Neuroprotective role of Indirubin-3'-monoxime, a GSKβ inhibitor in high fat diet induced cognitive impairment in mice

The Possible Neuroprotective Effect of Caffeic Acid on Cognitive Changes and Anxiety-Like Behavior Occurring in Young Rats Fed on High-Fat Diet and Exposed to Chronic Stress: Role of β-Catenin/GSK-3B Pathway

Lifestyle influences physical and cognitive development during the period of adolescence greatly. The most important of these lifestyle factors are diet and stress. Therefore, the aim of this study was to investigate the impact of high fat diet (HFD) and chronic mild stress on cognitive function and anxiety-like behaviors in young rats and to study the role of caffeic acid as a potential treatment for anxiety and cognitive dysfunction. Forty rats were assigned into 4 groups: control, HFD, HFD + stress, and caffeic acid-treated group. Rats were sacrificed after neurobehavioral testing. We detected memory impairment and anxiety-like behavior in rats which were more exaggerated in stressed rats. Alongside the behavioral changes, there were biochemical and histological changes. HFD and/or stress decreased hippocampal brain-derived neurotrophic factor (BDNF) levels and induced oxidative and inflammatory changes in the hippocampus. In addition, they suppressed Wnt/β-catenin pathway which was associated with activation of glycogen synthase kinase 3β (GSK3β). HFD and stress increased arginase 1 and inducible nitric oxide synthase (iNOS) levels as well. These disturbances were found to be aggravated in stressed rats than HFD group. However, caffeic acid was able to reverse these deteriorations leading to memory improvement and ameliorating anxiety-like behavior. So, the current study highlights an important neuroprotective role for caffeic acid that may guard against induction of cognitive dysfunction and anxiety disorders in adolescents who are exposed to HFD and/or stress.

Water vs. Organic Solvents: Water-Controlled Divergent Reactivity of 2-Substituted Indoles

Water is not a good solvent for most organic compounds, yet water can offer many benefits to some organic reactions, hence enriching organic chemistry. Herein, the unique divergent reactivity of 2-substituted indoles with ⋅NO sources is presented. The amount of water solvent was harnessed for a scalable, benign, and expedient synthesis of indolenine oximes, albeit with water's inability to dissolve the reactants. 2-Methoxyethyl nitrite, which has been tailored for reactions in water, empowered this protocol by enhancing the product selectivity. We further report on chemoselective transformations of the products that rely on their structural features. Our findings are expected to offer access to an underexplored chemical space. The platform is also applicable to oximinomalonate synthesis. Mechanistic studies revealed the important role of water in the reversal of stability between oxime and nitroso compounds, promoting the proton transfer.

Exploring the active compounds and potential mechanism of the anti-nonalcoholic fatty liver disease activity of the fraction from Schisandra chinensis fruit extract based on multi-technology integrated network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis fruit is a well-known traditional Chinese medicine (TCM) that has been used to treat various liver diseases. Our previous study revealed that its extract is effective against nonalcoholic fatty liver disease (NAFLD).

AIM OF THIS STUDY

This study aimed to elucidate the active components and explore the underlying mechanisms of action of S. chinensis fruit in the treatment of NAFLD.

MATERIALS AND METHODS

A HepG2 cell model was used to screen the anti-NAFLD activity of the fraction from S. chinensis fruit extract. Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) was used to determine the components of the active fraction. Active compounds, potential targets, and key pathways were predicted for the active fraction treatment of NAFLD using network pharmacology. The anti-NAFLD effects of the active fraction and core active compound 3 were further validated using a high-fat diet (HFD)-induced NAFLD mouse model, intraperitoneal glucose tolerance test (IPGTT), and intraperitoneal insulin tolerance test (IPITT). Related hepatic mRNA expression was detected using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) to preliminarily validate the mechanism.

RESULTS

In vitro experiments showed that the active fraction of S. chinensis fruit ethanol (EtOH) extract was mainly concentrated in the soluble fraction of petroleum ether (PET). Thirty-seven lignans were identified in this active fraction using UPLC-Q-TOF/MS. Network pharmacology studies have indicated that its anti-NAFLD effects lie in three major active lignans (3, 24, and 27) contained in PET, which may regulate the insulin resistance signaling pathway. In vivo experiments demonstrated that PET and core active compound 3 treatment significantly attenuated hepatic steatosis and reduced the levels of serum alanine transaminase (ALT), aspartate transaminase (AST), insulin, malondialdehyde (MDA), hepatic triglyceride (TG), and total cholesterol (TC) in HFD-induced mice (P < 0.05). Moreover, treatment with PET and compound 3 alleviated glucose tolerance and insulin resistance. These beneficial effects can be achieved by regulating the expression of Pik3ca, Gsk3β, Jnk1, and Tnf-α.

CONCLUSION

This study identified the main active fraction and compounds responsible for the anti-NAFLD activity of S. chinensis fruit. This mechanism may be related to regulation of the resistance pathway.

Epigenetic regulation and autophagy modulation debilitates insulin resistance associated Alzheimer's disease condition in rats

Insulin resistance (IR) and accumulation of amyloid beta (Aβ) oligomers are potential causative factor for Alzheimer's Disease (AD). Simultaneously, enhanced clearance level of these oligomers through autophagy activation bring novel insights into their therapeutic paradigm. Autophagy activation is negatively correlated with mammalian target of rapamycin (mTOR) and dysregulated mTOR level due to epigenetic alterations can further culminate towards AD pathogenesis. Therefore, in the current study we explored the neuroprotective efficacy of rapamycin (rapa) and vorinostat (vori) in-vitro and in-vivo. Aβ1-42 treated SH-SY5Y cells were exposed to rapa (20 μM) and vori (4 μM) to analyse mRNA expression of amyloid precursor protein (APP), brain derived neurotrophic factor (BDNF), glial cell derived neurotrophic factor (GDNF), neuronal growth factor (NGF), beclin-1, microtubule-associated protein 1A/1B-light chain 3-phosphatidylethanolamine conjugate (LC3), lysosome-associated membrane protein 2 (LAMP2) and microtubule associated protein 2 (MAP2). In order to develop IR condition, rats were fed a high fat diet (HFD) for 8 weeks and then subjected to intracerebroventricular Aβ1-42 administration. Subsequently, their treatment was initiated with rapa (1 mg/kg, i.p.) and vori (50 mg/kg, i.p.) once daily for 28 days. Morris water maze was performed to govern cognitive impairment followed by sacrification for subsequent mRNA, biochemical, western blot and histological estimations. For all the measured parameters, a significant improvement was observed amongst the combination treatment group in contrast to that of the HFD + Aβ1-42 group and that of the groups treated with the drugs alone. Outcomes of the present study thus suggest that combination therapy with rapa and vori provide a prospective therapeutic approach to ameliorate AD symptoms exacerbated by IR.

Neuroprotective Effect of Lentivirus-Mediated FGF21 Gene Delivery in Experimental Alzheimer's Disease is Augmented when Concerted with Rapamycin

Alzheimer type of dementia is accompanied with progressive loss of cognitive function that directly correlates with accumulation of amyloid beta plaques. It is known that Fibroblast growth factor 21 (FGF21), a metabolic hormone, with strong neuroprotective potential, is induced during oxidative stress in Alzheimer's disease. Interestingly, FGF21 cross-talks with autophagy, a mechanism involved in the clearance of abnormal protein aggregate. Moreover, autophagy activation by Rapamycin delivers neuroprotective role in Alzheimer's disease. However, the synergistic neuroprotective efficacy of overexpressed FGF21 along with Rapamycin is not yet investigated. Therefore, the present study examined whether overexpressed FGF21 along with autophagy activation ameliorated neurodegenerative pathology in Alzheimer's disease. We found that cognitive deficits in rats with intracerebroventricular injection of Amyloid beta_1-42 oligomers were restored when injected with FGF21-expressing lentiviral vector combined with Rapamycin. Furthermore, overexpression of FGF21 along with Rapamycin downregulated protein levels of Amyloid beta_1-42 and phosphorylated tau and expression of major autophagy proteins along with stabilization of oxidative stress. Moreover, FGF21 overexpressed rats treated with Rapamycin revamped the neuronal density as confirmed by histochemical, cresyl violet and immunofluorescence analysis. These results generate compelling evidence that Alzheimer's disease pathology exacerbated by oligomeric amyloid beta may be restored by FGF21 supplementation combined with Rapamycin and thus present an appropriate treatment paradigm for people affected with Alzheimer's disease.

Nanocarrier mediated drug delivery as an impeccable therapeutic approach against Alzheimer's disease

For the past several years, dementia, is one of the predominantly observed groups of symptoms in a geriatric population. Alzheimer's disease (AD) is a progressive memory related neurodegenerative disease, for which the current Food and drug administration approved therapeutics are only meant for a symptomatic management rather than targeting the root cause of AD. These therapeutics belong to two classes, Acetylcholine Esterase inhibitors and N-methyl D-aspartate antagonist. Furthermore, to facilitate neuroprotective action in AD, the drugs are majorly expected to reach the specific target area in the brain for the desired efficacy. Thus, there is a huge requirement for drug discovery and development for facilitating the entry of drugs more in brain to exert a specific action. The very first line of defense and the major limitation for the entry of drugs into the brain is the Blood Brain Barrier, followed by Blood-Cerebrospinal Fluid Barrier. More than a barrier, these mainly act as selectively permeable membranes, which allows entry of specific molecules into the brain. Furthermore, specific enzymes result in the degradation of xenobiotics. All these mechanisms pose as hurdles in the way of effective drug delivery in the brain. Thus, novel techniques need to be harbored for the facilitation of the delivery of such drugs into the brain. Nanocarriers are advantageous for facilitating the specific targeted drug treatment in AD. As nanomedicines are one of the novels and most useful approaches for AD, thus the present review mainly focuses on understanding the advanced use of nanocarriers for targeted drug delivery in the management of AD.

Triglyceride Glucose Index is Related with the Risk of Mild Cognitive Impairment in Type 2 Diabetes

BACKGROUND

The triglyceride glucose (TyG) index reflects insulin resistance; the latter being associated with mild cognitive impairment (MCI).

OBJECTIVE

To investigate the clinical value of the TyG index to identify MCI in patients living with type 2 diabetes (T2D) using a cross-sectional study.

METHODS

This cross-sectional study was performed on 517 patients with T2D. The diagnosis of MCI was based on criteria established by the National Institute on Aging-Alzheimer's Association workgroup, and patients were divided into the MCI group and the normal cognitive function (NCF) group. The logistic regression analysis determines whether the TyG index is related to MCI. Subsequently, we constructed the receiver operating characteristic curve (ROC) and calculated the area under the curve (AUC). The nomogram model of the influence factor was established and verified.

RESULTS

Compared to the type 2 diabetes-normal cognitive function (T2D-NCF) group, the MCI subjects were olderand had higher TyG indexes, lower cognitive scores, and lower education levels (p < 0.01). After adjusting for the confounders, the TyG index was associated with MCI (OR = 7.37, 95% CI = 4.72-11.50, p < 0.01), and TyG-BMI was also associated with MCI (OR = 1.02, 95% CI = 1.01-1.02, p<0.01). The TyG index AUC was 0.79 (95% CI = 0.76-0.83). The consistency index of the nomogram was 0. 83[95% CI (0. 79, 0. 86)].

CONCLUSION

Our results indicate that the TyG index and TyG-BMI are associated with MCI in T2D patients, and the TyG index is an excellent indicator of the risk of MCI in T2D patients. The nomogram incorporating the TyG index is useful to predict MCI risk in patients with T2D.

High fat diet and its effects on cognitive health: alterations of neuronal and vascular components of brain

It has been well recognized that intake of diets rich in saturated fats could result in development of metabolic disorders such as type 2 diabetes mellitus, obesity and cardiovascular diseases. Recent studies have suggested that intake of high fat diet (HFD) is also associated with cognitive dysfunction. Various preclinical studies have demonstrated the impact of short and long term HFD feeding on the biochemical and behavioural alterations. This review summarizes studies and the protocols used to assess the impacts of HFD feeding on cognitive performance in rodents. Further, it discuss the key mechanisms that are altered by HFD feeding, such as, insulin resistance, oxidative stress, neuro-inflammation, transcriptional dysregulation and loss of synaptic plasticity. Along with these, HFD feeding also alters the vascular components of brain such as loss of BBB integrity and reduced cerebral blood flow. It is highly possible that these factors are responsible for the development of cognitive deficits as a result of HFD feeding.

Neuroprotective Efficacy of Co-Encapsulated Rosiglitazone and Vorinostat Nanoparticle on Streptozotocin Induced Mice Model of Alzheimer Disease

Anomalies in brain insulin signaling have been demonstrated to be involved in the pathology of Alzheimer disease (AD). In this context, the neuroprotective efficacy of an insulin sensitizer, rosiglitazone, has been confirmed in our previous study. In the present study, we hypothesize that a combination of an epigenetic modulator, vorinostat, along with rosiglitazone can impart improved gene expression of neurotrophic factors and attenuate biochemical and cellular alteration associated with AD mainly by loading these drugs in a surface modified nanocarrier system for enhanced bioavailability and enhanced therapeutic efficacy. Hence, in this study, rosiglitazone and vorinostat were loaded onto a poloxamer stabilized polymeric nanocarrier system and administered to mice in the intracerebroventricular streptozotocin (3 mg/kg) induced model of AD. Treatment with the free drug combination (rosiglitazone 5 mg/kg, vorinostat 25 mg/kg) for 3 weeks attenuated the behavioral, biochemical, and cellular alterations as compared to either treatment alone (rosiglitazone 10 mg/kg, vorinostat 50 mg/kg). Further, the coencapsulated nanoformulation (rosiglitazone 5 mg/kg, vorinostat 25 mg/kg) exerted better neuroprotective efficacy than the free drug combination as evidenced by improved behavioral outcome, reduced oxidative stress, and elevated levels of neurotrophic factors. In conclusion, the synergistic neuroprotective efficacy of rosiglitazone and vorinostat has been increased through the poloxamer stabilized polymeric nanocarrier system.

Mechanisms of Insulin Resistance at the Crossroad of Obesity with Associated Metabolic Abnormalities and Cognitive Dysfunction

Obesity mediates most of its direct medical sequelae through the development of insulin resistance (IR). The cellular effects of insulin occur through two main postreceptor pathways that are the phosphatidylinositol 3-kinase (PI3-K) and the mitogen-activated protein kinase (MAP-K) pathways. Obesity-related IR implicates the PI3-K pathway that confers the metabolic effects of insulin. Numerous and complex pathogenic pathways link obesity with the development of IR, including chronic inflammation, mitochondrial dysfunction (with the associated production of reactive oxygen species and endoplasmic reticulum stress), gut microbiota dysbiosis and adipose extracellular matrix remodelling. IR itself plays a key role in the development of metabolic dysfunction, including hypertension, dyslipidaemia and dysglycaemia. Furthermore, IR promotes weight gain related to secondary hyperinsulinaemia, with a resulting vicious cycle of worsening IR and its metabolic sequelae. Ultimately, IR underlies obesity-related conditions such as type 2 diabetes mellitus (T2D) and polycystic ovary syndrome (PCOS). IR also underlies many obesity-related malignancies, through the effects of compensatory hyperinsulinaemia on the relatively intact MAP-K insulin pathway, which controls cellular growth processes and mitoses. Furthermore, the emergent data over recent decades support an important role of obesity- and T2D-related central IR in the development of cognitive dysfunction, including effects on hippocampal synaptic plasticity. Importantly, IR is largely reversible through the optimisation of lifestyle factors that include regular engagement in physical activity with the avoidance of sedentariness, improved diet including increased fibre intake and sleep sufficiency. IR lies at the key crossroad between obesity and both metabolic and cognitive dysfunction. Given the importance of IR in the pathogenesis of many 21st century chronic diseases and its eminent reversibility, it is important that we all embrace and facilitate optimised lifestyles to improve the future health and wellbeing of the populace.

Functions of Small Organic Compounds that Mimic the HNK-1 Glycan

Because of the importance of the HNK-1 carbohydrate for preferential motor reinnervation after injury of the femoral nerve in mammals, we screened NIH Clinical Collection 1 and 2 Libraries and a Natural Product library comprising small organic compounds for identification of pharmacologically useful reagents. The reason for this attempt was to obviate the difficult chemical synthesis of the HNK-1 carbohydrate and its isolation from natural sources, with the hope to render such compounds clinically useful. We identified six compounds that enhanced neurite outgrowth from cultured spinal motor neurons at nM concentrations and increased their neurite diameter, but not their neurite branch points. Axons of dorsal root ganglion neurons did not respond to these compounds, a feature that is in agreement with their biological role after injury. We refer to the positive functions of some of these compounds in animal models of injury and delineate the intracellular signaling responses elicited by application of compounds to cultured murine central nervous system neurons. Altogether, these results point to the potential of the HNK-1 carbohydrate mimetics in clinically-oriented settings.

Exploring the Neuroprotective Potential of Rosiglitazone Embedded Nanocarrier System on Streptozotocin Induced Mice Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder imposing great threat to an individual's cognitive capability. Mounting evidence suggests that type 2 diabetes mellitus (T2DM) and AD is closely associated with impaired insulin signalling and glucose metabolism in the brain. Member of the peroxisome proliferator-activated receptor (PPAR) family, especially PPARγ agonists, has been well known for their insulin-sensitizing actions, but due to low water solubility, poor penetration into the brain and associated toxicity limit their use clinically. Therefore, this study has been undertaken to investigate the neuroprotective potential of rosiglitazone embedded nanocarrier system on streptozotocin (STZ) induced mice model of AD. In vitro neuroprotective efficacy of rosiglitazone was determined on SH-SY5Y cells by assessing the messenger ribonulceic  acid (mRNA) expression level of genes implicated for cognitive function. AD in mice was developed by intracerebroventricular (ICV) administration of STZ (3 mg/kg) directly into the lateral ventricles of the mice brain. The cognitive parameters and mRNA expression levels were evaluated after treatment with the free form of rosiglitazone as well as its nano-formulated form. It was observed that rosiglitazone elicits neuroprotection on SH-SY5Y cells as evidenced from the upregulation of genes such as cyclic-AMP response element-binding protein (CREB), brain-derived neurotrophic factor (BDNF), glial cell derived neurotrophic factor (GDNF), and nerve growth factor (NGF), which are involved in cognitive functions. Further, the nano-formulated rosiglitazone induced better neuroprotective efficacy than its free drug treatment on animal model of AD as evidenced by attenuating the behavioural and cognitive abnormalities, oxido-nitrosative stress and pro-inflammatory cytokines, i.e. tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6a) along with improved antioxidant enzymes (superoxide dismutase (SOD), reduced glutathione (GSH), acetylcholine, neuronal density and expression of CREB, BDNF, GDNF and NGF in the hippocampal region. Based on the results, it can be concluded that rosiglitazone nanoformulation exerts strong neuroprotection via increasing the mRNA expression of growth factors and inhibition of oxidative stress, and neuroinflammation eventually prevents neuronal injury in AD.

Therapeutic Approaches to Alzheimer's Type of Dementia: A Focus on FGF21 Mediated Neuroprotection

Neurodegenerative disorders are the most devastating disorder of the nervous system. The pathological basis of neurodegeneration is linked with dysfunctional protein trafficking, mitochondrial stress, environmental factors and aging. With the identification of insulin and insulin receptors in some parts of the brain, it has become evident that certain metabolic conditions associated with insulin dysfunction like Type 2 diabetes mellitus (T2DM), dyslipidemia, obesity etc., are also known to contribute to neurodegeneration mainly Alzheimer's Disease (AD). Recently, a member of the fibroblast growth factor (FGF) superfamily, FGF21 has proved tremendous efficacy in diseases like diabetes mellitus, obesity and insulin resistance (IR). Increased levels of FGF21 have been reported to exert multiple beneficial effects in metabolic syndrome. FGF21 receptors are present in certain areas of the brain involved in learning and memory. However, despite extensive research, its function as a neuroprotectant in AD remains elusive. FGF21 is a circulating endocrine hormone which is mainly secreted by the liver primarily in fasting conditions. FGF21 exerts its effects after binding to FGFR1 and co-receptor, β-klotho (KLB). It is involved in regulating energy via glucose and lipid metabolism. It is believed that aberrant FGF21 signalling might account for various anomalies like neurodegeneration, cancer, metabolic dysfunction etc. Hence, this review will majorly focus on FGF21 role as a neuroprotectant and potential metabolic regulator. Moreover, we will also review its potential as an emerging candidate for combating metabolic stress induced neurodegenerative abnormalities.

Electroacupuncture improves cognitive deficits and insulin resistance in an OLETF rat model of Al/D-gal induced aging model via the PI3K/Akt signaling pathway

To investigate the effect of electroacupuncture (EA) on cognitive function and insulin resistance (IR) in an Al/D-gal-induced aging model for Alzheimer's disease (AD) using Ostuka Long-Evans Tokushima Fatty (OLETF) rats. The Al/D-gal-OLETF rats for AD were randomly divided into the EA and non-EA groups. Cognitive function was assessed using the Morris water maze (MWM). The morphology of the hippocampal neurons was observed using hematoxylin & eosin (H&E) staining. Aβ and total Tau in the hippocampus and cerebrospinal fluid (CSF) were detected using western blotting (WB) and enzyme-linked immunosorbent assay (ELISA). Fasting blood glucose (FPG) was determined using the glucose oxidase method. Plasma fasting insulin (FINS), serum C-peptide (C-P), and CSF insulin were detected using ELISA. The expression of the genes and proteins in the PI3K signaling pathway was detected using quantitative real-time PCR and WB. After EA intervention, the hippocampal Aβ and total Tau protein levels, body weight, FPG, FINS, and C-P were significantly decreased. The MWM showed that the percentage of time in the target quadrant of the EA group was elevated in the probe test. The protein levels of p-IRS1, p-IRS2, IDE, and p-GSK3β were significantly increased, while p-PI3K-p85α and p-Akt were decreased. In conclusion, EA improves cognitive function and insulin resistance in rat models of AD. The PI3K/Akt signaling pathway is involved in those changes.

Pentacyclic triterpenoid-rich fraction of the Hardy kiwi (Actinidia arguta) improves brain dysfunction in high fat diet-induced obese mice

This study was performed to investigate the effect of the chloroform fraction from Actinidia arguta (CFAA) on cognitive dysfunction in a C57BL/6 mouse model fed a high-fat diet (HFD) for 12 weeks. The CFAA has the protective effect on high glucose-induced neurotoxicity in MC-IXC cell (neuroblastoma cell line). In a C57BL/6 mouse model fed a HFD for 12 weeks, the improved glucose tolerance and cognitive dysfunction were observed in a group ingesting CFAA. In the brain tissue analysis, the impaired cholinergic, antioxidant system and mitochondria functions were improved in the CFAA group. In addition, in a molecular biology study, it was observed that CFAA improves HFD-induced abnormal insulin signaling such as increase of IRS phosphorylation at serine residues and reduction of Akt phosphorylation caused by the increase of JNK phosphorylation and then inhibited apoptosis. In the UPLC Q-TOF/MS analysis, pentacyclic triterpenoids such as asiatic acid (AA), madecassic acid (MA) were identified in CFAA as main compounds. Therefore, these results propose that Actinidia arguta rich in pentacyclic triterpenoids may be effective as preventive matter a therapeutic strategy to improve neurodegenerative disease caused by HFD.

Glycogen synthase kinase-3 as a key regulator of cognitive function

Glycogen synthase kinase-3 (GSK-3) is a highly conserved and multifunctional serine/threonine protein kinase widely distributed in eukaryotic cells. GSK-3 is originally thought to be an enzyme that regulates glycogen synthesis. It was subsequently found that GSK-3 influences many critical cellular functions, such as cell structure, neural plasticity, gene expression, and neuronal survival. Recently, GSK-3 has been found to be associated with cognition, and its dysregulation leads to cognitive impairments in many diseases, including Alzheimer's disease, diabetes, depression, Parkinson's disease, and others. In this review, we summarized the current knowledge about the structure of GSK-3, the regulation of GSK-3 activity, and its role in cognitive function and cognitive-related disease.

Exploring an anomaly: the synthesis of 7,7′-diazaindirubin through a 7-azaindoxyl intermediate

Generation of 7-azaindoxyl under acidic conditions leads exclusively to 7,7′-diazaindirubin over 7,7′-diazaindigo through a condensation pathway.

Viral Induced Oxidative and Inflammatory Response in Alzheimer's Disease Pathogenesis with Identification of Potential Drug Candidates: A Systematic Review using Systems Biology Approach

Alzheimer's disease (AD) is genetically complex with multifactorial etiology. Here, we aim to identify the potential viral pathogens leading to aberrant inflammatory and oxidative stress response in AD along with potential drug candidates using systems biology approach. We retrieved protein interactions of amyloid precursor protein (APP) and tau protein (MAPT) from NCBI and genes for oxidative stress from NetAge, for inflammation from NetAge and InnateDB databases. Genes implicated in aging were retrieved from GenAge database and two GEO expression datasets. These genes were individually used to create protein-protein interaction network using STRING database (score≥0.7). The interactions of candidate genes with known viruses were mapped using virhostnet v2.0 database. Drug molecules targeting candidate genes were retrieved using the Drug- Gene Interaction Database (DGIdb). Data mining resulted in 2095 APP, 116 MAPT, 214 oxidative stress, 1269 inflammatory genes. After STRING PPIN analysis, 404 APP, 109 MAPT, 204 oxidative stress and 1014 inflammation related high confidence proteins were identified. The overlap among all datasets yielded eight common markers (AKT1, GSK3B, APP, APOE, EGFR, PIN1, CASP8 and SNCA). These genes showed association with hepatitis C virus (HCV), Epstein- Barr virus (EBV), human herpes virus 8 and Human papillomavirus (HPV). Further, screening of drugs targeting candidate genes, and possessing anti-inflammatory property, antiviral activity along with a suggested role in AD pathophysiology yielded 12 potential drug candidates. Our study demonstrated the role of viral etiology in AD pathogenesis by elucidating interaction of oxidative stress and inflammation causing candidate genes with common viruses along with the identification of potential AD drug candidates.

Proteomics of the mediodorsal thalamic nucleus of rats with stress-induced gastric ulcer

BACKGROUND

Stress-induced gastric ulcer (SGU) is one of the most common visceral complications after trauma. Restraint water-immersion stress (RWIS) can cause serious gastrointestinal dysfunction and has been widely used to study the pathogenesis of SGU to identify medications that can cure the disease. The mediodorsal thalamic nucleus (MD) is the centre integrating visceral and physical activity and contributes to SGU induced by RWIS. Hence, the role of the MD during RWIS needs to be studied.

AIM

To screen for differentially expressed proteins in the MD of the RWIS rats to further elucidate molecular mechanisms of SGU.

METHODS

Male Wistar rats were selected randomly and divided into two groups, namely, a control group and an RWIS group. Gastric mucosal lesions of the sacrificed rats were measured using the erosion index and the proteomic profiles of the MD were generated through isobaric tags for relative and absolute quantitation (iTRAQ) coupled with two-dimensional liquid chromatography and tandem mass spectrometry. Additionally, iTRAQ results were verified by Western blot analysis.

RESULTS

A total of 2853 proteins were identified, and these included 65 dysregulated (31 upregulated and 34 downregulated) proteins (fold change ratio ≥ 1.2). Gene Ontology (GO) analysis showed that most of the upregulated proteins are primarily related to cell division, whereas most of the downregulated proteins are related to neuron morphogenesis and neurotransmitter regulation. Ingenuity Pathway Analysis revealed that the dysregulated proteins are mainly involved in the neurological disease signalling pathways. Furthermore, our results indicated that glycogen synthase kinase-3 beta might be related to the central mechanism through which RWIS gives rise to SGU.

CONCLUSION

Quantitative proteomic analysis elucidated the molecular targets associated with the production of SGU and provides insights into the role of the MD. The underlying molecular mechanisms need to be further dissected.

Indirubin-3'-monoxime prevents aberrant activation of GSK-3β/NF-κB and alleviates high fat-high fructose induced Aβ-aggregation, gliosis and apoptosis in mice brain

Deciphering the molecular mechanisms of amyloid pathology and glial cell-mediated neuroinflammation, offers a novel avenue for therapeutic intervention against neurodegeneration. Recent findings demonstrate a crucial link between activation of glycogen synthase kinase-3β (GSK-3β), amyloid deposition and a neuroinflammatory state. However, studies demonstrating the pharmacological effects of GSK-3β inhibition and the interlinked molecular mechanisms still remain elusive. The present study explores whether high fat-high fructose diet (HFFD)-induced neuropathological changes could be alleviated by indirubin-3'-monoxime (IMX), a GSK-3β inhibitor. Male Swiss albino mice (8 weeks old) were fed with normal pellet or HFFD for 60 days. HFFD mice were treated with IMX once daily for last 7 days of the experimental period. HFFD fed-mice had significant amyloid deposits in cerebral cortex and hippocampus, and protein expression analyses showed activation of GSK-3β, nuclear translocation of NF-κB p65 and upregulation of inflammatory (TNF-α, IL-6, COX-2), astrocytic (GFAP), glial surface (CD-68) and pro-apoptotic markers (Bax and caspase-3). IMX treatment promotes the inhibitory phosphorylation of GSK-3β at Ser⁹ and moreover, a marked reduction in the phosphorylation of IKK-β, which prevents translocation and activation of NF-κB. Protein expression studies in IMX-treated brain tissues positively correlate with the anti-neuroinflammatory effects of GSK-3β inhibition. Taken together, our results provide substantial evidence that IMX could potentially attenuate neuroinflammation in coordination with the master transcription factor-NF-κB.

Association of neck circumference and cognitive impairment among Chinese elderly

OBJECTIVES

To investigate the association between neck circumference (NC) and cognitive impairment and interactions between relevant variables to the risk of cognitive impairment.

METHODS

A population-based survey was conducted among elderly inhabitants aged 60 years and over from a community in Shanghai suburb. Multivariate logistic regression analyses were performed to evaluate associations and log likelihood ratio tests to examine interactions.

RESULTS

Cognitive impairment was identified in 269 (10.8%) subjects from 2,500 participants. Higher BMI (OR = 1.55; 95% CI = 1.11-2.16), higher WHR (OR = 1.44; 95% CI = 1.07-1.95), and higher total cholesterol (TC) (OR = 1.52; 95% CI = 1.09-2.13) were significantly associated with the increased risk of cognitive impairment. Significant interactions were observed between TC and a few other relevant variables, respectively.

CONCLUSIONS

NC was associated with the high risk of cognitive impairment. Additive effects of NC with TC on cognitive impairment were observed.

Indirubin Derivative 7-Bromoindirubin-3-Oxime (7Bio) Attenuates Aβ Oligomer-Induced Cognitive Impairments in Mice

Indirubins are natural occurring alkaloids extracted from indigo dye-containing plants. Indirubins could inhibit various kinases, and might be used to treat chronic myelocytic leukemia, cancer and neurodegenerative disorders. 7-bromoindirubin-3-oxime (7Bio), an indirubin derivative derived from indirubin-3-oxime, possesses inhibitory effects against cyclin-dependent kinase-5 (CDK5) and glycogen synthase kinase-3β (GSK3β), two pharmacological targets of Alzheimer's disease (AD). In this study, we have discovered that 2.3–23.3 μg/kg 7Bio effectively prevented β-amyloid (Aβ) oligomer-induced impairments of spatial cognition and recognition without affecting bodyweight and motor functions in mice. Moreover, 7Bio potently inhibited Aβ oligomer-induced expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Furthermore, 7Bio significantly prevented the decreased expression of synapsin-1 and PSD-95, biomarkers of pre-synaptic and post-synaptic proteins in Aβ oligomer-treated mice. The mean optical density (OD) with hyper-phosphorylated tau (pTau), glial fibrillary acidic protein (GFAP) and CD45 positive staining in the hippocampus of 7Bio-treated mice were significantly decreased compared to those of Aβ oligomer-treated mice. In addition, Western blotting analysis showed that 7Bio attenuated Aβ oligomer-decreased expression of pSer9-GSK3β. Those results suggested that 7Bio could potently inhibit Aβ oligomer-induced neuroinflammation, synaptic impairments, tau hyper-phosphorylation, and activation of astrocytes and microglia, which may contribute to the neuroprotective effects of 7Bio. Based on these findings, we expected that 7Bio might be developed as a novel anti-AD lead compound.

Melatonin prevents memory impairment induced by high-fat diet: Role of oxidative stress

Consumption of high-fat diet (HFD) induces oxidative stress in the hippocampus that leads to memory impairment. Melatonin has antioxidant and neuroprotective effects. In this study, we hypothesized that chronic administration of melatonin can prevent memory impairment induced by consumption of HFD. Melatonin was administered to rats via oral gavage (100mg/kg/day) for 4 weeks. HFD was also instituted for the same duration. Behavioral studies were conducted to test spatial memory using the radial arm water maze. Additionally, oxidative stress biomarkers were assessed in the hippocampus. Results showed that HFD impaired both short- and long- term memory (P<0.05), while melatonin treatment prevented such effects. Furthermore, melatonin prevented HFD-induced reduction in levels of GSH, and ratio of GSH/GSSG, and increase in GSSG in the hippocampus. Melatonin also prevented reduction in the catalase activity in hippocampus of animals on HFD. In conclusion, HFD induced memory impairment and melatonin prevented this impairment probably by preventing alteration of oxidative stress in the hippocampus.

Effects of Hypericum scabrum extract on learning and memory and oxidant/antioxidant status in rats fed a long-term high-fat diet

A high-fat diet (HFD) causes deficits in learning and memory by increasing oxidative stress. Antioxidants are known to improve learning and memory. Since Hypericum scabrum (H. scabrum) extract is rich in antioxidants, the aim of this study was to investigate the effects of the administration of H. scabrum extract on passive avoidance learning (PAL), novel object recognition (NOR), and locomotor activity in male rats on a HFD. Fifty-four male Wistar rats (weighing 220 ± 10 g) were divided into the following six groups: (1) Control (standard diet), (2) Ext100 (standard diet supplemented with 100 mg/kg extract once/day), (3) Ext300 (standard diet supplemented with 300 mg/kg extract once/day), (4) HFD (high-fat diet), (5) HFD + Ext100, and (6) HFD + Ext300. Rats in these groups were maintained on their respective diets for 3 months. In the PAL test, the step-through latencies in the retention test (STLr) were significantly higher in the HFD + extract group than in the HFD group. The time spent in the dark compartment (TDC) was significantly lesser and the time spent in exploring the novel object was significantly greater in the HFD + extract group than in the HFD group. In the HFD-fed rats, the activity of catalase had significantly decreased, and level of malondialdehyde had significantly increased; H. scabrum extract administration significantly reversed these changes. In conclusion, these results suggested that the administration of H. scabrum extract and its strong antioxidant properties enhanced learning and memory and reversed the memory impairment induced by chronic HFD consumption.

Bridging Type 2 Diabetes and Alzheimer's Disease: Assembling the Puzzle Pieces in the Quest for the Molecules With Therapeutic and Preventive Potential

Type 2 diabetes (T2D) and Alzheimer's disease (AD) are two age-related amyloid diseases that affect millions of people worldwide. Broadly supported by epidemiological data, the higher incidence of AD among type 2 diabetic patients led to the recognition of T2D as a tangible risk factor for the development of AD. Indeed, there is now growing evidence on brain structural and functional abnormalities arising from brain insulin resistance and deficiency, ultimately highlighting the need for new approaches capable of preventing the development of AD in type 2 diabetic patients. This review provides an update on overlapping pathophysiological mechanisms and pathways in T2D and AD, such as amyloidogenic events, oxidative stress, endothelial dysfunction, aberrant enzymatic activity, and even shared genetic background. These events will be presented as puzzle pieces put together, thus establishing potential therapeutic targets for drug discovery and development against T2D and diabetes-induced cognitive decline-a heavyweight contributor to the increasing incidence of dementia in developed countries. Hoping to pave the way in this direction, we will present some of the most promising and well-studied drug leads with potential against both pathologies, including their respective bioactivity reports, mechanisms of action, and structure-activity relationships.

Ginsenoside Re Ameliorates Brain Insulin Resistance and Cognitive Dysfunction in High Fat Diet-Induced C57BL/6 Mice

The ameliorating effects of ginsenoside Re (G Re) on high fat diet (HFD)-induced insulin resistance in C57BL/6 mice were investigated to assess its physiological function. In the results of behavioral tests, G Re improved cognitive dysfunction in diabetic mice using Y-maze, passive avoidance, and Morris water maze tests. G Re also significantly recovered hyperglycemia and fasting blood glucose level. In the results of serum analysis, G Re decreased triglyceride (TG), total cholesterol (TCHO), low-density lipoprotein cholesterol (LDLC), glutamic-oxaloacetic transaminase (GOT), and glutamic-pyruvic transaminase (GPT) and increased the ratio of high-density lipoprotein cholesterol (HDLC). G Re regulated acetylcholine (ACh), acetylcholinesterase (AChE), malondialdehyde (MDA), superoxide dismutase (SOD), and oxidized glutathione (GSH)/total GSH by regulating the c-Jun N-terminal protein kinase (JNK) pathway. These findings suggest that G Re could be used to improve HFD-induced insulin resistance condition by ameliorating hyperglycemia via protecting the cholinergic and antioxidant systems in the mouse brains.

Indirubin-3-Oxime Prevents H2O2-Induced Neuronal Apoptosis via Concurrently Inhibiting GSK3β and the ERK Pathway

Oxidative stress-induced neuronal apoptosis plays an important role in many neurodegenerative disorders. In this study, we have shown that indirubin-3-oxime, a derivative of indirubin originally designed for leukemia therapy, could prevent hydrogen peroxide (H₂O₂)-induced apoptosis in both SH-SY5Y cells and primary cerebellar granule neurons. H₂O₂ exposure led to the increased activities of glycogen synthase kinase 3β (GSK3β) and extracellular signal-regulated kinase (ERK) in SH-SY5Y cells. Indirubin-3-oxime treatment significantly reversed the altered activity of both the PI3-K/Akt/GSK3β cascade and the ERK pathway induced by H₂O₂. In addition, both GSK3β and mitogen-activated protein kinase inhibitors significantly prevented H₂O₂-induced neuronal apoptosis. Moreover, specific inhibitors of the phosphoinositide 3-kinase (PI3-K) abolished the neuroprotective effects of indirubin-3-oxime against H₂O₂-induced neuronal apoptosis. These results strongly suggest that indirubin-3-oxime prevents H₂O₂-induced apoptosis via concurrent inhibiting GSK3β and the ERK pathway in SH-SY5Y cells, providing support for the use of indirubin-3-oxime to treat neurodegenerative disorders caused or exacerbated by oxidative stress.

Epigenetic modifications by inhibiting histone deacetylases reverse memory impairment in insulin resistance induced cognitive deficit in mice

Insulin resistance has been reported as a strong risk factor for Alzheimer's disease. However the molecular mechanisms of association between these still remain elusive. Various studies have highlighted the involvement of histone deacetylases (HDACs) in insulin resistance and cognitive deficits. Thus, the present study was designed to investigate the possible neuroprotective role of HDAC inhibitor, suberoylanilide hydroxamic acid (SAHA) in insulin resistance induced cognitive impairment in mice. Mice were subjected to either normal pellet diet (NPD) or high fat diet (HFD) for 8 weeks. HFD fed mice were treated with SAHA at 25 and 50 mg/kg i.p. once daily for 2 weeks. Serum insulin, glucose, triglycerides, total cholesterol and HDL-cholesterol levels were measured. A battery of behavioral parameters was performed to assess cognitive functions. Level of tumour necrosis factor (TNF-α) was measured in hippocampus to assess neuroinflammation. To further explore the molecular mechanisms we measured the histone H3 acetylation and brain derived neurotrophic factor (BDNF) level. HFD fed mice exhibit characteristic features of insulin resistance. These mice also showed a severe deficit in learning and memory along with reduced histone H3 acetylation and BDNF levels. In contrast, the mice treated with SAHA showed significant and dose dependent improvement in insulin resistant condition. These mice also showed improved learning and memory performance. SAHA treatment ameliorates the HFD induced reduction in histone H3 acetylation and BDNF levels. Based upon these results, it could be suggested that HDAC inhibitors exert neuroprotective effects by increasing H3 acetylation and subsequently BDNF level.

Insulin resistance and cognitive dysfunction

Epidemiologic and biologic studies support a link between type 2 diabetes mellitus and Alzheimer's disease, but the precise mechanism linking the two remains unclear. Growing evidence supports the concept that insulin resistance is important in the pathogenesis of cognitive impairment and neurodegeneration. Insulin plays a profound role in cognitive function. Impaired insulin signaling in the advancement of cognitive dysfunction is relevant to the pathophysiologic mechanisms of cognitive impairment. In this paper we discuss the relationship between insulin resistance and cognitive impairment and review potential mechanisms of this disease process. Evidence, to date, suggests that brain insulin resistance is an independent risk factor for cognitive impairment.

Glycogen synthase kinase-3 as a therapeutic target for cognitive dysfunction in neuropsychiatric disorders

The serine/threonine kinase glycogen synthase kinase-3 (GSK-3) is involved in a broad range of cellular processes including cell proliferation, apoptosis and inflammation. It is now also increasingly acknowledged as having a role to play in cognitive-related processes such as neurogenesis, synaptic plasticity and neural cell survival. Cognitive impairment represents a major debilitating feature of many neurodegenerative and psychiatric disorders, including Alzheimer's disease, mood disorders, schizophrenia and fragile X syndrome, as well as being a result of traumatic brain injury or cranial irradiation. Accordingly, GSK-3 has been identified as an important therapeutic target for cognitive impairment, and recent preclinical studies have yielded important evidence demonstrating that GSK-3 inhibitors may be useful therapeutic interventions for restoring cognitive function in some of these brain disorders. The current review summarises the role of GSK-3 as a regulator of cognitive-dependent functions, examines current preclinical and clinical evidence of the potential of GSK-3 inhibitors as therapeutic agents for cognitive impairments in neuropsychiatric disorders, and offers some insight into the current obstacles that are impeding the clinical use of selective GSK-3 inhibitors in the treatment of cognitive impairment.

Synergistic effects of GSK-3β and HDAC inhibitors in intracerebroventricular streptozotocin-induced cognitive deficits in rats

Recent studies suggest the importance of combined treatment of glycogen synthase kinase-3β (GSK-3β) and histone deacetylase (HDAC) inhibition in various in vitro and in vivo models of neurological diseases. Lithium chloride (LiCl) and valproate (VPA), two well-known mood stabilizers, have been reported to act through GSK-3β and HDAC inhibition, respectively. The present study was designed to investigate the potential of low-dose combination of LiCl and VPA in intracerebroventricular streptozotocin (ICV-STZ)-induced cognitive deficits in rats. STZ was injected twice (3 mg/kg ICV) on alternate days (day 1 and day 3) in rats. The ICV-STZ-treated rats received LiCl (60 mg/kg, i.p.), VPA (200 mg/kg, i.p.), and combination of both LiCl (60 mg/kg, i.p.) and VPA (200 mg/kg, i.p.) drugs for a period of 3 weeks. The ICV-STZ administration results in significant memory impairment, elevated oxidative-nitrosative stress, and reduced brain-derived neurotrophic factor (BDNF) levels. Using a battery of behavioral and biochemical tests, we observed that co-treatment of both drugs showed synergistic effect in improving the spatial learning and memory impairment as well as significantly attenuated the oxidative stress markers in STZ-treated rats as compared to either drug alone. Moreover, the combination of both drugs reversed the hyperinsulinemic brain condition and improved the BDNF levels in STZ-treated rats. Based upon these results, it could be suggested that a low-dose combination of LiCl and VPA produces synergistic and more consistent neuroprotective effects in ICV-STZ-induced cognitive deficits in rats.

Histone deacetylase inhibitor, trichostatin A, improves learning and memory in high-fat diet-induced cognitive deficits in mice

Metabolic syndrome is increasingly recognized for its effects on cognitive health. Recent studies have highlighted the role of histone deacetylases (HDACs) in metabolic syndrome and cognitive functions. The present study was designed to investigate the possible therapeutic role of a HDAC inhibitor, trichostatin A (TSA), in cognitive impairment associated with metabolic syndrome. To ascertain the mechanisms involved, we fed mice with high-fat diet (HFD) for 4 weeks and examined changes in behavioral and biochemical/oxidative stress markers. Mice subjected to HFD exhibited characteristic features of metabolic disorder, viz., hyperglycemia, hypertriglyceridemia, hypercholesterolemia, and lower high-density lipoprotein (HDL) cholesterol levels. Moreover, these mice showed severe deficits in learning and memory as assessed by the Morris water maze and passive avoidance tasks along with elevated oxidative stress and inflammatory markers in brain homogenates. The observed changes occurred concurrently with reduced brain-derived neurotrophic factor (BDNF). In contrast, the mice treated with the HDAC inhibitor, TSA (0.5 and 1 mg/kg, i.p.), showed a significant and dose-dependent reduction in serum glucose, triglycerides, and total cholesterol along with improvement in HDL-cholesterol levels and learning and memory performance. TSA treatment also results in alleviation of oxidative stress and neuroinflammatory markers. Moreover, TSA significantly augmented the BDNF levels in HFD-fed mice. Thus, based upon these observations, it may be suggested that HDAC inhibition could be a novel therapeutic strategy to combat cognitive impairment associated with metabolic syndrome.