Effects of grape seed extract on oxidative stress and antioxidant defense markers in streptozotocin-induced diabetic rats.

BACKGROUND/AIM: To evaluate the effects of grape seed extract (GSE) supplementation on oxidative stress and antioxidant markers in streptozotocin (STZ)-induced diabetic rats. MATERIALS AND METHODS: Thirty-six male rats were divided into the following four groups: control, GSE-supplemented control, diabetic, and GSE-supplemented diabetic. Beginning on day 7 after STZ injection, the rats were administered GSE (100 mg kg(-1) day(-1) in drinking water for 6 weeks. At the end of week 6, rats were sacrificed by cardiac puncture. Plasma nitric oxide (NO) levels and xanthine oxidase (XO), adenosine deaminase (ADA), and glutathione peroxidase (GPx) activities were analyzed. RESULTS: Both XO and ADA activities increased and NO levels decreased in diabetic rats (P < 0.05). GSE supplementation normalized all of these changes. Antioxidant enzyme activities decreased in diabetic rats compared to the controls (P < 0.05). GSE supplementation increased antioxidant enzyme activities in both diabetic and healthy rats (P < 0.05). CONCLUSION: These findings suggest that 6 weeks of oral GSE supplementation may prevent oxidative stress and improve antioxidant status in diabetic rats.

Effects of grape seed polyphenols on oxidative damage in liver tissue of acutely and chronically exercised rats.

The objective of the present study was to investigate the effects of grape seed extract (GSE) supplementation on oxidative stress and antioxidant defense markers in liver tissue of acutely and chronically exercised rats. Rats were randomly assigned to six groups: Control (C), Control Chronic Exercise (CE), Control Acute Exercise (AE), GSE-supplemented Control (GC), GSE-supplemented Chronic Exercise(GCE) and GSE-supplemented Acute Exercise (GAE). Rats in the chronic exercise groups were subjected to a six-week treadmill running and in the acute exercise groups performed an exhaustive running. Rats in the GSE supplemented groups received GSE (100 mg.kg(-1) .day(-1) ) in drinking water for 6 weeks. Liver tissues of the rats were taken for the analysis of malondialdehyde (MDA), nitric oxide (NO) levels and total antioxidant activity (AOA) and xanthine oxidase (XO) activities. MDA levels decreased with GSE supplementation in control groups but increased in acute and chronic exercise groups compared to their non-supplemented control. NO levels increased with GSE supplementation. XO activities were higher in AE group compared to the CE group. AOA decreased with GSE supplementation. In conclusion, while acute exercise triggers oxidative stress, chronic exercise has protective role against oxidative stress. GSE has a limited antioxidant effect on exercise-induced oxidative stress in liver tissue.

Oxidative stress and anti-oxidant status in diabetic rat liver: effect of plant polyphenols.

Increased evidence in role of oxidative stress and grape seed extract (GSE) in diabetes and its complication led us to investigate the changes of oxidative stress and anti-oxidant defence in liver tissue of diabetic rats and possible effects of GSE. Diabetes was induced by a single intraperitoneal injection of streptozotocin. Seven days after STZ injection four groups were formed: Control, GSE-supplemented control, diabetic and GSE-supplemented diabetic and GSE was given for 6 weeks. Malondialdehyde levels and xanthine oxidase activities were not different among the groups. However, nitric oxide (NO) levels were higher in diabetic and GSE supplemented groups compared with non-diabetic and non-supplemented groups, respectively. Total anti-oxidant activity (TAA) was lower in diabetic groups compared with their non-diabetic controls and it was not affected by GSE. In conclusion, GSE supplementation has limited protective effect in liver tissue of diabetic rats via affecting NO levels and was not affecting TAA.

The protective effect of avocado soybean unsaponifilables on brain ischemia/reperfusion injury in rat prefrontal cortex.

OBJECT: We investigated the protective effects of avocado/soybean unsaponifiables (ASU) on the prefrontal cortex (PFC) after global brain ischemia/reperfusion (I/R) injury in rats. METHODS: Rats were randomly divided into three experimental groups as follows: Group I was control rats, Group II was ischemia rats, Group III was Isch + ASU rats. Brain ischemia was produced via four-vessel occlusion model. These processes followed by reperfusion for 30 min for both II and III groups. Rats were sacrificed and their brains were removed immediately. Malondialdehyde (MDA) and superoxide dismutase (SOD) were measured in left PFC, levels of TNF-α concentration were measured in the plasma. The number of apoptotic neurons was assayed in histological samples of the right PFC. RESULTS: MDA and TNF-α levels as well as the number of apoptotic neurons were observed to have decreased significantly in Group III compared to Group II, while SOD activities have been found to have increased significantly in Group III in comparison to Group II, significantly. CONCLUSIONS: We think that ASU might have an antioxidant and neuroprotective effects in brain I/R injured rats.

Effects of coenzyme Q10 supplementation on plasma adiponectin, interleukin-6, and tumor necrosis factor-alpha levels in men.

The aim of the study was to determine the effects of coenzyme Q10 supplementation on plasma adiponectin, interleukin (IL)-6, and tumor necrosis factor (TNF )-alpha levels in sedentary men. Fourteen healthy, nonsmoking, sedentary men participated in the study. The protocol was approved by the Ethical Committee of our institution. This study was a randomized, double-blind, crossover trial. Blood samples were collected from all participants before coenzyme Q10 or placebo supplementation. The participants were randomly allocated to two groups. Seven participants received oral coenzyme Q10 (100 mg/day) supplementation, and seven participants received placebo (glucose) for 8 weeks. At the end of the 8 weeks, a second blood sampling was performed. After a 4-week washout period, placebo was given to the participants who used coenzyme Q10 the first time, and vice versa, and blood sampling was repeated. Plasma was stored at -80 degrees C until the time of analysis for adiponectin, IL-6, and TNF-alpha. Both CoQ10 and placebo supplementation did not affect plasma adiponectin and TNF-alpha levels. IL-6 level increased with coenzyme Q10 supplementation, but this increase did not differ from that seen with placebo supplementation. Coenzyme Q10 supplementation did not affect plasma adiponectin, IL-6, and TNF-alpha levels in sedentary men.

Combination therapy of Nigella sativa and human parathyroid hormone on bone mass, biomechanical behavior and structure in streptozotocin-induced diabetic rats.

Extracts of the seeds of Nigella sativa (NS), an annual herbaceous plant of the Ranunculaceae family, have been used for many years for therapeutic purposes, including their potential anti-diabetic properties. The aim of the present study was to test the hypothesis that combined treatment with NS and human parathyroid hormone (hPTH) is more effective than treatment with NS or hPTH alone in improving bone mass, connectivity, biomechanical behaviour and strength in insulin-dependent diabetic rats. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) at a single dose of 50mg/kg. The diabetic rats received NS (2ml/kg/day, i.p.), hPTH (6microg/kg/day, i.p.) or NS and hPTH combined for 4 weeks, starting 8 weeks after STZ injection. The beta-cells of the pancreatic islets of Langerhans were examined by immunohistochemical methods. In addition, bone sections of femora were processed for histomorphometry and biomechanical analysis. In diabetic rats, the beta-cells were essentially negative for insulin-immunoreactivity. NS treatment (alone or in combination with hPTH) significantly increased the area of insulin immunoreactive beta-cells in diabetic rats; however, hPTH treatment alone only led to a slightly increase in the insulin-immunoreactivity. These results suggest that NS might be used in a similar manner to insulin as a safe and effective therapy for diabetes and might be useful in the treatment of diabetic osteopenia.

Role of caffeic acid phenethyl ester, an active component of propolis, against NAOH-induced esophageal burns in rats.

OBJECTIVES: This study was evaluated to investigate the efficacy of caffeic acid phenethyl ester (CAPE), which is a natural honeybee product exhibits a spectrum of biological activities including anti-microbial, anti-inflammatory, antioxidant and anti-tumoral actions, on the prevention of stricture development after esophageal caustic injuries in the rat. METHODS: Thirty healthy male Wistar albino rats were utilized in this study. The rats were randomly allotted into one of three experimental groups: group A (sham) animals were uninjured. Caustic esophageal burn was created by applying 1 ml 37.5% NaOH to the distal esophagus. Group B rats were injured but untreated. Group C rats were injured and received CAPE (10 micromol/kg/day i.p. for 28 days). Efficacy of the treatment was assessed by measuring the esophageal transit time, stenosis index, histopathologic damage score and biochemically by determining tissue hydroxyproline content, lipid peroxidation and antioxidant enzyme activities. RESULTS: The esophageal transit time, the stenosis index, histopathologic damage score and the hydroxyproline level were significantly increased in the untreated group compared with the sham and CAPE-treated groups. Treatment with CAPE decreased tissue hydroxyproline levels, histological damage, and the stenosis index, but except the esophageal transit time. Caustic esophageal burn also increased the lipid peroxidation and decreased the antioxidant enzyme activities in the untreated group. CAPE treatments decreased the elevated lipid peroxidation and also increased the reduced antioxidant enzyme activities. In corrosive esophageal burn group with no treatment, the most consistent findings were degenerative changes and increased in submucosal collagen content, and the luminal narrowing. CAPE treatment protected esophagus. Nevertheless, there was the slight increase in submucosal collagen. CONCLUSIONS: It is concluded that CAPE has a preventive effect on the stricture development after esophageal caustic injuries in the rat.