Quercetin ameliorates chronic unpredicted stress-mediated memory dysfunction in male Swiss albino mice by attenuating insulin resistance and elevating hippocampal GLUT4 levels independent of insulin receptor expression

Insights into the potential benefits of triphala polyphenols toward the promotion of resilience against stress-induced depression and cognitive impairment

In response to environmental challenges, stress is a common reaction, but dysregulation of the stress response can lead to neuropsychiatric disorders, including depression and cognitive impairment. Particularly, there is ample evidence that overexposure to mental stress can have lasting detrimental consequences for psychological health, cognitive function, and ultimately well-being. In fact, some individuals are resilient to the same stressor. A major benefit of enhancing stress resilience in at-risk groups is that it may help prevent the onset of stress-induced mental health problems. A potential therapeutic strategy for maintaining a healthy life is to address stress-induced health problems with botanicals or dietary supplements such as polyphenols. Triphala, also known as Zhe Busong decoction in Tibetan, is a well-recognized Ayurvedic polyherbal medicine comprising dried fruits from three different plant species. As a promising food-sourced phytotherapy, triphala polyphenols have been used throughout history to treat a variety of medical conditions, including brain health maintenance. Nevertheless, a comprehensive review is still lacking. Here, the primary objective of this review article is to provide an overview of the classification, safety, and pharmacokinetics of triphala polyphenols, as well as recommendations for the development of triphala polyphenols as a novel therapeutic strategy for promoting resilience in susceptible individuals. Additionally, we summarize recent advances demonstrating that triphala polyphenols are beneficial to cognitive and psychological resilience by regulating 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) receptors, gut microbiota, and antioxidant-related signaling pathways. Overall, scientific exploration of triphala polyphenols is warranted to understand their therapeutic efficacy. In addition to providing novel insights into the mechanisms of triphala polyphenols for promoting stress resilience, blood brain barrier (BBB) permeability and systemic bioavailability of triphala polyphenols also need to be improved by the research community. Moreover, well-designed clinical trials are needed to increase the scientific validity of triphala polyphenols' beneficial effects for preventing and treating cognitive impairment and psychological dysfunction.

Roles of traditional chinese medicine regulating neuroendocrinology on AD treatment

The incidence of sporadic Alzheimer's disease (AD) is increasing in recent years. Studies have shown that in addition to some genetic abnormalities, the majority of AD patients has a history of long-term exposure to risk factors. Neuroendocrine related risk factors have been proved to be strongly associated with AD. Long-term hormone disorder can have a direct detrimental effect on the brain by producing an AD-like pathology and result in cognitive decline by impairing neuronal metabolism, plasticity and survival. Traditional Chinese Medicine(TCM) may regulate the complex process of endocrine disorders, and improve metabolic abnormalities, as well as the resulting neuroinflammation and oxidative damage through a variety of pathways. TCM has unique therapeutic advantages in treating early intervention of AD-related neuroendocrine disorders and preventing cognitive decline. This paper reviewed the relationship between neuroendocrine and AD as well as the related TCM treatment and its mechanism. The advantages of TCM intervention on endocrine disorders and some pending problems was also discussed, and new insights for TCM treatment of dementia in the future was provided.

Antidepressant Potential of Quercetin and its Glycoside Derivatives: A Comprehensive Review and Update

Depression is a global health problem with growing prevalence rates and serious impacts on the daily life of patients. However, the side effects of currently used antidepressants greatly reduce the compliance of patients. Quercetin is a flavonol present in fruits, vegetables, and Traditional Chinese medicine (TCM) that has been proved to have various pharmacological effects such as anti-depressant, anti-cancer, antibacterial, antioxidant, anti-inflammatory, and neuroprotective. This review summarizes the evidence for the pharmacological application of quercetin to treat depression. We clarified the mechanisms of quercetin regulating the levels of neurotransmitters, promoting the regeneration of hippocampal neurons, improving hypothalamic-pituitary-adrenal (HPA) axis dysfunction, and reducing inflammatory states and anti-oxidative stress. We also summarized the antidepressant effects of some quercetin glycoside derivatives to provide a reference for further research and clinical application.

Quercetin: A Bioactive Compound Imparting Cardiovascular and Neuroprotective Benefits: Scope for Exploring Fresh Produce, Their Wastes, and By-Products

Quercetin, a bioactive secondary metabolite, holds incredible importance in terms of bioactivities, which has been proved by in vivo and in vitro studies. The treatment of cardiovascular and neurological diseases by quercetin has been extensively investigated over the past decade. Quercetin is present naturally in appreciable amounts in fresh produce (fruits and vegetables). However, today, corresponding to the growing population and global demand for fresh fruits and vegetables, a paradigm shift and focus is laid towards exploring industrial food wastes and/or byproducts as a new resource to obtain bioactive compounds such as quercetin. Based on the available research reports over the last decade, quercetin has been suggested as a reliable therapeutic candidate for either treating or alleviating health issues, mainly those of cardiovascular and neurological diseases. In the present review, we have summarized some of the critical findings and hypotheses of quercetin from the available databases foreseeing its future use as a potential therapeutic agent to treat cardiovascular and neurological diseases. It is anticipated that this review will be a potential reference material for future research activities to be undertaken on quercetin obtained from fresh produce as well as their respective processing wastes/byproducts that rely on the circular concept.

Quercetin relieves D-amphetamine-induced manic-like behaviour through activating TREK-1 potassium channels in mice

BACKGROUND AND PURPOSE

Quercetin is a well-known plant flavonoid with neuroprotective properties. Earlier work suggested it may relieve psychiatric disorders, cognition deficits and memory dysfunction through anti-oxidant and/or radical scavenging mechanisms. In addition, quercetin modulated the physiological function of some ion channels. However, the detailed ionic mechanisms of the bioeffects of quercetin remain unknown.

EXPERIMENTAL APPROACH

Effects of quercetin on neuronal activities in the prefrontal cortex (PFC) and its ionic mechanisms were analysed by calcium imaging using mice bearing a green fluorescent protein, calmodulin, and M13 fusion protein and patch clamp in acute brain slices from C57BL/6 J mice and in HEK 293 cells. The possible ionic mechanism of action of quercetin on D-amphetamine-induced manic-like effects in mice was explored with c-fos staining and the open field behaviour test.

KEY RESULTS

Quercetin reduced calcium influx triggered by PFC pyramidal neuronal activity. This effect involved increasing the rheobase of neuronal firing through decreasing membrane resistance following quercetin treatment. Spadin, a blocker of TREK-1 potassium channels, also blocked the effect of quercetin on the membrane resistance and neuronal firing. Further, spadin blocked the neuroprotective effects of quercetin. The effects of quercetin on TREK-1 channels could be mimicked by GF109203X, a protein kinase C inhibitor. In vivo, injection of quercetin relieved the manic hyperlocomotion in mice, induced by D-amphetamine. This action was partly alleviated by spadin.

CONCLUSION AND IMPLICATIONS

TREK-1 channels are a novel target for quercetin, by inhibiting PKC. This action could contribute to both the neuroprotective and anti-manic-like effects.

Repurposing of Anti-Diabetic Agents as a New Opportunity to Alleviate Cognitive Impairment in Neurodegenerative and Neuropsychiatric Disorders

Cognitive impairment is a shared abnormality between type 2 diabetes mellitus (T2DM) and many neurodegenerative and neuropsychiatric disorders, such as Alzheimer’s disease (AD) and schizophrenia. Emerging evidence suggests that brain insulin resistance plays a significant role in cognitive deficits, which provides the possibility of anti-diabetic agents repositioning to alleviate cognitive deficits. Both preclinical and clinical studies have evaluated the potential cognitive enhancement effects of anti-diabetic agents targeting the insulin pathway. Repurposing of anti-diabetic agents is considered to be promising for cognitive deficits prevention or control in these neurodegenerative and neuropsychiatric disorders. This article reviewed the possible relationship between brain insulin resistance and cognitive deficits. In addition, promising therapeutic interventions, especially current advances in anti-diabetic agents targeting the insulin pathway to alleviate cognitive impairment in AD and schizophrenia were also summarized.

Gut Microbiota Composition and Epigenetic Molecular Changes Connected to the Pathogenesis of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder, and its pathogenesis is not fully known. Although there are several hypotheses, such as neuroinflammation, tau hyperphosphorylation, amyloid-β plaques, neurofibrillary tangles, and oxidative stress, none of them completely explain the origin and progression of AD. Emerging evidence suggests that gut microbiota and epigenetics can directly influence the pathogenesis of AD via their effects on multiple pathways, including neuroinflammation, oxidative stress, and amyloid protein. Various gut microbes such as Actinobacteria, Bacteroidetes, E. coli, Firmicutes, Proteobacteria, Tenericutes, and Verrucomicrobia are known to play a crucial role in the pathogenesis of AD. These microbes and their metabolites modulate various physiological processes that contribute to AD pathogenesis, such as neuroinflammation and other inflammatory processes, amyloid deposition, cytokine storm syndrome, altered BDNF and NMDA signaling, impairing neurodevelopmental processes. Likewise, epigenetic markers associated with AD mainly include histone modifications and DNA methylation, which are under the direct control of a variety of enzymes, such as acetylases and methylases. The activity of these enzymes is dependent upon the metabolites generated by the host's gut microbiome, suggesting the significance of epigenetics in AD pathogenesis. It is interesting to know that both gut microbiota and epigenetics are dynamic processes and show a high degree of variation according to diet, stressors, and environmental factors. The bidirectional relation between the gut microbiota and epigenetics suggests that they might work in synchrony to modulate AD representation, its pathogenesis, and progression. They both also provide numerous targets for early diagnostic biomarkers and for the development of AD therapeutics. This review discusses the gut microbiota and epigenetics connection in the pathogenesis of AD and aims to highlight vast opportunities for diagnosis and therapeutics of AD.

Pathophysiology linking depression and type 2 diabetes: Psychotherapy, physical exercise, and fecal microbiome transplantation as damage control

Diabetes increases the likelihood of developing depression and vice versa. Research on this bidirectional association has somewhat managed to delineate the interplay among implicated physiological processes. Still, further exploration is required in this context. This review addresses the comorbidity by investigating suspected common pathophysiological mechanisms. One such factor is psychological stress which disturbs the hypothalamic-pituitary-adrenal axis causing hormonal imbalance. This includes elevated cortisol levels, a common biomarker of both depression and diabetes. Disrupted insulin signaling drives the hampered neurotransmission of serotonin, dopamine, and norepinephrine. Also, adipokine hormones such as adiponectin, leptin, and resistin and the orexigenic hormone, ghrelin, are involved in both depression and T2DM. This disarray further interferes with physiological processes encompassing sleep, the gut-brain axis, metabolism, and mood stability. Behavioral coping mechanisms, such as unhealthy eating, mediate disturbed glucose homeostasis, and neuroinflammation. This is intricately linked to oxidative stress, redox imbalance, and mitochondrial dysfunction. However, interventions such as psychotherapy, physical exercise, fecal microbiota transplantation, and insulin-sensitizing agents can help to manage the distressing condition. The possibility of glucagon-like peptide 1 possessing a therapeutic role has also been discussed. Nonetheless, there stands an urgent need for unraveling new correlating targets and biological markers for efficient treatment.

Depression with Comorbid Diabetes: What Evidence Exists for Treatments Using Traditional Chinese Medicine and Natural Products?

Comorbidity between diabetes mellitus (DM) and depression, two chronic and devastating diseases spreading worldwide, has been confirmed by a large body of epidemiological and clinical studies. Due to the bidirectional relationship between DM and depression, this comorbidity leads to poorer outcomes in both conditions. Given the adverse effects and limited effectiveness of the existing therapies for depression associated with diabetes, the development of novel therapeutic drugs with more potency and fewer side effects is still the most important goal. Hence, many researchers have made great efforts to investigate the potential usefulness of traditional Chinese medicine (TCM) and natural products, including natural extracts and purified compounds, in the treatment of comorbid depression in diabetes. Here, we reviewed the related literature on TCM and natural products that can remedy the comorbidity of diabetes and depression and presented them on the basis of their mechanism of action, focusing on shared risk factors, including insulin resistance, oxidative stress and inflammation, and nervous disturbances. In short, this review suggests that TCM and natural products could expand the therapeutic alternatives to ameliorate the association between DM and depressive disorders.

Morin hydrate attenuates chronic stress-induced memory impairment and degeneration of hippocampal subfields in mice: The role of oxidative, nitrergic and neuroinflammatory pathways

Morin hydrate (MH) is the major flavonoid constituent of Morus alba acclaimed to have antioxidant, anti-inflammatory, anti-stress and neuroprotective properties. However, report on the effect of MH on memory performance and the underlying mechanism following chronic stress exposure is lacking. The current study aimed at investigating the neuroprotective effect of MH on chronic unpredictable stress (CUS)-induced memory impairment in mice using the Y maze test. Mice were subjected to unpredicted stress for 14 days, during which MH (5, 10 and 20 mg/kg i.p) or 25 mg/kg Ginseng was administered to them. On the 14th day, 1 h after treatment, learning and memory deficit was evaluated using the Y maze test and thereafter brains were harvested for the estimation of glutathione (GSH), lipid peroxidation product; malondialdehyde (MDA) and nitrite. Levels of inflammatory mediators tumor necrosis factor-alpha (TNF-α) and interleukin1-beta (IL-1β), inducible nitric oxide synthase (iNOS) and nuclear factor-kappa B (NF-кB) expressions were also determined. The hippocampus was stained with hematoxylin-eosin (H&E) to examine any morphological changes in the neurons. Mice exposed to CUS showed evidence of impaired memory and increase levels of MDA, nitrite, TNF-α and IL-1β. Furthermore, CUS reduced GSH level, increased the expressions of iNOS and NFкB immune-positive cells and produced loss of neuronal cells in the hippocampus. The MH treatment however improved memory, reduced MDA and nitrite levels, and enhanced brain GSH levels in CUS-mice. Besides, MH reduced brain levels of TNF-α and IL-1β levels, down regulated the expressions of iNOS and NF-кB and rescue neurons in the hippocampal CA3 region of mice exposed to CUS. The results of the study indicate that MH improved CUS-induced memory impairment, which may be related to its ability to boost antioxidant defense system and suppress neuroinflammatory pathways.

Metformin/Donepezil combination modulates brain antioxidant status and hippocampal endoplasmic reticulum stress in type 2 diabetic rats

Purpose

Diabetes mellitus is associated with perturbations in brain biochemical parameters associated with dementia. This study aimed at comparing the effect of metformin and metformin/donepezil combination on oxidative stress, endoplasmic reticulum stress and inflammation in the brain of diabetic Wistar rats.

Methods

Diabetes was induced by single intraperitoneal injection of 40 mg/kg streptozotocin after administration of 10% fructose for 14 days. Animals were randomly assigned to four groups of five animals each. Group 1 was the normal control and received only distilled water. Groups 2 and 3 were diabetic rats treated with metformin/donepezil combination and metformin only respectively, while group 4 was diabetic control. Treatment lasted for 21 days after confirmation of diabetes. Activities of acetylcholinesterase (AchE), butyrylcholinesterase (BchE), superoxide dismutase (SOD), glutathione peroxidase (GPx) and catalase were evaluated in the brain of diabetic rats. Enzyme-linked immunosorbent assay was used to estimate brain levels of tumour necrosis factor-α (TNF-α), interleukin-6 (IL-6) malondialdehyde and glucose transporter-4 (GLUT4), while expression of endoplasmic reticulum stress markers - glucose regulated protein-78 (GRP78), activating transcription factor-4 (ATF4) and C/EBP homologous protein (CHOP) was determined using real-time PCR in the hippocampus of diabetic rats.

Results

Treatment with metformin/donepezil combination significantly reduced the activities of AchE, BchE as well as levels of malondialdehyde, TNF-α and IL-6, while the activities of SOD, GPx and catalase were significantly increased in the brain. Moreover, expression of ER stress markers was attenuated in the hippocampus.

Conclusion

Metformin/donepezil combination appeared more efficacious than metformin only and could be considered for managing diabetes-associated dementia.

Quercetin ameliorates diabetic encephalopathy through SIRT1/ER stress pathway in db/db mice

Studies have shown that diabetes is an important risk factor for cognitive dysfunction, also called diabetic encephalopathy (DE). Quercetin has been reported to be effective in improving cognitive dysfunction in DE. But its detailed mechanism is still ambiguous. In this study, we used db/db mice to investigate whether quercetin could activate SIRT1 and inhibit ER pathways to improve DE. Behavioral tests (Morris water maze and new objects) showed that quercetin (70 mg/kg) can effectively improve the learning and memory ability in db/db mice. OGTT and ITT tests indicated that quercetin could alleviate impaired glucose tolerance and insulin resistance in db/db mice. Western blot analysis and Nissl staining showed that quercetin can improve the expression of nerve and synapse-associated proteins (PSD93, PSD95, NGF and BDNF) and inhibit neurodegeneration. Meanwhile, quercetin up-regulates SIRT1 protein expression and inhibits the expression of ER signaling pathway-related proteins (PERK, IRE-1α, ATF6, eIF2α, BIP and PDI). In addition, oxidative stress levels were significantly reduced after quercetin treatment. In conclusion, current experimental results indicated that SIRT1/ER stress is a promising mechanism involved in quercetin-treated diabetic encephalopathy.

Simultaneous UPLC-TQ-MS/MS determination of six active components in rat plasma: application in the pharmacokinetic study of Cyclocarya paliurus leaves

Background

Cyclocarya paliurus (Batal.) Ijinskaja (CP) is a monotypic genus plant, also called sweet tea tree that belongs to the Juglandaceae family, which is mainly distributed in the subtropical highlands in China. Our previous work has verified that CP leaves exhibit a potent hyperglycemic effect by inhibiting pancreatic β cell apoptosis through the regulation of MPAK and Akt signaling pathways. However, the components that contribute to this potential health benefit remain undiscovered.

Method

A sensitive, reliable, and validated ultra-performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UPLC–TQ-MS/MS) method was developed to simultaneously determine the presence of six active components (neochlorogenic acid, chlorogenic acid, quercetin-3-O-glucuronide, kaempferol-3-O-rhamnoside, quercetin, and kaempferol) in rat plasma after a single oral administration (in a dosage of 10.5 g/kg) of an extract of CP leaves to rats. The separation was performed on a Waters ACQUITY BEH C₁₈ column (50 mm × 2.1 mm, 1.7 μm). The detection was conducted by multiple reaction monitoring (MRM) in negative ionization mode. The two highest abundant MRM transitions without interference were optimized for each analyte. Acetonitrile and formic acid aqueous solution (0.1%) was used as the mobile phase at a flow rate of 0.3 ml/min.

Result

The precision, accuracy, and recovery all satisfied the criteria of international guidance (Bioanalytical Method Validation Guidance for Industry, Food and Drug Administration), and the analytes were stable in plasma for all tested conditions. The main pharmacokinetic parameters were calculated by plasma concentration versus time profiles using the pharmacokinetics program.

Conclusion

The pharmacokinetic parameters of each compound can facilitate future clinical studies.

Dietary Polyphenols-Important Non-Nutrients in the Prevention of Chronic Noncommunicable Diseases. A Systematic Review

The improvement of the social and economic conditions of society has eliminated the threat of death from the majority of infectious diseases. However, the rapid progress of civilization has created new possibilities for the appearance of factors with adverse effects for the health of society. This has led to increased morbidity from certain diseases, the presence of which had not been observed several centuries ago. Chronic noncommunicable diseases (e.g., cancers, cardio-vascular disorders, diabetes, obesity, neurodegenerative diseases) result from an inappropriate relationship between people and their environment. The common characteristic for all chronic diseases is a “new” form of inflammation, very often called metaflammation, which is considered as a subclinical, permanent inflammation. As a result, metabolic cascade, including cellular oxidative stress, atherosclerotic process, and insulin resistance, occurs, which slowly generates significant deterioration in the organism. Polyphenols are the major group of non-nutrients, considering their diversity, food occurrence, and biological properties. The current review aims to present a wide spectrum of literature data, including the molecular mechanism of their activity and experimental model used, and summarize the recent findings on the multitude of physiological effects of dietary polyphenols towards the prevention of several chronic diseases. However, despite several studies, the estimation of their dietary intake is troublesome and inconclusive, which will be also discussed.

Quercetin conjugated with superparamagnetic iron oxide nanoparticles improves learning and memory better than free quercetin via interacting with proteins involved in LTP

Biomedical application of quercetin (QT) as an effective flavonoid has limitations due to its low bioavailability. Superparamagnetic iron oxide nanoparticle (SPION) is a novel drug delivery system that enhances the bioavailability of quercetin. The effect of short time usage of quercetin on learning and memory function and its signaling pathways in the healthy rat is not well understood. The aim of this study was to investigate the effect of free quercetin and in conjugation with SPION on learning and memory in healthy rats and to find quercetin target proteins involved in learning and memory using Morris water maze (MWM) and computational methods respectively. Results of MWM show an improvement in learning and memory of rats treated with either quercetin or QT-SPION. Better learning and memory functions using QT-SPION reveal increased bioavailability of quercetin. Comparative molecular docking studies show the better binding affinity of quercetin to RSK2, MSK1, CytC, Cdc42, Apaf1, FADD, CRK proteins. Quercetin in comparison to specific inhibitors of each protein also demonstrates a better QT binding affinity. This suggests that quercetin binds to proteins leading to prevent neural cell apoptosis and improves learning and memory. Therefore, SPIONs could increase the bioavailability of quercetin and by this way improve learning and memory.

Computational and In-Vitro Validation of Natural Molecules as Potential Acetylcholinesterase Inhibitors and Neuroprotective Agents

Background:

Cholinesterase inhibitors are the first line of therapy for the management of Alzheimer’s disease (AD), however, it is now established that they provide only temporary and symptomatic relief, besides, having several inherited side-effects. Therefore, an alternative drug discovery method is used to identify new and safer ‘disease-modifying drugs’.

Methods:

Herein, we screened 646 small molecules of natural origin having reported pharmacological and functional values through in-silico docking studies to predict safer neuromodulatory molecules with potential to modulate acetylcholine metabolism. Further, the potential of the predicted molecules to inhibit acetylcholinesterase (AChE) activity and their ability to protect neurons from degeneration was determined through in-vitro assays.

Results:

Based on in-silico AChE interaction studies, we predicted quercetin, caffeine, ascorbic acid and gallic acid to be potential AChE inhibitors. We confirmed the AChE inhibitory potential of these molecules through in-vitro AChE inhibition assay and compared results with donepezil and begacestat. Herbal molecules significantly inhibited enzyme activity and inhibition for quercetin and caffeine did not show any significant difference from donepezil. Further, the tested molecules did not show any neurotoxicity against primary (E18) hippocampal neurons. We observed that quercetin and caffeine significantly improved neuronal survival and efficiently protected hippocampal neurons from HgCl2 induced neurodegeneration, which other molecules, including donepezil and begacestat, failed to do.

Conclusion:

Quercetin and caffeine have the potential as “disease-modifying drugs” and may find application in the management of neurological disorders such as AD.

Safety assessment of Morus nigra L. leaves: Acute and subacute oral toxicity studies in Wistar rats

ETHNOPHARMACOLOGICAL RELEVANCE

Morus nigra L. is a plant native to Asia, and well adapted to the Brazilian climate. It is popularly known as "amoreira preta", and is part of the National List of Plants of Interest to the Brazilian Unified Health System. It is used in folk medicine mainly to soften the effects of menopause, as anti-inflammatory, antidiabetic and antihypertensive. However, information on safe doses and use is still precarious.

AIM OF THE STUDY

To identify the chemical composition of the ethanolic extract of Morus nigra L. leaves (EEMN), as well as perform a toxicological study in male and female rats.

MATERIALS AND METHODS

The chemical composition of the extract was performed by HPLC/DAD. In the acute study, the dose administered was 2000 mg/kg, and signs of toxicity and mortality was observed. In the sub-acute study, the extract was administered at doses of 500, 750 and 1000 mg/kg for 28 days. Behavioral changes, object recognition test, renal and hepatic tissue assessments, biochemical and hematological parameters were determined. The extract was administered orally to male and female rats in both studies.

RESULTS

Quercetin and caffeic acid showed as major compounds in the extract. In the acute treatment, the extract was classified as safe (category 5), according to the protocol. In the subacute study, there was a decrease in AST in males (750 and 1000 mg/kg) and females (1000 mg/kg), reduction of total cholesterol in females (750 and 1000 mg/kg), and increase in renal and hepatic change the LPO levels.

CONCLUSION

The present investigation showed that EEMN did not present significant toxic effects when administered orally. Moreover, presented a potentially protective action of organs and possesses hypocholesterolemic activity, thus, it is shown as a promising natural source to be used in pharmacology.

Combined corticosterone treatment and chronic restraint stress lead to depression associated with early cognitive deficits in mice

Many models, such as chronic mild stress, chronic stress or chronic corticosterone injections are used to induce depression associated with cognitive deficits. However, the induction period in these different models is still long and face constraints when it is short such as in the chronic mild stress done in a minimum period of 21 days. This study aimed to characterize a model of depression with early onset cognitive deficit. 14 days combined chronic injection of corticosterone followed by 2 h restraint stress using a restrainer was used to induce depression with early cognitive deficit onset. The forced swim test, sucrose test and plasma corticosterone concentration were used to assess depression-like characteristics. The Morris water maze, novel object recognition task, as well as hippocampal acetylcholinesterase activity were used to assess cognitive deficit. The combined corticosterone injection + chronic restraint stress group presented with marked depression-like behaviour and a higher plasma corticosterone concentration compared to corticosterone injection alone and restraint stress alone. It also showed an alteration in the learning process, memory deficit as well as increased acetylcholinesterase activity compared to corticosterone injection and restraint stress alone groups. These findings suggest that the combined corticosterone administration and chronic restraint stress can be used not only as an animal model for severe depression, but also for depression with early onset cognitive deficit.

The Implication of the Brain Insulin Receptor in Late Onset Alzheimer's Disease Dementia

Alzheimer's disease (AD) is progressive neurodegenerative disorder characterized by brain accumulation of the amyloid β peptide (Aβ), which form senile plaques, neurofibrillary tangles (NFT) and, eventually, neurodegeneration and cognitive impairment. Interestingly, epidemiological studies have described a relationship between type 2 diabetes mellitus (T2DM) and this pathology, being one of the risk factors for the development of AD pathogenesis. Information as it is, it would point out that, impairment in insulin signalling and glucose metabolism, in central as well as peripheral systems, would be one of the reasons for the cognitive decline. Brain insulin resistance, also known as Type 3 diabetes, leads to the increase of Aβ production and TAU phosphorylation, mitochondrial dysfunction, oxidative stress, protein misfolding, and cognitive impairment, which are all hallmarks of AD. Moreover, given the complexity of interlocking mechanisms found in late onset AD (LOAD) pathogenesis, more data is being obtained. Recent evidence showed that Aβ42 generated in the brain would impact negatively on the hypothalamus, accelerating the "peripheral" symptomatology of AD. In this situation, Aβ42 production would induce hypothalamic dysfunction that would favour peripheral hyperglycaemia due to down regulation of the liver insulin receptor. The objective of this review is to discuss the existing evidence supporting the concept that brain insulin resistance and altered glucose metabolism play an important role in pathogenesis of LOAD. Furthermore, we discuss AD treatment approaches targeting insulin signalling using anti-diabetic drugs and mTOR inhibitors.

Rutin alleviates chronic unpredictable stress-induced behavioral alterations and hippocampal damage in mice

Chronic stress results in neurological complications like depression, cognitive dysfunction, and anxiety disorders. In our previous study, we observed that Urtica dioica leaf extract attenuated chronic stress-induced complications. Further, we observed that Urtica dioica contained a great amount of the flavonoid rutin in it. Hence, we aimed to evaluate the effect of rutin on 21days chronic unpredictable stress (CUS) mouse model. CUS led to a decline in locomotion & muscle coordination abilities, cognitive deficits, anxiety, and depression. These neurobehavioral outcomes were associated with neurodegeneration in the CA3 region of the hippocampus as found by H&E staining. Rutin efficiently rescued the CUS-induced behavioral deficits by reducing depression, anxiety, improving cognition, and locomotor & muscle coordination skills. Further, rutin treatment protected the CUS-induced hippocampal neuronal loss. This study establishes the neuroprotective effect of rutin in chronic stress.