Çiğdem Özer

900 MHz pulse-modulated radiofrequency radiation induces oxidative stress on heart, lung, testis and liver tissues

Oxidative stress may affect many cellular and physiological processes including gene expression, cell growth, and cell death. In the recent study, we aimed to investigate whether 900 MHz pulse-modulated radiofrequency (RF) fields induce oxidative damage on lung, heart and liver tissues. We assessed oxidative damage by investigating lipid peroxidation (malondialdehyde, MDA), nitric oxide (NOx) and glutathione (GSH) levels which are the indicators of tissue toxicity. A total of 30 male Wistar albino rats were used in this study. Rats were divided randomly into three groups; control group (n = 10), sham group (device off, n = 10) and 900 MHz pulsed-modulated RF radiation group (n = 10). The RF rats were exposed to 900 MHz pulsed modulated RF radiation at a specific absorption rate (SAR) level of 1.20 W/kg 20 min/day for three weeks. MDA and NOx levels were increased significantly in liver, lung, testis and heart tissues of the exposed group compared to sham and control groups (p < 0.05). Conversely GSH levels were significantly lower in exposed rat tissues (p < 0.05). No significantly difference was observed between sham and control groups. Results of our study showed that pulse-modulated RF radiation causes oxidative injury in liver, lung, testis and heart tissues mediated by lipid peroxidation, increased level of NOx and suppression of antioxidant defense mechanism.

Effects of Taurine in Cellular Responses to Oxidative Stress in Young and Middle‐Aged Rat Liver

Abstract:  Aging is related with an increased cellular level of lipid peroxides and reactive oxygen species (ROS). The useful effects of taurine as an antioxidant in biological systems have been attributed to its capability to stabilize biomembranes, to scavenge ROS, and to decrease the peroxidation of unsaturated membrane lipids. The aim of the present study was to investigate the effects of taurine on malondialdehyde (MDA), glutathione (GSH), glutathione peroxidase (GPx), thioredoxin reductase (TR), and endothelial nitric oxide synthase (eNOS) in young and middle‐aged rat liver. There was not a significant difference in liver MDA levels between the control groups of young and middle‐aged rats (P > 0.05). However, liver GSH levels, and GPx and TR activities between the control groups of young and middle‐aged rats were significantly different (P < 0.05). Liver MDA level was significantly lower in the taurine group of middle‐aged rats (P < 0.05). Liver GSH levels, and GPx and TR activities were significantly increased in the taurine group of middle‐aged rats when compared to the control group (P < 0.05). Liver MDA level was significantly lower in the taurine group of young rats than the ones in the control group (P < 0.05). Liver TR activity was significantly increased in the taurine group of young rats when compared to the control group (P < 0.05). Liver GPx activity was not statistically different between the taurine and the control groups in young rats (P > 0.05). Liver GSH levels were not different between the young taurine and the control groups (P > 0.05). Immunohistochemical studies exhibited no change in eNOS activity after taurine injection in young rats. However, in middle‐aged rats, taurine lowered the eNOS reactivity to the same level found in young rats. These results suggested that exogenous taurine might play a role in aging by means of its reducing effects on free radical levels in parallel to an increase in the antioxidant capacity.

Effects of taurine in glucose and taurine administration

Summary.Taurine has several biological processes such as hypoglycemic action, antioxidation, detoxification, etc. To assess the effect of taurine administration on the guinea pigs with hyperglycemia, blood glucose, C-peptide levels together with morphologic alterations in the pancreatic ultrastructure were investigated in terms of hypoglycemic action and malondialdehyde and total sulfhydryl group levels with regard to oxidation-antioxidation relation. Animals were divided into four groups of six. Glucose supplementation group was administrated a single dose of glucose (400 mg/kg, i.p.) injection. Glucose and taurine supplementation group was administrated glucose treatment (a single dose, 400 mg/kg, i.p.) following taurine (a single dose, 200 mg/kg, i.p.). Taurine and glucose supplementation group was administered taurine treatment (a single dose, 200 mg/kg, i.p.) following glucose treatment (a single dose, 400 mg/kg, i.p.). Control animals received no treatment. Blood samples were collected at the end of the experiments for the determination of glucose, C-peptide (indicator of insulin secretion), lipid peroxidation (thiobarbituric acid reactive substances), and total sulfhydryl groups levels. Pancreatic tissue samples were then collected and processed for transmission electron microscopy. The findings showed that glucose supplementation following taurine administration significantly decreased blood glucose level by increasing C-peptide level and the pancreatic secretion stimulated morphologically and insignificantly changed thiobarbituric acid reactive substances and total sulfhydryl group levels. These observations suggest that taurine administration may be useful in hyperglycemia because of its hypoglycemic and protective effects.

Chemoprotective effect of ascorbic acid, α-tocopherol, and selenium on cyclophosphamide-induced toxicity in the rat ovarium

OBJECTIVE The aim of the study was to evaluate the protective efficacy of ascorbic acid, α-tocopherol, and selenium by measuring the glutathione (GSH) levels and proliferating cell nuclear antigen (PCNA) and growth differentiation factor-9 (GDF-9) expression in the ovarian tissues of rats treated with cyclophosphamide (CP) therapy. METHODS Female Wistar rats were divided into 5 groups of 6 rats each: (I) control, (II) only CP, (III) CP + ascorbic acid, (IV) CP + α-tocopherol, and (V) CP + selenium. Immunohistochemical stainings and GSH protocol were then applied. RESULTS Following CP administration, the rats exhibited significantly lower GDF-9 expression in oocytes and PCNA expression in granulosa cells of follicles in all stages of development (P < 0.05). In CP + antioxidant groups (Groups III, IV, V), GDF-9 immunoreaction in oocytes and PCNA immunoreaction in granulosa cells of the developing follicles were found to show an increase towards the levels observed in the control group (P < 0.05). CONCLUSIONS CP was found to cause remarkable degenerative effects in normal ovarian tissue, and we believe that this damage can be reduced and ovarian tissue can be spared from the toxic effects of CP by using antioxidants such as ascorbic acid, α-tocopherol, and selenium.

The effects of dexfenfluramine administration on brain serotonin immunoreactivity and lipid peroxidation in mice

Obesity continues to be an increasing health problem in worldwide and antiobesity drugs have commonly been used by obese patients. During the use of anorectic drugs, the antioxidant defense may be affected, especially by reactive oxygen species. It was decided to investigate the effects of dexfenfluramine on body weight, daily food intake, brain thiobarbituric acid-reactive substances (TBARS), glutathione (GSH) and nitric oxide (NO) levels, and 5-HT immunoreactivity. Mice were divided into two groups each containing 8 Swiss Albino adult (6 months) mice. Group 1, untreated, was used as a control; group 2 was treated with dexfenfluramine 0.4 mg/kg per day intraperitoneally for 7 days. Brain TBARS and GSH levels were assayed spectrophotometrically. The stable end-products of NO, nitrite and nitrate, were analyzed spectrophotometrically. Brain tissue 5-HT immunoreactivity was observed using an immunohistochemical method. There were significant decreases in body weight in the dexfenfluramine group (p < 0.05). Although brain GSH and NOx levels decreased significantly, brain TBARS levels increased in the dexfenfluramine group (p < 0.05). Brain 5-HT immunoreactivity also increased in the dexfenfluramine-treated group compared to control. In conclusion, our findings show that dexfenfluramine is effective in achieving weight loss and also increases lipid peroxidation in mouse brain.

The effect of repeated tryptophan administration on body weight, food intake, brain lipid peroxidation and serotonin immunoreactivity in mice

Tryptophan as a circulating precursor of serotonin (5-HT) may suppress food intake and body weight. Tryptophan administration can enhance the generation of reactive oxygen species (ROS) by inducing oxidative pathway in vivo and in vitro. We have examined the effect of repeated tryptophan administration on food consumption, body weight, brain lipid peroxidation and 5-HT immunoreactivity. Tryptophan was given at the dose of 100 mg/kg/24 hr in 0.2 ml saline solution i.p. for 7 days to mice. Control mice received 0.9% NaCL solution at the same manner and volume. Body weights were recorded at the beginning and end of the experiments. Thiobarbituric acid reactive substance (TBARS), the last product of lipid peroxidation, was measured spectrophotometrically. Brain 5-HT levels were determined by the immunohistochemical method. Our findings indicate that the tryptophan suppresses food intake significantly in mice. Body weight decreased and brain TBARS levels increased significantly by repeated tryptophan treatment. Immunohistochemical detection showed that 5-HT levels increased by tryptophan administration. There is a link between increased 5-HT level and oxidative stress by tryptophan administration on brain tissue. Tryptophan at repeated doses should be exercised carefully in clinical practice.

Methylene Blue Decreases Ischemia-Reperfusion (I/R)-Induced Spinal Cord Injury: An in vivo Study in an I/R Rabbit Model

Objectives: To evaluate the effects of intravenous methylene blue (MB) administration on ischemia-reperfusion (I/R) injury of the spinal cord (SC). Methods: 16 rabbits were randomly assigned either to group M (n = 8; receiving MB, intervention group) or group C (n = 8; control group) and underwent a 30-min period of SC ischemia by clamping the abdominal aorta between the left renal artery and the aortic bifurcation. 15 min before clamping, rabbits received either intravenous MB (10 mg/kg; group M) or normal saline (group C). The two groups were compared 24 h postoperatively both histologically and for neurological function, using a Tarlov score. Measurements to determine levels of malondialdehyde (MDA) and glutathione (GSH) in the SC tissue were also performed. Results: Neurological impairment and spinal tissue MDA levels were significantly lower in animals treated with MB (p < 0.001). In contrast, spinal GSH levels were significantly higher in group M (p < 0.001). Histological examination revealed that the integrity of the SC was better preserved in the MB group, whereas cords from the control group exhibited evidence of acute neuronal injury. Conclusions: The prophylactic use of MB reduces neurological injury and improves clinical outcomes in the rabbit SC I/R model. These effects are probably mediated by the drug’s antioxidant properties.

The Role of Transforming Growth Factor α Formulation on Aspirin-Induced Ulcer Healing and Oxidant Stress in the Gastric Mucosa

PurposeTransforming growth factor (TGF) α accelerates wound healing, especially in gastric ulcers. Transforming growth factor α can be affected by acid and pepsin in the gastric juice. Oxidative stress also plays a role in the formation of gastric lesions. This study was designed (1) to investigate the effects of microemulsion dosage form on the healing of gastric ulcers, and (2) to determine the relationship between oxidative mechanisms and TGF-α during ulcer healing.MethodsGastric ulcers were induced in Wistar rats (male, 200 ± 25 g), by 150 mg/kg acidified aspirin application. The animals were divided into five groups consisting of 7–11 animals. The rats were killed after ulcer induction with aspirin (acute ulcer), or 2 days after ulcer induction (chronic ulcer), or after the daily application of microemulsion and TGF-α for 2 days. The ulcer area was measured planimetrically. Thiobarbituric acid reactive substance, glutathione, and gastric mucus levels of tissues were measured by spectrophotometric methods. The total nitric oxide level was measured by a VCl3 / Griess assay. Statistical comparisons were made by an analysis of variance and the Mann-Whitney U-test.ResultsThe ulcer area and malondialdehyde level of gastric tissue both decreased and the glutathione level increased to intact gastric tissue levels, while the mucus and total nitric oxide levels increased significantly after the application of intragastric TGF-α.ConclusionThese findings suggest that TGF-α accelerates the healing process after aspirin-induced gastric injury, and a relationship was observed between this application and the oxidative reactions.

The effect of tryptophan administration on ileum contractility and oxidant status in mice

Summary.L-Tryptophan (TRP) is the precursor amino acid for the synthesis of serotonin (5-HT). 5-HT is effective both on the food intake and gastrointestinal system contractility. The aim of this study was to search the effects of systemic TRP treatment on 5-HT levels of ileum and searching the effect of ileal contractility and oxidant status. Swiss-albino mice were divided into two groups: 1. Control, 2. TRP-treated (100 mg/kg/24 h, i.p., for 7 days). Body weights were recorded at the beginning and at the end of experiments. Acetylcholine-induced contractile responses in the isolated ileum were recorded on polygraph. Ileal tissue malondialdehyde and glutathione levels determined by spectrophotometric and ileal tissue 5-HT levels were measured by immunohistochemical methods. TRP treatment decreased body weight and increased ileal contractile response. In the TRP-treated group, ileum malondialdehyde levels increased and glutathione levels decreased. Immunohistochemical detection showed that ileal 5-HT levels were increased by TRP treatment. There is a relationship between increased oxidative stress and increased contractility in the ileal tissue of the TRP-treated animals. These effects may be related to increased ileal 5-HT synthesis.

Effects of vitamin C on muscle glycogen and oxidative events in experimental diabetes

Streptozotocin (STZ) is an agent used in creating experimental diabetes. Varying findings have been reported about the striated muscle glycogen levels in diabetes. In this study, it was planned to observe interaction of vitamin C (AA), of which deficiency has been shown in diabetics, with soleus muscle glycogen levels and oxidative events on STZ-diabetic subjects. Material and Method: In the study, 38 male adult Wistar Albino rats with weights 200 ± 20 g were used by separating them into four groups: Control, Vitamin C, Diabetes, Diabetes + Vitamin C. Body weights and fasting blood glucose were measured at the beginning and end of the experiment. AA, TBARS, GSH, NOx and glycogen levels of soleus muscles, and AA level of blood were measured. The results were compared using Anova variance and Mann-Whitney U tests. Results showed that AA levels in blood increased with vitamin C administration; AA, GSH and NOx levels in the muscle were low and MDA and glycogen levels were high in diabetics; and that vitamin C in the given dosage partially corrected these values. These results indicate that higher dosage than daily 20 mg/kg Vitamin C is required for being effective on metabolic and oxidizing events in diabetic rats.