Sevgi Eskiocak

The protective role of melatonin in experimental hypoxic brain damage.

Background : It is known that oxygen‐derived free radicals play an important role in the pathogenesis of brain injury. Melatonin is a powerful scavenger of the oxygen free radicals. In this study, the protective effect of melatonin against the damage inflicted by reactive oxygen species during brain hypoxia was investigated in newborn rats using biochemical parameters.

The effect of melatonin on protein oxidation and nitric oxide in the brain tissue of hypoxic neonatal rats

Melatonin is a potent antioxidant agent that can scavenge oxy- and nitroradicals generated under hypoxic conditions in the brain. In this study, we investigated the effect of melatonin on protein oxidation and nitric oxide (NO) during hypoxia. Seven-day-old Sprague-Dawley newborn rats were divided into three groups. Hypoxic (n=9) and melatonin (n=11) groups were subjected to 2h of hypoxic exposure (a humidity mixture of gases consisting of 92% nitrogen and 8% oxygen). Melatonin (at a dose of 10mg/kg) was administrated 30 min before the onset hypoxia and then at 24th and 48th hours after the end of the hypoxic exposure. Control (n=10) and hypoxic groups received the isotonic sodium chloride according to the same schedule. The brain tissue concentration of advanced oxidation protein products (AOPP) and protein thiol (P-SH) was used as an index of protein oxidation. In our study, although AOPP and NO increased significantly, the levels of P-SH decreased in the hypoxic group. The level of AOPP was declined by melatonin treatment. However, perturbed thiol status could not be recovered by melatonin treatment. There was no relationship between the levels of NO and protein oxidation markers. These results indicate that exogenous melatonin could prevent AOPP, but that it is inadequate in recovering perturbed thiol status. Therefore, melatonin alone was observed to be an incomplete treatment to prevent protein oxidation in hypoxia-induced brain damage.

Comparison of the protective roles of L-carnitine and amifostine against radiation-induced acute ovarian damage by histopathological and biochemical methods.

PURPOSE The aim of this study was to compare the radioprotective efficacies of L-carnitine (LC) and amifostine against radiation-induced acute ovarian damage. MATERIALS AND METHODS Forty-five, 3-month-old Wistar albino rats were randomly assigned to six groups. Control (CONT, n = 7); irradiation alone RT: radiation therapy (RT, n = 8); amifostine plus irradiation (AMI + RT, n = 8); LC plus irradiation (LC + RT, n = 8); LC and sham irradiation (LC, n = 7); and amifostine and sham irradiation (AMI, n = 7). The rats in the AMI + RT, LC + RT and RT groups were irradiated with a single dose of 20 Gy to the whole abdomen. LC (300 mg/kg) and amifostine (200 mg/kg) was given intraperitoneally 30 min before irradiation. Five days after irradiation, both antral follicles and corpus luteum in the right ovaries were counted, and tissue levels of malondialdehyde (MDA) and advanced oxidation protein product (AOPP) were measured. RESULTS Irradiation significantly decreased antral follicles and corpus luteum (P: 0.005 and P < 0.0001). LC increased the median number of antral follicles and corpus luteum (P: 0.009 and P < 0.0001, respectively). Amifostine improved median corpus luteum numbers but not antral follicle (P < 0.000, P > 0.05). The level of MDA and AOPP significantly increased after irradiation (P = 0.001 and P < 0.0001, respectively). MDA and AOPP levels were significantly reduced by LC (P: 0.003, P < 0.0001) and amifostine (P < 0.0001, P: 0.018). When comparing CONT group with AMI + RT and LC + RT groups, MDA and AOPP levels were similar (P > 0.005). The levels of both MDA and AOPP were also similar when LC + RT is compared with AMI + RT group (P > 0.005). CONCLUSIONS L-carnitine and amifostine have a noteworthy and similar radioprotective effect against radiation-induced acute ovarian toxicity.

Effect of lidocaine on reducing injury in a rat electrical burn model.

AbstractElectrical injuries induce progressive tissue loss. We evaluated the effect of lidocaine on tissue necrosis after electrical burn injuries. Forty-two male Wistar albino rats (250–300 g) were divided into 3 groups [Group A (n = 6), control group without an electrical burn injury; and Groups B (n = 18) and C (n = 18), electrical burn injury groups without and with lidocaine therapy, respectively]. Three separate analyses were performed at different time points on 6 of 18 rats from Groups B and C at each time point. Electrical burns were induced by applying 220 V AC between the left upper and right lower extremities for 10 seconds. Myeloperoxidase and malondialdehyde levels were measured in skin and muscle biopsy specimens after the first hour, fresh and dry weight differences in the amputated extremities were calculated after 24 hours, and live and necrotic tissue areas were measured at 7 days after burn injury. We found that lidocaine reduced edema, the number of neutrophils, and neutrophil damage in tissues. We conclude that lidocaine decreased the amount of necrotic tissue caused by electric injury.

Fucoidin, a neutrophil rolling inhibitor, reduces damage in a rat electrical burn injury model ☆ ☆☆

BACKGROUND Electrical injuries induce progressive tissue loss caused by free oxygen radicals released from neutrophil aggregates. Fucoidin, a potent inhibitor of L-selectin function, reduces the aggregation of neutrophils. The aim of this study was to evaluate the effect of fucoidin on tissue damage in rat electrical burn injury model. METHODS Forty-two male Wistar albino rats (250-300 g) were divided into 3 groups (Group A (n=6), control group without electrical burn injury; Groups B (n=18) and C (n=18), electrical burn injury groups without and with fucoidin therapy, respectively). Three separate analyses were performed at different time points on 6 out of 18 mice from Group B and C at each time point. Biochemistry (myeloperoxidase and malondialdehyde levels) and histopathology (number of neutrophils) of the skin and muscle biopsies at 1st hour; tissue edema (ratio of wet weight/dry weight of extremities) at 24th hour; and necrotic areas at 7th day after electrical injury were evaluated. The electrical burn was induced by exposing rats to 220 V AC between their left upper extremity and right lower extremity for 10 s. Fucoidin was administered as 25 mg/kg intravenous bolus injection at 15 min after electrical burn injury. RESULTS Myeloperoxidase and malondialdehyde levels, number of neutrophils, tissue edema, and necrotic area were significantly less in fucoidin-applied rats than the group without fucoidin therapy. CONCLUSIONS Fucoidin inhibits tissue damage induced by electrical burn injury in rats by reducing necrotic area, edema and number of neutrophils.

RADIATION-INDUCED CHRONIC-OXIDATIVE RENAL DAMAGE CAN BE REDUCED BY AMIFOSTINE

In the current study, amifostine is evaluated for its radioprotective role in serum and kidney tissue by oxidative (malondialdehyde-MDA, advanced oxidation protein product-AOPP) and antioxidative markers (catalase, glutathione-GSH, free-thiols-F-SH). Thirty Wistar albino 3–4 months old, female rats, were randomly divided into Group I (n = 10): Control, Group II (n = 10): Irradiation-alone, Group III (n = 10): Amifostine before irradiation. In Group II and III, right kidneys of the rats were irradiated with a single dose of 6 Gy using a 60Co treatment unit. Rats in Group III received 200 mg/kg amifostine intraperitoneally, 30 min prior to irradiation. Following sacrification at 24th week, blood and kidney tissue samples were collected. Statistical analysis was done by One-way ANOVA, Post hoc Bonferroni, Dunnett T3, and Mann–Whitney U tests. Administration of amifostine significantly decreased the serum AOPP and MDA levels when compared to the irradiation-only group (P = 0.004, P = 0.006; respectively). Also amifostine significantly increased serum catalase activities and GSH levels, when given 30 min prior to irradiation (P = 00.02, P = 0.000; respectively). In the kidney tissue, administration of amifostine significantly decreased AOPP and MDA levels (P = 0.002, P = 0.016; respectively). Tissue GSH activity was increased following amifostine administration (P = 0.001). There was no statistically significant result on histopathological evaluation. Amifostine may reduce radiation-induced nephropathy by inhibiting chronic oxidative stress. Biomarkers of oxidative stress in serum and kidney tissue may be used for evaluation of the radiation-induced nephropathy.

Effect of lipoic acid on paraoxonase-1 and paraoxonase-3 protein levels, mRNA expression and arylesterase activity in liver hepatoma cells

Paraoxonase-1 (PON1) and PON3 (PON3) are anti-atherosclerotic enzymes, synthesized primarily in liver and bound to HDL in circulation. The aim of the present study was to investigate the effects of therapeutic doses of lipoic acid on PON1 and PON3 protein levels, mRNA expression and arylesterase activity in liver. We treated HepG2 cells with 10, 40 and 200 μM lipoic acid for 72 h. Cell viability was evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. PON1 and PON3 protein levels were measured by Western blotting, their mRNA expression was measured by quantitative PCR and arylesterase activity was measured spectrophotometrically. 200 µM lipoic acid caused a significant increase on PON1 and PON3 protein levels and arylesterase activity as compared with control, 10 µM and 40 µM lipoic acid-treated cells. 200 µM lipoic acid also caused a significant decrease on PON1 mRNA expression whereas on a significant increase PON3 mRNA expression as compared with control, 10 µM and 40 µM lipoic acid-treated cells. Our study showed that although lipoic acid up-regulates PON3 but down-regulates PON1 mRNA expression, it increases both PON1 and PON3 protein levels and arylesterase activity in HepG2 cells. We can report that lipoic acid may be useful for preventing atherosclerosis at therapeutic doses.

Caffeine Increases Apolipoprotein A-1 and Paraoxonase-1 but not Paraoxonase-3 Protein Levels in Human-Derived Liver (HepG2) Cells

Background: Apolipoprotein A-1, paraoxonase-1 and paraoxonase-3 are antioxidant and anti-atherosclerotic structural high-density lipoprotein proteins that are mainly synthesized by the liver. No study has ever been performed to specifically examine the effects of caffeine on paraoxonase enzymes and on liver apolipoprotein A-1 protein levels. Aims: To investigate the dose-dependent effects of caffeine on liver apolipoprotein A-1, paraoxonase-1 and paraoxonase-3 protein levels. Study Design: In vitro experimental study. Methods: HepG2 cells were incubated with 0 (control), 10, 50 and 200 μM of caffeine for 24 hours. Cell viability was evaluated by 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. Apolipoprotein A-1, paraoxonase-1 and paraoxonase-3 protein levels were measured by western blotting. Results: We observed a significant increase on apolipoprotein A-1 and paraoxonase-1 protein levels in the cells incubated with 50 µM of caffeine and a significant increase on paraoxonase-1 protein level in the cells incubated with 200 µM of caffeine. Conclusion: Our study showed that caffeine does not change paraoxonase-3 protein level, but the higher doses used in our study do cause an increase in both apolipoprotein A-1 and paraoxonase-1 protein levels in liver cells.

Effect of Lipoic Acid on Serum Paraoxonase-1 and Paraoxonase-3 Protein Levels and Activities in Diabetic Rats

The aim of the present study was to investigate the effect of streptozotocin-induced diabetes mellitus and lipoic acid treatment on serum paraoxonase-1 and paraoxonase-3 protein levels and paraoxonase, arylesterase and lactonase activities.36 rats were equally and randomly divided into 4 groups as control, lipoic acid, diabetes and diabetes+lipoic acid. To induce diabetes, a single dose of streptozotocin (40 mg/kg) was injected intraperitoneally to diabetes and diabetes+lipoic acid groups. Lipoic acid (10 mg/kg/day) was injected intraperitoneally for 14 days to lipoic acid and diabetes+lipoic acid groups. Serum PON1 and PON3 protein levels were measured by western blotting. Serum paraoxonase, arylesterase and lactonase activities were determined by the measuring initial rate of substrate (paraoxon, phenylacetate and dihydrocoumarin) hydrolysis.Streptozotocin-induced diabetes mellitus caused a significant decrease whereas lipoic acid treatment caused a significant increase in serum PON1 and PON3 protein levels and paraoxonase, arylesterase and lactonase activities. The increase percent of serum PON3 protein was higher than that of serum PON1 protein and the increase percent of serum lactonase activity was higher than that of serum paraoxonase and arylesterase activities in diabetes+lipoic acid group.We can report that, like PON1 protein, PON3 protein and actually its lactonase activity may also have a role as an antioxidant in diabetes mellitus and lipoic acid treatment may be useful for the prevention of the atherosclerotic complications of diabetes by increasing serum PON1 and PON3 protein levels and serum enzyme activities.

An interference study of the copper-induced plasma oxidizability test.

OBJECTIVES The aim of this study is to investigate the effect of cristaloid cardioplegic fluid (CCF) and its contents on the susceptibility of plasma to copper-catalyzed lipid peroxidation test. DESIGN AND METHODS The plasma pool was divided into eight groups. Equal volumes of CCF or one of its contents were added to each group of the plasma pool. The accumulation of conjugated diene (CD) by copper-induced oxidation was monitored for a period of 5 h. Thiobarbituric acid-reactive substances (TBARS) formed during the incubation of plasma with copper was also measured. RESULTS It was found that, the production of CD and TBARS were inhibited and the lag time had increased, when the plasma was mixed with CCF or its contents. CONCLUSIONS As a result, we conclude that that the susceptibility of plasma to copper-induced lipid peroxidation is interfered by CCF. The chloride ions, which major content of CCF, may play an important role on this effect.