Resveratrol exerts anti-inflammatory and neuroprotective effects to prevent memory deficits in rats exposed to chronic unpredictable mild stress

Stilbenes: a journey from folklore to pharmaceutical innovation

In modern times, medicine is predominantly based on evidence-based practices, whereas in ancient times, indigenous people relied on plant-based medicines with factual evidence documented in ancient books or folklore that demonstrated their effectiveness against specific infections. Plants and microbes account for 70% of drugs approved by the USFDA (U.S. Food and Drug Administration). Stilbenes, polyphenolic compounds synthesized by plants under stress conditions, have garnered significant attention for their therapeutic potential, bridging ancient wisdom with modern healthcare. Resveratrol, the most studied stilbene, initially discovered in grapes, red wine, peanuts, and blueberries, exhibits diverse pharmacological properties, including cardiovascular protection, antioxidant effects, anticancer activity, and neuroprotection. Traditional remedies, documented in ancient texts like the Ayurvedic Charak Samhita, foreshadowed the medicinal properties of stilbenes long before their modern scientific validation. Today, stilbenes are integral to the booming wellness and health supplement market, with resveratrol alone projected to reach a market value of 90 million US$ by 2025. However, challenges in stilbene production persist due to limited natural sources and costly extraction methods. Bioprospecting efforts reveal promising candidates for stilbene production, particularly endophytic fungi, which demonstrate high-yield capabilities and genetic modifiability. However, the identification of optimal strains and fermentation processes remains a critical consideration. The current review emphasizes the knowledge of the medicinal properties of Stilbenes (i.e., cardiovascular, antioxidant, anticancer, anti-inflammatory, etc.) isolated from plant and microbial sources, while also discussing strategies for their commercial production and future research directions. This also includes examples of novel stilbenes compounds reported from plant and endophytic fungi.

Exploring Medicinal Herbs' Therapeutic Potential and Molecular Docking Analysis for Compounds as Potential Inhibitors of Human Acetylcholinesterase in Alzheimer's Disease Treatment

Background and Objectives: Alzheimer's disease (AD) stands as a pervasive neurodegenerative ailment of global concern, necessitating a relentless pursuit of remedies. This study aims to furnish a comprehensive exposition, delving into the intricate mechanistic actions of medicinal herbs and phytochemicals. Furthermore, we assess the potential of these compounds in inhibiting human acetylcholinesterase through molecular docking, presenting encouraging avenues for AD therapeutics. Materials and Methods: Our approach entailed a systematic exploration of phytochemicals like curcumin, gedunin, quercetin, resveratrol, nobiletin, fisetin, and berberine, targeting their capability as human acetylcholinesterase (AChE) inhibitors, leveraging the PubChem database. Diverse bioinformatics techniques were harnessed to scrutinize molecular docking, ADMET (absorption, distribution, metabolism, excretion, and toxicity), and adherence to Lipinski's rule of five. Results: Results notably underscored the substantial binding affinities of all ligands with specific amino acid residues within AChE. Remarkably, gedunin exhibited a superior binding affinity (-8.7 kcal/mol) compared to the reference standard. Conclusions: These outcomes accentuate the potential of these seven compounds as viable candidates for oral medication in AD treatment. Notably, both resveratrol and berberine demonstrated the capacity to traverse the blood-brain barrier (BBB), signaling their aptitude for central nervous system targeting. Consequently, these seven molecules are considered orally druggable, potentially surpassing the efficacy of the conventional drug, donepezil, in managing neurodegenerative disorders.

Folate Deficiency Increased Microglial Amyloid-β Phagocytosis via the RAGE Receptor in Chronic Unpredictable Mild-Stress Rat and BV2 Cells

Depression is often considered one of the prevalent neuropsychiatric symptoms of Alzheimer's disease (AD). β-amyloid (Aβ) metabolism disorders and impaired microglia phagocytosis are potential pathological mechanisms between depression and AD. Folate deficiency (FD) is a risk factor for depression and AD. In this study, we used a chronic unpredictable mild stress (CUMS) rat model and a model of Aβ phagocytosis by BV2 cells to explore the potential mechanisms by which FD affects depression and AD. The results revealed that FD exacerbated depressive behavior and activated microglia in CUMS rats, leading to an increase in intracellular Aβ and phagocytosis-related receptors for advanced glycation end products (RAGE). Then, in vitro results showed that the expression of the RAGE receptor and M2 phenotype marker (CD206) were upregulated by FD treatment in BV2 cells, leading to an increase in Aβ phagocytosis. However, there was no significant difference in the expression of toll-like receptor 4 (TLR4) and clathrin heavy chain (CHC). Furthermore, when using the RAGE-specific inhibitor FPS-ZM1, there was no significant difference in Aβ uptake between folate-normal (FN) and FD BV2 cell groups. In conclusion, these findings suggest FD may promote microglia phagocytosis Aβ via regulating the expression of RAGE or microglia phenotype under Aβ treatment.

Intranasal in situ gelling liquid crystal for delivery of resveratrol ameliorates memory and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin.

Resveratrol exerts anxiolytic-like effects through anti-inflammatory and antioxidant activities in rats exposed to chronic social isolation

Emerging evidence has confirmed resveratrol's (RES) antioxidant, anti-inflammatory, and antidepressant effects. The beneficial effects of RES were confirmed for several emotional and cognitive deficits. This research aimed to assess the impacts of RES on behavior and hippocampal levels of anti-inflammatory and pro-inflammatory factors in rats exposed to chronic social isolation (SI) stress, which is known to induce mental disorders such as depressive-like behavior. The animals were treated by RES (20, 40, or 80 mg/kg/intraperitoneally) for 28 days following a 28-day exposure to stress. Behavioral tests, including the forced swim test (FST), open-field test (OFT), tail suspension test (TST), and sucrose preference test (SPT), assessed depressive symptoms. Finally, the animals were sacrificed, and molecular studies (qPCR and ELISA) were performed. Exposure of animals to SI dramatically increased the immobility of animals in TST and FST, enhanced the time spent in the open-field peripheral zone of the OFT, and reduced the sucrose preference rate. In addition, SI increased serum levels of corticosterone and hippocampal content of MDA, whereas it reduced hippocampal SOD and CAT activities. Moreover, SI upregulated the expression of IL-10, IL-18, and IL-1β and downregulated the expression of TGF-β in the hippocampus. RES treatment (40 & 80 mg/kg) significantly improved the behavioral alterations through the modulation of neuroinflammation and oxidative stress. The 20 mg/kg RES dose was inefficient for treating SI-induced depressive-like behavior. These results indicated that RES attenuated depressive-like behavior in prolonged stressed animals. These properties might be associated with RES-mediated improvements in serum corticosterone and hippocampal inflammatory and oxidative stress biomarkers.

Resveratrol improves vascular endothelial dysfunction in the unpredictable chronic mild stress model of depression in rats by reducing inflammation

Chronic psychological stress may cause depression and it is a risk factor for vascular endothelial dysfunction. Inflammation may contribute to endothelial dysfunction. Resveratrol, which has antiinflammatory and vasculoprotective properties, has been reported its beneficial effects on endothelial dysfunction induced by hypertension, diabetes and, aging. The effects of resveratrol on stress-induced endothelial dysfunction is not investigated yet. This study aimed to investigate the efficacy of resveratrol on vascular function in the unpredictable chronic moderate stress (UCMS) model of rats and to examine the possible mechanisms of resveratrol by assessment of proinflammatory markers. Male rats were assigned to 4 groups (n = 8 for each group): Control, Control+Resveratrol, UCMS, UCMS+Resveratrol. UCMS and UCMS+Resveratrol groups were exposed to the UCMS procedure for 12 weeks. Resveratrol (20 mg/kg/day, i.p., during 12 weeks) was given to the Control+Resveratrol and UCMS+Resveratrol groups.Then depressive-like behaviors were evaluated by forced swimming test. After behavioral tests, systolic blood pressure was recorded. Endothelial function of the thoracic aorta was evaluated by isolated organ bath system. Vascular eNOS expression and inflammatory markers such as TNF-α, IL-1β, IL-6, CRP, ICAM1, MCP in serum and vascular tissue were analyzed to explore the mechanisms of resveratrol. UCMS resulted in depressive-like behavior, endothelial dysfunction and increased inflammatory cytokines in both serum and tissue samples. Resveratrol treatment improved depressive-like behavior, ameliorated vascular dysfunction, and reversed stress-induced inflammation. Our findings suggest that resveratrol exerted antidepressant-like effect and prevented vascular endothelial dysfunction by reducing systemic and peripheral inflammation in UCMS-induced depression in rats. Therefore, resveratrol may be a therapeutic option with a vasculoprotective effect in depression.

Anti-Neuroinflammatory Potential of Natural Products in the Treatment of Alzheimer's Disease

Alzheimer's disease (AD) is an age-related chronic progressive neurodegenerative disease, which is the main cause of dementia in the elderly. Much evidence shows that the onset and late symptoms of AD are caused by multiple factors. Among them, aging is the main factor in the pathogenesis of AD, and the most important risk factor for AD is neuroinflammation. So far, there is no cure for AD, but the relationship between neuroinflammation and AD may provide a new strategy for the treatment of AD. We herein discussed the main etiology hypothesis of AD and the role of neuroinflammation in AD, as well as anti-inflammatory natural products with the potential to prevent and alleviate AD symptoms, including alkaloids, steroids, terpenoids, flavonoids and polyphenols, which are available with great potential for the development of anti-AD drugs.

Resveratrol regulates insulin resistance to improve the glycolytic pathway by activating SIRT2 in PCOS granulosa cells

Scope

Insulin resistance (IR) has a close relationship with the main clinical manifestations of patients with PCOS; hence, the research and development of new drugs to treat PCOS by improving IR is a desiderate task at present. Resveratrol (RES) possesses a variety of beneficial pharmacological functions, such as antioxidation, anti-inflammatory, regulating glucose, and lipid metabolism. However, whether RES could improve IR and the underlying mechanisms remained unclear in PCOS.

Methods and results

SD rats received a high-fat diet and letrozole for 30 days to establish the PCOS model and then intervened with RES for 30 days. The results demonstrated that RES played a protective role on the IR in PCOS rats, which significantly decreased the levels of blood glucose and serum insulin, up regulated the expression of IGF1R, and down regulated the expression of IGF1. In vitro, KGN cells were treated with insulin, RES, and AGK2, respectively. We found that a high dose of insulin (4μg/mL) significantly inhibited KGN cell viability, decreased the level of lactic acid, and increased the level of pyruvate, while RES (25μM) attenuated the growth-inhibitory effect, as well as increased the level of lactic acid and decreased the level of pyruvate after high levels of insulin treatment. Simultaneously, RES up regulated the expression level of the crucial rate-limiting enzymes relating to glycolytic pathways, such as LDHA, HK2, and PKM2. Furthermore, AGK2 remarkably inhibited the expression level of SIRT2, which was similar to the same negative effects processed by insulin. Meanwhile, RES overtly repaired the glycolysis process by reversing the levels of lactic acid and pyruvate, together with up regulating the expression level of LDHA, HK2, and PKM2, after AGK2 treatment.

Conclusion

RES could effectively improve insulin resistance and restore the glycolysis pathway by regulating SIRT2, which may contribute to attenuating the ovarian damage of PCOS rats and provide a potential treatment for patients with PCOS.

Resveratrol alleviates pyraclostrobin-induced lipid peroxidation, oxidative stress, and DNA damage in rats

Pyraclostrobin (Pyra) is a fungicide in the strobilurin class and has proven to be very toxic to organisms primarily aquatic species. Resveratrol (Res) is a phytoalexin that exhibits multiple bioactivities as anti-oxidative, anti-inflammatory, cardiovascular protective, and anti-aging and is found in plant species such as mulberry, peanut, and grape. This study aimed to determine the protective effect of Res against Pyra-induced lipid peroxidation, oxidative stress, and DNA damage in rats. For this purpose, a total of 48 male rats divided into 6 groups - 8 in each group - were exposed to 30 mg/kg Pyra by oral gavage once a day for 30 days and to three different concentrations of Res (5, 10, and 20 mg/kg) together with Pyra. Pyra administration increased liver enzyme parameters and malondialdehyde (MDA) levels whereas decreased glutathione (GSH) levels and activities of superoxide dismutase (SOD) and catalase (CAT). Also, Pyra treatment increased pro-apoptotic (Bax), apoptotic (Caspase-3, Caspase-8, and Caspase-9), pro-inflammatory (NFκB), cancer (CYP2E1), and cell regulatory (p53) gene expressions and decreased anti-apoptotic (Bcl-2) gene expression in the liver. Furthermore, DNA damage in blood and histopathological changes in the liver and kidney were observed with Pyra administration. In contrast, Res administrations in a dose-dependent manner improved Pyra-induced lipid peroxidation, oxidative and DNA damages, expression levels of these genes in the liver, and histopathological changes in the liver and kidney. Consequently, the treatment of Res, known for its anti-oxidant and protective properties, exhibited a protective effect on Pyra-induced lipid peroxidation, oxidant/anti-oxidant status, gene expressions, and DNA damage in rats.

Resveratrol improves follicular development of PCOS rats via regulating glycolysis pathway and targeting SIRT1

Polycystic ovary syndrome (PCOS) is a disease characterized by metabolic disorders. This study aimed to examine the effects of resveratrol treatment on ovulation in the PCOS rat model. Quantitative real-time PCR and immunohistochemistry were used to determine the mRNA and protein expression levels. TNUEL assay was used to evaluate cell apoptosis in ovary. The metabolites were evaluated by liquid chromatography with tandem mass spectrometry. Resveratrol alleviated disrupted estrous cycle and improved granular cell layers, and reversed the decreased proliferation and increased cell apoptosis of granulosa cells in the ovarian tissues of PCOS rats. Resveratrol restored the changes in the mRNA expression levels in the rate-limiting genes of glycolysis in the PCOS ovary. The expression of lactate dehydrogenase A (LDH-A), pyruvate kinase isozyme M2 (PKM2), and sirtuin 1 (SIRT1) was significantly downregulated in ovarian tissues of the PCOS rats; while the resveratrol treatment significantly increased the expression of LDH-A, PKM2, and SIRT1 in the ovarian tissues of PCOS rats. Collectively, the protective effects of resveratrol in the PCOS rats may be associated with the regulation of glycolysis-related mediators including PKM2, LDH-A, and SIRT1. Resveratrol may represent a good candidate in alleviating the development of PCOS.

The effect of minocycline on beta-amyloid-induced memory and learning deficit in male rats: A behavioral, biochemical, and histological study

OBJECTIVES

Minocycline hydrochloride is a semi-synthetic, second-generation tetracycline with neuroprotective, neurorestorative, anti-amyloidogenic, anti-inflammatory, antioxidant, and anti-apoptotic properties. The present study was designed to investigate the potential protective effects of minocycline against beta-amyloid (Aβ)-induced Alzheimer's disease (AD), recognition memory decline, and the possible involved anti-apoptotic mechanisms.

METHODS

The rats were treated with minocycline (50 and 100 mg/kg/day; P.O.) after AD induction for 30 days. Behavioral functions were assessed by employing standard behavioral tests, including novel object recognition (NOR) and passive avoidance learning (PAL) tasks. Then, total antioxidant capacity (TAC) and total oxidant status (TOS) were measured in blood serum using ELISA kits. Apoptosis and the number of Aβ plaques were examined by the TUNEL and Congo red staining, respectively.

RESULTS

Treatment of Aβ rats with minocycline improved memory deficit in the PAL task and a decline in recognition memory in the NOR test. Minocycline at 50 and 100 mg/kg significantly reduced the TOS levels and increased the TAC levels (P < 0.0001). Also, minocycline at 50 and 100 mg/kg reduced the apoptotic index in the hippocampus of Aβ rats. After Congo red staining, the minocycline group showed improved cell morphology and markedly fewer Aβ plaques.

CONCLUSIONS

Minocycline reduced memory and learning deficit in behavioral experiments after Aβ injection, which may be due to its anti-inflammatory and anti-apoptotic effects.

A comprehensive review on the prevention and regulation of Alzheimer's disease by tea and its active ingredients

Alzheimer's disease (AD) has brought a heavy burden to society as a representative neurodegenerative disease. The etiology of AD combines multiple factors, concluding family, gender, head trauma, diseases and social psychology. There are multiple hypotheses explaining the pathogenesis of AD such as β-amyloid (Aβ) deposition and tau hyperphosphorylation, which lead to extracellular amyloid plaques and neurofibrillary tangles in neurons. The existing therapeutic drugs have several disadvantages including single target, poor curative effect, and obvious side effects. Tea contains many bioactive components, such as tea polyphenols (TPP), L-theanine (L-TH), tea pigment, tea polysaccharides and caffeine. The epidemiological investigations have shown that drinking tea can reduce the risk of AD. The mechanisms of tea active ingredients in the prevention and regulation of AD includes reducing the generation and aggregation of Aβ; inhibiting tau aggregation and hyperphosphorylation; inhibiting neuronal apoptosis and regulate neurotransmitters; relieving oxidative stress and neuroinflammation as well as the regulation of intestinal flora. This review summarizes the different signaling pathways that tea active ingredients regulate AD. Furthermore, we propose the main limitations of current research and future research directions, hoping to contribute to the development of natural functional foods based on tea active ingredients in the prevention and treatment of AD.

Neurogenesis in aging and age-related neurodegenerative diseases

Adult neurogenesis, the process by which neurons are generated in certain areas of the adult brain, declines in an age-dependent manner and is one potential target for extending cognitive healthspan. Aging is a major risk factor for neurodegenerative diseases and, as lifespans are increasing, these health challenges are becoming more prevalent. An age-associated loss in neural stem cell number and/or activity could cause this decline in brain function, so interventions that reverse aging in stem cells might increase the human cognitive healthspan. In this review, we describe the involvement of adult neurogenesis in neurodegenerative diseases and address the molecular mechanistic aspects of neurogenesis that involve some of the key aggregation-prone proteins in the brain (i.e., tau, Aβ, α-synuclein, …). We summarize the research pertaining to interventions that increase neurogenesis and regulate known targets in aging research, such as mTOR and sirtuins. Lastly, we share our outlook on restoring the levels of neurogenesis to physiological levels in elderly individuals and those with neurodegeneration. We suggest that modulating neurogenesis represents a potential target for interventions that could help in the fight against neurodegeneration and cognitive decline.

Resveratrol Improves Follicular Development of PCOS Rats by Regulating the Glycolytic Pathway

SCOPE

Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disorder that can cause infertility; however, the underlying mechanisms remain ill-defined, and there are no available drugs or strategies for the treatment of PCOS. This study examined the therapeutic effect of resveratrol in a rat model of PCOS.

METHODS AND RESULTS

PCOS is induced in rats by administration of letrozole and a high fat diet to determine whether resveratrol has a protective effect. Oral administration of resveratrol significantly decreased body weight, as well as the serum levels of testosterone and follicle stimulating hormone. Resveratrol improved the estrous cycle by restoring the thickness and number of granular cells. Resveratrol increased the levels of lactate and ATP, decreased pyruvate levels, and restored the glycolytic process, upregulating LDHA, HK2, and PKM2. Resveratrol also upregulated SIRT2, thereby modulating the expression of rate-limiting enzymes of glycolysis.

CONCLUSION

Resveratrol suppressed damage to the ovaries in PCOS rats by restoring glycolytic activity, providing potential targets for the treatment of PCOS.

Effects of Quercetin and Resveratrol on Zinc Chloride- and Sodium Metavanadate-Induced Passive Avoidance Memory Retention Deficits in Male Mice

Quercetin and resveratrol are found in a variety of fruits and vegetables and have several biological and pharmacological properties. In this study, the effects of quercetin [50 mg/kg, intraperitoneal (i.p.)] and resveratrol (50 mg/kg, i.p.) on zinc chloride (ZnCl₂; 75 mg/kg/d, 2 weeks oral gavage) and sodium metavanadate (SMV; 22.5 mg/kg/d, 2 weeks oral gavage) induced passive avoidance memory retention were investigated in step-through passive avoidance tasks. ZnCl₂ was dissolved in saline and SMV was dissolved in drinking water. Mice received ZnCl₂ or SMV orally for two weeks and were administered quercetin or resveratrol by i.p. injection on day 14, days 12 and 14, or days 10, 12, and 14. At the end of treatment, animals were trained for one day in a step-through passive avoidance task, then alterations in avoidance memory retention were evaluated after 24, 48, 96, and 168 h. Oral consumption of ZnCl₂ and SMV decreased latency time compared with control groups. Both quercetin and resveratrol (50 mg/kg, i.p.) prevented ZnCl₂- and SMV-induced avoidance memory retention impairments and did not significantly alter muscle strength, as demonstrated in rotarod tasks. No significant differences were observed between mice who received single, double, or triple doses of quercetin or resveratrol. The results suggest that quercetin and resveratrol may have preventive effects on ZnCl₂- and SMV-induced memory impairment in male mice.

The Emerging Roles of Antioxidant Enzymes by Dietary Phytochemicals in Vascular Diseases

Vascular diseases are major causes of death worldwide, causing pathologies including diabetes, atherosclerosis, and chronic obstructive pulmonary disease (COPD). Exposure of the vascular system to a variety of stressors and inducers has been implicated in the development of various human diseases, including chronic inflammatory diseases. In the vascular wall, antioxidant enzymes form the first line of defense against oxidative stress. Recently, extensive research into the beneficial effects of phytochemicals has been conducted; phytochemicals are found in commonly used spices, fruits, and herbs, and are used to prevent various pathologic conditions, including vascular diseases. The present review aims to highlight the effects of dietary phytochemicals role on antioxidant enzymes in vascular diseases.

The deleterious effect of stress-induced depression on rat liver: Protective role of resveratrol and dimethyl fumarate via inhibiting the MAPK/ERK/JNK pathway

This study aimed to uncover the protective potentiality of resveratrol and dimethyl fumarate (DMF) in the liver of a chronic unpredictable mild stress (CUMS)-induced depression animal model. Resveratrol and DMF significantly alleviated CUMS-induced behavioral abnormalities in stressed rats through improving sucrose preference in sucrose preference test and decreasing immobility time in a forced swimming test. They also mitigated serum corticosterone levels and elevated serum serotonin levels, which were formerly disturbed in CUMS rats. The hepatoprotective effect is evidenced by improvement in hepatic histopathological examinations, as well as normalized serum alanine aminotransferase and aspartate aminotransferase activities. Molecular signaling of resveratrol and DMF was estimated by diminishing hepatic expression of phosphorylated p38 mitogen-activated protein kinase (MAPK), extracellular signal-regulated kinase1/2 (ERK1/2), and c-Jun N-terminal kinase (JNK). Consequently, they improved the hepatic antioxidant and anti-inflammatory activities as elaborated by the normalization of total antioxidant capacity, glutathione, malondialdehyde, nuclear factor-κB, tumor necrosis factor-α, and myeloperoxidase levels. In addition, they inhibited hepatocyte apoptosis as evidenced by the increased expression of B-cell lymphoma 2, the decreased expression of Bax, as well as the suppressed activity of caspase-3. In conclusion, resveratrol and DMF purveyed a significant anti-depressant effect, which may be mediated, at least in part, via inhibiting the MAPK/ERK/JNK pathway in the CUMS rat model.

Boosting the autophagy-lysosomal pathway by phytochemicals: A potential therapeutic strategy against Alzheimer's disease

The lysosome is a membrane-enclosed organelle in eukaryotic cells, which has basic pattern recognition for nutrient-dependent signal transduction. In Alzheimer's disease, the already declining autophagy-lysosomal function is exacerbated by an increased need for clearance of damaged proteins and organelles in aged cells. Recent evidence suggests that numerous diseases are linked to impaired autophagy upstream of lysosomes. In this way, a comprehensive survey on the pathophysiology of the disease seems necessary. Hence, in the first section of this review, we will discuss the ultimate findings in lysosomal signaling functions and how they affect cellular metabolism and trafficking under neurodegenerative conditions, specifically Alzheimer's disease. In the second section, we focus on how natural products and their derivatives are involved in the regulation of inflammation and lysosomal dysfunction pathways, including how these should be considered a crucial target for Alzheimer's disease therapeutics.

Grape-Derived Polyphenols Ameliorate Stress-Induced Depression by Regulating Synaptic Plasticity

Major depressive disorder (MDD) is associated with stress-induced immune dysregulation and reduced brain-derived neurotrophic factor (BDNF) levels in sensitive brain regions associated with depression. Elevated levels of proinflammatory cytokines and reduced BDNF levels lead to impaired synaptic plasticity mechanisms that contribute to the pathophysiology of MDD. There is accumulating evidence that the administration of polyphenols at doses ranging from 5 to 180 mg/kg of body weight can normalize elevated levels of proinflammatory cytokines and abnormal levels of BDNF and, thus, restore impaired synaptic plasticity mechanisms that mediate depressive behavior in animal models of stress. This review will focus on the mechanisms by which grape-derived polyphenols normalize impaired synaptic plasticity and reduce depressive behavior in animal models of stress.

Resveratrol attenuates intestinal injury in irradiated rats via PI3K/Akt/mTOR signaling pathway

Radiation-induced enteritis is one of the greatest challenges in radiotherapy. The current study was designed to evaluate the ameliorative effect of resveratrol, which exhibits anti-inflammatory property, against radiation-induced intestinal injury in rats and to explore the underlying mechanism. Rats were exposed to a single dose of 5 Gy. Resveratrol (20 mg/kg/day) was orally administered to irradiated rats over 3 weeks. Results showed that resveratrol ameliorated the intestinal oxidative stress parameters; malondialdehyde (MDA) content, glutathione (GSH) level, and catalase (CAT) activity compared to irradiated group. Furthermore, resveratrol reduced the contents of inflammatory cytokines; tumor necrosis factor α (TNF-α), nuclear factor-kappa (NF-κB), and interleukin 1β (IL-1β) in intestine. Western blotting analysis revealed that resveratrol down-regulated the proteins expression of phosphoinositide 3-kinases (PI3K), protein kinase B (Akt) as well as the mammalian target of rapamycin (mTOR) in intestinal tissues of irradiated rats and thus reduced the inflammatory mediator production. These results were confirmed by histopathological investigation. In conclusion, resveratrol attenuated intestinal inflammation following irradiation via modulating PI3K/Akt/mTOR pathway and thereby could be a promising adjuvant in radiotherapy.

Homeostatic changes of some trace elements in geriatric rats in the condition of oxidative stress induced by aluminum and the beneficial role of resveratrol

BACKGROUND

Elderly individuals are exposed to trace element imbalances due to the reduced capacity of their organism to utilize minerals in a direct relationship with many circumstances.

OBJECTIVES AND METHODS

The aim of this study was to assess the protective role of resveratrol upon the homeostatic changes of some trace elements in geriatric rats in the condition of oxidative stress induced by aluminum exposure. Forty Wistar rats, 18-20 months old, were divided randomly into four groups (n = 10): control (C) - receiving 1 ml of physiologically saline (P.S.) via intraperitoneal (i.p) administration, E1 - 1 ml of P.S. and 1000 ppb aluminum sulphate (AS) in drinking water ad libitum, E2 - 20 mg/kg^-1 resveratrol, i.p. and 1000 ppb AS in drinking water, E3 - 20 mg/kg^-1 resveratrol i.p. The groups C and E3 received distilled water as drinking water ad libitum. The i.p administrations were once a week for four weeks period. The levels of oxidative stress marker's were analyzed (glutathione, glutathione' peroxidase, superoxide dismutase, and catalase) of the proteins' (total protein, albumin, and hemoglobin) in serum and also the levels of the main trace elements (copper, zinc, iron, selenium, manganese and magnesium) in blood, liver, kidney and spleen.

RESULTS

Significant decrease (p < 0.05) of total protein (TP), albumin (ALB), catalase (CAT), increase significant (p < 0.05) of glutathione reductase (GSH-r), glutathione peroxidase (GPx) and superoxide dismutase (SOD) in E1 groups, compared with control, E2, and E3 groups was ascertained. There were also observed significant (p < 0.05) decreases in Cu, Zn, Fe and Mg, not significant (p > 0.05) increase of Se and Mn in blood, significant (p < 0.01) increase of Cu, Zn, Mg, Se, Mn in kidney and liver and Fe, in spleen of geriatric rats from E1 group compared to the control group. Insignificant differences (p > 0.05) were recorded in groups which received resveratrol (E2 and E3) compared to the control group, but significant differences (p < 0.05), especially in blood and liver samples, compared to E1.

CONCLUSIONS

The results suggest that resveratrol can prevent the homeostatic imbalance of trace elements in geriatric rats in the condition of oxidative stress induced by aluminum exposure.

Tetramethylpyrazine ameliorates depression by inhibiting TLR4-NLRP3 inflammasome signal pathway in mice

Depression is a common but serious mental illness; meanwhile, it is also an inflammatory disorder. Toll-like receptor 4 (TLR4), as the pattern recognition receptor, has been shown to play a vital role in neuroinflammation. The nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome acts as an important signaling molecule downstream of TLR4 and can promote the maturation of inflammatory cytokines, such as interleukin-1β (IL-1β). Tetramethylpyrazine (TMP) is a natural compound with neuroprotective effects but with unknown mechanisms on its antidepressant-like effect. In this study, we hypothesized that TMP ameliorates depression may be through the inhibition of the TLR4-NF-κB-NLRP3 signal pathway. Our results have shown that chronic unpredictable mild stress (CUMS) that induced the decreased sucrose preference and increased immobile time was prominently reversed by TMP and fluoxetine. Additionally, we also found that CUMS induced the upregulation of proinflammatory cytokines; TLR4 and NLRP3-associated proteins were significantly suppressed by TMP in the prefrontal cortex and hippocampus. TMP also exhibited potent antioxidant effects and increased the monoamine levels in the serum and brain, such as increasing the activity of SOD and GSH-Px, and reducing the activity of MDA in the serum, and elevating the 5-HT and NE concentration in the serum and brain. Moreover, treatment with Cli-095 (TLR4 inhibitor) also markedly inhibited CUMS-induced depression-like behaviors. Taken together, our findings suggested that TMP exerted a potential antidepressant-like effect in CUMS mice, and the molecular mechanisms may relate to inhibit the TLR4-NF-κB-NLRP3 signaling pathway in the brain.

Resveratrol and cognitive decline: a clinician perspective

Resveratrol (3,5,4'-trihydroxystilbene) belongs to a family of polyphenolic compounds known as stilbenes, particularly concentrated in grape and red wine. The aim of our review was to critically review the available evidence of resveratrol effects on brain function and its potential impact on therapy. In preclinical models of cognitive decline, resveratrol displays potent antioxidant activity by scavenging free radicals, reducing quinone reductase 2 activity and upregulating endogenous enzymes. Resveratrol also inhibits pro-inflammatory enzyme expression, reduces nuclear factor-κB activation and cytokine release. Treatment with resveratrol can affect multiple signaling pathway effectors involved in cell survival, programmed cell death and synaptic plasticity. Direct and/or indirect activation of the deacetylase sirtuins by resveratrol has also been suggested. In humans, clinical evidence derived from randomized clinical trials suggests that resveratrol is able to improve cerebral blood flow, cerebral vasodilator responsiveness to hypercapnia, some cognitive tests, perceived performances, and the Aβ₄₀ plasma and cerebrospinal fluid level.

Resveratrol prevents cognitive deficits by attenuating oxidative damage and inflammation in rat model of streptozotocin diabetes induced vascular dementia

Diabetes is one of the risk factors for the development of vascular dementia (VD), leading to endothelial dysfunction and cognitive impairment. Resveratrol has been shown to have antioxidant, antiinflammatory, and neuroprotective effects. The previous studies have also reported that resveratrol improves cognitive and vascular endothelial functions in several pathological conditions. In the present study we aimed to evaluate the effect of resveratrol on cognitive and vascular endothelial function and to explore the mechanisms of its effects in the streptozotocin-induced diabetic rat model of VD. Male Wistar rats were divided into 3 groups (n = 10 in each group): Control, diabetes (DM), DM + resveratrol (DM + RSV) groups. Rats from the DM + RSV group received resveratrol (20 mg/kg/day, ip) for 4 weeks after induction of diabetes and then cognitive functions of the rats were tested by the Morris water maze and a passive avoidance tests. After behavioral tests, endothelial function of thoracic aorta (the endothelium-dependent and -independent vasorelaxant responses) was investigated. To explore the mechanisms of resveratrol, endothelial eNOS, aortic superoxide dismutase (SOD), NADPH oxidase, heme oxygenase-1 (HO-1) levels, TNF-α and IL-1β expressions; serum SOD and NADPH oxidase levels and, hippocampal BDNF, TNF-α and IL-1β expressions were measured. It was shown that DM resulted in severe learning and memory deficits associated with endothelial dysfunction, increased expression of TNF-α and IL-1β, increased oxidative stress levels and decreased expression of eNOS and BDNF. In contrast, resveratrol treatment improved the cognitive decline. It was also found that chronic treatment with resveratrol ameliorated the impaired vascular reactivity. Reveratrol significantly reversed diabetes-induced changes of protein expression. Our data suggest that resveratrol prevents memory deficits, endothelial dysfunction, increased oxidative stress, inflammation and impairment of neurotrophin expression in a VD rat model. Thus, the vasculoprotective and neuroprotective effects of resveratrol may be beneficial in DM patients.

Neuroprotective Role of Phytochemicals

Neurodegenerative diseases are normally distinguished as disorders with loss of neurons. Various compounds are being tested to treat neurodegenerative diseases (NDs) but they possess solitary symptomatic advantages with numerous side effects. Accumulative studies have been conducted to validate the benefit of phytochemicals to treat neurodegenerative diseases including Alzheimer's disease (AD) and Parkinson's disease (PD). In this present review we explored the potential efficacy of phytochemicals such as epigallocatechin-3-galate, berberin, curcumin, resveratrol, quercetin and limonoids against the most common NDs, including Alzheimer's disease (AD) and Parkinson's disease (PD). The beneficial potentials of these phytochemicals have been demonstrated by evidence-based but more extensive investigation needs to be conducted for reducing the progression of AD and PD.

Anti-neuroinflammatory Potential of Natural Products in Attenuation of Alzheimer's Disease

Alzheimer's disease (AD) is a chronic progressive neurodegenerative disorder associated with dementia and cognitive impairment most common in elderly population. Various pathophysiological mechanisms have been proposed by numerous researcher, although, exact mechanism is not yet elucidated. Several studies have been indicated that neuroinflammation associated with deposition of amyloid- beta (Aβ) in brain is a major hallmark toward the pathology of neurodegenerative diseases. So, there is a need to unravel the link of inflammatory process in neurodegeneration. Increased microglial activation, expression of cytokines, reactive oxygen species (ROS), and nuclear factor kappa B (NF-κB) participate in inflammatory process of AD. This review mainly concentrates on involvement of neuroinflammation and the molecular mechanisms adapted by various natural compounds, phytochemicals and herbal formulations in various signaling pathways involved in neuroprotection. Currently, pharmacologically active natural products, having anti-neuroinflammatory potential are being focused which makes them potential candidate to cure AD. A number of preclinical and clinical trials have been done on nutritional and botanical agents. Analysis of anti-inflammatory and neuroprotective phytochemicals such as terpenoids, phenolic derivatives, alkaloids, glycosides, and steroidal saponins displays therapeutic potential toward amelioration and prevention of devastating neurodegeneration observed in AD.

The subchronic exposure to malathion, an organophosphate pesticide, causes lipid peroxidation, oxidative stress, and tissue damage in rats: the protective role of resveratrol

The present study was planned to evaluate the protective role of resveratrol (Res) against subchronic malathion exposure in rats over four weeks. In total, 48 Wistar rats were used and divided equally into six groups. The groups were designed as the control group (received only a rodent diet and tap water), the corn oil group (0.5 ml corn oil by the oral route), and the malathion group (100 mg kg-1 day-1 by the oral route). Other three groups received malathion (100 mg kg-1 day-1) plus Res (5, 10, and 20 mg kg-1 day-1, respectively) by the oral route. Malathion increased malondialdehyde and 8-OHdG levels, whereas it decreased glutathione levels. Also, acetylcholinesterase, superoxide dismutase, and catalase activities were found to be low in the blood, liver, kidney, heart, and brain tissues. Biochemical parameters were not notably changed in all groups. In contrast, Res treatment inverted malathion-induced oxidative stress, lipid peroxidation, and activity of enzymes. Additionally, malathion-induced histopathological changes in the liver, kidney, heart, and brain were ameliorated by Res treatment. These results demonstrate that malathion increases oxidative stress and decreases the antioxidant status while Res has a protective function against malathion toxicity in rats.

Curcumin and resveratrol rescue cortical-hippocampal system from chronic fluoride-induced neurodegeneration and enhance memory retrieval

Objective: The aim of this study was: (1) to evaluate the neuroprotective effect of resveratrol and curcumin on nicotinamide adenine dinucleotide phosphate diaphorase activity in neuronal cell in subregions of mice brain, (2) to evaluate the effects on antioxidant status and (3) to evaluate the protective effects of phytochemicals on learning and memory following fluoride exposure. Method: Young mice (one month old, body weight (BW) 30 ± 5 mg) were provided with 120 ppm sodium fluoride dissolved in drinking water. They were given curcumin (30 mg/kg BW) or resveratrol (30 mg/kg BW) orally once in a day up to 30 days. Effects of resveratrol and curcumin on spatial learning and memory were studied using Morris water maze and classic maze test. Effects on brain antioxidants' (lactose dehydrogenase (LDH), malondialdehyde and reactive oxygen species) status were also studied in vitro. Histochemistry was done to assess the effect of treatments on nitric oxide neurotransmitter. Result: Our study showed that in fluoride-treated animals, the number of nicotinamide adenine dinucleotide phosphate diaphorase positive neurons, intracellular Ca²⁺, reactive oxygen species level, LDH and malondialdehyde concentration increased significantly. Interestingly, after treatment with curcumin or resveratrol, a significant decrease in the number of nicotinamide adenine dinucleotide phosphate diaphorase positive neurons and antioxidant status was observed. This decrease was more considerable in resveratrol-treated group. Conclusion: Our study indicates that both antioxidants, curcumin and resveratrol, are useful in reducing neurodegeneration in selective areas of cornus ammonis 1 (CA1), CA3, dentate gyrus (DG) and the cortex of mice brain and in recuperating the loss of memory and learning caused due to fluoride exposure.

Brain-derived neurotrophic factor: a mediator of inflammation-associated neurogenesis in Alzheimer's disease

In early- or late-onset Alzheimer's disease (AD), inflammation, which is triggered by pathologic conditions, influences the progression of neurodegeneration. Brain-derived neurotrophic factor (BDNF) has emerged as a crucial mediator of neurogenesis, because it exhibits a remarkable activity-dependent regulation of expression, which suggests that it may link inflammation to neurogenesis. Emerging evidence suggests that acute and chronic inflammation in AD differentially modulates neurotrophin functions, which are related to the roles of inflammation in neuroprotection and neurodegeneration. Recent studies also indicate novel mechanisms of BDNF-mediated neuroprotection, including the modulation of autophagy. Numerous research studies have demonstrated reverse parallel alterations between proinflammatory cytokines and BDNF during neurodegeneration; thus, we hypothesize that one mechanism that underlies the negative impact of chronic inflammation on neurogenesis is the reduction of BDNF production and function by proinflammatory cytokines.

Antidepressant-like effects and cognitive enhancement of Schisandra chinensis in chronic unpredictable mild stress mice and its related mechanism

The aim of this study was to evaluate whether Schisandra chinensis extract (SCE) administration influences chronic unpredictable mild stress (CUMS)-induced depression and cognitive impairment, and explores underlying mechanisms. Sucrose preference test (SPT) and forced swimming test (FST) were used for assessing depressive symptoms, and Y-maze, Morris water maze were used for evaluating cognition processes. The results showed that CUMS (4 weeks) was effective in producing both depression and memory deficits in mice. Additionally, CUMS exposure significantly decreased brain derived neurotrophic factor (BDNF) levels in hippocampus as indicated by ELISA, immunohistochemistry and immunofluorescence assays, accompanied by down-regulated tyrosine kinase receptor B (TrkB)/cAMP-response element binding protein (CREB)/extracellular signal-regulated kinase (ERK) and phosphatidylinositol 3 kinase (PI3K)/ protein kinase B (AKT)/ glycogen synthase kinase-3β (GSK-3β) signaling pathways. Chronic administration of SCE (600 or 1200 mg/kg, i.g.) significantly prevented all these CUMS-induced behavioral and biochemical alterations. It suggested that SCE could improve the depression-like emotional status and associated cognitive deficits in CUMS mice, which might be mediated by regulation of BDNF levels in hippocampus, as well as up-regulating of TrkB/CREB/ERK and PI3K/AKT/GSK-3β pathways.

Anti-inflammatory and antioxidant role of resveratrol on nicotine-induced lung changes in male rats

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Nicotine decreased the antioxidant capacities in male rats.

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The lung of nicotine-treated rats showed severe congestion of the alveolar lung tissues.

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Resveratrol exerts its protective effect by alleviating the extent of oxidative status induced by nicotine.

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Resveratrol improve the enzymatic/non-enzymatic antioxidant defense system in rats treated with combination of nicotine and resveratrol.

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Resveratrol decreases the pathological changes in animals against the lung damage caused by nicotine.

Male albino rats of Wistar strain were injected intraperitoneally with nicotine or/and resveratrol for 4 weeks. Serum Interleukin-2, Interleukin-6, alpha-fetoprotein and tumor necrosis-alpha, as well as plasma 8-hydroxydeoxyguanosine of nicotine-treated rats were increased significantly. Myeloperoxidase, xanthine oxidase, nitric oxide, lipid peroxidation and total oxidative status of the lung in nicotine-treated rats were increased significantly, which were brought down to normal in resveratrol co-treated group. Endogenous antioxidant status as the activity of superoxide dismutase, catalase, glutathione peroxidase, and glucose-6-phosphate dehydrogenases were found to be decreased significantly in the lung of the nicotine-treated group, which were significantly raised in resveratrol-administered groups. The non-enzymatic antioxidants as total antioxidant and thiol levels were decreased significantly as the effect of nicotine that was effectively enhanced by resveratrol treatment. The lung of nicotine-treated rats showed severe congestion of the alveolar lung tissues with scattered congestion per bronchiolar and perivascular cells, as well as, inflammatory cells were observed. The data suggested that resveratrol exerts its protective effect by modulating the extent of oxidative status and improving the enzymatic/non-enzymatic antioxidant defense system, moreover, decreases the pathological changes in animals against the lung damage caused by nicotine.

Resveratrol reversed chronic restraint stress-induced impaired cognitive function in rats

Chronic stress occurs in everyday life, and often results in memory impairments and depressive symptoms. Resveratrol is a natural polyphenol that possesses numerous biological properties, including potent antidepressant‑like effects. The present study aimed to examine the effects of resveratrol treatment on chronic restraint stress (CRS)‑induced cognitive impairment and to explore the underlying molecular mechanisms. Male Wistar rats were exposed to CRS for 21 days in order to induce depressive‑like behavior. The results demonstrated that CRS (6 h/day, 21 days) was able to induce cognitive deficits in rats, as evidenced by Morris water maze and novel object recognition tests. In addition, CRS exposure significantly decreased the mRNA and protein expression levels of hippocampal brain‑derived neurotrophic factor (BDNF) in the rats. Conversely, chronic treatment with resveratrol (80 mg/kg, i.p.; 21 days) significantly prevented the behavioral and biochemical alterations induced by CRS. The effects of resveratrol were nearly identical to those observed with fluoxetine treatment. In conclusion, the present study demonstrated that resveratrol may be a potential therapeutic agent for the treatment of chronic stress‑induced cognitive impairments, and its underlying molecular mechanism may be associated with the increased levels of hippocampal BDNF.

Huanglian-Jie-Du-Tang Extract Ameliorates Depression-Like Behaviors through BDNF-TrkB-CREB Pathway in Rats with Chronic Unpredictable Stress

Neuroinflammation is considered as one of the common pathogeneses of depression. Huanglian-Jie-Du-Tang (HJDT) is a traditional Chinese herbal formula. The present study investigates the antidepressant-like effect of HJDT and its possible mechanism in rats. Rats were given HJDT (2, 4, and 8 g/kg, intragastrically), paroxetine (1.8 mg/kg, intragastrically), or an equivalent volume of saline for 42 days. The depression-related behaviors, including sucrose preference test (SPT), open field test (OFT), novel objective recognition task (NORT), and forced swimming test (FST), were detected. 5-Hydroxytryptamine (5-HT) and dopamine (DA) contents, microglial activation, proinflammatory cytokines, and brain derived neurotrophic factor (BDNF), tropomyosin receptor kinases B (TrkB), and cAMP-responsive element binding protein (CREB) expression were investigated. The results indicated HJDT (2 and 4 g/kg) dramatically ameliorated the depression-like behaviors. Also HJDT decreased the number of microglia and the proinflammatory cytokines in hippocampus. Western-blotting analysis displayed HJDT upregulated BDNF, TrkB, and pCREB/CREB expression in hippocampus. Particularly, pCREB DNA activity enhanced with HJDT treatment in hippocampus. But there was no difference in the 5-HT and DA contents with HJDT treatment. In conclusion, it was supposed that HJDT might be a potential Chinese medicine decoction for treating or alleviating complex symptoms of depression through BDNF-TrkB-CREB pathway.

Lifestyle Modulators of Neuroplasticity: How Physical Activity, Mental Engagement, and Diet Promote Cognitive Health during Aging

The number of the elderly across the globe will approximate 2.1 billion by 2050. Juxtaposed against this burgeoning segment of the population is evidence that nonpathological aging is associated with an increased risk for cognitive decline in a variety of domains, changes that can cause mild disability even before the onset of dementia. Given that pharmacological treatments that mitigate dementia are still outstanding, alternative therapeutic options are being investigated increasingly. The results from translational studies have shown that modifiable lifestyle factors-including physical activity, cognitive engagement, and diet-are a key strategy for maintaining brain health during aging. Indeed, a multiplicity of studies has demonstrated relationships between lifestyle factors, brain structure and function, and cognitive function in aging adults. For example, physical activity and diet modulate common neuroplasticity substrates (neurotrophic signaling, neurogenesis, inflammation, stress response, and antioxidant defense) in the brain whereas cognitive engagement enhances brain and cognitive reserve. The aims of this review are to evaluate the relationship between modifiable lifestyle factors, neuroplasticity, and optimal brain health during aging; to identify putative mechanisms that contribute positive brain aging; and to highlight future directions for scientists and clinicians. Undoubtedly, the translation of cutting-edge knowledge derived from the field of cognitive neuroscience will advance our understanding and enhance clinical treatment interventions as we endeavor to promote brain health during aging.

Semisynthesis and biological evaluation of prenylated resveratrol derivatives as multi-targeted agents for Alzheimer's disease

A series of prenylated resveratrol derivatives were designed, semisynthesized and biologically evaluated for inhibition of β-secretase (BACE1) and amyloid-β (Aβ) aggregation as well as free radical scavenging and neuroprotective and neuritogenic activities, as potential novel multifunctional agents against Alzheimer's disease (AD). The results showed that compound 4b exhibited good anti-Aβ aggregation (IC₅₀ = 4.78 µM) and antioxidant activity (IC₅₀ = 41.22 µM) and moderate anti-BACE1 inhibitory activity (23.70% at 50 µM), and could be a lead compound. Moreover, this compound showed no neurotoxicity along with a greater ability to inhibit oxidative stress on P19-derived neuronal cells (50.59% cell viability at 1 nM). The neuritogenic activity presented more branching numbers (9.33) and longer neurites (109.74 µm) than the control, and was comparable to the quercetin positive control. Taken together, these results suggest compound 4b had the greatest multifunctional activities and might be a very promising lead compound for the further development of drugs for AD.

Mechanism of depression as a risk factor in the development of Alzheimer's disease: the function of AQP4 and the glymphatic system

BACKGROUND

Many studies have indicated that a history of depression increases the risk of developing Alzheimer's disease (AD); however, the potential pathogenestic mechanism by which depression functions as a high risk factor for AD remains unknown. Recently, a "cerebral lymphatic system" referred to as "glymphatic system" has been demonstrated to be responsible for neuronal extracellular waste protein clearance via a paravascular pathway. However, the function of glymphatic pathway has not been determined in depressive disorders.

METHODS

The present study used an animal model of chronic unpredictable mild stress (CUMS) to determine the function of glymphatic pathway by using fluorescence tracers. Immunohistochemistry was used to assess the accumulation of endogenous mouse and exogenous human amyloid beta 42 (Aβ42) in CUMS-treated mice with or without treatment with antidepressant fluoxetine.

FINDINGS

Glymphatic pathway circulation was impaired in mice treated with CUMS; moreover, glymphatic pathway dysfunction suppressed Aβ42 metabolism, because the accumulation of endogenous and exogenous Aβ42 was increased in the brains of the CUMS-treated mice. However, treatment with fluoxetine reversed these destructive effects of CUMS on glymphatic system. In anhedonic mice, the expression of the water channel aquaporin 4 (AQP4), a factor in glymphatic pathway dysfunction, was down-regulated in cortex and hippocampus.

CONCLUSION

The dysfunction of glymphatic system suggested why a history of depression may be a strong risk factor for AD in anhedonic mice. We hope our study will contribute to an understanding of the risk mechanism of depressive disorder in the development of AD and the mechanisms of antidepressant therapies in AD.

Resveratrol: A Potential Hippocampal Plasticity Enhancer

The search for molecules capable of restoring altered hippocampal plasticity in psychiatric and neurological conditions is one of the most important tasks of modern neuroscience. It is well established that neural plasticity, such as the ability of the postnatal hippocampus to continuously generate newly functional neurons throughout life, a process called adult hippocampal neurogenesis (AHN), can be modulated not only by pharmacological agents, physical exercise, and environmental enrichment, but also by “nutraceutical” agents. In this review we focus on resveratrol, a phenol and phytoalexin found in the skin of grapes and red berries, as well as in nuts. Resveratrol has been reported to have antioxidant and antitumor properties, but its effects as a neural plasticity inducer are still debated. The current review examines recent evidence implicating resveratrol in regulating hippocampal neural plasticity and in mitigating the effects of various disorders and diseases on this important brain structure. Overall, findings show that resveratrol can improve cognition and mood and enhance hippocampal plasticity and AHN; however, some studies report opposite effects, with resveratrol inhibiting aspects of AHN. Therefore, further investigation is needed to resolve these controversies before resveratrol can be established as a safe coadjuvant in preventing and treating neuropsychiatric conditions.

Protective effects of resveratrol on aging-induced cognitive impairment in rats

Resveratrol, a polyphenol phytoalexine, has been shown to play a neuroprotective role in the neurodegenerative process in Alzheimer's disease (AD) and improve memory function in dementia. However, the in vivo effect of resveratrol in normal aging models of learning and memory has not yet been evaluated. Therefore, the present neurobehavioral study was undertaken to evaluate the effect of resveratrol on cognitive impairment induced by aging in passive avoidance and Morris water maze (MWM) tests. Male Wistar albino rats were divided into four groups: young control (4month), young resveratrol (4month+RESV), old control (24month) and old resveratrol (24month+RESV). Resveratrol (50mg/kg/day) was given to the 4month+RESV and 24month+RESV groups orally for 12weeks. There was no significant difference between the groups for the first day of latency, while in aged rats, the second day of latency was significantly shortened compared to the young group in the passive avoidance test (p<0.05). Additionally, in the MWM test, the results showed a decrease in the time spent in the escape platform's quadrant in the probe test in aged rats (p<0.05). The administration of resveratrol at 50mg/kg/day increased the retention scores in the passive avoidance test and the time spent in the escape platform's quadrant in the MWM task (p<0.05). Furthermore resveratrol attenuated the protein levels of TNFα and IL1β in the 24-month group. These findings indicate that aging impairs emotional and spatial learning-memory and resveratrol reverses the effect of age-related learning and memory impairment. The results of this study suggest that resveratrol is effective in preventing cognitive deficit in aged rats by inhibiting the production of inflammatory cytokines.