Neuroprotective effect of resveratrol in diabetic cerebral ischemic-reperfused rats through regulation of inflammatory and apoptotic events

Effect and mechanisms of resveratrol in animal models of ischemic stroke: A systematic review and Bayesian meta-analysis

Resveratrol (RSV) holds promise as cerebroprotective treatment in cerebral ischemia. This systematic review aims to assess the effects and mechanisms of RSV in animal models of ischemic stroke. We searched Medline, Embase and Web of Science to identify 75 and 57 eligible rodent studies for qualitative and quantitative syntheses, respectively. Range of evidence met 10 of 13 STAIR criteria. Median (Q1, Q3) quality score was 7 (5, 8) on the CAMARADES 15-item checklist. Bayesian meta-analysis showed SMD estimates (95% CI) favoring RSV: infarct size (-1.72 [-2.03; -1.41]), edema size (-1.61 [-2.24; -0.98]), BBB impairment (-1.85 [-2.54; -1.19]), neurofunctional impairment (-1.60 [-1.92; -1.29]), and motor performance (1.39 [0.64; 2.08]); and less probably neuronal survival (0.63 [-1.40; 2.48]) and apoptosis (-0.96 [-2.87; 1.02]). Species (rat vs mouse) was associated to a larger benefit. Sensitivity analyses confirmed robustness of the estimates. Reduction of oxidative stress, inflammation, and apoptosis underlie these effects. Our results quantitatively state the beneficial effects of RSV on structural and functional outcomes in rodent stroke models, update the evidence on the mechanisms of action, and provide an exhaustive list of targeted signaling pathways. Current evidence highlights the need for conducting further high-quality preclinical research to better inform clinical research.

Neuroprotective Effects of Resveratrol by Modifying Cholesterol Metabolism and Aβ Processing in SAMP8 Mice

Cholesterol metabolism seems dysregulated and linked to amyloid-β (Aβ) formation in neurodegeneration, but the underlying mechanisms are poorly known. Resveratrol (RSV) is a polyphenol with antioxidant activity and neuroprotective properties. Here, we analyzed the effect of age and RSV supplementation on cholesterol metabolism in the brain and blood serum, and its potential link to Aβ processing, in SAMP8 mice—an animal model of aging and Alzheimer’s disease. In the brain, our results revealed an age-related increase in ApoE and unesterified cholesterol in the plasma membrane whereas LDL receptor, HMG-CoA reductase, HMG-CoA-C1 synthase, and ABCA1 transporter remained unaltered. Furthermore, BACE-1 and APP gene expression was decreased. This dysregulation could be involved in the amyloidogenic processing pathway of APP towards Aβ formation. In turn, RSV exhibited an age-dependent effect. While levels of unesterified cholesterol in the plasma membrane were not affected by RSV, several participants in cholesterol uptake, release, and de novo synthesis differed, depending on age. Thus, RSV supplementation exhibited a different neuroprotective effect acting on Aβ processing or cholesterol metabolism in the brain at earlier or later ages, respectively. In blood serum, HDL lipoprotein and free cholesterol were increased by age, whereas VLDL and LDL lipoproteins remained unaltered. Again, the protective effect of RSV by decreasing the LDL or increasing the HDL levels also seems to depend on the intervention’s moment. In conclusion, age is a prominent factor for cholesterol metabolism dysregulation in the brain of SAMP8 mice and influences the protective effects of RSV through cholesterol metabolism and Aβ processing.

Therapeutic Potential of Polyphenols in the Management of Diabetic Neuropathy

Diabetic neuropathy (DN) is a common and serious diabetes-associated complication that primarily takes place because of neuronal dysfunction in patients with diabetes. Use of current therapeutic agents in DN treatment is quite challenging because of their severe adverse effects. Therefore, there is an increased need of identifying new safe and effective therapeutic agents. DN complications are associated with poor glycemic control and metabolic imbalances, primarily oxidative stress (OS) and inflammation. Various mediators and signaling pathways such as glutamate pathway, activation of channels, trophic factors, inflammation, OS, advanced glycation end products, and polyol pathway have a significant contribution to the progression and pathogenesis of DN. It has been indicated that polyphenols have the potential to affect DN pathogenesis and could be used as potential alternative therapy. Several polyphenols including kolaviron, resveratrol, naringenin, quercetin, kaempferol, and curcumin have been administered in patients with DN. Furthermore, chlorogenic acid can provide protection against glutamate neurotoxicity via its hydrolysate, caffeoyl acid group, and caffeic acid through regulating the entry of calcium into neurons. Epigallocatechin-3-gallate treatment can protect motor neurons by regulating the glutamate level. It has been demonstrated that these polyphenols can be promising in combating DN-associated damaging pathways. In this article, we have summarized DN-associated metabolic pathways and clinical manifestations. Finally, we have also focused on the roles of polyphenols in the treatment of DN.

Assessment of the Anti-apoptotic Effects of Peganum harmala Leaf Extract on Type 2 Diabetes in the Kidney of Male Wistar Rats

Background: Growing evidence has shown that the apoptosis of cells plays an important role in the advancement of the Diabetic nephropathy (DN). Objectives: This study attempted to discover the therapeutic potential of Peganum harmala leaf extract in the apoptosis of diabetic kidney disease. Methods: In the present experimental research, 32 male Wistar rats were studied, and diabetes was induced by streptozotocin (STZ) (65 mg/kg). The animals were randomly divided into four groups (n=8, in each group) as follows: control, diabetic, control+leaf extract, diabetic+leaf extract. For our purposes, the methanolic extract of P. harmala leaves (150 mg/kg) was given by gavage for 28 days. Flow cytometry and real-time polymerase chain reaction (PCR) analyses were utilized to determine the percentages of apoptotic cells. Also, histological alterations and blood biochemical parameters were evaluated. Results: The P. harmala leaf extract has a high amount of flavonoids (25.84%), a lower percentage of alkaloids (0.14%), and some antioxidant properties. Serum urea (P<0.001) and apoptosis (P<0.05) significantly elevated in diabetic rats relative to the control ones. The mean of fasting blood creatinine, urea, and albumin level was not significantly changed in diabetic+leaf extract rats as compared to the diabetic ones. Histopathological results also displayed that diabetic complications in the kidney could not be improved following treatment by the leaf extract of P. harmala. In addition, the leaf extract could not significantly reduce the apoptosis and caspase-3 expression compared to diabetics in renal cells. Conclusion: Based on our findings, the leaf extract of P. harmala is unable to inhibit apoptosis in the diabetic kidney model.

Opening eyes to therapeutic perspectives of bioactive polyphenols and their nanoformulations against diabetic neuropathy and related complications

Introduction: Diabetic neuropathy (DN) is one of the major complications arising from hyperglycaemia in diabetic patients. In recent years polyphenols present in plants have gained attention to treat DN. The main advantages associated with them are their action via different molecular pathways to manage DN and their safety. However, they failed to gain clinical attention due to challenges associated with their formulation development such as lipophilicity,poor bioavailability, rapid systemic elimination, and enzymatic degradation.Area covered: This article includes different polyphenols that have shown their potential against DN in preclinical studies and the research carried out towards development of their nanoformulations in order to overcome aforementioned issues.Expert opinion: In this review various polyphenol based nanoformulations such as nanospheres, self-nanoemulsifying drug delivery systems, niosomes, electrospun nanofibers, metallic nanoparticles explored exclusively to treat DN are discussed. However, the literature available related to polyphenol based nanoformulations to treat DN is limited. Moreover, these experiments are limited to preclinical studies. Hence, more focus is required towards  development of nanoformulations using simple and single step process as well as inexpensive and non-toxic excipients so that a stable, scalable, reproducible and non-toxic formulation could be achieved and clinical trials could be initiated.

Melatonin suppresses the brain injury after cerebral ischemia/reperfusion in hyperglycaemic rats

Background and purpose

Diabetes mellitus is a disorder accompanied by oxidative and inflammatory responses, that might exacerbate vascular complications. The purpose of this study was to investigate the potential antioxidant and anti-inflammatory effects of melatonin (MLN) on streptozotocin (STZ)-induced diabetic rats subjected to middle cerebral artery occlusion followed by reperfusion (MCAO/Re).

Experimental approach

Diabetes was induced in rats by a single injection of STZ (55 mg/kg; i.p.). The cerebral injury was then induced by MCAO/Re after six weeks. After 24 h of MCAO/Re the MLN (10 mg/kg) was administered orally for 14 days. Serum and tissue samples were extracted to determine malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), interleukin-1β (IL-1β), and the tumor necrosis factor- α (TNF-α). Part of the brain tissue was kept in formalin for pathological and immunohistochemical studies to determine nuclear factor kappa B (NF-kB) and cyclooxygenase-2 (COX-2) immune reactivity.

Findings/Results

MCAO/Re in STZ-induced hyperglycaemic rats caused a decrease in brain GSH, an increase in brain MDA, and NO was increased in both serum and brain tissue. Rats showed a prominent increase in the serum and brain inflammatory markers viz. IL-1β and TNF-α. Oral treatment with MLN (10 mg/kg) for two weeks reduced the brain levels of MDA, NO, IL-1β, and TNF-α. Impressive amelioration in pathological findings, as well as a significant decrease in NF-kB and COX2 immune stained cells of the cerebral cortex, hippocampus, and cerebellum, occurred after treatment with MLN. It also succeeded to suppress the exacerbation of damage in the brain of hyperglycaemic rats.

Conclusion and implications

Daily intake of MLN attenuates the exacerbation of cerebral ischemic injury in a diabetic state.

Metabolome modulatory effects of Kigelia africana (Lam.) Benth. fruit extracts on oxidative stress, hyperlipidaemic biomarkers in STZ-induced diabetic rats and antidiabetic effects in 3T3 L1 adipocytes

OBJECTIVES

The management of diabetes is considered a global problem, and a cure is yet to be discovered. This study investigated the modulatory effect of Kigelia africana fruit on oxidative stress and hyperlipidaemic biomarkers in STZ-induced diabetic rats, profiled phytoconstituents using GC-TOF-MS and evaluated antidiabetic effects on 3T3 L1 adipocytes.

METHODS

Thirty male Wistar rats (120-150 g) were divided into six groups (n = 5). Diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg) and treated with 100, 200 and 400 of hexane fraction of KA for 28 days. Immunohistochemical evaluation was carried out using avidin-biotin immunoperoxidase (ABI) method. Catalase and SOD activities as well as the levels of total protein, albumin, bilirubin, triglyceride, cholesterol, and high-density lipoprotein were measured.

KEY FINDINGS

The expressions of oxidative stress and hyperlipidaemic biomarkers alongside fasting blood glucose concentrations were remarkedly decreased in KA-treated diabetic rats. Moreover, there was a significant increase in endocrine cell distribution, area covered with increase in β-cell mass, composition and morphology of KA-treated animals. Additionally, there was constant up-regulation in 3T3 L1 adipocytes due to the presence of phytoconstituents.

CONCLUSION

Kigelia africana fruit can act as a modulatory agent due to its ameliorative effects against oxidative stress.

A review on the potential of Resveratrol in prevention and therapy of diabetes and diabetic complications

Diabetes mellitus (DM) is a major world health problem and one of the most studied diseases, which are highly prevalent in the whole world, it is frequently associated with severe clinical complications, such as diabetic cardiomyopathy, nephropathy, retinopathy, neuropathy etc. Scientific research is continuously casting about for new monomer molecules from Chinese herbal medicine that could be invoked as candidate drugs for fighting against diabetes and its complications. Resveratrol (RES), a polyphenol phytoalexin, possesses diverse biochemical and physiological actions, including antiplatelet, estrogenic, and anti-inflammatory properties. It is recently gaining scientific interest for RES in controlling blood sugar and fighting against diabetes and its complications properties in various types of diabetic models. These beneficial effects seem to be due to the multiple actions of RES on cellular functions, which make RES become a promising molecule for the treatment of diabetes and diabetic complications. Here, we review the mechanism of action and potential therapeutic use of RES in prevention and mitigation of these diseases in recent ten years to provide a reference for further research and development of RES.

Polyphenols for diabetes associated neuropathy: Pharmacological targets and clinical perspective

OBJECTIVES

Diabetic neuropathy (DNP) is a widespread and debilitating complication with complex pathophysiology that is caused by neuronal dysfunction in diabetic patients. Conventional therapeutics for DNP are quite challenging due to their serious adverse effects. Hence, there is a need to investigate novel effective and safe options. The novelty of the present study was to provide available therapeutic approaches, emerging molecular mechanisms, signaling pathways and future directions of DNP as well as polyphenols' effect, which accordingly, give new insights for paving the way for novel treatments in DNP.

EVIDENCE ACQUISITION

A comprehensive review was done in electronic databases including Medline, PubMed, Web of Science, Scopus, national database (Irandoc and SID), and related articles regarding metabolic pathways on the pathogenesis of DNP as well as the polyphenols' effect. The keywords "diabetic neuropathy" and "diabetes mellitus" in the title/abstract and "polyphenol" in the whole text were used. Data were collected from inception until May 2019.

RESULTS

DNP complications is mostly related to a poor glycemic control and metabolic imbalances mainly inflammation and oxidative stress. Several signaling and molecular pathways play key roles in the pathogenesis and progression of DNP. Among natural entities, polyphenols are suggested as multi-target alternatives affecting most of these pathogenesis mechanisms in DNP.

CONCLUSION

The findings revealed novel pathogenicity signaling pathways of DNP and affirmed the auspicious role of polyphenols to tackle these destructive pathways in order to prevent, manage, and treat various diseases. Graphical Abstract .

Cardioprotective and Anti-Aggregatory Effects of Levosimendan on Isoproterenol-Induced Myocardial Injury in High-Fat-Fed Rats Involves Modulation of PI3K/Akt/mTOR Signaling Pathway and Inhibition of Apoptosis

Hyperlipidemia and hypercoagulability states are linked with the increased risks of myocardial infarction (MI). Levosimendan has vasorelaxant and anti-aggregatory properties. The present study evaluated the anti-aggregatory and cardioprotective effects of levosimendan versus cilostazol in high-fat diet (HFD)-fed rats subjected to isoproterenol-induced MI. Rats were assigned to normal, HFD, HFD + isoproterenol, HFD + isoproterenol + cilostazol, and HFD + isoproterenol + levosimendan. The present study investigated the anti-aggregatory effect of both levosimendan and cilostazol and revealed that both drugs attenuated the severity of platelet aggregation. Moreover, both levosimendan and cilostazol revealed effectiveness in attenuating the severity of HFD/isoproterenol-induced myocardial injury as revealed by electrocardiogram signs, apoptotic markers, and histopathological score via counteracting the oxidative stress burden, increments in the expression of inflammatory mediators, and modulating nuclear factor kappa-B (NF-κB) and phosphatidylinositide 3-kinases (PI3K)/protein kinase B (Akt)/ mechanistic target of rapamycin (mTOR) pathway. It was obvious that levosimendan offered more cardioprotective properties than cilostazol. The study showed the relations between hyperlipedemia, hyperaggregability state, and myocardial injury with the modulation of NF-κB and PI3K/Akt/mTOR pathway.

5-HT7 receptor antagonism (SB-269970) attenuates bleomycin-induced pulmonary fibrosis in rats via downregulating oxidative burden and inflammatory cascades and ameliorating collagen deposition: Comparison to terguride

The neurotransmitter 5-hydroxytryptamine (5-HT) is involved in regulation of local tissue inflammation and repair through a set of receptors (5-HT1-7 receptors), which are expressed in the lung. Considering the protective importance of 5-HT receptor antagonists against development of pulmonary fibrosis, we evaluated whether 5-HT7 receptor antagonist (SB-269970) modulates lung inflammatory and fibrogenic processes in comparison with 5-HT2A/B receptor antagonist (terguride), in bleomycin (BLM)-induced idiopathic pulmonary fibrosis (IPF) model. IPF model induced by a single dose of intra-tracheal BLM instillation (5mg/kg), and rats were treated with intraperitoneal injection of SB-269970 (1mg/kg day) or terguride (1.2mg/kg/d). The experiment was carried out on two separate sets of rats that were killed at day 7th and day 21st to evaluate the endpoint of the IPF inflammatory and fibrogenic phases, respectively. During the inflammatory phase 5-HT2A/B and 5-HT7 receptor antagonists attenuated the BLM-induced increase in the lung fluid content, the inflammatory cytokines levels and oxidative stress burden. In the fibrogenic phase, both SB-269970 and terguride reduced the serotonin concentrations in lung homogenates and significantly protected against IPF fibrogenic phase by attenuating collagen deposition and mRNA expression of both transforming growth factor-β1 (TGF- β1), and procollagen type Ӏ (PINP). 5-hydroxytryptamine 5-HT7 receptor antagonist showed more benefits than 5-HT2A/B receptor antagonist on the deleterious effects accompanied BLM instillation. The present study showed involvement of 5-HT7 receptor in the pathophysiology of BLM-induced IPF in rats and identified it as a potential therapeutic target in lung fibrotic disorders.

Inhibition of DPP-4 Activity and Neuronal Atrophy with Genistein Attenuates Neurological Deficits Induced by Transient Global Cerebral Ischemia and Reperfusion in Streptozotocin-Induced Diabetic Mice

Genistein, an isoflavonoid phytoestrogen, has been known for its potential pharmacological properties especially for neuroprotection and treating diabetes. The present study aims to determine the neuroprotective efficacy of genistein against global cerebral ischemia-reperfusion-induced neuronal injury in streptozotocin-induced diabetic mice and explore the underlying mechanisms. Streptozotocin-induced diabetic mice were subjected to transient cerebral ischemia by occluding both common carotid arteries for 30 min followed by 24 h reperfusion to induce neuronal injury. Effect of genistein (2.5, 5.0, and 10.0 mg/kg, i.p., o.d.) treatment on ischemia-reperfusion-induced neuronal injury in diabetic mice was evaluated in terms of cerebral infarct size, oxidative damage, mitochondrial activity in terms of neuronal apoptosis and cellular viability, dipeptidyl peptidase-4 activity and active glucagon-like peptide-1 concentration, and neurological functions measured as short-term memory and motor performance. Genistein administration following transient cerebral ischemia significantly (p ˂ 0.0001) counteracted cognitive impairment and re-established (p ˂ 0.001) motor performance in diabetic mice. Ischemia-reperfusion increased the infarct size, genistein administration prevented the increase in cerebral infarct size (p ˂ 0.0001) and significantly suppressed (p ˂ 0.001) the increase in cerebral oxidative stress in transient cerebral ischemia-reperfusion subjected diabetic mice. Genistein treatment significantly (p ˂ 0.001) reduced neuronal apoptosis and increased cellular viability (p ˂ 0.0001), almost completely suppressed (p ˂ 0.0001) the circulating dipeptidyl peptidase-4 activity, and enhanced (p ˂ 0.0001) glucagon-like peptide-1 concentration in diabetic mice with cerebral ischemia-reperfusion. This study suggests that genistein has potent neuroprotective activity against global cerebral ischemia-reperfusion-induced neuronal injury and consequent neurological deficits in streptozotocin-induced diabetic mice.

The mechanism of neuroprotective action of natural compounds

Disturbance of cerebral redox homeostasis is the primary cause of human neurodegenerative disorders, such as Parkinson's disease or Alzheimer's disease. Well known experimental research demonstrates that oxidative stress is a main cause of cell death. A high concentration of reactive oxygen and nitrogen species leads to damage of a lot of proteins, lipids and also DNA. Synthetic compounds used for the treatment in the neurodegenerative diseases failed to meet the hopes they had raised and often exhibit a number of side effects. Therefore, in recent years interest in natural compounds derived from plants appears to be on the rise. This review describes a few natural compounds (1MeTIQ, resveratrol, curcumin, vitamin C and Gingko biloba) which revealed neuroprotective potential both in experimental studies and clinical trials. 1MeTIQ has a privileged position because, as opposed to the remaining compounds, it is an endogenous amine synthesized in human and animal brain. Based on evidence from research, it seems that a common protective mechanism for all the above-mentioned natural compounds relies on their ability to inhibit or even scavenge the excess of free radicals generated in oxidative and neurotoxin-induced processes in nerve cells of the brain. However, it was demonstrated that further different molecular processes connected with neurotoxicity (e.g. the inhibition of mitochondrial complex I, activation of caspase-3, apoptosis) follow later and are initiated by the reactive oxygen species. What is more, these natural compounds are able to inhibit further stages of apoptosis triggered by neurotoxins in the brain.

Dose-dependent short- and long-term effects of ionizing irradiation on neural stem cells in murine hippocampal tissue cultures: neuroprotective potential of resveratrol

INTRODUCTION

Radiation therapy plays an essential role in the treatment of brain tumors, but neurocognitive deficits remain a significant risk, especially in pediatric patients. In recent trials, hippocampal sparing techniques are applied to reduce these adverse effects. Here, we investigate dose-dependent effects of ionizing radiation (IR) on juvenile hippocampal neurogenesis. Additionally, we evaluate the radioprotective potential of resveratrol, a plant polyphenol recognized for its bifunctional tumor-preventive and anticancer effects.

METHODS

Organotypic entorhinal-hippocampal slice cultures from transgenic nestin-CFPnuc C57BL/J6 mice, postnatal days 3-6, were irradiated on a X-ray machine (4.5, 8, 12, and 16 Gy, single doses) after about 2 weeks. Nestin-positive neural stem cells were counted at a confocal live imaging microscope 0, 2, 4, 14, 25, and 42 days after IR. Resveratrol (15 μmol/L) was added 2 hr before and 24 hr after IR. Proliferation and cell death were assessed by BrdU pulse label, 48 hr after and by propidium iodide staining 96 hr after IR. GFAP- and NeuN-positive cells were counted 42 days after IR in cryosectioned immunofluorescence-stained slices.

RESULTS

The observed age-related changes of nestin-positive stem cells in the organotypic slice culture model resembled the reduction of neural stem cells in vivo. IR (4.5-16 Gy) led to a dose-dependent damage of the neural stem cell pool in the dentate gyrus. No recovery was seen within 42 days after doses from 4.5 Gy onward. The decline of nestin-positive cells was paralleled by increased cell death and decreased proliferation. The number of GFAP-positive cells was significantly enhanced. No significant change was detected in the overall NeuN-positive cell population, whereas the number of newborn, NeuN/BrdU double-positive neurons was reduced. Resveratrol treatment reversed the irradiation-induced decline of neural stem cells.

CONCLUSION

The neuroprotective action of resveratrol on irradiated hippocampal tissue warrants further investigation as a possible supplement to hippocampal sparing procedures.

Resveratrol shows neuronal and vascular-protective effects in older, obese, streptozotocin-induced diabetic rats

Diabetes-induced CVD is the most significant complication of prolonged hyperglycaemia. The aim of this study was to determine whether resveratrol, a polyphenol antioxidant compound, when administered at a dose that can be reasonably obtained through supplementation could prevent the development of cardiovascular complications in older, obese, diabetic rats. Diabetes was induced in 6-month old, obese, male Wistar rats via a single intravenous dose of streptozotocin (65 mg/kg). Randomly selected animals were administered resveratrol (2 mg/kg) via oral gavage daily for 8 weeks. Body weights, blood glucose levels, food intake and water consumption were monitored, and assessments of vascular reactivity, tactile allodynia and left ventricular function were performed. Resveratrol therapy significantly improved tactile allodynia and vascular contractile functionality in diabetic rats (P<0·05). There were no significant changes in standardised vasorelaxation responses, plasma glucose concentrations, water consumption, body weight, left ventricular hypertrophy, kidney hypertrophy, heart rate or left ventricular compliance with resveratrol administration. Resveratrol-mediated improvements in vascular and nerve function in old, obese, diabetic rats were associated with its reported antioxidant effects. Resveratrol did not improve cardiac function nor mitigate the classic clinical symptoms of diabetes mellitus (i.e. hyperglycaemia, polydypsia and a failure to thrive). This suggests that supplementation with resveratrol at a dose achievable with commercially available supplements would not produce significant cardioprotective effects in people with diabetes mellitus.

Ischemic postconditioning protects against ischemic brain injury by up-regulation of acid-sensing ion channel 2a

Ischemic postconditioning renders brain tissue tolerant to brain ischemia, thereby alleviating ischemic brain injury. However, the exact mechanism of action is still unclear. In this study, a rat model of global brain ischemia was subjected to ischemic postconditioning treatment using the vessel occlusion method. After 2 hours of ischemia, the bilateral common carotid arteries were blocked immediately for 10 seconds and then perfused for 10 seconds. This procedure was repeated six times. Ischemic postconditioning was found to mitigate hippocampal CA1 neuronal damage in rats with brain ischemia, and up-regulate acid-sensing ion channel 2a expression at the mRNA and protein level. These findings suggest that ischemic postconditioning up-regulates acid-sensing ion channel 2a expression in the rat hippocampus after global brain ischemia, which promotes neuronal tolerance to ischemic brain injury.

Antidiabetic Effects of Resveratrol: The Way Forward in Its Clinical Utility

Despite recent advances in the understanding and management of diabetes mellitus, the prevalence of the disease is increasing unabatedly with resulting disabling and life-reducing consequences to the global human population. The limitations and side effects associated with current antidiabetic therapies have necessitated the search for novel therapeutic agents. Due to the multipathogenicity of diabetes mellitus, plant-derived compounds with proven multiple pharmacological actions have been postulated to "hold the key" in the search for an affordable, efficacious, and safer therapeutic agent in the treatment of the disease and associated complications. Resveratrol, a phytoalexin present in few plant species, has demonstrated beneficial antidiabetic effects in animals and humans through diverse mechanisms and multiple molecular targets. However, despite the enthusiasm and widespread successes achieved with the use of resveratrol in animal models of diabetes mellitus, there are extremely limited clinical data to confirm the antidiabetic qualities of resveratrol. This review presents an update on the mechanisms of action and protection of resveratrol in diabetes mellitus, highlights challenges in its clinical utility, and suggests the way forward in translating the promising preclinical data to a possible antidiabetic drug in the near future.

Resveratrol neuroprotection in stroke and traumatic CNS injury

Resveratrol, a stilbene formed in many plants in response to various stressors, elicits multiple beneficial effects in vertebrates. Particularly, resveratrol was shown to have therapeutic properties in cancer, atherosclerosis and neurodegeneration. Resveratrol-induced benefits are modulated by multiple synergistic pathways that control oxidative stress, inflammation and cell death. Despite the lack of a definitive mechanism, both in vivo and in vitro studies suggest that resveratrol can induce a neuroprotective state when administered acutely or prior to experimental injury to the CNS. In this review, we discuss the neuroprotective potential of resveratrol in stroke, traumatic brain injury and spinal cord injury, with a focus on the molecular pathways responsible for this protection.

Resveratrol ameliorates high glucose-induced oxidative stress injury in human umbilical vein endothelial cells by activating AMPK

AIMS

To investigate the effects of resveratrol on high glucose (HG)-induced vascular injury, and to establish the mechanism(s) underlying these effects.

MAIN METHODS

Human umbilical vein endothelial cells (HUVECs) were treated with glucose, and then incubated with resveratrol in the presence or absence of Compound C, an AMP-activated protein kinase (AMPK) inhibitor. Cell viability was determined using the Cell Counting Kit-8 (CCK-8) method. Reactive oxygen species, malondialdehyde, and superoxide dismutase were detected by flow cytometry, thiobarbituric acid reaction, and the nitroblue tetrazolium method, respectively. Protein levels of total and phosphorylated AMPKα and acetyl-CoA carboxylase were detected by immunoblotting.

KEY FINDINGS

Resveratrol significantly ameliorated HG-induced decreases in cell viability and superoxide dismutase levels and increases in reactive oxygen species and MDA levels. Moreover, resveratrol significantly reversed HG-induced dephosphorylation of AMPKα and acetyl-CoA carboxylase. However, treatment with Compound C curtailed the beneficial effects of resveratrol on HG-treated HUVECs.

SIGNIFICANCE

Resveratrol ameliorates HG-induced injury in HUVECs by activation of AMPKα, leading to increased cellular reductive reactions and decreased oxidative stress. These results provide further evidence for resveratrol-mediated activation of AMPKα.