Diabetes mellitus and Alzheimer's disease: shared pathology and treatment?

Application potential of modulation of cyclooxygenase-2 activity: a cognitive approach

Cognitive functions of the brain depend largely on the condition of the cell membranes and the proportion of fatty acids. It is known and accepted that arachidonic acid (AA) is one of the main ω-6 fatty acids (phospholipids) in brain cells. Metabolism of that fatty acid depends on the functionality and presence of cyclooxygenase (COX). COX is a primary enzyme in the cycle of transformation of AA to prostanoids, which may mediate response of immune cells, contributing to brain function and cognition. Two COX isoforms (COX-1 and COX-2), as well as a splice variant (COX-3), have been detected in the brain. Findings released in the last decade showed that COX-2 may play an important role in cognition. There are many preclinical and clinical reports showing its engagement in Alzheimer disease, spatial learning, and plasticity. This manuscript focuses on summarizing the above-mentioned discoveries.

The interplay among oxidative stress, brain insulin resistance and AMPK dysfunction contribute to neurodegeneration in type 2 diabetes and Alzheimer disease

Alzheimer's disease (AD) is the most common form of dementia in the elderly followed by vascular dementia. In addition to clinically diagnosed dementia, cognitive dysfunction has been reported in diabetic patients. Recent studies are now beginning to recognize type 2 diabetes mellitus (T2DM), characterized by chronic hyperglycemia and insulin resistance, as a risk factor for AD and other cognitive disorders. While studies on insulin action have remained traditionally in the domain of peripheral tissues, the detrimental effects of insulin resistance in the central nervous system on cognitive dysfunction are increasingly being reported in recent clinical and preclinical studies. Brain functions require continuous supply of glucose and oxygen and a tight regulation of metabolic processes. Loss of this metabolic regulation has been proposed to be a contributor to memory dysfunction associated with neurodegeneration. Within the above scenario, this review will focus on the interplay among oxidative stress (OS), insulin resistance and AMPK dysfunctions in the brain by highlighting how these neurotoxic events contribute to neurodegeneration. We provide an overview on the detrimental effects of OS on proteins regulating insulin signaling and how these alterations impact cell metabolic dysfunctions through AMPK dysregulation. Such processes, we assert, are critically involved in the molecular pathways that underlie AD.

A Revisit to Etiopathogenesis and Therapeutic Strategies in Alzheimer's Disease

Dementia is a cluster of brain abnormalities that trigger progressive memory deficits and other cognitive abilities such as skills, language, or executive function. Alzheimer's disease (AD) is the foremost type of age-associated dementia that involves progressive neurodegeneration accompanied by profound cognitive deficits in advanced stages that severely hamper social or occupational abilities with or without the involvement of any other psychiatric condition. The last two decades witnessed a sharp increase (~123%) in mortality due to AD type dementia, typically owing to a very low disclosure rate (~45%) and hence, the prophylactic, as well as the therapeutic cure of AD, has been a huge challenge. Although understanding of AD pathogenesis has witnessed a remarkable growth (e.g., tauopathy, oxidative stress, lipid transport, glucose uptake, apoptosis, synaptic dysfunction, inflammation, and immune system), still a dearth of an effective therapeutic agent in the management of AD prompts the quest for newer pharmacological targets in the purview of its growing epidemiological status. Most of the current therapeutic strategies focus on modulation of a single target, e.g., inhibition of acetylcholinesterase, glutamate excitotoxicity (memantine), or nootropics (piracetam), even though AD is a multifaceted neurological disorder. There is an impedance urgency to find not only symptomatic but effective disease-modifying therapies. The present review focuses on the risk / protective factors and pathogenic mechanisms involved in AD. In addition to the existing symptomatic therapeutic approach, a diverse array of possible targets linked to pathogenic cascades have been re-investigated to envisage the pharmacotherapeutic strategies in AD.

Is diabetes associated with increased pathological burden in Alzheimer's disease?

INTRODUCTION

We examined the association between Alzheimer's disease (AD) and type 2 diabetes mellitus (DM) and hypothesized that diabetes is associated with an increased pathological burden in clinically and pathologically diagnosed AD.

METHODS

All data were obtained from the Uniform Data Set (UDS) v3, the Neuropathology Data Set, and the Researcher's Data Dictionary-Genetic Data from the National Alzheimer's Coordinating Center. The dataset (37 cases with diabetes and 1158 cases without) relies on autopsy-confirmed data in clinically diagnosed AD patients who were assessed for diabetes type in form A5 or D2 during at least one visit. Differences in scores were explored using a general linear model. Effect sizes were calculated using sample means and standard deviations (Cohen's d).

RESULTS

The presence of diabetes was associated with a lower Thal phase of amyloid plaques (A score; 4.6 ± 0.79 vs. 4.3 ± 0.85, P < .05) and lower Braak stage for neurofibrillary degeneration (B score; 5.58 ± 0.72 vs. 5.16 ± 0.96, P < 0.05) but not for density of neocortical neuritic plaques (CERAD score-C score). The National Institute on Aging-Alzheimer's Association Alzheimer's disease neuropathologic change (ABC score) was not different between AD+DM and AD-DM.

DISCUSSION

This pilot study found a significantly lower Thal phase of amyloid plaques and Braak stage for neurofibrillary degeneration in AD-confirmed individuals with diabetes compared to those without. Thus type 2 DM is not associated with increased AD pathology in clinically and pathologically confirmed cases of AD.

Metformin and cyanidin 3-O-galactoside from Aronia melanocarpa synergistically alleviate cognitive impairment in SAMP8 mice

Cyanidin 3-O-galactoside (Cy3Gal) from Aronia melanocarpa has been reported to alleviate cognitive impairment. Metformin for preventing the neurodegenerative disease is attracting increasing attention. However, the neuroprotective and metabolic health promoting both of their effects are not clear. We chose the senescence accelerated mouse prone 8 (SAMP8) as a model of spontaneous learning and memory impairment. This study aimed to investigate the synergistic neuroprotective effect of metformin and Cy3Gal by behavioral and histopathological assays and metabolite analysis in SAMP8 mice. The SAMR1 mice were the normal group, and the SAMP8 mice were divided into five groups, including the SAMP8 model group, the donepezil (1 mg kg^-1, ig) group, the metformin (100 mg kg^-1, ig) group, the Cy3Gal (25 mg kg^-1, ig) group, and the combination of metformin plus Cy3Gal (Met + Cy3Gal, 100 mg kg^-1, 25 mg kg^-1, ig) group. The behavior experiments showed that the SAMP8 mice treated with metformin and Cy3Gal showed improved spatial learning and memory compared to the SAMP8 model group. The number of neurons in the Met + Cy3Gal group was significantly higher than that in the SAMP8 group and the Met + Cy3Gal group showed significantly reduced Aβ aggregation in the brain, which was elevated in SAMP8 mice. Compared with SAMP8 mice, the Met + Cy3Gal group showed decreased indole, methyl esters and ketones and increased short-chain fatty acids and alcohols in feces and urine by regulating the fatty acid biosynthesis and degradation. This study confirmed the neuroprotective effects of coadministration of metformin and cyanidin 3-O-galactoside in the SAMP8 mice, and suggested its positive effect on postponing the progression of Alzheimer's disease.

Association of Alzheimer's Disease and Insulin Resistance in King Abdulaziz Medical City, Jeddah

Background Alzheimer's disease (AD) and insulin resistance (IR) are common in the elderly. IR reduces the ability of insulin to work effectively on target tissues. This results in hyperglycemia, increased triglyceride levels, decreased high-density lipoprotein (HDL) levels, elevated blood pressure, and central obesity, a condition known as metabolic syndrome (MetS). MetS eventually affects cognition, but its relationship with AD is unclear. Therefore, we studied the association between AD and IR and the relation between AD and diabetic patients treated with insulin. Methods This was a record-based retrospective cohort study using data from King Abdulaziz Medical City, Jeddah, Ministry of National Guards-Health Affairs. for all patients with dementia and AD, from 2009 to 2018. We examined 354 patient files. The triglyceride-glucose (TyG) index was used for the assessment of IR. Results There was no significant association between patients' demographic data, glycated hemoglobin, and co-morbidities and developing AD. Statistical models showed that, after adjustment for age, patients with IR had a significantly higher likelihood of AD (adjusted OR = 1.4; 95% CI: 1.01-2.33). After multivariate adjustment, patients with IR still had a 20% higher probability of developing AD than others (adjusted OR = 1.2; 95% CI: 1.0-3.1). Conclusion These results suggest that AD is associated with IR. Moreover, the association may be confounded by many patient-related factors.

Genetic associated complications of type 2 Diabetes Mellitus: a review

According to the International Diabetes Federation, the number of adults (age of 20-79) being diagnosed with Diabetes Mellitus (DM) have increased from 285 million in year 2009 to 463 million in year 2019 which comprises of 95% Type 2 DM patient (T2DM). Research have claimed that genetic predisposition could be one of the factors causing T2DM complications. In addition, T2DMcomplications cause an incremental risk to mortality. Therefore, this article aims to discuss some complications of T2DM in and their genetic association. The complications that are discussed in this article are diabetic nephropathy, diabetes induced cardiovascular disease, diabetic neuropathy, Diabetic Foot Ulcer (DFU) and Alzheimer's disease. According to the information obtained, genes associated with diabetic nephropathy (DN) are gene GABRR1 and ELMO1 that cause injury to glomerular. Replication of genes FRMD3, CARS and MYO16/IRS2 shown to have link with DN. The increase of gene THBS2, NGAL, PIP, TRAF6 polymorphism, ICAM-1 encoded for rs5498 polymorphism and C667T increase susceptibility towards DN in T2DM patient. Genes associated with cardiovascular diseases are Adiponectin gene (ACRP30) and Apolipoprotein E (APOE) polymorphism gene with ξ2 allele. Haptoglobin (Hp) 1-1 genotype and Mitochondria Superoxide Dismutase 2 (SOD2) plays a role in cardiovascular events. As for genes related to diabetic neuropathy, Janus Kinase (JAK), mutation of SCN9A and TRPA1 gene and destruction of miRNA contribute to pathogenesis of diabetic neuropathy among T2DM patients. Expression of cytokine IL-6, IL-10, miR-146a are found to cause diabetic neuropathy. Besides, A1a16Va1 gene polymorphism, an oxidative stress influence was found as one of the gene factors. Diabetic retinopathy (DR) is believed to have association with Monocyte Chemoattractant Protein-1 (MCP-1) and Insulin-like Growth Factor 1 (IGF1). Over-expression of gene ENPP1, IL-6 pro-inflammatory cytokine, ARHGAP22's protein rs3844492 polymorphism and TLR4 heterozygous genotype are contributing to significant pathophysiological process causing DR, while research found increases level of UCP1 gene protects retina cells from oxidative stress. Diabetic Foot Ulcer (DFU) is manifested by slowing in reepithelialisation of keratinocyte, persistence wound inflammation and healing impairment. Reepithelialisation disturbance was caused by E2F3 gene, reduction of Tacl gene encoded substance P causing persistence inflammation while expression of MMp-9 polymorphism contributes to healing impairment. A decrease in HIF-1a gene expression leads to increased risk of pathogenesis, while downregulation of TLR2 increases severity of wound in DFU patients. SNPs alleles has been shown to have significant association between the genetic dispositions of T2DM and Alzheimer's disease (AD). The progression of AD can be due to the change in DNA methylation of CLOCK gene, followed with worsening of AD by APOE4 gene due to dyslipidaemia condition in T2DM patients. Insulin resistance is also a factor that contributes to pathogenesis of AD.

A Review of Current Trends with Type 2 Diabetes Epidemiology, Aetiology, Pathogenesis, Treatments and Future Perspectives

Type 2 diabetes (T2D), which has currently become a global pandemic, is a metabolic disease largely characterised by impaired insulin secretion and action. Significant progress has been made in understanding T2D aetiology and pathogenesis, which is discussed in this review. Extrapancreatic pathology is also summarised, which demonstrates the highly multifactorial nature of T2D. Glucagon-like peptide (GLP)-1 is an incretin hormone responsible for augmenting insulin secretion from pancreatic beta-cells during the postprandial period. Given that native GLP-1 has a very short half-life, GLP-1 mimetics with a much longer half-life have been developed, which are currently an effective treatment option for T2D by enhancing insulin secretion in patients. Interestingly, there is continual emerging evidence that these therapies alleviate some of the post-diagnosis complications of T2D. Additionally, these therapies have been shown to induce weight loss in patients, suggesting they could be an alternative to bariatric surgery, a procedure associated with numerous complications. Current GLP-1-based therapies all act as orthosteric agonists for the GLP-1 receptor (GLP-1R). Interestingly, it has emerged that GLP-1R also has allosteric binding sites and agonists have been developed for these sites to test their therapeutic potential. Recent studies have also demonstrated the potential of bi- and tri-agonists, which target multiple hormonal receptors including GLP-1R, to more effectively treat T2D. Improved understanding of T2D aetiology/pathogenesis, coupled with the further elucidation of both GLP-1 activity/targets and GLP-1R mechanisms of activation via different agonists, will likely provide better insight into the therapeutic potential of GLP-1-based therapies to treat T2D.

Activation of PI3K/Akt Signaling Pathway in Rat Hypothalamus Induced by an Acute Oral Administration of D-Pinitol

D-Pinitol (DPIN) is a natural occurring inositol capable of activating the insulin pathway in peripheral tissues, whereas this has not been thoroughly studied in the central nervous system. The present study assessed the potential regulatory effects of DPIN on the hypothalamic insulin signaling pathway. To this end we investigated the Phosphatidylinositol-3-kinase (PI3K)/Protein Kinase B (Akt) signaling cascade in a rat model following oral administration of DPIN. The PI3K/Akt-associated proteins were quantified by Western blot in terms of phosphorylation and total expression. Results indicate that the acute administration of DPIN induced time-dependent phosphorylation of PI3K/Akt and its related substrates within the hypothalamus, indicating an activation of the insulin signaling pathway. This profile is consistent with DPIN as an insulin sensitizer since we also found a decrease in the circulating concentration of this hormone. Overall, the present study shows the pharmacological action of DPIN in the hypothalamus through the PI3K/Akt pathway when giving in fasted animals. These findings suggest that DPIN might be a candidate to treat brain insulin-resistance associated disorders by activating insulin response beyond the insulin receptor.

Hemocompatible L-Type amino acid transporter 1 (LAT1)-Utilizing prodrugs of perforin inhibitors can accumulate into the pancreas and alleviate inflammation-induced apoptosis

Cytolytic pore-forming protein, perforin, has been associated with autoimmune destruction of pancreatic β-cells in type 1 diabetes mellitus (T1DM) once released from CD8⁺ T cells. Curiously, perforinopathy has also been implicated in numerous brain diseases. Therefore, inhibitors of perforin have been in demand with targeted delivery in mind. l-Type amino acid transporter 1 (LAT1) is known to be expressed in both the above-mentioned target tissues, in the pancreas as well as in the brain. Thus, in the present study, the distribution of two LAT1-utilizing prodrugs of investigational perforin inhibitors into the pancreas was explored after intraperitoneal (i.p., 30 μmol/kg) bolus injection to mice. The effects of prodrug 1 were also studied in lipopolysaccharide (LPS)-induced in vitro (50 μg/mL) and in vivo (250 μg/kg x 3 days) apoptosis and pancreatitis models by determining the cellular apoptotic levels with human umbilical vein endothelial cells (HUVEC) and pancreatic caspase-3/-7 activity in mice. Furthermore, the biocompatibility of prodrug 1 was explored in human plasma and towards red blood cells. According to the results, both prodrugs were accumulated more effectively into the pancreas than their parent drugs (in addition to the brain that has been previously reported). Prodrug 1 (30 μmol/kg) also decreased the pancreatic caspase-3/-7 activity (52%) and with 2.5 μM concentration, the number of early and late apoptotic cells (32-53%). Since prodrug 1 was also found to be hemocompatible and not affecting human plasma hemostasis or inducing hemolysis of erythrocytes at the concentration <50 μM, it can be considered biocompatible in systemic circulation and ready to be studied in the future as a dual-acting drug candidate (in the pancreas and brain) in diseases like T1DM with neurodegenerative comorbidities.

Antidiabetic, anticholinergic and antioxidant activities of aerial parts of shaggy bindweed (Convulvulus betonicifolia Miller subsp.) - profiling of phenolic compounds by LC-HRMS

In order to evaluate the antioxidant activity of evaporated ethanolic extract (EESB) and lyophilized water extract (WESB) of Shaggy bindweed (Convulvulus betonicifolia Mill. Subs), some putative antioxidant methods such as DPPH· scavenging activity, ABTS^•+ scavenging effect, ferric ions (Fe³⁺) reduction method, cupric ions (Cu²⁺) reducing capacity, and ferrous ions (Fe²⁺) binding activities were separately performed. Also, ascorbic acid, α-tocopherol and BHT were used as the standard compounds. Additionally, some phenolic compounds that responsible for antioxidant abilities of EESB and WESB were screened by liquid chromatography-high resolution mass spectrometry (LC-HRMS). At the same concentration, EESB and WESB demonstrated effective antioxidant abilities when compared to standards. In addition, EESB demonstrated IC₅₀ values of 1.946 μg/mL against acetylcholinesterase (AChE), 0.815 μg/mL against α-glycosidase and 0.675 μg/mL against α-amylase enzymes.

LC-HRMS Profiling and Antidiabetic, Anticholinergic, and Antioxidant Activities of Aerial Parts of Kınkor (Ferulago stellata)

Kınkor (Ferulago stellata) is Turkish medicinal plant species and used in folk medicine against some diseases. As far as we know, the data are not available on the biological activities and chemical composition of this medicinal plant. In this study, the phytochemical composition; some metabolic enzyme inhibition; and antidiabetic, anticholinergic, and antioxidant activities of this plant were assessed. In order to evaluate the antioxidant activity of evaporated ethanolic extract (EEFS) and lyophilized water extract (WEFS) of kınkor (Ferulago stellata), some putative antioxidant methods such as DPPH· scavenging activity, ABTS^•+ scavenging activity, ferric ions (Fe³⁺) reduction method, cupric ions (Cu²⁺) reducing capacity, and ferrous ions (Fe²⁺)-binding activities were separately performed. Furthermore, ascorbic acid, BHT, and α-tocopherol were used as the standard compounds. Additionally, the main phenolic compounds that are responsible for antioxidant abilities of ethanol and water extracts of kınkor (Ferulago stellata) were determined by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Ethanol and water extracts of kınkor (Ferulago stellata) demonstrated effective antioxidant abilities when compared to standards. Moreover, ethanol extract of kınkor (Ferulago stellata) demonstrated IC₅₀ values of 1.772 μg/mL against acetylcholinesterase (AChE), 33.56 ± 2.96 μg/mL against α-glycosidase, and 0.639 μg/mL against α-amylase enzyme respectively.

Effects of Calorie Restriction on Health Span and Insulin Resistance: Classic Calorie Restriction Diet vs. Ketosis-Inducing Diet

As the incidence of Chronic Non-Communicable Diseases (CNCDs) increases, preventive approaches become more crucial. In this review, calorie restriction (CR) effects on human beings were evaluated, comparing the benefits and risks of different CR diets: classic CR vs. ketosis-inducing diets, including intermittent fasting (IF), classic ketogenic diet (CKD), fasting mimicking diet (FMD), very-low-calorie ketogenic Diet (VLCKD) and Spanish ketogenic Mediterranean diet (SKMD). Special emphasis on insulin resistance (IR) was placed, as it mediates metabolic syndrome (MS), a known risk factor for CNCD, and is predictive of MS diagnosis. CR is the most robust intervention known to increase lifespan and health span, with high evidence and known biochemical mechanisms. CR improves cardiometabolic risk parameters, boosts exercise insulin sensitivity response, and there may be benefits of implementing moderate CR on healthy young and middle-aged individuals. However, there is insufficient evidence to support long-term CR. CKD is effective for weight and MS management, and may have additional benefits such as prevention of muscle loss and appetite control. SKMD has extreme significance benefits for all the metabolic parameters studied. Studies show inconsistent benefits of IF compared to classic CR. More studies are required to study biochemical parameters, reinforce evidence, identify risks, and seek effective and safe nutritional CR approaches.

Amyloid-related protein changes associated with dementia differ according to severity of hypoglycemia

INTRODUCTION

Hypoglycemia in type 2 diabetes (T2D) may increase risk for Alzheimer's disease (AD), but no data on changes in AD-related proteins with differing degrees of hypoglycemia exist. We hypothesized that milder prolonged hypoglycemia would cause greater AD-related protein changes versus severe transient hypoglycemia.

RESEARCH DESIGN AND METHODS

Two prospective case-control induced hypoglycemia studies were compared: study 1, hypoglycemic clamp to 2.8 mmol/L (50 mg/dL) for 1 hour in 17 subjects (T2D (n=10), controls (n=7)); study 2, hypoglycemic clamp to 2.0 mmol/L (36 mg/dL) undertaken transiently and reversed in 46 subjects (T2D (n=23), controls (n=23)). Blood sampling at baseline, hypoglycemia and 24-hour post-hypoglycemia, with proteomic analysis of amyloid-related proteins performed.

RESULTS

In control subjects, the percentage change from baseline to hypoglycemia differed between study 1 and study 2 for 5 of 11 proteins in the AD-related panel: serum amyloid A1 (SAA1) (p=0.009), pappalysin (PAPPA) (p=0.002), apolipoprotein E2 (p=0.02), apolipoprotein E3 (p=0.03) and apolipoprotein E4 (p=0.02). In controls, the percentage change from baseline to 24 hours differed between studies for two proteins: SAA1 (p=0.003) and PAPPA (p=0.004); however, after Bonferroni correction only SAA1 and PAPPA remain significant. In T2D, there were no differential protein changes between the studies.

CONCLUSIONS

The differential changes in AD-related proteins were seen only in control subjects in response to iatrogenic induction of hypoglycemic insults of differing length and severity and may reflect a protective response that was absent in subjects with T2D. Milder prolonged hypoglycemia caused greater AD-related protein changes than severe acute hypoglycemia in control subjects.

TRIAL REGISTRATION NUMBERS

NCT02205996, NCT03102801.

Gut Microbiome Features of Chinese Patients Newly Diagnosed with Alzheimer's Disease or Mild Cognitive Impairment

BACKGROUND

Patients with Alzheimer's disease (AD) have gut microbiome alterations compared with healthy controls. However, previous studies often assess AD patients who have been on medications or other interventions for the disease. Also, simultaneous determination of gut microbiome in patients with mild cognitive impairment (MCI) or AD in a study is rare.

OBJECTIVE

To determine whether there was a gut microbiome alteration in patients newly diagnosed with AD or MCI and whether the degree of gut microbiome alteration was more severe in patients with AD than patients with MCI.

METHODS

Fecal samples of 18 patients with AD, 20 patients with MCI, and 18 age-matched healthy controls were collected in the morning for 16S ribosomal RNA sequencing. No patient had medications or interventions for AD or MCI before the samples were collected.

RESULTS

Although there was no difference in the microbial α-diversity among the three groups, patients with AD or MCI had increased β-diversity compared with healthy controls. Patients with AD had decreased Bacteroides, Lachnospira, and Ruminiclostridium_9 and increased Prevotella at the genus level compared with healthy controls. The changing direction of these genera in patients with MCI was the same as patients with AD. However, Lachnospira was the only genus whose abundance in patients with MCI was statistically significantly lower than healthy controls. Bacteroides, Lachnospira, and Ruminiclostridium_9 were positively associated with better cognitive functions whereas Prevotella was on the contrary when subjects of all three groups were considered. The negative correlation of Prevotella with cognitive functions remained among patients with MCI.

CONCLUSION

Patients newly diagnosed with AD or MCI have gut dysbiosis that includes the decrease of potentially protective microbiome, such as Bacteroides, and the increase of microbiome that can promote inflammation, such as Prevotella. Our results support a novel idea that the degree of gut dysbiosis is worsened with the disease stage from MCI to AD.

Downregulation of Candidate Gene Expression and Neuroprotection by Piperine in Streptozotocin-Induced Hyperglycemia and Memory Impairment in Rats

There is accumulating evidence showing that hyperglycemia conditions like diabetes possess a greater risk of impairment to the neuronal system because high glucose levels exacerbate oxidative stress, accumulation of amyloid-beta peptides, and mitochondrial dysfunction, and impair cognitive functions and cause neurodegeneration conditions like Alzheimer’s diseases. Due to the extensive focus on pharmacological intervention to prevent neuronal cells’ impairment induced by hyperglycemia, the underlying molecular mechanism that links between Diabetes and Alzheimer’s is still lacking. Given this, the present study aimed to evaluate the protective effect of piperine on streptozotocin (STZ) induced hyperglycemia and candidate gene expression. In the present study, rats were divided into four groups: control (Vehicle only), diabetic control (STZ only), piperine treated (20 mg/kg day, i.p), and sitagliptin (Positive control) treated. The memory function was assessed by Morris water maze and probe test. After treatment, biochemical parameters such as HOMA index and lipid profile were estimated in the serum, whereas histopathology was evaluated in pancreatic and brain tissue samples. Gene expression studies were done by real-time PCR technique. Present data indicated that piperine caused significant memory improvement as compared to diabetic (STZ) control. The assessment of HOMA indices in serum samples showed that piperine and sitagliptin (positive control, PC) caused significant alterations of insulin resistance, β cell function, and insulin sensitivity. Assessment of brain and pancreas histopathology shows significant improvement in tissue architecture in piperine and sitagliptin treated groups compared to diabetic control. The gene expression profile in brain tissue shows significantly reduced BACE1, PSEN1, APAF1, CASPASE3, and CATALASE genes in the piperine and sitagliptin (PC) treated groups compared to Diabetic (STZ) control. The present study demonstrated that piperine not only improves memory in diabetic rats but also reduces the expression of specific AD-related genes that can help design a novel strategy for therapeutic intervention at the molecular level.

Pathology, Risk Factors, and Oxidative Damage Related to Type 2 Diabetes-Mediated Alzheimer's Disease and the Rescuing Effects of the Potent Antioxidant Anthocyanin

The pathology and neurodegeneration in type 2 diabetes- (T2D-) mediated Alzheimer's disease (AD) have been reported in several studies. Despite the lack of information regarding the basic underlying mechanisms involved in the development of T2D-mediated AD, some common features of the two conditions have been reported, such as brain atrophy, reduced cerebral glucose metabolism, and insulin resistance. T2D phenotypes such as glucose dyshomeostasis, insulin resistance, impaired insulin signaling, and systemic inflammatory cytokines have been shown to be involved in the progression of AD pathology by increasing amyloid-beta accumulation, tau hyperphosphorylation, and overall neuroinflammation. Similarly, oxidative stress, mitochondrial dysfunction, and the generation of advanced glycation end products (AGEs) and their receptor (RAGE) as a result of chronic hyperglycemia may serve as critical links between diabetes and AD. The natural dietary polyflavonoid anthocyanin enhances insulin sensitivity, attenuates insulin resistance at the level of the target tissues, inhibits free fatty acid oxidation, and abrogates the release of peripheral inflammatory cytokines in obese (prediabetic) individuals, which are responsible for insulin resistance, systemic hyperglycemia, systemic inflammation, brain metabolism dyshomeostasis, amyloid-beta accumulation, and neuroinflammatory responses. In this review, we have shown that obesity may induce T2D-mediated AD and assessed the recent therapeutic advances, especially the use of anthocyanin, against T2D-mediated AD pathology. Taken together, the findings of current studies may help elucidate a new approach for the prevention and treatment of T2D-mediated AD by using the polyflavonoid anthocyanin.

Modeling Cell Energy Metabolism as Weighted Networks of Non-autonomous Oscillators

Networks of oscillating processes are a common occurrence in living systems. This is as true as anywhere in the energy metabolism of individual cells. Exchanges of molecules and common regulation operate throughout the metabolic processes of glycolysis and oxidative phosphorylation, making the consideration of each of these as a network a natural step. Oscillations are similarly ubiquitous within these processes, and the frequencies of these oscillations are never truly constant. These features make this system an ideal example with which to discuss an alternative approach to modeling living systems, which focuses on their thermodynamically open, oscillating, non-linear and non-autonomous nature. We implement this approach in developing a model of non-autonomous Kuramoto oscillators in two all-to-all weighted networks coupled to one another, and themselves driven by non-autonomous oscillators. Each component represents a metabolic process, the networks acting as the glycolytic and oxidative phosphorylative processes, and the drivers as glucose and oxygen supply. We analyse the effect of these features on the synchronization dynamics within the model, and present a comparison between this model, experimental data on the glycolysis of HeLa cells, and a comparatively mainstream model of this experiment. In the former, we find that the introduction of oscillator networks significantly increases the proportion of the model's parameter space that features some form of synchronization, indicating a greater ability of the processes to resist external perturbations, a crucial behavior in biological settings. For the latter, we analyse the oscillations of the experiment, finding a characteristic frequency of 0.01–0.02 Hz. We further demonstrate that an output of the model comparable to the measurements of the experiment oscillates in a manner similar to the measured data, achieving this with fewer parameters and greater flexibility than the comparable model.

Association between exenatide use and incidence of Alzheimer's disease

INTRODUCTION

Recent developments suggest that insulin-sensitizing agents used to treat type II diabetes (T2DM) may also prove useful in reducing the risk of Alzheimer's disease (AD). The objective of this study is to analyze the association between exenatide use among Medicare beneficiaries with T2DM and the incidence of AD.

METHODS

We performed a retrospective cohort analysis on claims data from a 20% random sample of Medicare beneficiaries with T2DM from 2007 to 2013 (n = 342,608). We compared rates of incident AD between 2009 and 2013 according to exenatide use in 2007-2008, measured by the number of 30-day-equivalent fills. We adjusted for demographics, comorbidities, and use of other drugs. Unmeasured confounding was assessed with an instrumental variables approach.

RESULTS

The sample was mostly female (65%), White (76%), and 74 years old on average. Exenatide users were more likely to be male (38% vs. 35%), White (87% vs. 76%), and younger (by 4.2 years) than non-users. Each additional 30-day-equivalent claim was associated with a 2.4% relative reduction in incidence (odds ratio 0.976; 95% confidence interval 0.963-0.989; P < .001). There was no evidence of unmeasured confounding.

DISCUSSION

Exenatide use is associated with a reduced incidence of AD among Medicare beneficiaries aged 65 years or older with T2DM. The association shown in this study warrants consideration by clinicians prescribing insulin sensitizing agents to patients.

Hypoglycaemia in type 2 diabetes exacerbates amyloid-related proteins associated with dementia

AIMS

Hypoglycaemia in diabetes (T2D) may increase the risk of Alzheimer's disease (AD). We hypothesized that hypoglycaemia-induced amyloid-related protein changes would be exacerbated in T2D.

MATERIALS AND METHODS

A prospective, parallel study in T2D (n = 23) and controls (n = 23). Subjects underwent insulin-induced hypoglycaemia with blood sampling at baseline, hypoglycaemia and post-hypoglycaemia; proteomic analysis of amyloid-related proteins was undertaken.

RESULTS

At baseline, amyloid-precursor protein (APP) (P < .01) was elevated and alpha-synuclein (SNCA) (P < .01) reduced in T2D. At hypoglycaemia, amyloid P-component (P < .01) was elevated and SNCA (P < .05) reduced in T2D; APP (P < .01) and noggin (P < .05) were elevated and SNCA (P < .01) reduced in controls. In the post-hypoglycaemia follow-up period, APP and microtubule-associated protein tau normalized in controls but showed a below-baseline decrease in T2D; noggin normalized in both; SNCA normalized in T2D, with a below-baseline decrease in controls.

CONCLUSION

The AD-associated protein pattern found in T2D, with basal elevated APP and reduced SNCA, was exaggerated by hypoglycaemia with increased APP and decreased SNCA. Additional AD-associated protein levels that changed in response to hypoglycaemia, particularly in T2D, included amyloid P-component, microtubule-associated protein tau, apolipoproteins A1 and E3, pappalysin and noggin. These results are in accordance with the reported detrimental effects of hypoglycaemia.

Liraglutide Has Anti-Inflammatory and Anti-Amyloid Properties in Streptozotocin-Induced and 5xFAD Mouse Models of Alzheimer's Disease

Recent clinical and epidemiological studies support the contention that diabetes mellitus (DM) is a strong risk factor for the development of Alzheimer’s disease (AD). The use of insulin cell toxin, streptozotocin (STZ), when injected into the lateral ventricles, develops an insulin resistant brain state (IRBS) and represents a non-transgenic, or sporadic AD model (SAD), with several AD-like neuropathological features. The present study explored the effects of an anti-diabetic drug, liraglutide (LIR), in reversing major pathological hallmarks in the prodromal disease stage of both the 5xFAD transgenic and SAD mouse models of AD. Three-month-old 5xFAD and age-matched wild type mice were given a single intracerebroventricular (i.c.v) injection of STZ or vehicle (saline) and were subsequently treated with LIR, intraperitoneally (IP), once a day for 30 days. The extent of neurodegeneration, Aβ plaque load, and key proteins associated with the insulin signaling pathways were measured using Western blot and neuroinflammation (via immunohistological assays) in the cortical and hippocampal regions of the brain were assessed following a series of behavioral tests used to measure cognitive function after LIR or vehicle treatments. Our results indicated that STZ significantly increased neuroinflammation, Aβ plaque deposition and disrupted insulin signaling pathway, while 25 nmol/kg LIR, when injected IP, significantly decreased neuroinflammatory responses in both SAD and 5xFAD mice before significant cognitive changes were observed, suggesting LIR can reduce early neuropathology markers prior to the emergence of overt memory deficits. Our results indicate that LIR has neuroprotective effects and has the potential to serve as an anti-inflammatory and anti-amyloid prophylactic therapy in the prodromal stages of AD.

High-fat diet induced discrepant peripheral and central nervous systems insulin resistance in APPswe/PS1dE9 and wild-type C57BL/6J mice

This study was designed to examine whether AD pathological phenotype in APPswe/PS1dE9 (APP/PS1) mice exposed to continuous high-fat diet predispose these murine models to metabolic dysfunction and neuropathological impairments. One-month old male APP/PS1 and C57BL/6J mice were provided with 60% high-fat diet for 6.5 months. After dietary intervention, metabolic phenotyping, cognitive behaviors, AD-related brain pathological changes and insulin signaling were compared. high fat diet induced hyperglycemia, hypercholesterolemia, and aggravated inflammatory stress in both APP/PS1 and C57BL/6J mice. Compared with C57BL/6J control mice, APP/PS1 mice showed lower glucose transporter protein expression in liver, muscle, and brain. High-fat diet caused a decrease of glucose transporter protein expression in muscle and liver but increased cortical glucose transporter protein expression in APP/PS1 mice. High-fat diet-fed APP/PS1 mice demonstrated decreased cognitive function, as well as elevated cortical soluble amyloid-β levels and APP protein expression. Decrease in cortical IR, p-IR protein expression and p-GSK3β/GSK3β ratio were observed in high-fat diet-fed APP/PS1 mice. High-fat diet caused discrepant peripheral and central nervous system metabolic phenotype in APP/PS1 and C57BL/6J mice. AD pathological phenotype might accelerate metabolic changes and cognitive impairment in APP/PS1 mice treated with HFD.

The Potential Roles of Artemisinin and Its Derivatives in the Treatment of Type 2 Diabetes Mellitus

Type 2 diabetes mellitus (T2DM) is a chronic disease that has become a global public health problem. Studies on T2DM prevention and treatment mostly focus on discovering therapeutic drugs. Artemisinin and its derivatives were originally used as antimalarial treatments. In recent years, the roles of artemisinins in T2DM have attracted much attention. Artemisinin treatments not only attenuate insulin resistance and restore islet ß-cell function in T2DM but also have potential therapeutic effects on diabetic complications, including diabetic kidney disease, cognitive impairment, diabetic retinopathy, and diabetic cardiovascular disease. Many in vitro and in vivo experiments have confirmed the therapeutic utility of artemisinin and its derivatives on T2DM, but no article has systematically demonstrated the specific role artemisinin plays in the treatment of T2DM. This review summarizes the potential therapeutic effects and mechanism of artemisinin and its derivatives in T2DM and associated complications, providing a reference for subsequent related research.

Developing Effective Alzheimer's Disease Therapies: Clinical Experience and Future Directions

Alzheimer's disease (AD) clinical trials, focused on disease modifying drugs and conducted in patients with mild to moderate AD, as well as prodromal (early) AD, have failed to reach efficacy endpoints in improving cognitive function in most cases to date or have been terminated due to adverse events. Drugs that have reached clinical stage were reviewed using web resources (such as clinicaltrials.gov, alzforum.org, company press releases, and peer reviewed literature) to identify late stage (Phase II and Phase III) efficacy clinical trials and summarize reasons for their failure. For each drug, only the latest clinical trials and ongoing trials that aimed at improving cognitive function were included in the analysis. Here we highlight the potential reasons that have hindered clinical success, including clinical trial design and choice of outcome measures, heterogeneity of patient populations, difficulties in diagnosing and staging the disease, drug design, mechanism of action, and toxicity related to the long-term use. We review and suggest approaches for AD clinical trial design aimed at improving our ability to identify novel therapies for this devastating disease.

Metabolic Dysregulation Contributes to the Progression of Alzheimer's Disease

Alzheimer's disease (AD) is an incurable neurodegenerative disease. Numerous studies have demonstrated a critical role for dysregulated glucose metabolism in its pathogenesis. In this review, we summarize metabolic alterations in aging brain and AD-related metabolic deficits associated with glucose metabolism dysregulation, glycolysis dysfunction, tricarboxylic acid (TCA) cycle, oxidative phosphorylation (OXPHOS) deficits, and pentose phosphate pathway impairment. Additionally, we discuss recent treatment strategies targeting metabolic defects in AD, including their limitations, in an effort to encourage the development of novel therapeutic strategies.

Prevalence of Psychiatric Morbidity and Cognitive Impairment among Patients Attending the Rural Noncommunicable Disease Clinic

Objective  This study aimed to assess the prevalence of cognitive impairment and psychiatric morbidity among the patients attending the rural noncommunicable disease clinic after controlling for various confounders (i.e., psychological morbidity, obesity, gender, level of education, duration of the illness and age).

Materials and Methods  One-hundred twenty-four patients were evaluated on the Hindi Mental State Examination for the cognitive function, Physical Health Questionnaire-9 for depression, and Generalized Anxiety Disorder-7 for anxiety disorders.

Results  About one-fourth (26.6%) of the participants had cognitive impairment. The prevalence of cognitive impairment was more among patients with hypertension (35.5%) as compared with the diabetes mellitus (13.6%) and those with comorbid hypertension and diabetes mellitus (26.6%). About one of the participants had depression (35.5%) and 29% of the patients had anxiety disorder. No significant difference was found in the level of cognitive deficits between those with hypertension and diabetes mellitus, when the confounding factors were not taken into account in the analysis. However, after controlling for psychiatric morbidity, obesity, gender, level of education, duration of the illness and age, those with hypertension were found to have significantly higher level of cognitive impairment compared with those with diabetes mellitus. A higher level of dysfunction was seen in the domains of orientation, registration, attention, recall, language, and visuospatial domains.

Conclusion  Present study suggests that patients of hypertension have higher level of cognitive impairment, when compared with those with diabetes mellitus, even after controlling for various confounders. Lack of difference between the two groups can be accounted by the confounding variables.

Are Heat Shock Proteins an Important Link between Type 2 Diabetes and Alzheimer Disease?

Type 2 diabetes (T2D) and Alzheimer’s disease (AD) are growing in prevalence worldwide. The development of T2D increases the risk of AD disease, while AD patients can show glucose imbalance due to an increased insulin resistance. T2D and AD share similar pathological features and underlying mechanisms, including the deposition of amyloidogenic peptides in pancreatic islets (i.e., islet amyloid polypeptide; IAPP) and brain (β-Amyloid; Aβ). Both IAPP and Aβ can undergo misfolding and aggregation and accumulate in the extracellular space of their respective tissues of origin. As a main response to protein misfolding, there is evidence of the role of heat shock proteins (HSPs) in moderating T2D and AD. HSPs play a pivotal role in cell homeostasis by providing cytoprotection during acute and chronic metabolic stresses. In T2D and AD, intracellular HSP (iHSP) levels are reduced, potentially due to the ability of the cell to export HSPs to the extracellular space (eHSP). The increase in eHSPs can contribute to oxidative damage and is associated with various pro-inflammatory pathways in T2D and AD. Here, we review the role of HSP in moderating T2D and AD, as well as propose that these chaperone proteins are an important link in the relationship between T2D and AD.

Data-Driven Modeling of Knowledge Assemblies in Understanding Comorbidity Between Type 2 Diabetes Mellitus and Alzheimer's Disease

Background:

Recent studies have suggested comorbid association between Alzheimer’s disease (AD) and type 2 diabetes mellitus (T2DM) through identification of shared molecular mechanisms. However, the inference is pre-dominantly literature-based and lacks interpretation of pre-disposed genomic variants and transcriptomic measurables.

Objective:

In this study, we aim to identify shared genetic variants and dysregulated genes in AD and T2DM and explore their functional roles in the comorbidity between the diseases.

Methods:

The genetic variants for AD and T2DM were retrieved from GWAS catalog, GWAS central, dbSNP, and DisGeNet and subjected to linkage disequilibrium analysis. Next, shared variants were prioritized using RegulomeDB and Polyphen-2. Afterwards, a knowledge assembly embedding prioritized variants and their corresponding genes was created by mining relevant literature using Biological Expression Language. Finally, coherently perturbed genes from gene expression meta-analysis were mapped to the knowledge assembly to pinpoint biological entities and processes and depict a mechanistic link between AD and T2DM.

Results:

Our analysis identified four genes (i.e., ABCG1, COMT, MMP9, and SOD2) that could have dual roles in both AD and T2DM. Using cartoon representation, we have illustrated a set of causal events surrounding these genes which are associated to biological processes such as oxidative stress, insulin resistance, apoptosis and cognition.

Conclusion:

Our approach of using data as the driving force for unraveling disease etiologies eliminates literature bias and enables identification of novel entities that serve as the bridge between comorbid conditions.

Exploring Shared Pathogenesis of Alzheimer's Disease and Type 2 Diabetes Mellitus via Co-expression Networks Analysis

BACKGROUND

Alzheimer's Disease (AD) and Type 2 Diabetes Mellitus (T2DM) have an increased incidence in modern society. Although increasing evidence has supported the close linkage between these two disorders, the inter-relational mechanisms remain to be fully elucidated.

OBJECTIVE

The primary purpose of this study is to explore the shared pathophysiological mechanisms of AD and T2DM.

METHODS

We downloaded the microarray data of AD and T2DM from the Gene Expression Omnibus (GEO) database and constructed co-expression networks by Weighted Gene Co-Expression Network Analysis (WGCNA) to identify gene network modules related to AD and T2DM. Then, Gene Ontology (GO) and pathway enrichment analysis were performed on the common genes existing in the AD and T2DM related modules by clusterProfiler and DOSE package. Finally, we utilized the STRING database to construct the protein-protein interaction network and found out the hub genes in the network.

RESULTS

Our findings indicated that seven and four modules were the most significant with AD and T2DM, respectively. Functional enrichment analysis showed that AD and T2DM common genes were mainly enriched in signaling pathways such as circadian entrainment, phagosome, glutathione metabolism and synaptic vesicle cycle. Protein-protein interaction network construction identified 10 hub genes (CALM1, LRRK2, RBX1, SLC6A1, TXN, SNRPF, GJA1, VWF, LPL, AGT) in AD and T2DM shared genes.

CONCLUSION

Our work identified common pathogenesis of AD and T2DM. These shared pathways might provide a novel idea for further mechanistic studies and hub genes that may serve as novel therapeutic targets for diagnosis and treatment of AD and T2DM.

The Potential Roles of Ghrelin in Metabolic Syndrome and Secondary Symptoms of Alzheimer's Disease

Although the major causative factors of Alzheimer's disease (AD) are the accumulation of amyloid β and hyperphosphorylated tau, AD can also be caused by metabolic dysfunction. The major clinical symptom of AD is cognitive dysfunction. However, AD is also accompanied by various secondary symptoms such as depression, sleep-wake disturbances, and abnormal eating behaviors. Interestingly, the orexigenic hormone ghrelin has been suggested to have beneficial effects on AD-related metabolic syndrome and secondary symptoms. Ghrelin improves lipid distribution and alters insulin sensitivity, effects that are hypothesized to delay the progression of AD. Furthermore, ghrelin can relieve depression by enhancing the secretion of hormones such as serotonin, noradrenaline, and orexin. Moreover, ghrelin can upregulate the expression of neurotrophic factors such as brain-derived neurotrophic factor and modulate the release of proinflammatory cytokines such as tumor necrosis factor α and interleukin 1β. Ghrelin alleviates sleep-wake disturbances by increasing the levels of melatonin, melanin-concentrating hormone. Ghrelin reduces the risk of abnormal eating behaviors by increasing neuropeptide Y and γ-aminobutyric acid. In addition, ghrelin increases food intake by inhibiting fatty acid biosynthesis. However, despite the numerous studies on the role of ghrelin in the AD-related pathology and metabolic disorders, there are only a few studies that investigate the effects of ghrelin on secondary symptoms associated with AD. In this mini review, our purpose is to provide the insights of future study by organizing the previous studies for the role of ghrelin in AD-related pathology and metabolic disorders.

Synthesis of nitrogen, phosphorus, selenium and sulfur-containing heterocyclic compounds - Determination of their carbonic anhydrase, acetylcholinesterase, butyrylcholinesterase and α-glycosidase inhibition properties

Sulfur-containing pyrroles (1-3), tris(2-pyridyl)phosphine(selenide) sulfide (4-5) and 4-benzyl-6-(thiophen-2-yl)pyrimidin-2-amine (6) were synthesized and characterized by elemental analysis, IR and NMR spectra. In this study, the synthesized compounds of nitrogen, phosphorus, selenium and sulfur-containing heterocyclic compounds (1-6) were evaluated against the human erythrocyte carbonic anhydrase I, and II isoenzymes, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and α-glycosidase enzymes. The synthesized heterocyclic compounds showed IC₅₀ values in range of 33.32-60.79 nM against hCA I, and 37.05-66.64 nM against hCA II closely associated with various physiological and pathological processes. On the other hand, IC₅₀ values were found in range of 13.13-22.21 nM against AChE, 0.54-31.22 nM against BChE, and 13.51-26.55 nM against α-glycosidase as a hydrolytic enzyme. As a result, nitrogen, phosphorus, selenium and sulfur-containing heterocyclic compounds (1-6) demonstrated potent inhibition profiles against indicated metabolic enzymes. Therefore, we believe that these results may contribute to the development of new drugs particularly in the treatment of some global disorders including glaucoma, Alzheimer's disease and diabetes.

Urolithin A suppresses high glucose-induced neuronal amyloidogenesis by modulating TGM2-dependent ER-mitochondria contacts and calcium homeostasis

Hyperglycemia in diabetes mellitus (DM) patients is a causative factor for amyloidogenesis and induces neuropathological changes, such as impaired neuronal integrity, neurodegeneration, and cognitive impairment. Regulation of mitochondrial calcium influx from the endoplasmic reticulum (ER) is considered a promising strategy for the prevention of mitochondrial ROS (mtROS) accumulation that occurs in the Alzheimer's disease (AD)-associated pathogenesis in DM patients. Among the metabolites of ellagitannins that are produced in the gut microbiome, urolithin A has received an increasing amount of attention as a novel candidate with anti-oxidative and neuroprotective effects in AD. Here, we investigated the effect of urolithin A on high glucose-induced amyloidogenesis caused by mitochondrial calcium dysregulation and mtROS accumulation resulting in neuronal degeneration. We also identified the mechanism related to mitochondria-associated ER membrane (MAM) formation. We found that urolithin A-lowered mitochondrial calcium influx significantly alleviated high glucose-induced mtROS accumulation and expression of amyloid beta (Aβ)-producing enzymes, such as amyloid precursor protein (APP) and β-secretase-1 (BACE1), as well as Aβ production. Urolithin A injections in a streptozotocin (STZ)-induced diabetic mouse model alleviated APP and BACE1 expressions, Tau phosphorylation, Aβ deposition, and cognitive impairment. In addition, high glucose stimulated MAM formation and transglutaminase type 2 (TGM2) expression. We first discovered that urolithin A significantly reduced high glucose-induced TGM2 expression. In addition, disruption of the AIP-AhR complex was involved in urolithin A-mediated suppression of high glucose-induced TGM2 expression. Markedly, TGM2 silencing inhibited inositol 1, 4, 5-trisphosphate receptor type 1 (IP3R1)-voltage-dependent anion-selective channel protein 1 (VDAC1) interactions and prevented high glucose-induced mitochondrial calcium influx and mtROS accumulation. We also found that urolithin A or TGM2 silencing prevented Aβ-induced mitochondrial calcium influx, mtROS accumulation, Tau phosphorylation, and cell death in neuronal cells. In conclusion, we suggest that urolithin A is a promising candidate for the development of therapies to prevent DM-associated AD pathogenesis by reducing TGM2-dependent MAM formation and maintaining mitochondrial calcium and ROS homeostasis.

Reduction of hippocampal IL-6 levels in LPS-injected rats following acute exendin-4 treatment

Preclinical evidence on the role of glucagon-like peptide-1 receptor (GLP-1r) agonists in the brain led to an increased interest in repurposing these compounds as a therapy for central nervous system (CNS) disorders and associated comorbidities. We aimed to investigate the neuroprotective effects of acute treatment with exendin (EX)-4, a GLP-1r agonist, in an animal model of inflammation. We evaluated the effect of different doses of EX-4 on inflammatory, neurotrophic, and oxidative stress parameters in the hippocampus and serum of lipopolysaccharide (LPS)-injected animals. Male Wistar rats were injected with LPS (0.25 mg/kg i.p.) and treated with different doses of EX-4 (0.1, 0.3, or 0.5 μg/kg i.p.). Sickness behavior was assessed by locomotor activity and body weight, and depressive-like behavior was also evaluated using forced swim test (FST). Brain-derived neurotrophic factor (BDNF), thiobarbituric acid reactive species (TBARS), and interleukin (IL)-6 were quantified in the serum and hippocampus. Glycemia was also analyzed pre- and post-EX-4 treatment. LPS groups exhibited decreased frequency of crossing and reduced body weight (p < 0.001), while alterations on FST were not observed. The higher dose of EX-4 reduced IL-6 in the hippocampus of LPS-injected animals (p = 0.018), and EX-4 per se reduced TBARS serum levels with a modest antioxidant effect in the LPS groups (p ≤ 0.005). BDNF hippocampal levels seemed to be increased in the LPS+EX-4 0.5 group compared with LPS+Saline (p > 0.05). Our study provides evidence on acute anti-inflammatory effects of EX-4 in the hippocampus of rats injected with LPS, contributing to future studies on repurposing compounds with potential neuroprotective properties.

Cognitive Dysfunction in Older Adults with Type 2 Diabetes: Links, Risks, and Clinical Implications

The prevalence of comorbid diabetes and cognitive dysfunction increases as the population ages. Diabetes increases the risk of progression of cognitive dysfunction through a spectrum of cognitive decline to mild cognitive impairment then to dementia. Cognitive dysfunction, especially impairment in the executive domain, has a negative impact on patients' self-care tasks. With further progression of dementia and the development of behavioral problems, the challenge to carers and health care professionals looking after these patients is significant. Therefore, clinical trials are needed to explore the impact of novel hypoglycemic therapy on cognitive function as an important outcome in this population.

Metformin Ameliorates Synaptic Defects in a Mouse Model of AD by Inhibiting Cdk5 Activity

Cyclin-dependent kinase 5 (Cdk5) is a serine/threonine kinase that is activated by the neuron-specific activators p35/p39 and plays important roles in neuronal development, synaptic plasticity, and cognitive behavior. However, the proteolytic cleavage of p35 to p25 leads to prolonged and aberrant Cdk5 activation and results in synaptic depression, highly mimicking the early pathology of Alzheimer’s disease (AD). Therefore, Cdk5 inhibition is a potential promising strategy for AD drug development. Here in the present study, we showed that metformin, the most widely used drug for type 2 diabetes, suppressed Cdk5 hyper-activation and Cdk5-dependent tau hyper-phosphorylation in the APP/PS1 mouse hippocampus. We also identified the underlying molecular and cellular mechanism that metformin prevented Cdk5 hyper-activation by inhibiting the calpain-dependent cleavage of p35 into p25. Moreover, chronic metformin treatment rescued the core phenotypes in APP/PS1 mice as evidenced by restored spine density, surface GluA1 trafficking, Long-term potentiation (LTP) expression, and spatial memory. Altogether our study discovered an unidentified role of metformin in suppressing Cdk5 hyper-activation and thus preventing AD pathogenesis and suggested that metformin is a potential promising AD therapeutic drug.

Extending Arms of Insulin Resistance from Diabetes to Alzheimer's Disease: Identification of Potential Therapeutic Targets

BACKGROUND & OBJECTIVE

Type 3 diabetes (T3D) is chronic insulin resistant state of brain which shares pathology with sporadic Alzheimer's disease (sAD). Insulin signaling is a highly conserved pathway in the living systems that orchestrate cell growth, repair, maintenance, energy homeostasis and reproduction. Although insulin is primarily studied as a key molecule in diabetes mellitus, its role has recently been implicated in the development of Alzheimer's disease (AD). Severe complications in brain of diabetic patients and metabolically compromised status is evident in brain of AD patients. Underlying shared pathology of two disorders draws a trajectory from peripheral insulin resistance to insulin unresponsiveness in the central nervous system (CNS). As insulin has a pivotal role in AD, it is not an overreach to address diabetic condition in AD brain as T3D. Insulin signaling is indispensable to nervous system and it is vital for neuronal growth, repair, and maintenance of chemical milieu at synapses. Downstream mediators of insulin signaling pathway work as a regulatory hub for aggregation and clearance of unfolded proteins like Aβ and tau.

CONCLUSION

In this review, we discuss the regulatory roles of insulin as a pivotal molecule in brain with the understanding of defective insulin signaling as a key pathological mechanism in sAD. This article also highlights ongoing trials of targeting insulin signaling as a therapeutic manifestation to treat diabetic condition in brain.

The inefficacy of donepezil on glycated-AChE inhibition: Binding affinity, complex stability and mechanism

Donepezil (DPZ) is a well-known drug for Alzheimer's disease that inhibits acetylcholinesterase activity (AChE). In the present study, the inhibitory effect of DPZ on non-enzymatic glycated-AChE (GLY-AChE) was studied by different experimental and simulation techniques. The initial investigation revealed that glycation process could reduce AChE activity approximately 60% in the pure enzyme and 38% in the extracted crude AChE from neural cells cultured in the presence of high glucose (HG) concentration. It is suggested that glycation of lysine residues on the structure of AChE could change the conformation of the active site (Trp-86 and His-447) in a way that the orientation of acetylcholine interrupted. The further studies indicated that DPZ is although a strong inhibitor for the native enzyme, it is not able to affect the GLY-AChE activity. The K_D values of AChE-DPZ and GLY-AChE-DPZ complexes were estimated to be 1.88 × 10^-9 and 2.10 × 10^-6, respectively. The stability assessment showed that AChE-DPZ complex is more stable than the glycated complex. Our results indicate that, glycation process could impact on the conformation of the residues involved in the DPZ binding cavity on α-helix domain. Therefore, DPZ is not able to bind its specific cavity to induce its inhibitory effects on GLY-AChE.

Combination Drug Therapy for the Management of Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia worldwide. Even though the number of AD patients is rapidly growing, there is no effective treatment for this neurodegenerative disorder. At present, implementation of effective treatment approaches for AD is vital to meet clinical needs. In AD research, priorities concern the development of disease-modifying therapeutic agents to be used in the early phases of AD and the optimization of the symptomatic treatments predominantly dedicated to the more advanced AD stages. Until now, available therapeutic agents for AD treatment only provide symptomatic treatment. Since AD pathogenesis is multifactorial, use of a multimodal therapeutic intervention addressing several molecular targets of AD-related pathological processes seems to be the most practical approach to modify the course of AD progression. It has been demonstrated through numerous studies, that the clinical efficacy of combination therapy (CT) is higher than that of monotherapy. In case of AD, CT is more effective, mostly when started early, at slowing the rate of cognitive impairment. In this review, we have covered the major studies regarding CT to combat AD pathogenesis. Moreover, we have also highlighted the safety, tolerability, and efficacy of CT in the treatment of AD.

Regulation of Adipogenesis and Lipid Deposits by Collapsin Response Mediator Protein 2

As emerging evidence suggesting neurodegenerative diseases and metabolic diseases have common pathogenesis, we hypothesized that the neurite outgrowth-controlling collapsin response mediator protein 2 (CRMP2) was involved in energy homeostasis. Therefore, putative roles of CRMP2 in adipocyte differentiation (adipogenesis) and lipid metabolism were explored and addressed in this study. CRMP2 expression profiles were in vitro and in vivo characterized during adipogenic process of 3T3-L1 pre-adipocytes and diet-induced obese (DIO) mice, respectively. Effects of CRMP2 on lipid metabolism and deposits were also analyzed. Our data revealed that CRMP2 expression pattern was coupled with adipogenic stages. CRMP2 overexpression inhibited cell proliferation at MCE phase, and significantly reduced lipid contents by down-regulating adipogenesis-driving transcription factors and lipid-synthesizing enzymes. Interestingly, GLUT4 translocation and the lipid droplets fusion were disturbed in CRMP2-silencing cells by affecting actin polymerization. Moreover, adipose CRMP2 was significantly increased in DIO mice, indicating CRMP2 is associated with obesity. Accordingly, CRMP2 exerts multiple functions in adipogenesis and lipid deposits through mediating cell proliferation, glucose/lipid metabolism and cytoskeleton dynamics. The present study identifies novel roles of CRMP2 in mediating adipogenesis and possible implication in metabolic disorders, as well as provides molecular evidence supporting the link of pathogenesis between neurodegenerative diseases and metabolic abnormalities.

The Protective Effect of Vanadium on Cognitive Impairment and the Neuropathology of Alzheimer's Disease in APPSwe/PS1dE9 Mice

Alzheimer's disease (AD) is a widely distributed neurodegenerative disease characterized clinically by cognitive deficits and pathologically by formation of amyloid-β (Aβ) plaque and neurofibrillary tangles (NFTs) in the brain. Vanadium is a biological trace element that has a function to mimic insulin for diabetes. Bis(ethylmaltolato) oxidovanadium (IV) (BEOV) has been reported to have a hypoglycemic property, but its effect on AD remains unclear. In this study, BEOV was supplemented at doses of 0.2 and 1.0 mmol/L to the AD model mice APPSwe/PS1dE9 for 3 months. The results showed that BEOV substantially ameliorated glucose metabolic disorder as well as synaptic and behavioral deficits of the AD mice. Further investigation revealed that BEOV significantly reduced Aβ generation by increasing the expression of peroxisome proliferator-activated receptor gamma and insulin-degrading enzyme and by decreasing β-secretase 1 in the hippocampus and cortex of AD mice. BEOV also reduced tau hyperphosphorylation by inhibiting protein tyrosine phosphatase-1B and regulating the pathway of insulin receptor/insulin receptor substrate-1/protein kinase B/glycogen synthase kinase 3 beta. Furthermore, BEOV could enhance autophagolysosomal fusion and restore autophagic flux to increase the clearance of Aβ deposits and phosphorylated tau in the brains of AD mice. Collectively, the present study provides solid data for revealing the function and mechanism of BEOV on AD pathology.

Shared Causal Paths underlying Alzheimer's dementia and Type 2 Diabetes

Although Alzheimer's disease (AD) is a central nervous system disease and type 2 diabetes MELLITUS (T2DM) is a metabolic disorder, an increasing number of genetic epidemiological studies show clear link between AD and T2DM. The current approach to uncovering the shared pathways between AD and T2DM involves association analysis; however such analyses lack power to discover the mechanisms of the diseases. As an alternative, we developed novel causal inference methods for genetic studies of AD and T2DM and pipelines for systematic multi-omic casual analysis to infer multilevel omics causal networks for the discovery of common paths from genetic variants to AD and T2DM. The proposed pipelines were applied to 448 individuals from the ROSMAP Project. We identified 13 shared causal genes, 16 shared causal pathways between AD and T2DM, and 754 gene expression and 101 gene methylation nodes that were connected to both AD and T2DM in multi-omics causal networks.

Diabetes as a risk factor for Alzheimer's disease in the Middle East and its shared pathological mediators

The incidence of Alzheimer's disease (AD) has risen exponentially worldwide over the past decade. A growing body of research indicates that AD is linked to diabetes mellitus (DM) and suggests that impaired insulin signaling acts as a crucial risk factor in determining the progression of this devastating disease. Many studies suggest people with diabetes, especially type 2 diabetes, are at higher risk of eventually developing Alzheimer's dementia or other dementias. Despite nationwide efforts to increase awareness, the prevalence of Diabetes Mellitus (DM) has risen significantly in the Middle East and North African (MENA) region which might be due to rapid urbanization, lifestyle changes, lack of physical activity and rise in obesity. Growing body of evidence indicates that DM and AD are linked because both conditions involve impaired glucose homeostasis and altered brain function. Current theories and hypothesis clearly implicate that defective insulin signaling in the brain contributes to synaptic dysfunction and cognitive deficits in AD. In the periphery, low-grade chronic inflammation leads to insulin resistance followed by tissue deterioration. Thus insulin resistance acts as a bridge between DM and AD. There is pressing need to understand on how DM increases the risk of AD as well as the underlying mechanisms, due to the projected increase in age related disorders. Here we aim to review the incidence of AD and DM in the Middle East and the possible link between insulin signaling and ApoE carrier status on Aβ aggregation, tau hyperphosphorylation, inflammation, oxidative stress and mitochondrial dysfunction in AD. We also critically reviewed mutation studies in Arab population which might influence DM induced AD. In addition, recent clinical trials and animal studies conducted to evaluate the efficiency of anti-diabetic drugs have been reviewed.

The Roles of the NLRP3 Inflammasome in Neurodegenerative and Metabolic Diseases and in Relevant Advanced Therapeutic Interventions

Inflammasomes are intracellular multiprotein complexes in the cytoplasm that regulate inflammation activation in the innate immune system in response to pathogens and to host self-derived molecules. Recent advances greatly improved our understanding of the activation of nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasomes at the molecular level. The NLRP3 belongs to the subfamily of NLRP which activates caspase 1, thus causing the production of proinflammatory cytokines (interleukin 1β and interleukin 18) and pyroptosis. This inflammasome is involved in multiple neurodegenerative and metabolic disorders including Alzheimer's disease, multiple sclerosis, type 2 diabetes mellitus, and gout. Therefore, therapeutic targeting to the NLRP3 inflammasome complex is a promising way to treat these diseases. Recent research advances paved the way toward drug research and development using a variety of machine learning-based and artificial intelligence-based approaches. These state-of-the-art approaches will lead to the discovery of better drugs after the training of such a system.

The Structure and Function of α, β and γ-Secretase as Therapeutic Target Enzymes in the Development of Alzheimer’s Disease: A Review

:

Alzheimer's disease is a progressive neurodegenerative disorder that affects the central nervous system. There are several factors that cause AD, like, intracellular hyperphosphorylated Tau tangles, collection of extracellular Amyloid-β42 and generation of reactive oxygen species due to mitochondrial dysfunction. This review analyses the most active target of AD and both types of AD-like early-onset AD and late-onset AD. BACE1 is a β-secretase involved in the cleavage of amyloid precursor protein and the pathogenesis of Alzheimer's disease. The presenilin proteins play a critical role in the pathogenesis of Alzheimer malady by intervening the intramembranous cleavage of amyloid precursor protein and the generation of amyloid β. The two homologous proteins PS1 and PS2 speak to the reactant subunits of particular γ-secretase edifices that intercede an assortment of cellular processes. Natural products are common molecular platforms in drug development in AD. Many natural products are being tested in various animal model systems for their role as a potential therapeutic target in AD. Presently, there are a few theories clarifying the early mechanisms of AD pathogenesis. Recently, research advancements in the field of nanotechnology, which utilize macromolecular strategies to make drugs in nanoscale measurements, offer nanotechnology-based diagnostic tools and drug carriers which are highly sensitive for effective drug targeting in the treatment of Alzheimer’s disease.

Unwinding Complexities of Diabetic Alzheimer by Potent Novel Molecules

Diabetes mellitus is one of the aggressive disorders in global society. No pharmacotherapy is available for permanent diabetes cure, although management is possible with drugs and physical activities. One of the recent complications noticed in type 2 diabetes mellitus includes diabetes-induced Alzheimer. It has been proposed that the possible diabetes-induced Alzheimer could be of type 3 diabetes. A variety of cross-sectional studies have proved that type 2 diabetes mellitus is one of the factors responsible for the pathophysiology of Alzheimer. New drug molecules developed by pharmaceutical companies with adequate neuroprotective effect have demonstrated their efficacy in treatment of Alzheimer in various preclinical diabetic studies. Patients of type 2 diabetes mellitus may show the benefit with existing drugs but may not cause complete cure. Extensive studies are being carried out to find new drug molecules that show their potential as antidiabetic drug and could treat type 2 diabetes-induced Alzheimer as well. This review provides an overview about the recent advancement in pharmacotherapy of diabetes-induced Alzheimer. The pathomechanistic links between diabetes and Alzheimer as well as neurochemical changes in diabetes-induced Alzheimer are also briefed.

Palm Fruit Bioactives augment expression of Tyrosine Hydroxylase in the Nile Grass Rat basal ganglia and alter the colonic microbiome

Tyrosine hydroxylase (TH) catalyzes the hydroxylation of L-tyrosine to L-DOPA. This is the rate-limiting step in the biosynthesis of the catecholamines - dopamine (DA), norepinephrine (NE), and epinephrine (EP). Catecholamines (CA) play a key role as neurotransmitters and hormones. Aberrant levels of CA are associated with multiple medical conditions, including Parkinson's disease. Palm Fruit Bioactives (PFB) significantly increased the levels of tyrosine hydroxylase in the brain of the Nile Grass rat (NGR), a novel and potentially significant finding, unique to PFB among known botanical sources. Increases were most pronounced in the basal ganglia, including the caudate-putamen, striatum and substantia nigra. The NGR represents an animal model of diet-induced Type 2 Diabetes Mellitus (T2DM), exhibiting hyperglycemia, hyperinsulinemia, and insulin resistance associated with hyperphagia and accelerated postweaning weight gain induced by a high-carbohydrate diet (hiCHO). The PFB-induced increase of TH in the basal ganglia of the NGR was documented by immuno-histochemical staining (IHC). This increase in TH occurred equally in both diabetes-susceptible and diabetes-resistant NGR fed a hiCHO. PFB also stimulated growth of the colon microbiota evidenced by an increase in cecal weight and altered microbiome.  The metabolites of colon microbiota, e.g. short-chain fatty acids, may influence the brain and behavior significantly.

Anti-cholinesterase potential of diverse botanical families from Malaysia: Evaluation of crude extracts and fractions from liquid-liquid extraction and acid-base fractionation

ETHNOPHARMACOLOGICAL RELEVANCE

Enhancement of cholinergic functions in the brain via acetylcholinesterase inhibition is one of the main therapeutic strategies to improve symptoms associated with Alzheimer's or related cognitive deficits. There is a pathophysiological correlation between Alzheimer's and Diabetes Mellitus, as well as inflammation and oxidative stress that may cause cognitive decline.

AIM OF THE STUDY

The present study was intended to evaluate anti-cholinesterase potential of 177 Malaysian plant extracts from 148 species known to have related ethnomedicinal uses such as anti-inflammatory, anti-oxidant, anti-diabetic, epilepsy, headache, memory enhancement and anti-aging.

MATERIALS AND METHODS

Anti-cholinesterase screening against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) enzymes was performed on the basis of in-vitro colorimetric 96-well microplate-based assay method. Potent active plant extracts were subjected to liquid-liquid extraction and acid-base fractionation for further analysis.

RESULTS

Fifty-seven plant extracts exhibited potent anti-cholinesterase activities (50-100% inhibition) at 200 μg/ml. Majority of the active plants originated from Fabaceae family. Coccoloba uvifera (L.) L. stem extract manifested the lowest IC₅₀ of 3.78 μg/ml for AChE and 5.94 μg/ml for BChE. A few native species including Tetracera indica (Christm. & Panz.) Merr., Cyrtostachys renda Blume and Ixora javanica (Blume) DC. showed cholinesterase inhibition despite limited local medical applications. Further anti-AChE evaluation (50 μg/ml) of 18 potent plant extracts harbored active polar components in butanol and water fractions, except Senna pendula (Willd.) H.S.Irwin & Barneby (leaves and stems), Acacia auriculiformis Benth. (leaves), Artocarpus altilis (Parkinson ex F.A.Zorn) Fosberg (leaves), and Macaranga tanarius (L.) Mull.Arg. (leaves) that showed inhibitory activity in less polar fractions. The acidic extraction of these four plant species improved their inhibition level against AChE.

CONCLUSION

This study rendered a preliminary overview of anti-cholinesterase activity from diverse Malaysian botanical families in which provided the medical relevance toward these native plant species, especially ones with limited ethnobotanical record or practice.