brain.

Glucoregulatory Properties of a Protein Hydrolysate from Atlantic Salmon (Salmo salar): Preliminary Characterization and Evaluation of DPP-IV Inhibition and Direct Glucose Uptake In Vitro

Metabolic disorders are increasingly prevalent conditions that manifest pathophysiologically along a continuum. Among reported metabolic risk factors, elevated fasting serum glucose (FSG) levels have shown the most substantial increase in risk exposure. Ultimately leading to insulin resistance (IR), this condition is associated with notable deteriorations in the prognostic outlook for major diseases, including neurodegenerative diseases, cancer risk, and mortality related to cardiovascular disease. Tackling metabolic dysfunction, with a focus on prevention, is a critically important aspect for human health. In this study, an investigation into the potential antidiabetic properties of a salmon protein hydrolysate (SPH) was conducted, focusing on its potential dipeptidyl peptidase-IV (DPP-IV) inhibition and direct glucose uptake in vitro. Characterization of the SPH utilized a bioassay-guided fractionation approach to identify potent glucoregulatory peptide fractions. Low-molecular-weight (MW) fractions prepared by membrane filtration (MWCO = 3 kDa) showed significant DPP-IV inhibition (IC50 = 1.01 ± 0.12 mg/mL) and glucose uptake in vitro (p ≤ 0.0001 at 1 mg/mL). Further fractionation of the lowest MW fractions (<3 kDa) derived from the permeate resulted in three peptide subfractions. The subfraction with the lowest molecular weight demonstrated the most significant glucose uptake activity (p ≤ 0.0001), maintaining its potency even at a dilution of 1:500 (p ≤ 0.01).

Comparative analysis of kinetic realizations of insulin signaling

Several studies have developed dynamical models to understand the underlying mechanisms of insulin signaling, a signaling cascade that leads to the translocation of glucose, the human body's main source of energy. Fortunately, reaction network analysis allows us to extract properties of dynamical systems without depending on their model parameter values. This study focuses on the comparison of insulin signaling in healthy state (INSMS or INSulin Metabolic Signaling) and in type 2 diabetes (INRES or INsulin RESistance) using reaction network analysis. The analysis uses network decomposition to identify the different subsystems involved in insulin signaling (e.g., insulin receptor binding and recycling, GLUT4 translocation, and ERK signaling pathway, among others). Furthermore, results show that INSMS and INRES are similar with respect to some network, structo-kinetic, and kinetic properties. Their differences, however, provide insights into what happens when insulin resistance occurs. First, the variation in the number of species involved in INSMS and INRES suggests that when irregularities occur in the insulin signaling pathway, other complexes (and, hence, other processes) get involved, characterizing insulin resistance. Second, the loss of concordance exhibited by INRES suggests less restrictive interplay between the species involved in insulin signaling, leading to unusual activities in the signaling cascade. Lastly, GLUT4 losing its absolute concentration robustness in INRES may signify that the transporter has lost its reliability in shuttling glucose to the cell, inhibiting efficient cellular energy production. This study also suggests possible applications of the equilibria parametrization and network decomposition, resulting from the analysis, to potentially establish absolute concentration robustness in a species.

Nanotechnology-based Drug Delivery for Alzheimer's and Parkinson's Diseases

The delivery of drugs to the brain is quite challenging in the treatment of the central nervous system (CNS) diseases due to the blood-brain barrier and the blood-cerebrospinal fluid barrier. However, significant developments in nanomaterials employed by nanoparticle drug-delivery systems have substantial potential to cross or bypass these barriers leading to enhanced therapeutic efficacies. Advances in nanoplatform, nanosystems based on lipids, polymers and inorganic materials have been extensively studied and applied in treating Alzheimer's and Parkinson's diseases. In this review, various types of brain drug delivery nanocarriers are classified, summarized, and their potential as drug delivery systems in Alzheimer's and Parkinson's diseases is discussed. Finally, challenges facing the clinical translation of nanoparticles from bench to bedside are highlighted.

Assess Alzheimer's Disease via Plasma Extracellular Vesicle-derived mRNA

Alzheimer's disease (AD), the most prevalent neurodegenerative disorder globally, has emerged as a significant health concern, particularly due to the increasing aging population. Recently, it has been revealed that extracellular vesicles (EVs) originating from neurons play a critical role in AD pathogenesis and progression. These neuronal EVs can cross the blood-brain barrier and enter peripheral circulation, offering a less invasive means for assessing blood-based AD biomarkers. In this study, we analyzed plasma EV-derived messenger RNA (mRNA) from 82 subjects, including individuals with AD, mild cognitive impairment (MCI), and healthy controls, using next-generation sequencing (NGS) to profile their gene expression for functional enrichment and pathway analysis. Based on the differentially expressed genes identified in both MCI and AD groups, we established a diagnostic model by implementing a machine learning classifier. The refined model demonstrated an average diagnostic accuracy over 98% and showed a strong correlation with different AD stages, suggesting the potential of plasma EV-derived mRNA as a promising non-invasive biomarker for early detection and ongoing monitoring of AD.

The Potential Role of Gossypetin in the Treatment of Diabetes Mellitus and Its Associated Complications: A Review

Type 2 diabetes mellitus (T2DM) is a metabolic disorder caused by insulin resistance and dysfunctional beta (β)-cells in the pancreas. Hyperglycaemia is a characteristic of uncontrolled diabetes which eventually leads to fatal organ system damage. In T2DM, free radicals are continuously produced, causing extensive tissue damage and subsequent macro-and microvascular complications. The standard approach to managing T2DM is pharmacological treatment with anti-diabetic medications. However, patients' adherence to treatment is frequently decreased by the side effects and expense of medications, which has a detrimental impact on their health outcomes. Quercetin, a flavonoid, is a one of the most potent anti-oxidants which ameliorates T2DM. Thus, there is an increased demand to investigate quercetin and its derivatives, as it is hypothesised that similar structured compounds may exhibit similar biological activity. Gossypetin is a hexahydroxylated flavonoid found in the calyx of Hibiscus sabdariffa. Gossypetin has a similar chemical structure to quercetin with an extra hydroxyl group. Furthermore, previous literature has elucidated that gossypetin exhibits neuroprotective, hepatoprotective, reproprotective and nephroprotective properties. The mechanisms underlying gossypetin's therapeutic potential have been linked to its anti-oxidant, anti-inflammatory and immunomodulatory properties. Hence, this review highlights the potential role of gossypetin in the treatment of diabetes and its associated complications.

Therapeutic potential of flavonoids in the management of obesity-induced Alzheimer's disease: an overview of preclinical and clinical studies

Obesity is a global epidemic that affects people of all ages, genders, and backgrounds. It can lead to a plethora of disorders, including diabetes mellitus, renal dysfunction, musculoskeletal problems, metabolic syndrome, cardiovascular, and neurodegenerative abnormalities. Obesity has also been linked to neurological diseases such as cognitive decline, dementia, and Alzheimer's disease (AD), caused by oxidative stress, pro-inflammatory cytokines, and the production of reactive oxygen free radicals (ROS). Secretion of insulin hormone is impaired in obese people, leading to hyperglycaemia and increased accumulation of amyloid-β in the brain. Acetylcholine, a key neurotransmitter necessary for forming new neuronal connections in the brain, decreases in AD patients. To alleviate acetylcholine deficiency, researchers have proposed dietary interventions and adjuvant therapies that enhance the production of acetylcholine and assist in the management of AD patients. Such measures include dietary intervention with antioxidant and anti-inflammatory flavonoid-rich diets, which have been found to bind to tau receptors, reduce gliosis, and reduce neuroinflammatory markers in animal models. Furthermore, flavonoids like curcumin, resveratrol, epigallocatechin-3-gallate, morin, delphinidins, quercetin, luteolin, and oleocanthal have shown to cause significant reductions in interleukin-1β, increase BDNF levels, stimulate hippocampal neurogenesis and synapse formation, and ultimately prevent the loss of neurons in the brain. Thus, flavonoid-rich nutraceuticals can be a potential cost-effective therapeutic option for treating obesity-induced AD, but further well-designed, randomized, and placebo-controlled clinical studies are needed to assess their optimal dosages, efficacy, and long-term safety of flavonoids in humans. The main objectives of this review are to underscore the therapeutic potential of different nutraceuticals containing flavonoids that can be added in the daily diet of AD patients to enhance acetylcholine and reduce neuronal inflammation in the brain.

Recent Advancements in Nanomaterials: A Promising Way to Manage Neurodegenerative Disorders

Neurodegenerative diseases (NDs) such as dementia, Alzheimer's disease, Parkinson's disease, frontotemporal dementia, and amyotrophic lateral sclerosis are some of the most prevalent disorders currently afflicting healthcare systems. Many of these diseases share similar pathological hallmarks, including elevated oxidative stress, mitochondrial dysfunction, protein misfolding, excitotoxicity, and neuroinflammation, all of which contribute to the deterioration of the nervous system's structure and function. The development of diagnostic and therapeutic materials in the monitoring and treatment of these diseases remains challenging. One of the biggest challenges facing therapeutic and diagnostic materials is the blood-brain barrier (BBB). The BBB is a multifunctional membrane possessing a plethora of biochemical, cellular, and immunological features that ensure brain homeostasis by preventing the entry and accumulation of unwanted compounds. With regards to neurodegenerative diseases, the recent application of tailored nanomaterials (nanocarriers and nanoparticles) has led to advances in diagnostics and therapeutics. In this review, we provide an overview of commonly used nanoparticles and their applications in NDs, which may offer new therapeutic strategies for the prevention and treatment of neurodegenerative diseases.

Visit-to-visit HbA1c variability, dementia, and hippocampal atrophy among adults without diabetes

OBJECTIVES

Adults without diabetes are not completely healthy; they are probably heterogeneous with several potential health problems. The management of hemoglobin A1c (HbA1c) is crucial among patients with diabetes; but whether similar management strategy is needed for adults without diabetes is unclear. Thus, this study aimed to investigate the associations of visit-to-visit HbA1c variability with incident dementia and hippocampal volume among middle-aged and older adults without diabetes, providing potential insights into this question.

METHODS

We conducted a prospective analysis for incident dementia in 10,792 participants (mean age 58.9 years, 47.8 % men) from the UK Biobank. A subgroup of 3793 participants (mean age 57.8 years, 48.6 % men) was included in the analysis for hippocampal volume. We defined HbA1c variability as the difference in HbA1c divided by the mean HbA1c over the 2 sequential visits ([latter - former]/mean). Dementia was identified using hospital inpatient records with ICD-9 codes. T1-structural brain magnetic resonance imaging was conducted to derive hippocampal volume (normalized for head size). The nonlinear and linear associations were examined using restricted cubic spline (RCS) models, Cox regression models, and multiple linear regression models.

RESULTS

During a mean follow-up (since the second round) of 8.4 years, 90 (0.8 %) participants developed dementia. The RCS models suggested no significant nonlinear associations of HbA1c variability with incident dementia and hippocampal volume, respectively (All P > 0.05). Above an optimal cutoff of HbA1c variability at 0.08, high HbA1c variability (increment in HbA1c) was associated with an increased risk of dementia (Hazard Ratio, 1.88; 95 % Confidence Interval, 1.13 to 3.14, P = 0.015), and lower hippocampal volume (coefficient, -96.84 mm3, P = 0.037), respectively, in models with adjustment of covariates including age, sex, etc. Similar results were found for a different cut-off of 0. A series of sensitivity analyses verified the robustness of the findings.

CONCLUSIONS

Among middle-aged and older adults without diabetes, increasing visit-to-visit HbA1c variability was associated with an increased dementia risk and lower hippocampal volume. The findings highlight the importance of monitoring and controlling HbA1c fluctuation in apparently healthy adults without diabetes.

Alzheimer's disease: a mini-review for the clinician

Alzheimer's disease (AD), the most common form of dementia, is a striking example of the connection between neurophysiological abnormalities and higher-order cognitive deficiencies. Since its initial description in 1906, research into the pathophysiology and etiology of AD has led to the illumination of an incredibly complex set of genetic and molecular mechanisms for the disease's progression, characterized by much more than the neuropathological hallmarks of beta-amyloid (Aβ) plaques and neurofibrillary tangles (NFTs). In this review, findings relating the neurodegeneration present in AD to its clinical presentation and treatment are summarized, with an emphasis on the interconnectedness of disease pathophysiology. Further, diagnostic guidelines are provided based on the National Institute on Aging-Alzheimer's Association (NIA-AA) workgroup's clinical recommendations. Through the dissemination of detailed but digestible open access resources such as this one, we can move towards an increase in the equity and accessibility of education for the modern clinician.

Selenoprotein P concentrations and risk of progression from mild cognitive impairment to dementia

There is a growing literature investigating the effects of selenium on the central nervous system and cognitive function. However, little is known about the role of selenoprotein P, the main selenium transporter, which can also have adverse biological effects. We conducted a prospective cohort study of individuals aged 42-81 years who received a clinical diagnosis of mild cognitive impairment. Using sandwich ELISA methods, we measured full-length selenoprotein P concentrations in serum and cerebrospinal fluid to assess the relation with dementia incidence during a median follow-up of 47.3 months. We used Cox proportional hazards regression and restricted cubic splines to model such relation. Of the 54 participants, 35 developed dementia during follow-up (including 26 cases of Alzheimer's dementia). Selenoprotein P concentrations in serum and cerebrospinal fluid were highly correlated, and in spline regression analyses they each showed a positive non-linear association with dementia risk, particularly after excluding dementia cases diagnosed within 24 months of follow-up. We also observed differences in association according to the dementia subtypes considered. Risk ratios of dementia peaked at 2-6 at the highest levels of selenoprotein P, when compared to its median level, also depending on matrix, analytical methodology and dementia subtype. Findings of this study, the first to assess selenoprotein P levels in the central nervous system in vivo and the first to use a prospective study design to evaluate associations with dementia, suggest that higher circulating concentrations of selenoprotein P, both in serum and cerebrospinal fluid, predict progression of MCI to dementia. However, further confirmation of these findings is required, given the limited statistical precision of the associations and the potential for residual confounding.

Diabetic Retinopathy and Dementia Association, Beyond Diabetes Severity

PURPOSE

To investigate whether associations between diabetic retinopathy (DR) and dementia and Alzheimer's disease (AD) remain significant after controlling for several measures of diabetes severity.

DESIGN

Retrospective cohort study.

METHODS

Adult Changes in Thought (ACT) is a prospective cohort study of adults aged ≥65 years, randomly selected and recruited from the membership rolls of Kaiser Permanente Washington, who are dementia free at enrollment and followed biennially until incident dementia. The ACT participants were included in this study if they had type 2 diabetes mellitus at enrollment or developed it during follow-up, and data were collected through September, 2018 (3516 person-years of follow-up). Diabetes was defined by ≥ 2 diabetes medication fills in 1 year. Diagnosis of DR was based on International Classification of Diseases Ninth and Tenth Revision codes. Estimates of microalbuminuria, long-term glycemia, and renal function from longitudinal laboratory records were used as indicators of diabetes severity. Alzheimer's disease and dementia were diagnosed using research criteria at expert consensus meetings.

RESULTS

A total of 536 participants (median baseline age 75 [interquartile range 71-80], 54% women) met inclusion criteria. Significant associations between DR >5 years duration with dementia (hazard ratio 1.81 [95% CI 1.23, 2.65]) and AD (1.80 [1.15, 2.82]) were not altered by adjustment for estimates of microalbuminuria, long-term glycemia, and renal function (dementia: 1.69 [1.14, 2.50]; AD: 1.73 [1.10, 2.74]).

CONCLUSIONS

Among people with type 2 diabetes, DR itself appears to be an important biomarker of dementia risk in addition to glycemia and renal complications.

Alzheimer's Disease and Impaired Bone Microarchitecture, Regeneration and Potential Genetic Links

Alzheimer's Disease (AD) and osteoporosis are both age-related degenerative diseases. Many studies indicate that these two diseases share common pathogenesis mechanisms. In this review, the osteoporotic phenotype of AD mouse models was discussed, and shared mechanisms such as hormonal imbalance, genetic factors, similar signaling pathways and impaired neurotransmitters were identified. Moreover, the review provides recent data associated with these two diseases. Furthermore, potential therapeutic approaches targeting both diseases were discussed. Thus, we proposed that preventing bone loss should be one of the most important treatment goals in patients with AD; treatment targeting brain disorders is also beneficial for osteoporosis.

Mechanistic Insights, Treatment Paradigms, and Clinical Progress in Neurological Disorders: Current and Future Prospects

Neurodegenerative diseases (NDs) are a major cause of disability and are related to brain development. The neurological signs of brain lesions can vary from mild clinical shortfalls to more delicate and severe neurological/behavioral symptoms and learning disabilities, which are progressive. In this paper, we have tried to summarize a collective view of various NDs and their possible therapeutic outcomes. These diseases often occur as a consequence of the misfolding of proteins post-translation, as well as the dysfunctional trafficking of proteins. In the treatment of neurological disorders, a challenging hurdle to cross regarding drug delivery is the blood-brain barrier (BBB). The BBB plays a unique role in maintaining the homeostasis of the central nervous system (CNS) by exchanging components between the circulations and shielding the brain from neurotoxic pathogens and detrimental compounds. Here, we outline the current knowledge about BBB deterioration in the evolving brain, its origin, and therapeutic interventions. Additionally, we summarize the physiological scenarios of the BBB and its role in various cerebrovascular diseases. Overall, this information provides a detailed account of BBB functioning and the development of relevant treatments for neurological disorders. This paper will definitely help readers working in the field of neurological scientific communities.

Diet's Role in Modifying Risk of Alzheimer's Disease: History and Present Understanding

Diet is an important nonpharmacological risk-modifying factor for Alzheimer's disease (AD). The approaches used here to assess diet's role in the risk of AD include multi-country ecological studies, prospective and cross-sectional observational studies, and laboratory studies. Ecological studies have identified fat, meat, and obesity from high-energy diets as important risk factors for AD and reported that AD rates peak about 15-20 years after national dietary changes. Observational studies have compared the Western dietary pattern with those of the Dietary Approaches to Stop Hypertension (DASH), Mediterranean (MedDi), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets. Those studies identified AD risk factors including higher consumption of saturated and total fats, meat, and ultraprocessed foods and a lower risk of AD with higher consumption of fruits, legumes, nuts, omega-3 fatty acids, vegetables, and whole grains. Diet-induced factors associated with a significant risk of AD include inflammation, insulin resistance, oxidative stress, elevated homocysteine, dietary advanced glycation end products, and trimethylamine N-oxide. The molecular mechanisms by which dietary bioactive components and specific foods affect risk of AD are discussed. Given most countries' entrenched food supply systems, the upward trends of AD rates would be hard to reverse. However, for people willing and able, a low-animal product diet with plenty of anti-inflammatory, low-glycemic load foods may be helpful.

Nanomedicine-based immunotherapy for Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease caused by the deposition of amyloid β (Aβ) fibrils forming extracellular plaques and the development of neurofibrillary tangles (NFT) of intracellular hyperphosphorylated tau protein. Currently, the AD treatments focus on improving cognitive and behavioral symptoms and have limited success. It is imperative to develop novel treatment approaches that can control/inhibit AD progression, especially in the elderly population. Immunotherapy provides a promising and safe treatment option for AD by boosting the patient's immune system. The minimum immune surveillance in the immune-privileged brain, however, makes immunotherapy for AD a challenging endeavor. Therefore, the success of AD immunotherapy depends mainly on the strategy by which therapeutics is delivered to the brain rather than its efficacy. The blood-brain barrier (BBB) is a major obstacle to therapeutic delivery into the brain microenvironment. Various nano-formulations have been exploited to improve the efficacy of AD immunotherapy. In this review, the applications of different types of nano-formulations in augmenting AD immunotherapy have been discussed.

The Interrelated Multifactorial Actions of Cortisol and Klotho: Potential Implications in the Pathogenesis of Parkinson's Disease

The pathogenesis of Parkinson's disease (PD) is complex, multilayered, and not fully understood, resulting in a lack of effective disease-modifying treatments for this prevalent neurodegenerative condition. Symptoms of PD are heterogenous, including motor impairment as well as non-motor symptoms such as depression, cognitive impairment, and circadian disruption. Aging and stress are important risk factors for PD, leading us to explore pathways that may either accelerate or protect against cellular aging and the detrimental effects of stress. Cortisol is a much-studied hormone that can disrupt mitochondrial function and increase oxidative stress and neuroinflammation, which are recognized as key underlying disease mechanisms in PD. The more recently discovered klotho protein, considered a general aging-suppressor, has a similarly wide range of actions but in the opposite direction to cortisol: promoting mitochondrial function while reducing oxidative stress and inflammation. Both hormones also converge on pathways of vitamin D metabolism and insulin resistance, also implicated to play a role in PD. Interestingly, aging, stress and PD associate with an increase in cortisol and decrease in klotho, while physical exercise and certain genetic variations lead to a decrease in cortisol response and increased klotho. Here, we review the interrelated opposite actions of cortisol and klotho in the pathogenesis of PD. Together they impact powerful and divergent mechanisms that may go on to influence PD-related symptoms. Better understanding of these hormones in PD would facilitate the design of effective interventions that can simultaneously impact the multiple systems involved in the pathogenesis of PD.

Brain insulin resistance and cognitive function: influence of exercise

Exercise has systemic health benefits in people, in part, through improving whole body insulin sensitivity. The brain is an insulin-sensitive organ that is often underdiscussed relative to skeletal muscle, liver, and adipose tissue. Although brain insulin action may have only subtle impacts on peripheral regulation of systemic glucose homeostasis, it is important for weight regulation as well as mental health. In fact, brain insulin signaling is also involved in processes that support healthy cognition. Furthermore, brain insulin resistance has been associated with age-related declines in memory and executive function as well as Alzheimer's disease pathology. Herein, we provide an overview of brain insulin sensitivity in relation to cognitive function from animal and human studies, with particular emphasis placed on the impact exercise may have on brain insulin sensitivity. Mechanisms discussed include mitochondrial function, brain growth factors, and neurogenesis, which collectively help combat obesity-related metabolic disease and Alzheimer's dementia.

Altered glucose metabolism in Alzheimer's disease: Role of mitochondrial dysfunction and oxidative stress

Increasing evidence suggests that abnormal cerebral glucose metabolism is largely present in Alzheimer's disease (AD). The brain utilizes glucose as its main energy source and a decline in its metabolism directly reflects on brain function. Weighing on recent evidence, here we systematically assessed the aberrant glucose metabolism associated with amyloid beta and phosphorylated tau accumulation in AD brain. Interlink between insulin signaling and AD highlighted the involvement of the IRS/PI3K/Akt/AMPK signaling, and GLUTs in the disease progression. While shedding light on the mitochondrial dysfunction in the defective glucose metabolism, we further assessed functional consequences of AGEs (advanced glycation end products) accumulation, polyol activation, and other contributing factors including terminal respiration, ROS (reactive oxygen species), mitochondrial permeability, PINK1/parkin defects, lysosome-mitochondrial crosstalk, and autophagy/mitophagy. Combined with the classic plaque and tangle pathologies, glucose hypometabolism with acquired insulin resistance and mitochondrial dysfunction potentiate these factors to exacerbate AD pathology. To this end, we further reviewed AD and DM (diabetes mellitus) crosstalk in disease progression. Taken together, the present work discusses the emerging role of altered glucose metabolism, contributing impact of insulin signaling, and mitochondrial dysfunction in the defective cerebral glucose utilization in AD.

Intranasal Peptide Therapeutics: A Promising Avenue for Overcoming the Challenges of Traditional CNS Drug Development

The central nervous system (CNS) has, among all organ systems in the human body, the highest failure rate of traditional small-molecule drug development, ranging from 80-100% depending on the area of disease research. This has led to widespread abandonment by the pharmaceutical industry of research and development for CNS disorders, despite increased diagnoses of neurodegenerative disorders and the continued lack of adequate treatment options for brain injuries, stroke, neurodevelopmental disorders, and neuropsychiatric illness. However, new approaches, concurrent with the development of sophisticated bioinformatic and genomic tools, are being used to explore peptide-based therapeutics to manipulate endogenous pathways and targets, including "undruggable" intracellular protein-protein interactions (PPIs). The development of peptide-based therapeutics was previously rejected due to systemic off-target effects and poor bioavailability arising from traditional oral and systemic delivery methods. However, targeted nose-to-brain, or intranasal (IN), approaches have begun to emerge that allow CNS-specific delivery of therapeutics via the trigeminal and olfactory nerve pathways, laying the foundation for improved alternatives to systemic drug delivery. Here we review a dozen promising IN peptide therapeutics in preclinical and clinical development for neurodegenerative (Alzheimer's, Parkinson's), neuropsychiatric (depression, PTSD, schizophrenia), and neurodevelopmental disorders (autism), with insulin, NAP (davunetide), IGF-1, PACAP, NPY, oxytocin, and GLP-1 agonists prominent among them.

The relationship between Alzheimer's disease and intestinal microflora structure and inflammatory factors

To analyze the structural characteristics of intestinal microflora and changes of serum inflammatory factors of the Alzheimer's disease, and to explore the relationship between them and dementia, we selected 30 patients in the AD group and 30 patients in the normal group, and collected stool samples to analyze the intestinal flora structure characteristics of the two groups of patients, and statistically analyzed the inflammatory cytokines TNF-α, IL-1β, IL-6, and IL-8 by ELISA from the venous blood of the two groups. The results show that the dominant Bacteroides in the two groups are Bacteroides, Firmicutes, Proteobacteria, and Actinobacteria. The abundance of Bacteroides, Firmicutes, and Proteobacteria in the AD group shows a statistical difference. At the genus level, the abundance of anti-inflammatory bacteria such as Lactobacillus, Bifidobacterium, and Ruminococcus drops in AD group, while the abundance of pro-inflammatory bacteria such as Escherichia and Enterococcus raises. Statistical analysis of inflammatory cytokines in the two groups suggests that TNF-α and IL-6 levels significantly increase in the AD group, with statistical differences. Therefore, it is speculated that the increased abundance of pro-inflammatory bacteria in intestinal flora may lead to or aggravate neuroinflammation through the release of inflammatory factors, thus further leading to the occurrence and development of AD.

Potential mechanism of the Shunaoxin pill for preventing cognitive impairment in type 2 diabetes mellitus

Objective

This study aims to analyze the efficacy and mechanism of action of the Shunaoxin pill in preventing cognitive impairment in diabetic patients using network pharmacology.

Methods

The main active compounds of the Shunaoxin pills and their action targets were identified via the TCMSP and Batman-TCM databases. The GEO database was used to identify the genes in type 2 diabetic individuals associated with cognitive impairment. Subsequently, a common target protein-protein interaction (PPI) network was constructed using the STRING database, and targets associated with diabetes and cognitive impairment were screened by performing a topological analysis of the PPI network. The AutoDock Vina software was used for molecular docking to evaluate the reliability of the bioinformatic analysis predictions and validate the interactions between the active ingredients of the Shunaoxin pill and proteins associated with diabetes and cognitive impairment.

Results

Based on the TCMSP and Batman-Tcm platform, 48 active ingredients of the Shunaoxin pill were identified, corresponding to 222 potential action targets. Further analysis revealed that 18 active components of the Shunaoxin pill might contribute to cognitive impairment in type 2 diabetic patients. Molecular docking simulations demonstrated that the active ingredients of the Shunaoxin pill (hexadecanoic acid, stigmasterol, beta-sitosterol, and angelicin) targeted four core proteins: OPRK1, GABRA5, GABRP, and SCN3B.

Conclusion

Active ingredients of the Shunaoxin pill may alleviate cognitive impairment in diabetic patients by targeting the proteins OPRK1, GABRA5, GABRP, and SCN3B.

Trends in insulin resistance: insights into mechanisms and therapeutic strategy

The centenary of insulin discovery represents an important opportunity to transform diabetes from a fatal diagnosis into a medically manageable chronic condition. Insulin is a key peptide hormone and mediates the systemic glucose metabolism in different tissues. Insulin resistance (IR) is a disordered biological response for insulin stimulation through the disruption of different molecular pathways in target tissues. Acquired conditions and genetic factors have been implicated in IR. Recent genetic and biochemical studies suggest that the dysregulated metabolic mediators released by adipose tissue including adipokines, cytokines, chemokines, excess lipids and toxic lipid metabolites promote IR in other tissues. IR is associated with several groups of abnormal syndromes that include obesity, diabetes, metabolic dysfunction-associated fatty liver disease (MAFLD), cardiovascular disease, polycystic ovary syndrome (PCOS), and other abnormalities. Although no medication is specifically approved to treat IR, we summarized the lifestyle changes and pharmacological medications that have been used as efficient intervention to improve insulin sensitivity. Ultimately, the systematic discussion of complex mechanism will help to identify potential new targets and treat the closely associated metabolic syndrome of IR.

Pathophysiological mechanisms explaining the association between low skeletal muscle mass and cognitive function

Low skeletal muscle mass is associated with cognitive impairment and dementia in older adults. This review describes the possible underlying pathophysiological mechanisms: systemic inflammation, insulin metabolism, protein metabolism, and mitochondrial function. We hypothesize that the central tenet in this pathophysiology is the dysfunctional myokine secretion consequent to minimal physical activity. Myokines, such as fibronectin type III domain containing 5/irisin and cathepsin B, are released by physically active muscle and cross the blood–brain barrier. These myokines upregulate local neurotrophin expression such as brain-derived neurotrophic factor (BDNF) in the brain microenvironment. BDNF exerts anti-inflammatory effects that may be responsible for neuroprotection. Altered myokine secretion due to physical inactivity exacerbates inflammation and impairs muscle glucose metabolism, potentially affecting the transport of insulin across the blood–brain barrier. Our working model also suggests other underlying mechanisms. A negative systemic protein balance, commonly observed in older adults, contributes to low skeletal muscle mass and may also reflect deficient protein metabolism in brain tissues. As a result of age-related loss in skeletal muscle mass, decrease in the abundance of mitochondria and detriments in their function lead to a decrease in tissue oxidative capacity. Dysfunctional mitochondria in skeletal muscle and brain result in the excessive production of reactive oxygen species, which drives tissue oxidative stress and further perpetuates the dysfunction in mitochondria. Both oxidative stress and accumulation of mitochondrial DNA mutations due to aging drive cellular senescence. A targeted approach in the pathophysiology of low muscle mass and cognition could be to restore myokine balance by physical activity.

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.

MicroRNA modulation is a potential molecular mechanism for neuroprotective effects of intranasal insulin administration in amyloid βeta oligomer induced Alzheimer's like rat model

Substantial evidence indicates that imbalance in the expression of miR-132-3p, miR-181b-5p, miR-125b-5p, miR-26a-5p, miR-124-3p, miR-146a-5p, miR-29a-3p, and miR-30a-5p in the AD brain are associated with amyloid-beta (Aβ) aggregation, tau pathology, neuroinflammation, and synaptic dysfunction, the major pathological hallmarks of Alzheimer's disease)AD(. Several studies have reported that intranasal insulin administration ameliorates memory in AD patients and animal models. However, the underlying molecular mechanisms are not yet completely elucidated. Therefore, the aim of this study was to determine whether insulin is involved in regulating the expression of AD-related microRNAs. Pursuing this objective, we first investigated the therapeutic effect of intranasal insulin on Aβ oligomer (AβO)-induced memory impairment in male rats using the Morris water maze task. Then, molecular and histological changes in response to AβO and/or insulin time course were assessed in the extracted hippocampi on days 1, 14, and 21 of the study using congo red staining, western blot and quantitative real-time PCR analyses. We observed memory impairment, Aβ aggregation, tau hyper-phosphorylation, neuroinflammation, insulin signaling dys-regulation, and down-regulation of miR-26a, miR-124, miR-29a, miR-181b, miR-125b, miR-132, and miR-146a in the hippocampus of AβO-exposed rats 21 days after AβO injection. Intranasal insulin treatment ameliorated memory impairment and concomitantly increased miR-132, miR-181b, and miR-125b expression, attenuated tau phosphorylation levels, Aβ aggregation, and neuroinflammation, and regulated the insulin signaling as well. In conclusion, our study suggest that the neuroprotective effects of insulin on memory observed in AD-like rats could be partially due to the restoration of miR-132, miR-181b, and miR-125b expression in the brain.

The neuroprotective effects of intermittent fasting on brain aging and neurodegenerative diseases via regulating mitochondrial function

Intermittent fasting (IF) has been studied for its effects on lifespan and the prevention or delay of age-related diseases upon the regulation of metabolic pathways. Mitochondria participate in key metabolic pathways and play important roles in maintaining intracellular signaling networks that modulate various cellular functions. Mitochondrial dysfunction has been described as an early feature of brain aging and neurodegeneration. Although IF has been shown to prevent brain aging and neurodegeneration, the mechanism is still unclear. This review focuses on the mechanisms by which IF improves mitochondrial function, which plays a central role in brain aging and neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease. The cellular and molecular mechanisms of IF in brain aging and neurodegeneration involve activation of adaptive cellular stress responses and signaling- and transcriptional pathways, thereby enhancing mitochondrial function, by promoting energy metabolism and reducing oxidant production.

Comprehensive Review on Neuro-degenerative Type 3 DM

According to research, Alzheimer's disease (AD) is considered a metabolic illness caused by defective insulin signaling, insulin resistance, and low insulin levels in the brain. Type 3 diabetes has been postulated for AD because reduced insulin signaling has molecular and physiological consequences that are comparable to type I and type 2 diabetes mellitus, respectively. The similarities between type 2 diabetes and Alzheimer's disease suggest that these clinical trials might yield therapeutic benefits. However, it is important to note that lowering your risk of Alzheimer's dementia, whether you have diabetes or not, is still a multidimensional process involving factors like exercise, smoking, alcohol, food, and mental challenges. The current aim is to show that the relationship between T3D and AD is based on both the processing of amyloid-β (Aβ) precursor protein toxicity and the clearance of Aβ, which are the results of impaired insulin signaling. The brain's metabolism, with its high lipid content and energy needs, places excess demands on mitochondria and appears more susceptible to oxidative damage than the rest of the body. Current data suggests that increased oxidative stress relates to amyloid-β (Aβ) pathology and the onset of AD.

2-Dodecyl-6-Methoxycyclohexa-2,5-Diene-1,4-Dione Ameliorates Diabetic Cognitive Impairment Through Inhibiting Hif3α and Apoptosis

Diabetes mellitus (DM) is an independent risk factor for cognitive impairment. Although the etiology of diabetic cognitive impairment is complex and multifactorial, the hippocampus neuronal apoptosis is recognized as a main cause of diabetes-induced cognitive impairment. 2-Dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD) was purified from the roots of Averrhoa carambola L. Previous research demonstrated that DMDD was safe and effective in delaying some diabetic complications. However, the efficacy of DMDD to ameliorate diabetic cognitive impairment in type 2 diabetes mice has not been reported. In the present study, the behavioral evaluation was performed by Y maze and novel object recognition in db/db mice. Gene expression profiles were detected using mouse lncRNA microarray analysis in the hippocampi of db/db mice. Changes in the neurodegeneration-associated proteins and the apoptosis-related proteins were determined in both db/db mice and high glucose-treated HT22 cells by Western blotting. We observed that DMDD treatment significantly ameliorated the spatial working memory and object recognition memory impairment in db/db mice. Further study showed that neurodegeneration-associated protein tau was decreased after DMDD treatment in the hippocampi of db/db mice. Eleven lncRNAs and four mRNAs including pro-apoptotic gene Hif3a were significantly differently expressed after DMDD treatment in the hippocampi of db/db mice. The expression of Hif3a, cleaved parp, and caspase 3 proteins was significantly increased in the hippocampi of diabetic db/db mice compared with db/m control mice and then decreased after DMDD treatment. Similar beneficial effects of DMDD were observed in HG-treated HT22 cells. These data indicate that DMDD can alleviate cognitive impairment by inhibiting neuronal apoptosis through decreasing the expression of pro-apoptotic protein Hif3a. In conclusion, our study suggests that DMDD has great potential to be a new preventive and therapeutic compound for diabetic cognitive impairment.

A Tale of Two Diseases: Exploring Mechanisms Linking Diabetes Mellitus with Alzheimer's Disease

Dementias, including the type associated with Alzheimer's disease (AD), are on the rise worldwide. Similarly, type 2 diabetes mellitus (T2DM) is one of the most prevalent chronic diseases globally. Although mechanisms and treatments are well-established for T2DM, there remains much to be discovered. Recent research efforts have further investigated factors involved in the etiology of AD. Previously perceived to be unrelated diseases, commonalities between T2DM and AD have more recently been observed. As a result, AD has been labeled as "type 3 diabetes". In this review, we detail the shared processes that contribute to these two diseases. Insulin resistance, the main component of the pathogenesis of T2DM, is also present in AD, causing impaired brain glucose metabolism, neurodegeneration, and cognitive impairment. Dysregulation of insulin receptors and components of the insulin signaling pathway, including protein kinase B, glycogen synthase kinase 3β, and mammalian target of rapamycin are reported in both diseases. T2DM and AD also show evidence of inflammation, oxidative stress, mitochondrial dysfunction, advanced glycation end products, and amyloid deposition. The impact that changes in neurovascular structure and genetics have on the development of these conditions is also being examined. With the discovery of factors contributing to AD, innovative treatment approaches are being explored. Investigators are evaluating the efficacy of various T2DM medications for possible use in AD, including but not limited to glucagon-like peptide-1 receptor agonists, and peroxisome proliferator-activated receptor-gamma agonists. Furthermore, there are 136 active trials involving 121 therapeutic agents targeting novel AD biomarkers. With these efforts, we are one step closer to alleviating the ravaging impact of AD on our communities.

Does Alzheimer's disease stem in the gastrointestinal system?

Over the last decades, our knowledge of the key pathogenic mechanisms of Alzheimer's disease (AD) has dramatically improved. Regarding the limitation of current therapeutic strategies for the treatment of multifactorial diseases, such as AD, to be translated into the clinic, there is a growing trend in research to identify risk factors associated with the onset and progression of AD. Here, we review the current literature with a focus on the relationship between gastrointestinal (GI)/liver diseases during the lifespan and the incidence of AD, and discuss the possible mechanisms underlying the link between the diseases. We also aim to review studies evaluating the possible link between the chronic use of the most common GI medications and the future risk of AD development.

Modulating effects of capsaicin on glucose homeostasis and the underlying mechanism

Abnormal glucose homeostasis is linked to a variety of metabolic syndromes, such as insulin resistance, obesity, type-2 diabetes mellitus, hypertension and cardiovascular diseases. Maintenance of normal glucose homeostasis is important for the body to keep normal biological functions. As the major bioactive ingredient in chili peppers responsible for the pungent flavor, capsaicin has been reported to effectively improve glucose homeostasis with low cytotoxicity. In this review, the modulating effects of capsaicin on glucose homeostasis in cell models, animal models and human trials are summarized through both TRPV1 dependent and TRPV1 independent pathways. The relevant molecular mechanisms underlying its regulatory effects are also evaluated. Understanding the effects and mechanisms of capsaicin on glucose metabolism could provide theoretical evidence for its application in the food and pharmaceutical industries.

Nanotechnology-based drug delivery for central nervous system disorders

Drug delivery to central nervous system (CNS) diseases is very challenging since the presence of the innate blood-brain barrier (BBB) and the blood-cerebrospinal fluid barrier that impede drug delivery. Among new strategies to overcome these limitations and successfully deliver drugs to the CNS, nanotechnology-based drug delivery platform, offers potential therapeutic approach for the treatment of some common neurological disorders like Alzheimer's disease, frontotemporal dementia, amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease. This review aimed to highlight advances in research on the development of nano-based therapeutics for their implications in therapy of CNS disorders. The challenges during clinical translation of nanomedicine from bench to bed side is also discussed.

Evaluation of Antidiabetic Properties of Adenosma Bracteosum Bonati Extracts in Mice with Streptozotocin-Induced Diabetes

Diabetes mellitus is a chronic metabolic disorder characterized by persistent hyperglycemia. Traditional medicinal plants with antidiabetic properties can be used as drugs or dietary adjuvants to existing therapies. This chapter presents the preparation of aqueous and ethanol extracts of Adenosma bracteosum Bonati (A. bracteosum) and evaluation of these for antioxidant and α-glucosidase inhibition activities in vitro. In addition, we tested the extracts and the purified A. bracteosum compound (isoscutellarein 8-O-β-D-glucopyranoside) for antihyperglycemic effects in glucose-loaded hyperglycemic and streptozotocin (STZ)-induced diabetic mice.

Genome-Scale Metabolic Modeling of the Human Microbiome in the Era of Personalized Medicine

The human microbiome plays an important role in human health and disease. Meta-omics analyses provide indispensable data for linking changes in microbiome composition and function to disease etiology. Yet, the lack of a mechanistic understanding of, e.g., microbiome-metabolome links hampers the translation of these findings into effective, novel therapeutics. Here, we propose metabolic modeling of microbial communities through constraint-based reconstruction and analysis (COBRA) as a complementary approach to meta-omics analyses. First, we highlight the importance of microbial metabolism in cardiometabolic diseases, inflammatory bowel disease, colorectal cancer, Alzheimer disease, and Parkinson disease. Next, we demonstrate that microbial community modeling can stratify patients and controls, mechanistically link microbes with fecal metabolites altered in disease, and identify host pathways affected by the microbiome. Finally, we outline our vision for COBRA modeling combined with meta-omics analyses and multivariate statistical analyses to inform and guide clinical trials, yield testable hypotheses, and ultimately propose novel dietary and therapeutic interventions. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Metabolic Syndrome: Is It Time to Add the Central Nervous System?

Metabolic syndrome (MS) is a set of cardio-metabolic risk factors that includes central obesity, hyperglycemia, hypertension, and dyslipidemias. The syndrome affects 25% of adults worldwide. The definition of MS has evolved over the last 80 years, with various classification systems and criteria, whose limitations and benefits are currently the subject of some controversy. Likewise, hypotheses regarding the etiology of MS add more confusion from clinical and epidemiological points of view. The leading suggestion for the pathophysiology of MS is insulin resistance (IR). IR can affect multiple tissues and organs, from the classic “triumvirate” (myocyte, adipocyte, and hepatocyte) to possible effects on organs considered more recently, such as the central nervous system (CNS). Mild cognitive impairment (MCI) and Alzheimer’s disease (AD) may be clinical expressions of CNS involvement. However, the association between MCI and MS is not understood. The bidirectional relationship that seems to exist between these factors raises the questions of which phenomenon occurs first and whether MCI can be a precursor of MS. This review explores shared pathophysiological mechanisms between MCI and MS and establishes a hypothesis of a possible MCI role in the development of IR and the appearance of MS.

Neuroinflammation in Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disease associated with human aging. Ten percent of individuals over 65 years have AD and its prevalence continues to rise with increasing age. There are currently no effective disease modifying treatments for AD, resulting in increasingly large socioeconomic and personal costs. Increasing age is associated with an increase in low-grade chronic inflammation (inflammaging) that may contribute to the neurodegenerative process in AD. Although the exact mechanisms remain unclear, aberrant elevation of reactive oxygen and nitrogen species (RONS) levels from several endogenous and exogenous processes in the brain may not only affect cell signaling, but also trigger cellular senescence, inflammation, and pyroptosis. Moreover, a compromised immune privilege of the brain that allows the infiltration of peripheral immune cells and infectious agents may play a role. Additionally, meta-inflammation as well as gut microbiota dysbiosis may drive the neuroinflammatory process. Considering that inflammatory/immune pathways are dysregulated in parallel with cognitive dysfunction in AD, elucidating the relationship between the central nervous system and the immune system may facilitate the development of a safe and effective therapy for AD. We discuss some current ideas on processes in inflammaging that appear to drive the neurodegenerative process in AD and summarize details on a few immunomodulatory strategies being developed to selectively target the detrimental aspects of neuroinflammation without affecting defense mechanisms against pathogens and tissue damage.

Inflammation and Insulin Resistance as Risk Factors and Potential Therapeutic Targets for Alzheimer's Disease

Overnutrition and modern diets containing high proportions of saturated fat are among the major factors contributing to a low-grade state of inflammation, hyperglycemia and dyslipidemia. In the last decades, the global rise of type 2 diabetes and obesity prevalence has elicited a great interest in understanding how changes in metabolic function lead to an increased risk for premature brain aging and the development of neurodegenerative disorders such as Alzheimer's disease (AD). Cognitive impairment and decreased neurogenic capacity could be a consequence of metabolic disturbances. In these scenarios, the interplay between inflammation and insulin resistance could represent a potential therapeutic target to prevent or ameliorate neurodegeneration and cognitive impairment. The present review aims to provide an update on the impact of metabolic stress pathways on AD with a focus on inflammation and insulin resistance as risk factors and therapeutic targets.

Role of protein tyrosine phosphatase 1B inhibitor in central insulin resistance and associated cognitive deficits

BACKGROUND

Protein tyrosine phosphatase 1B (PTP1B) inhibitors are potential candidates for the treatment of peripheral insulin resistance and diabetes mellitus. Similar to peripheral action within the brain also, PTP1B activation impairs insulin signaling pathways. Activation of PTP1B in brain also accentuates neuroinflammation, oxidative stress and decreases neurotrophic factors in various brain dysfunctions including cognitive decline.

OBJECTIVES

The main objective of our study was to elucidate the role of alendronate, a potent PTP1B inhibitor (blood brain barrier crossing bisphosphonate) in central insulin resistance and associated memory deficits.

METHODOLOGY

To induce central insulin resistance, streptozotocin (3 mg/kg) intracerebroventricular (ICV) was administered in two alternate days (1^st and 3^rd). After 21 days, memory was assessed via using the passive avoidance and Morris water maze paradigm. At the end of behavioral studies, animals were sacrificed to assess a variety of biochemical and molecular parameters in the hippocampus and cerebral cortex region of the brain. Treatment drug alendronate (3 mg/kg/day, p.o) and standard drug donepezil (3 mg/kg/i.p.) were administered from the 3^rd day of STZ administration till the end of the study. Inhibition of PTP1B activates phosphoinsotide-3 kinase (PI3 K) (down-stream regulator of insulin signaling pathway).Thus, to illuminate the mechanism of action of alendronate, PI3 K inhibitor, wortmannin was administered in presence of alendronate in one group.

RESULTS

Administration of alendronate to ICV streprozotocin treated rats resulted in modulation of the insulin signaling pathway and associated behavioral, biochemical and molecular changes in central insulin resistance. However, the protective effect of alendronate was entirely vanished when it was administered in the presence of wortmannin.

CONCLUSION

Alendronate can be an important treatment strategy in central insulin signaling pathway dysfunction and associated cognitive deficits. Protective effect of alendronate is via modulation of PI3-K/Akt signaling pathway.

Microglia and bradykinin cross talk in poststroke cognitive impairment in diabetes

Stroke is one of the leading causes of mortality and the leading cause of long-term disability worldwide. Although cognitive impairment is a common consequence of stroke, the underlying pathophysiological processes that lead to it are still poorly understood. Recently, more studies have shown evidence of the involvement of diabetes in producing a chronic neuroinflammatory state, which ultimately alters the recovery of function and cognition after stroke. To better understand the impact of diabetes on poststroke recovery, here we highlight the recent insights on the role of diabetes in neuroinflammation, especially regarding its effect on microglial function, and the emerging data on the involvement of kinins in both diabetes and neuroinflammation.

Therapeutic Strategies and Nano-Drug Delivery Applications in Management of Aging Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder in which the death of brain cells causes memory loss and cognitive decline. Existing drugs only suppress symptoms or delay further deterioration but do not address the cause of the disease. In spite of screening numerous drug candidates against various molecular targets of AD, only a few candidates, such as acetylcholinesterase inhibitors, are currently utilized as an effective clinical therapy. Currently, nano-based therapies can make a difference, providing new therapeutic options by helping drugs to cross the blood-brain barrier and enter the brain more effectively. The main aim of this review was to highlight advances in research on the development of nano-based therapeutics for improved treatment of AD.

Gut Microbiota and Dysbiosis in Alzheimer's Disease: Implications for Pathogenesis and Treatment

Understanding how gut flora influences gut-brain communications has been the subject of significant research over the past decade. The broadening of the term “microbiota-gut-brain axis” from “gut-brain axis” underscores a bidirectional communication system between the gut and the brain. The microbiota-gut-brain axis involves metabolic, endocrine, neural, and immune pathways which are crucial for the maintenance of brain homeostasis. Alterations in the composition of gut microbiota are associated with multiple neuropsychiatric disorders. Although a causal relationship between gut dysbiosis and neural dysfunction remains elusive, emerging evidence indicates that gut dysbiosis may promote amyloid-beta aggregation, neuroinflammation, oxidative stress, and insulin resistance in the pathogenesis of Alzheimer’s disease (AD). Illustration of the mechanisms underlying the regulation by gut microbiota may pave the way for developing novel therapeutic strategies for AD. In this narrative review, we provide an overview of gut microbiota and their dysregulation in the pathogenesis of AD. Novel insights into the modification of gut microbiota composition as a preventive or therapeutic approach for AD are highlighted.

Type 3 Diabetes and Its Role Implications in Alzheimer's Disease

The exact connection between Alzheimer’s disease (AD) and type 2 diabetes is still in debate. However, poorly controlled blood sugar may increase the risk of developing Alzheimer’s. This relationship is so strong that some have called Alzheimer’s “diabetes of the brain” or “type 3 diabetes (T3D)”. Given more recent studies continue to indicate evidence linking T3D with AD, this review aims to demonstrate the relationship between T3D and AD based on the fact that both the processing of amyloid-β (Aβ) precursor protein toxicity and the clearance of Aβ are attributed to impaired insulin signaling, and that insulin resistance mediates the dysregulation of bioenergetics and progress to AD. Furthermore, insulin-related therapeutic strategies are suggested to succeed in the development of therapies for AD by slowing down their progressive nature or even halting their future complications.