Antioxidant, hepatoprotective, genoprotective, and cytoprotective effects of quercetin in a murine model of arthritis.

Rheumatoid arthritis is a highly debilitating inflammatory autoimmune disease which is characterized by joint destruction. The present study sought to investigate the effect of quercetin in rats with complete Freund's adjuvant-induced arthritis. Animals were divided into control/saline, control/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg) arthritis/saline, and arthritis/quercetin (5 mg/kg, 25 mg/kg, and 50 mg/kg); the treatments were administered for 45 days. Biochemical, oxidative stress, genotoxicity, and cytotoxicity parameters were evaluated. All doses of quercetin reduced the levels of aspartate aminotransferase, thiobarbituric acid-reactive substances, and reactive oxygen species; however, only treatment with 25 or 50 mg/kg increased catalase activity. Total thiol and reduced glutathione levels were not significantly affected by the induction nor by the treatments. Genotoxicity assessed by DNA damage, and cytotoxicity through picogreen assay, decreased after treatments with quercetin. Our results present evidence of the antioxidant, cytoprotective, genoprotective and hepatoprotective, and effects of quercetin, demonstrating its potential as a candidate for coadjuvant therapy.

Effect of quercetin on E-NTPDase/E-ADA activities and cytokine secretion of complete Freund adjuvant-induced arthritic rats.

The effect of quercetin was assessed in rats induced with complete Freund adjuvant (CFA). Arthritis scores, paw oedema, latency, activities of myeloperoxidase (MPO), ectonucleoside triphosphate diphosphohydrolase (E-NTPDase), and ectoadenosine deaminase (E-ADA) in lymphocytes were determined. Furthermore, nucleotide and nucleoside levels as well as the secretion of pro- and anti-inflammatory cytokines were evaluated. Animals were treated with saline and quercetin in doses of 5, 25, and 50 mg/kg for 45 days. The result revealed that quercetin (50 mg/kg) reduced arthritis score and paw oedema, and increased the latency in the thermal hyperalgesia test. Histopathological analysis showed that all the doses of quercetin reduced infiltration of inflammatory cells. MPO activity was increased in the arthritis group; however, quercetin reduced this activity. E-NTPDase activity was increased in lymphocytes of arthritis rats, and treatment with quercetin reversed this increase. However, E-ADA activity was reduced in the arthritis group, and treatment with quercetin modulated the activity of this enzyme in arthritis rat groups. Serum adenosine levels were increased in arthritis, and the levels were lowered with quercetin treatment. Quercetin treatment in arthritis groups decreased the elevated levels of cytokines in the arthritis control group. Thus, quercetin demonstrated an anti-inflammatory effect, and this flavonoid may be a promising natural compound for the treatment of arthritis. SIGNIFICANCE OF THE STUDY: Quercetin may represent a potential therapeutic compound in the treatment of rheumatoid arthritis. Findings from this study indicate that quercetin suppresses swelling and attenuates the underlying inflammatory responses. This is the first report where quercetin was shown to modulate the immune response to arthritis via attenuation of the purinergic system (E-NTPDase and E-ADA activities) and the levels of IFN-gamma and IL-4. Thus, this work is relevant to basic research and may be translated into clinical practice.

Neuroprotective effects of berberine on recognition memory impairment, oxidative stress, and damage to the purinergic system in rats submitted to intracerebroventricular injection of streptozotocin.

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disease. The present study investigated the effects of 50 and 100 mg/kg berberine (BRB) on recognition memory, oxidative stress, and purinergic neurotransmission, in a model of sporadic dementia of the Alzheimer's type induced by intracerebroventricular (ICV) injection of streptozotocin (STZ) in rats. Rats were submitted to ICV-STZ 3 mg/kg or saline, and 3 days later, were started on a treatment of BRB or saline for 21 days. The results demonstrated that BRB was effective in protecting against memory impairment, increased reactive oxygen species, and the subsequent increase in protein and lipid oxidation in the cerebral cortex and hippocampus, as well as δ-aminolevulinate dehydratase inhibition in the cerebral cortex. Moreover, the decrease in total thiols, and the reduced glutathione and glutathione S-transferase activity in the cerebral cortex and hippocampus of ICV-STZ rats, was prevented by BRB treatment. Besides an antioxidant effect, BRB treatment was capable of preventing decreases in ecto-nucleoside triphosphate diphosphohydrolase (NTPDase), 5'-nucleotidase (EC-5'-Nt), and adenosine deaminase (ADA) activities in synaptosomes of the cerebral cortex and hippocampus. Thus, our data suggest that BRB exerts a neuroprotective effect on recognition memory, as well as on oxidative stress and oxidative stress-related damage, such as dysfunction of the purinergic system. This suggests that BRB may act as a promising multipotent agent for the treatment of AD.

Increased oxidative stress alters nucleosides metabolite levels in sickle cell anemia.

OBJECTIVES: This study was conducted to assess the markers of oxidative stress, myeloperoxidase (MPO), acetylcholinesterase (AChE) and xanthine oxidase (XO) activities as well as the levels of nucleotide metabolites in sickle cell anemia (SCA) patients. METHODS: Fifteen SCA treated patients and 30 health subjects (control group) were selected. The markers of oxidative stress (levels of reactive oxygen species (ROS), plasma proteins, carbonyl content, lipid peroxidation (TBARS), total thiols (T-SH), glutathione and catalase activity), MPO, AChE and XO activities as well as the levels of nucleotide metabolites were measured in SCA patients. RESULTS: ROS, thiobarbituric acid-reactive substances (TBARS) and T-SH levels as well as the activities of catalase and MPO were significantly increased while glutathione level was reduced in SCA patients. Furthermore, a significant (P < 0.001) increase in hypoxanthine level was demonstrated in SCA patients. However, the serum levels for xanthine (P < 0.01) and uric acid (P < 0.001) were decreased in SCA patients. A significant (P < 0.001) decrease in XO activity was detected in SCA patients. DISCUSSION: The altered parameters in SCA patients suggest that the generation and impairment of oxidative stress in this disease as well as antioxidant markers are contributory factors towards cellular redox homeostasis and alteration of purine metabolites.

Biochemical and oxidative stress markers in the liver and kidneys of rats submitted to different protocols of anabolic steroids.

The objective of this study was to evaluate the effects of different protocols (P1, P2, and P3) of boldenone undecylenate (BU) and stanozolol (ST) on markers of liver and kidney function and variables of oxidative stress in these organs. For this, 54 male Wistar rats were divided into nine groups of six animals each. Each animal received intramuscularly 5.0 mg kg-1 of BU or ST once a week for 4 weeks (P1); 2.5 mg kg-1 of BU or ST once a week for 8 weeks (P2); and 1.25 mg kg-1 of BU or ST once a week for 12 weeks (P3). For each protocol, a control group was used, and they received 0.1 ml of olive oil intramuscularly. Blood and fragments of liver and kidney were collected for alanine aminotransferase activity (ALT), alkaline phosphatase, albumin, creatinine, cholesterol, total protein, triglycerides, urea, reactive oxygen species, thiobarbituric acid reactive substances, total thiols, and glutathione evaluation. The results show that the BU in doses of 5 (day 30) and 2.5 mg kg-1 (day 60) changes the ALT seric activity, possibly showing a hepatotoxic effect. High doses of BU may lead to increased levels of cholesterol (protocol P1) possibly due to inhibition of the normal steroid biosynthesis process. All protocols used caused changes in the redox balance of the organs studied (except in the liver, protocol P2), which indicates that these drugs might be harmful even at low doses.

Hypothyroidism Enhanced Ectonucleotidases and Acetylcholinesterase Activities in Rat Synaptosomes can be Prevented by the Naturally Occurring Polyphenol Quercetin.

Thyroid hormones have an influence on the functioning of the central nervous system. Furthermore, the cholinergic and purinergic systems also are extensively involved in brain function. In this context, quercetin is a polyphenol with antioxidant and neuroprotective properties. This study investigated the effects of (MMI)-induced hypothyroidism on the NTPDase, 5'-nucleotidase, adenosine deaminase (ADA), and acetylcholinesterase (AChE) activities in synaptosomes of rats and whether the quercetin can prevent it. MMI at a concentration of 20 mg/100 mL was administered for 90 days in the drinking water. The animals were divided into six groups: control/water (CT/W), control/quercetin 10 mg/kg, control/quercetin 25 mg/kg, methimazole/water (MMI/W), methimazole/quercetin 10 mg/kg (MMI/Q10), and methimazole/quercetin 25 mg/kg (MMI/Q25). On the 30th day, hormonal dosing was performed to confirm hypothyroidism, and the animals were subsequently treated with 10 or 25 mg/kg quercetin for 60 days. NTPDase activity was not altered in the MMI/W group. However, treatment with quercetin decreased ATP and ADP hydrolysis in the MMI/Q10 and MMI/Q25 groups. 5'-nucleotidase activity increased in the MMI/W group, but treatments with 10 or 25 mg/kg quercetin decreased 5'-nucleotidase activity. ADA activity decreased in the CT/25 and MMI/Q25 groups. Furthermore, AChE activity was reduced in all groups with hypothyroidism. In vitro tests also demonstrated that quercetin per se decreased NTPDase, 5'-nucleotidase, and AChE activities. This study demonstrated changes in the 5'-nucleotidase and AChE activities indicating that purinergic and cholinergic neurotransmission are altered in this condition. In addition, quercetin can alter these parameters and may be a promising natural compound with important neuroprotective actions in hypothyroidism.

Berberine protects against memory impairment and anxiogenic-like behavior in rats submitted to sporadic Alzheimer's-like dementia: Involvement of acetylcholinesterase and cell death.

The present study aimed to investigate the effects of berberine (BRB) on spatial and learning memory, anxiety, acetylcholinesterase activity and cell death in an experimental model of intracerebroventricular streptozotocin (ICV-STZ) induced sporadic Alzheimer's-like dementia. Sixty male Wistar rats were randomly divided into six groups: control (CTR), BRB 50mg/kg (BRB 50), BRB 100mg/kg (BRB 100), streptozotocin (STZ), streptozotocin plus BRB 50mg/kg (STZ+BRB 50), and streptozotocin plus BRB 100mg/kg (STZ+BRB 100). Rats were injected with ICV-STZ (3mg/kg) or saline, and daily oral BRB treatment began on day 4 for a period of 21days. Behavioral tests were carried out on day 17, and rats were euthanized on day 24. Cell death analysis and determination of acetylcholinesterase activity was performed on the cerebral cortex and hippocampus of the brain. Administration of BRB prevented the memory loss, anxiogenic behavior, increased acetylcholinesterase activity and cell death induced by ICV-STZ. This may be explained, in part, by a protective effect of BRB on ameliorating the progression of neurodegenerative diseases, including Alzheimer's disease, and the results of this study provide a better understanding of the effect of BRB on the brain. Thus, BRB may act as a potential neuroprotective agent.

Regular exercise training reverses ectonucleotidase alterations and reduces hyperaggregation of platelets in metabolic syndrome patients.

BACKGROUND: Alterations in the activity of ectonucleotidase enzymes have been implicated in cardiovascular diseases, whereas regular exercise training has been shown to prevent these alterations. However, nothing is known about it relating to metabolic syndrome (MetS). We investigated the effect of exercise training on platelet ectonucleotidase enzymes and on the aggregation profile of MetS patients. METHODS: We studied 38 MetS patients who performed regular concurrent exercise training for 30 weeks. Anthropometric measurements, biochemical profiles, hydrolysis of adenine nucleotides in platelets and platelet aggregation were collected from patients before and after the exercise intervention as well as from individuals of the control group. RESULTS: An increase in the hydrolysis of adenine nucleotides (ATP, ADP and AMP) and a decrease in adenosine deamination in the platelets of MetS patients before the exercise intervention were observed (P<0.001). However, these alterations were reversed by exercise training (P<0.001). Additionally, an increase in platelet aggregation was observed in the MetS patients (P<0.001) and the exercise training prevented platelet hyperaggregation in addition to decrease the classic cardiovascular risks. CONCLUSIONS: An alteration of ectonucleotidase enzymes occurs during MetS, whereas regular exercise training had a protective effect on these enzymes and on platelet aggregation.

Swimming training prevents alterations in ecto-NTPDase and adenosine deaminase activities in lymphocytes from Nω-nitro-L-arginine methyl ester hydrochloride induced hypertension rats.

BACKGROUND AND METHOD: Hypertension is accompanied by inflammatory process and purinergic system has been recognized as having an important role in modulating immune functions. Physical training is being considered one of the major lifestyle changes that contributes to the cardiovascular health as well as has an important role in regulating purinergic system. Thus, the aim of this study was to investigate the effect of chronic swimming training on lymphocytic purinergic system enzymes activities related to inflammatory process, as well as in lipid profile and classic inflammatory markers in rats that developed hypertension in response to the oral administration of N-nitro-L-arginine methyl ester hydrochloride (L-NAME). RESULTS: After 6 weeks of training, lymphocytes and serum were separated to be analysed. L-NAME-treated group displayed an increase in SBP as well as in ecto-NTPDase and adenosine deaminase (ADA) activities (P < 0.05). Six weeks of swimming training were able to prevent these alterations and keep the blood pressure and enzymes activities in the same levels of control group. Exercise per se was associated with a decrease in the expression of ecto-NTPDase1 in lymphocytes (-23.4%). Exercise was also efficient in preventing the rise in classic inflammatory markers observed in L-NAME group. CONCLUSION: These findings highlight the link between purinergic signalling and inflammatory process and suggest a novel mechanism in which moderate aerobic exercise possesses the potential to attenuate inflammation caused by hypertension.

Swimming training prevents alterations in acetylcholinesterase and butyrylcholinesterase activities in hypertensive rats.

BACKGROUND: Cholinergic enzyme activities are altered in hypertension, reflecting a low-grade inflammation. Regular physical exercise exerts anti-inflammatory effects and has been described as a coadjutant in the treatment of hypertension. In this study, we investigated the effect of 6 weeks of swimming training on cholinergic enzyme activities (acetylcholinesterase and butyrylcholinesterase) in Nω-Nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced hypertensive rats. METHODS: The rats were divided into 4 groups: control (n = 10), exercise (n = 10), L-NAME (n = 10), and exercise L-NAME (n = 10). The animals were trained 5 times per week in an adapted swimming system for 60 minutes with a gradual increase of the workload up to 5% of animal's body weight. Enzyme activities were measured spectrophotometrically in lymphocytes, whole blood, and serum. RESULTS: A significant rise in acetylcholinesterase activity was observed in lymphocytes and whole blood as well as in serum butyrylcholinesterase activity in the L-NAME group when compared with the other groups (P < 0.05), and the increase in cholinesterase activities was positively correlated with the rise in blood pressure (r = 0.5721, r = 0.6121, and r = 0.5811, respectively). Swimming training was efficient in preventing these alterations in the exercise L-NAME group, which displayed values similar to those of the control group. Exercise training demonstrated a significant hypotensive effect in hypertensive rats. CONCLUSIONS: Exercise training was shown to prevent increased cholinesterase related to inflammatory processes in hypertensive rats, providing a new insight about protective exercise mechanisms to avoid hypertension-related inflammation.

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.

Evaluation of acetylcholinesterase and adenosine deaminase activities in brain and erythrocytes and proinflammatory cytokine levels in rats submitted to neonatal hypoxia-ischemia model.

Perinatal hypoxic-ischemic (HI) brain injury is a common problem with severe neurologic sequelae. The definitive brain injury is a consequence of pathophysiological mechanisms that begin at the moment of HI insult and may extend for days or weeks. In this context, the inflammatory response and the formation of reactive oxygen species seem to play a key role during evolution of brain damage after injury. Thus, the aim of this study was to describe the chronological sequence of acetylcholinesterase (AChE) activity and the lipid peroxidation changes in the cerebral cortex using the classic model of neonatal HI. Furthermore, the erythrocyte AChE and adenosine deaminase (ADA) activities as well as the serum levels of proinflammatory cytokines were assessed. We observed that neonatal HI caused an increase of lipid peroxidation immediately after HI insult, which remained for several days afterward. There was a time-related change in the AChE activity in the cerebral cortex and the same was observed in erythrocyte AChE and ADA activities. In addition, immediately after HI, ADA activity showed a strong positive correlation with all proinflammatory cytokines assessed. Together, these findings may help the understanding of some mechanism related to the pathophysiology of neonatal HI, therefore highlighting the putative therapeutic targets to minimize brain injury and enhance recovery.

Physical training prevents oxidative stress in L-NAME-induced hypertension rats.

The present study investigated the effects of a 6-week swimming training on blood pressure, nitric oxide (NO) levels and oxidative stress parameters such as protein and lipid oxidation, antioxidant enzyme activity and endogenous non-enzymatic antioxidant content in kidney and circulating fluids, as well as on serum biochemical parameters (cholesterol, triglycerides, urea and creatinine) from Nω-nitro-L-arginine methyl ester hydrochloride (L-NAME)-induced hypertension treated rats. Animals were divided into four groups (n = 10): Control, Exercise, L-NAME and Exercise L-NAME. Results showed that exercise prevented a decrease in NO levels in hypertensive rats (P < 0·05). An increase in protein and lipid oxidation observed in the L-NAME-treated group was reverted by physical training in serum from the Exercise L-NAME group (P < 0·05). A decrease in the catalase (CAT) and superoxide dismutase (SOD) activities in the L-NAME group was observed when compared with normotensive groups (P < 0·05). In kidney, exercise significantly augmented the CAT and SOD activities in the Exercise L-NAME group when compared with the L-NAME group (P < 0·05). There was a decrease in the non-protein thiols (NPSH) levels in the L-NAME-treated group when compared with the normotensive groups (P < 0·05). In the Exercise L-NAME group, there was an increase in NPSH levels when compared with the L-NAME group (P < 0·05). The elevation in serum cholesterol, triglycerides, urea and creatinine levels observed in the L-NAME group were reverted to levels close to normal by exercise in the Exercise L-NAME group (P < 0·05). Exercise training had hypotensive effect, reducing blood pressure in the Exercise L-NAME group (P < 0·05). These findings suggest that physical training could have a protector effect against oxidative damage and renal injury caused by hypertension.

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.