Ectonucleotidase and acetylcholinesterase activities in synaptosomes from the cerebral cortex of streptozotocin-induced diabetic rats and treated with resveratrol

Aspirin ameliorates the neurotoxicity of benzo[a]pyrene in mice and HT22 cells: Possible role of miRNA-mRNA network

Benzo[a]pyrene (B[a]P) is neurotoxic, however, the mechanism and potential prevention are yet not clear. This study explored the miRNA-mRNA network in the B[a]P-induced neurotoxicity in mice and HT22 cells and the intervention of aspirin (ASP). HT22 cells were treated for 48 h with DMSO, B[a]P (20 μM), or both B[a]P (20 μM) and ASP (4 μM). Following B[a]P treatment, compared to the DMSO controls, HT22 cells showed injured cell morphology, reduced cell viability and neurotrophic factor concentrations, and increased LDH leakage, Aβ_1-42, and inflammatory factor concentrations, which were improved by ASP. RNA sequencing and qPCR verified the significant differences of miRNA and mRNA profiles following B[a]P treatment, which were rescued by ASP. Bioinformatics analysis suggested the miRNA-mRNA network could be involved in the neurotoxicity of B[a]P and the intervention of ASP. The neurotoxicity and neuroinflammation were induced in mice's brains by B[a]P, and the target miRNA and mRNA were proved to be consistent with in vitro, which were ameliorated by ASP. The findings demonstrate a possible role of miRNA-mRNA network in the B[a]P-induced neurotoxicity. If this is confirmed by additional experiments, it will provide a promising pathway of intervention against B[a]P, using ASP or other agents with fewer toxic effects.

Neuroprotection elicited by resveratrol in a rat model of hypothyroidism: Possible involvement of cholinergic signaling and redox status

Both the cholinergic pathway and oxidative stress are important mechanisms involved in the pathogenesis of hypothyroidism, a condition characterized by low levels of thyroid hormone that predispose the patient to brain dysfunction. Phenolic compounds have numerous health benefits, including antioxidant activity. This study evaluates the preventive effects of resveratrol in the cholinergic system and redox status in rats with methimazole-induced hypothyroidism. Hypothyroidism increases acetylcholinesterase (AChE) activity and density in the cerebral cortex and hippocampus and decreases the α7 and M1 receptor densities in the hippocampus. Hypothyroidism also increases cellular levels of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS), but reduces total thiol content, and catalase and superoxide dismutase activities in the serum. In the cerebral cortex and hippocampus, hypothyroidism increases the levels of ROS and nitrites. In this study, resveratrol (50 mg/kg) treatment prevents the observed increase in AChE in the cerebral cortex, and increases the protein levels of NeuN, a marker of mature neurons. Resveratrol also prevents changes in serum ROS levels and brain structure, as well as the levels of TBARS, total thiol content, and serum catalase enzyme activity. These collective findings suggest that resveratrol has a high antioxidant capacity and can restore hypothyroidism-triggered alterations related to neurotransmission. Thus, it is a promising agent for the prevention of brain damage resulting from hypothyroidism.

The neuroprotective effect and action mechanism of polyphenols in diabetes mellitus-related cognitive dysfunction

BACKGROUND

Diabetes mellitus (DM) is a complex and prevalent metabolic disorder worldwide. Strong evidence has emerged that DM is a risk factor for the accelerated rate of cognitive decline and the development of dementia. Though traditional pharmaceutical agents are efficient for the management of DM and DM-related cognitive decrement, long-term use of these drugs are along with undesired side effects. Therefore, tremendous studies have focused on the therapeutic benefits of natural compounds at present. Ample evidence exists to prove that polyphenols are capable to modulate diabetic neuropathy with minimal toxicity and adverse effects.

PURPOSE

To describe the benefits and mechanisms of polyphenols on DM-induced cognitive dysfunction. In this review, we introduce an updated overview of associations between DM and cognitive dysfunction. The risk factors as well as pathological and molecular mechanisms of DM-induced cognitive dysfunction are summarized. More importantly, many active polyphenols that possess preventive and therapeutic effects on DM-induced cognitive dysfunction and the potential signaling pathways involved in the action are highlighted.

CONCLUSIONS

The therapeutic effects of polyphenols on DM-related cognitive dysfunction pave a novel way for the management of diabetic encephalopathy.

Phenotypic relationships, genetic parameters, genome-wide associations, and identification of potential candidate genes for ketosis and fat-to-protein ratio in German Holstein cows

Energy demand for milk production in early lactation exceeds energy intake, especially in high-yielding Holstein cows. Energy deficiency causes increasing susceptibility to metabolic disorders. In addition to several blood parameters, the fat-to-protein ratio (FPR) is suggested as an indicator for ketosis, because a FPR >1.5 refers to high lipolysis. The aim of this study was to analyze phenotypic, quantitative genetic, and genomic associations between FPR and ketosis. In this regard, 8,912 first-lactation Holstein cows were phenotyped for ketosis according to a veterinarian diagnosis key. Ketosis was diagnosed if the cow showed an abnormal carbohydrate metabolism with increased content of ketone bodies in the blood or urine. At least one entry for ketosis in the first 6 wk after calving implied a score = 1 (diseased); otherwise, a score = 0 (healthy) was assigned. The FPR from the first test-day was defined as a Gaussian distributed trait (FPRgauss), and also as a binary response trait (FPRbin), considering a threshold of FPR = 1.5. After imputation and quality controls, 45,613 SNP markers from the 8,912 genotyped cows were used for genomic studies. Phenotypically, an increasing ketosis incidence was associated with significantly higher FPR, and vice versa. Hence, from a practical trait recording perspective, first test-day FPR is suggested as an indicator for ketosis. The ketosis heritability was slightly larger when modeling the pedigree-based relationship matrix (pedigree-based: 0.17; SNP-based: 0.11). For FPRbin, heritabilities were larger when modeling the genomic relationship matrix (pedigree-based: 0.09; SNP-based: 0.15). For FPRgauss, heritabilities were almost identical for both pedigree and genomic relationship matrices (pedigree-based: 0.14; SNP-based: 0.15). Genetic correlations between ketosis with FPRbin and FPRgauss using either pedigree- or genomic-based relationship matrices were in a moderate range from 0.39 to 0.71. Applying genome-wide association studies, we identified the specific SNP rs109896020 (BTA 5, position: 115,456,438 bp) significantly contributing to ketosis. The identified potential candidate gene PARVB in close chromosomal distance is associated with nonalcoholic fatty liver disease in humans. The most important SNP contributing to FPRbin was located within the DGAT1 gene. Different SNP significantly contributed to ketosis and FPRbin, indicating different mechanisms for both traits genomically.

Coffee, caffeine, chlorogenic acid, and the purinergic system

Coffee is a drink prepared from roasted coffee beans and is lauded for its aroma and flavour. It is the third most popular beverage in the world. This beverage is known by its stimulant effect associated with the presence of methylxanthines. Caffeine, a purine-like molecule (1,3,7 trymetylxantine), is the most important bioactive compound in coffee, among others such as chlorogenic acid (CGA), diterpenes, and trigonelline. CGA is a phenolic acid with biological properties as antioxidant, anti-inflammatory, neuroprotector, hypolipidemic, and hypoglicemic. Purinergic system plays a key role inneuromodulation and homeostasis. Extracellular ATP, other nucleotides and adenosine are signalling molecules that act through their specific receptors, namely purinoceptors, P1 for nucleosides and P2 for nucleotides. They regulate many pathological processes, since adenosine, for instance, can limit the damage caused by ATP in the excitotoxicity from the neuronal cells. The primary purpose of this review is to discuss the effects of coffee, caffeine, and CGA on the purinergic system. This review focuses on the relationship/interplay between coffee, caffeine, CGA, and adenosine, and their effects on ectonucleotidases activities as well as on the modulation of P1 and P2 receptors from central nervous system and also in peripheral tissue.

Lingonberry Extract Provides Neuroprotection by Regulating the Purinergic System and Reducing Oxidative Stress in Diabetic Rats

SCOPE

Beneficial effects produced by polyphenolic compounds are used in the treatment of various diseases, including diabetes. Thus it is relevant to investigate the protective effect of lingonberry extract (LB) on the activities of nucleoside triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase (5'-NT), and adenosine deaminase (ADA); the density of A1, A2A, and P2×7 receptors; production of reactive species (RS); and the levels of thiobarbituric acid reactive substances (TBARS) in the cerebral cortex of streptozotocin-induced diabetic rats.

METHODS AND RESULTS

Animals were divided into five groups (n = 10): control/saline; control/LB 50 mg kg^-1 ; diabetic/saline; diabetic/LB 25 mg kg^-1 ; and diabetic/LB 50 mg kg^-1 ; and treated for 30 days. Our results demonstrate that the treatment with LB increased NTPDase activity in the diabetic/LB 50 group compared to diabetic/saline group. Western blot analysis showed that LB restored the density of purinergic receptors to the approximate values of the control/saline group. An increase in the levels of RS and TBARS was observed in the diabetic/saline group compared with the control/saline group, and treatment with LB can prevent this increase.

CONCLUSION

This study showed that LB could reverse the modifications found in the diabetic state, suggesting that lingonberry may be a coadjuvant in the treatment of diabetes.

Resveratrol Ameliorates Cardiac Dysfunction by Inhibiting Apoptosis via the PI3K/Akt/FoxO3a Pathway in a Rat Model of Diabetic Cardiomyopathy

The aim of this study was to explore the effect and mechanism of action of resveratrol (RSV) on cardiac function in diabetic cardiomyopathy (DCM). Hyperglycemia-induced apoptosis contributes to the pathogenic changes in DCM. RSV treatment inhibited high glucose-induced apoptosis of neonatal rat ventricular myocytes. Additionally, high glucose decreased cell viability, prevented serine-threonine kinase (Akt) and FoxO3a phosphorylation, and suppressed cytoplasmic translocation of FoxO3a. However, these effects of apoptosis were reversed by 10 μM of RSV. The PI3K inhibitor LY294002 abolished the RSV protective effect in vitro. RSV (5 or 50 mg·kg·d orally for 8 weeks) prevented the deterioration of cardiac function and structural cardiomyopathy in a streptozotocin-induced rat model of diabetes and reduced apoptosis in diabetic myocardium. Furthermore, it restored streptozotocin-impaired phosphorylation of Akt and FoxO3a (p-Akt and p-FoxO3a) and suppressed nuclear translocation of FoxO3a in vivo. Together, these data indicate that RSV has therapeutic potential against DCM by inhibiting apoptosis via the PI3K/Akt/FoxO3a pathway.

Cholinesterase targeting by polyphenols: A therapeutic approach for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a progressive irreversible neurodegenerative disorder characterized by excessive deposition of β-amyloid (Aβ) oligomers, and neurofibrillary tangles (NFTs), comprising of hyperphosphorylated tau proteins. The cholinergic system has been suggested as the earliest and most affected molecular mechanism that describes AD pathophysiology. Moreover, cholinesterase inhibitors (ChEIs) are the potential class of drugs that can amplify cholinergic activity to improve cognition and global performance and reduce psychiatric and behavioral disturbances. Approximately, 60%-80% of all cases of dementia in the world are patients with AD. In view of the continuous rise of this disease especially in the aged population, there is a dire need to come up with a novel compound and/or mixture that could work against this devastating disease. In this regard, the best is to rely on natural compounds rather than synthetic ones, because natural compounds are easily available, cost-effective, and comparatively less toxic. To serve this purpose, lately, scientific community has started exploring the possibility of using different polyphenols either solitary or in combination that can serve as therapeutics against AD. In the current article, we have summarized the role of various polyphenols, namely quercetin, resveratrol, curcumin, gallocatechins, cinnamic acid, caffeine, and caffeic acid as an inhibitor of cholinesterase for the treatment of AD. We have also tried to uncover the mechanistic insight on the action of these polyphenols against AD pathogenicity.

Effect of gallic acid on purinergic signaling in lymphocytes, platelets, and serum of diabetic rats

Diabetes Mellitus (DM) is associated with an increased susceptibility to various infections, which might be attributed to changes in immune response owing to chronic hyperglycemia. Nucleoside triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase, and adenosine deaminase (ADA) are important enzymes involved in the generation of anti-aggregant and anti-inflammatory microenvironments. The aim of this study was to evaluate the effect of gallic acid (GA) on the hematological parameters and ectonucleotidase activities in platelets, lymphocytes, and serum of diabetic rats. Experimental rats were categorized into 4 groups: (i) control -saline, (ii) control - GA, (iii) diabetic -saline, and (iv) diabetic - GA. One week after induction of DM using streptozotocin (65 mg/kg), GA (30 mg/kg) or saline was orally administered to the rats for 21 days. Our results demonstrated that the concentration of mean corpuscular hemoglobin was decreased, whereas that of red cell distribution was increased in the diabetic group, however, GA could revert these alterations. Moreover, in diabetic rats, GA reverted the increase in ATP and ADP hydrolysis and ADA activity in lymphocytes, and it prevented the increase in NTPDase and ADA activities in platelets. A decrease in ATP hydrolysis and an increase in ADP and AMP hydrolysis were observed in the serum of diabetic rats; however, GA treatment could solely revert changes in ATP hydrolysis. Our study suggests that GA exhibits beneficial effects on immuno- and thrombo-regulatory responses in DM and that these effects may be related to the modulation of purinergic signaling.

Effect of natural products on diabetes associated neurological disorders

Diabetes mellitus, a metabolic disorder, is associated with neurological complications such as depression, anxiety, hypolocomotion, cognitive dysfunction, phobias, anorexia, stroke, pain, etc. Traditional system of medicine is long known for its efficient management of diabetes. The current review discusses the scope of some common medicinal herbs as well as secondary metabolites with a special focus on diabetes-mediated central nervous system complications. Literatures suggest that natural products reduce diabetes-mediated neurological complications partly by reducing oxidative stress and/or inflammation or apoptosis in certain brain regions. Natural products are known to modulate diabetes-mediated alterations in the level of acetylcholinesterase, choline acetyltransferase, monoamine oxidase, serotonin receptors, muscarinic receptors, insulin receptor, nerve growth factor, brain-derived neurotrophic factor, and neuropeptide in brain. Further, there are several natural products reported to manage diabetic complications with unknown mechanism. In conclusion, medicinal plants or their secondary metabolites have a wide scope and possess therapeutic potential to effectively manage neurological complications associated with chronic diabetes.

Neuroprotective effects of quercetin on memory and anxiogenic-like behavior in diabetic rats: Role of ectonucleotidases and acetylcholinesterase activities

The present study investigated the protective effect of quercetin (Querc) on memory, anxiety-like behavior and impairment of ectonucleotidases and acetylcholinesterase (AChE) activities in brain of streptozotocin-induced diabetic rats (STZ-diabetes). The type 1 diabetes mellitus was induced by an intraperitoneal injection of 70mg/kg of streptozotocin (STZ), diluted in 0.1M sodium-citrate buffer (pH 4.5). Querc was dissolved in 25% ethanol and administered by gavage at the doses of 5, 25 and 50mg/kg once a day during 40days. The animals were distributed in eight groups of ten animals as follows: vehicle, Querc 5mg/kg, Querc 25mg/kg, Querc 50mg/kg, diabetes, diabetes plus Querc 5mg/kg, diabetes plus Querc 25mg/kg and diabetes plus Querc 50mg/kg. Querc was able to prevent the impairment of memory and the anxiogenic-like behavior induced by STZ-diabetes. In addition, Querc prevents the decrease in the NTPDase and increase in the adenosine deaminase (ADA) activities in SN from cerebral cortex of STZ-diabetes. STZ-diabetes increased the AChE activity in SN from cerebral cortex and hippocampus. Querc 50mg/kg was more effective to prevent the increase in AChE activity in the brain of STZ-diabetes. Querc also prevented an increase in the malondialdehyde levels in all the brain structures. In conclusion, the present findings showed that Querc could prevent the impairment of the enzymes that regulate the purinergic and cholinergic extracellular signaling and improve the memory and anxiety-like behavior induced by STZ-diabetes.

Effects of chlorogenic acid, caffeine and coffee on components of the purinergic system of streptozotocin-induced diabetic rats

We evaluated the effect of chlorogenic acid (CGA), caffeine (CA) and coffee (CF) on components of the purinergic system from the cerebral cortex and platelets of streptozotocin-induced diabetic rats. Animals were divided into eight groups: control animals treated with (I) water (WT), (II) CGA (5 mg/kg), (III) CA (15 mg/kg) and (IV) CF (0.5 g/kg), and diabetic animals treated with (V) WT, (VI) CGA (5 mg/kg), (VII) CA (15 mg/kg) and (VIII) CF (0.5 g/kg). Our results showed an increase (173%) in adenosine monophosphate (AMP) hydrolysis in the cerebral cortex of diabetic rats. In addition, CF treatment increased adenosine diphosphate (ADP) and AMP hydrolysis in group VIII synaptosomes. Platelets showed an increase in ectonucleotidase activity in group V, and all treatments reduced the increase in adenosine triphosphate and ADP hydrolysis. Furthermore, there was an increase in platelet aggregation of 72% in the diabetic rats, and CGA and CF treatment reduced platelet aggregation by nearly 60% when compared to diabetic rats. In this context, we can suggest that CGA and CF treatment should be considered a therapeutic and scientific target to be investigated in diseases associated with hyperglycemia.

Hyperglycemia alters E-NTPDases, ecto-5'-nucleotidase, and ectosolic and cytosolic adenosine deaminase activities and expression from encephala of adult zebrafish (Danio rerio)

Hyperglycemia is the main feature for the diagnosis of diabetes mellitus (DM). Some studies have demonstrated the relationship between DM and dysfunction on neurotransmission systems, such as the purinergic system. In this study, we evaluated the extracellular nucleotide hydrolysis and adenosine deamination activities from encephalic membranes of hyperglycemic zebrafish. A significant decrease in ATP, ADP, and AMP hydrolyses was observed at 111-mM glucose-treated group, which returned to normal levels after 7 days of glucose withdrawal. A significant increase in ecto-adenosine deaminase activity was observed in 111-mM glucose group, which remain elevated after 7 days of glucose withdrawal. The soluble-adenosine deaminase activity was significantly increased just after 7 days of glucose withdrawal. We also evaluated the gene expressions of ecto-nucleoside triphosphate diphosphohydrolases (E-NTPDases), ecto-5'-nucleotidase, ADA, and adenosine receptors from encephala of adult zebrafish. The entpd 2a.1, entpd 2a.2, entpd 3, and entpd 8 mRNA levels from encephala of adult zebrafish were decreased in 111-mM glucose-treated and glucose withdrawal groups. The gene expressions of adenosine receptors (adora 1 , adora 2aa , adora 2ab , and adora 2b ) were decreased in 111-mM glucose-treated and glucose withdrawal groups. The gene expression of ADA (ada 2a.1) was decreased in glucose withdrawal group. Maltodextrin, used as a control, did not affect the expression of adenosine receptors, ADA and E-NTPDases 2, 3, and 8, while the expression of ecto-5'-nucleotidase was slightly increased and the E-NTPDases 1 decreased. These findings demonstrated that hyperglycemia might affect the ecto-nucleotidase and adenosine deaminase activities and gene expression in zebrafish, probably through a mechanism involving the osmotic effect, suggesting that the modifications caused on purinergic system may also contribute to the diabetes-induced progressive cognitive impairment.

Self-emulsifying drug delivery systems as a tool to improve solubility and bioavailability of resveratrol

Resveratrol is a nonflavonoid polyphenolic compound which has a broad range of desirable biological actions which include antioxidant, anti-inflammatory, antidiabetic, cardioprotective, and antitumor activities. However, there is concern that the bioavailability of resveratrol may limit some of its clinical utility. So, the aim of this study was to enhance the dissolution rate and oral hypoglycemic and hypolipidemic effect of resveratrol. This was achieved using self-emulsifying drug delivery system. The solubility of resveratrol was determined in various oils, surfactants, and cosurfactants. Phase diagram was plotted to identify the efficient self-emulsification regions using olive oil, Tween 80, and propylene glycol. The prepared self-emulsifying drug delivery system formulations were tested for thermodynamic stability, emulsification efficiency, droplet size, zeta potential, and in vitro drug release. Self-emulsification time averaged 17-99 seconds without precipitation and the mean droplet sizes ranged from 285 to 823 nm with overall zeta potential of -2.24 to -15.4 mv. All formulations improved drug dissolution in relation to unprocessed drug with a trend of decreased dissolution parameters with increasing oil content. The optimized formula, F19, with dissolution efficiency of 94% compared to only 42% of pure drug was used to study the in vivo hypoglycemic and hypolipidemic effects of resveratrol in diabetic-induced albino rats and comparing these effects with that of pure resveratrol in different doses. Treatment with the optimized formula, F19, at 10 mg/kg had significant hypoglycemic and hypolipidemic effects in diabetic-induced albino rats which were nearly similar to the high dose (20 mg/kg) of unprocessed resveratrol. From the study, it was concluded that formulation F19 has good emulsification property with uniform globule size, satisfactory in vitro drug release profile, and significant in vivo hypoglycemic effects which identify future opportunities for resveratrol delivery.

Naringenin Mitigates Iron-Induced Anxiety-Like Behavioral Impairment, Mitochondrial Dysfunctions, Ectonucleotidases and Acetylcholinesterase Alteration Activities in Rat Hippocampus

Studies demonstrated that the iron chelating antioxidant restores brain dysfunction induced by iron toxicity in animals. Earlier, we found that iron overload-induced cerebral cortex apoptosis correlated with oxidative stress could be protected by naringenin (NGEN). In this respect, the present study is focused on the mechanisms associated with the protective efficacy of NGEN, natural flavonoid compound abundant in the peels of citrus fruit, on iron induced impairment of the anxiogenic-like behaviour, purinergic and cholinergic dysfunctions with oxidative stress related disorders on mitochondrial function in the rat hippocampus. Results showed that administration of NGEN (50 mg/kg/day) by gavage significantly ameliorated anxiogenic-like behaviour impairment induced by the exposure to 50 mg of Fe-dextran/kg/day intraperitoneally for 28 days in rats, decreased iron-induced reactive oxygen species formation and restored the iron-induced decrease of the acetylcholinesterase expression level, mitochondrial membrane potential and mitochondrial complexes activities in the hippocampus of rats. Moreover, NGEN was able to restore the alteration on the activity and expression of ectonucleotidases such as adenosine triphosphate diphosphohydrolase and 5'-nucleotidase, enzymes which hydrolyze and therefore control extracellular ATP and adenosine concentrations in the synaptic cleft. These results may contribute to a better understanding of the neuroprotective role of NGEN, emphasizing the influence of including this flavonoid in the diet for human health, possibly preventing brain injury associated with iron overload.

The pharmacology of resveratrol in animals and humans

In addition to thousands of research papers related to resveratrol (RSV), approximately 300 review articles have been published. Earlier research tended to focus on pharmacological activities of RSV related to cardiovascular systems, inflammation, and carcinogenesis/cancer development. More recently, the horizon has been broadened by exploring the potential effect of RSV on the aging process, diabetes, neurological dysfunction, etc. Herein, we primarily focus on the in vivo pharmacological effects of RSV reported over the past 5 years (2009-2014). In addition, recent clinical intervention studies performed with resveratrol are summarized. Some discrepancies exist between in vivo studies with animals and clinical studies, or between clinical studies, which are likely due to disparate doses of RSV, experimental settings, and subject variation. Nevertheless, many positive indications have been reported with mammals, so it is reasonable to advocate for the conduct of more definitive clinical studies. Since the safety profile is pristine, an added advantage is the use of RSV as a dietary supplement. This article is part of a Special Issue entitled: Resveratrol: Challenges in translating pre-clinical findings to improved patient outcomes.

Neuroprotective effect of quercetin in ectoenzymes and acetylcholinesterase activities in cerebral cortex synaptosomes of cadmium-exposed rats

This study investigated the effect of quercetin on nucleoside triphosphate diphosphohydrolase (NTP-Dase), 50-nucleotidase, adenosine deaminase (ADA), and acetylcholinesterase (AChE) activities in synaptosomes from cerebral cortex of adult rats exposed to cadmium (Cd). Rats were exposed to Cd (2.5 mg/Kg) and quercetin (5, 25 or 50 mg/Kg) by gavage for 45 days. Rats were randomly divided into eight groups (n = 8-10): saline/ethanol, saline/Querc 5 mg/kg, saline/Querc 25 mg/kg, saline/Querc 50 mg/kg, Cd/ethanol, Cd/Querc 5 mg/kg, Cd/Querc 25 mg/kg, and Cd/Querc 50 mg/kg. Results demonstrated that AChE activity increased in the Cd/ethanol group when compared to saline/ethanol group. Treatment with quercetin prevented the increase in AChE activity when compared to Cd/ethanol group. Quercetin treatment prevented the cadmium-induced increase in NTPDase, 5-nucleotidase, and ADA activities in Cd/ethanol group when compared to saline/ethanol group. Our data showed that quercetin have a protector effect against Cd intoxication. This way, is a promising candidate among the flavonoids to be investigated as a therapeutic agent to attenuate neurological disorders associated with Cd intoxication.

Resveratrol and diabetes

Resveratrol is a stilbene compound, and a phytoalexin, synthesized by plants in response to stressful stimuli, usually caused by infection. It is abundantly present in red wine, ports and sherries, red grapes, blueberries, peanuts, itadori tea, as well as hops, pistachios, and in grape and cranberry juices. The anti-hyperglycemic effects of resveratrol seem to be the result of an increased action of the glucose transporter in the cytoplasmic membrane. Studies on rats with streptozotocin-induced diabetes have demonstrated that the expression of the insulin-dependent glucose transporter, GLUT4, is increased after resveratrol ingestion. Also, resveratrol enhances adiponectin levels, which could be one of the potential mechanisms by which it improves insulin sensitivity. Another important observation is that resveratrol induces the secretion of the gut incretin hormone, glucagon-like peptide-1. Resveratrol is also reported to activate Sir2 (silent information regulatory 2), a SIRT1 homolog, thus mimicking the benefits of calorie restriction. It produces a wide variety of effects in mammalian cells, including activation of AMP-activated protein kinase, which is involved in some of the same metabolic pathways as SIRT1, which may influence other mechanisms via the involvement of nuclear factor kappa B (NF-κB). In the near future, resveratrol-based therapies with either resveratrol or its analogs that have better bioavailability could be useful in the treatment of diabetes and its complications, either alone or in combination with other anti-diabetic drugs.

Effects of resveratrol on biomarkers of oxidative stress and on the activity of delta aminolevulinic acid dehydratase in liver and kidney of streptozotocin-induced diabetic rats

The present study investigated the effects of resveratrol (RV), a polyphenol with potent antioxidant properties, on oxidative stress parameters in liver and kidney, as well as on serum biochemical parameters of streptozotocin (STZ)-induced diabetic rats. Animals were divided into six groups (n = 8): control/saline; control/RV 10 mg/kg; control/RV 20 mg/kg; diabetic/saline; diabetic/RV10 mg/kg; diabetic/RV 20 mg/kg. After 30 days of treatment with resveratrol the animals were sacrificed and the liver, kidney and serum were used for experimental determinations. Results showed that TBARS levels were significantly increased in the diabetic/saline group and the administration of resveratrol prevented this increase in the diabetic/RV10 and diabetic/RV20 groups (P < 0.05). The activities of catalase (CAT), superoxide dismutase (SOD) and aminolevulinic acid dehydratase (δ-ALA-D) and the levels of non protein thiols (NPSH) and vitamin C presented a significant decrease in the diabetic/saline group when compared with the control/saline group (P < 0.05). The treatment with resveratrol was able to prevent these decrease improving the antioxidant defense of the diabetic/RV10 and diabetic/RV20 groups (P < 0.05). In addition, the elevation in serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) and γ-glutamiltransferase (γ-GT) activities as well as in levels of urea, creatinine, cholesterol and triglycerides observed in the diabetic/saline group were reverted to levels close to normal by the administration of resveratrol in the diabetic/RV10 and diabetic/RV20 groups (P < 0.05). These findings suggest that resveratrol could have a protector effect against hepatic and renal damage induced by oxidative stress in the diabetic state, which was evidenced by the capacity of this polyphenol to modulate the antioxidant defense and to decrease the lipid peroxidation in these tissues.

What is new for an old molecule? Systematic review and recommendations on the use of resveratrol

Background

Resveratrol is a natural compound suggested to have beneficial health effects. However, people are consuming resveratrol for this reason without having the adequate scientific evidence for its effects in humans. Therefore, scientific valid recommendations concerning the human intake of resveratrol based on available published scientific data are necessary. Such recommendations were formulated after the Resveratrol 2010 conference, held in September 2010 in Helsingør, Denmark.

Methodology

Literature search in databases as PubMed and ISI Web of Science in combination with manual search was used to answer the following five questions: ¹Can resveratrol be recommended in the prevention or treatment of human diseases?; ²Are there observed “side effects” caused by the intake of resveratrol in humans?; ³What is the relevant dose of resveratrol?; ⁴What valid data are available regarding an effect in various species of experimental animals?; ⁵Which relevant (overall) mechanisms of action of resveratrol have been documented?

Conclusions/Significance

The overall conclusion is that the published evidence is not sufficiently strong to justify a recommendation for the administration of resveratrol to humans, beyond the dose which can be obtained from dietary sources. On the other hand, animal data are promising in prevention of various cancer types, coronary heart diseases and diabetes which strongly indicate the need for human clinical trials. Finally, we suggest directions for future research in resveratrol regarding its mechanism of action and its safety and toxicology in human subjects.

Beneficial effects of resveratrol on scopolamine but not mecamylamine induced memory impairment in the passive avoidance and Morris water maze tests in rats

Resveratrol (3,5,4-trihydroxy-trans-stilbene), which is found in grapes and red wine has been shown to protect neuronal cells with its antioxidant activity, improve memory function in dementia and reverse acetylcholine esterase (AChE) activity. The aim of this study was to investigate the effect of resveratrol on emotional and spatial memory in naive rats, as well as on scopolamine- and mecamylamine-induced memory impairment in the passive avoidance and Morris water maze (MWM) tests. Resveratrol (12.5, 25 and 50 mg/kg), scopolamine (0.6 mg/kg) and mecamylamine (10mg/kg) were administered to male Wistar rats. In the passive avoidance test, there was no significant difference in the first day latency between all groups, whereas scopolamine and mecamylamine significantly shortened the second day latency compared to the control group. Resveratrol reversed the effect of scopolamine at all doses used, but it had no effect on mecamylamine-induced memory impairment in the passive avoidance test. Both scopolamine and mecamylamine significantly decreased the time spent in the escape platform quadrant during the probe trial of the MWM test compared to the control group. Resveratrol reversed the effect of scopolamine at all doses, but did not change the effect of mecamylamine in the MWM test. There were no significant differences in the locomotor activities of any of the groups. In conclusion, we suggested that resveratrol had improving effects on learning and memory by acting on muscarinic cholinergic receptors and at least in part, may reverse AChE activity.

Anti-diabetic effects of resveratrol

Diabetes mellitus is a complex metabolic disease affecting about 5% of people all over the world. Data from the literature indicate that resveratrol is a compound exerting numerous beneficial effects in organisms. Rodent studies, for example, have demonstrated that resveratrol decreases blood glucose in animals with hyperglycemia. This effect seems to predominantly result from increased intracellular transport of glucose. Resveratrol was also demonstrated to induce effects that may contribute to the protection of β cells in diabetes. In experiments on pancreatic islets, the ability of resveratrol to reduce insulin secretion was demonstrated; this effect was confirmed in animals with hyperinsulinemia, in which resveratrol decreased blood insulin levels. Moreover, inhibition of cytokine action and attenuation of the oxidative damage of the pancreatic tissue by resveratrol were recently shown. Studies of animals with insulin resistance indicate that resveratrol may also improve insulin action. The mechanism through which resveratrol improves insulin action is complex and involves reduced adiposity, changes in gene expression, and changes in the activities of some enzymes. These data indicate that resveratrol may be useful in preventing and treating diabetes.