Serdar Sadir

Melatonin ameliorates bladder damage induced by cyclophosphamide in rats

Abstract:  Cyclophosphamide (CP), an alkylating antineoplastic agent, has potential urotoxicity including causing hemorrhagic cystitis (HC). HC is now accepted as a non‐infectious inflammation and the pathogenesis of HC includes cytokine production which leads to inducible nitric oxide synthase (iNOS) induction. Moreover, overproduction of reactive oxygen species (ROS) during inflammation leads to extensive oxidative stress, cellular injury and apoptosis/necrosis via several mechanisms. Based on these facts, the aim of this study was to evaluate the protective effects of melatonin as an antioxidant, iNOS inhibitor and peroxynitrite scavenger against CP‐induced urinary bladder damage. A total of 30 male Sprague–Dawley rats were divided into four groups. Three groups received a single dose of CP (100 mg/kg) intraperitoneally with the same times. Group 2 received CP only, group 3 received 5 mg/kg/day and group 4 received 10 mg/kg/day melatonin before and the day after CP administration. Group 1 served as the control. Increased iNOS induction, bladder malonyldialdehyde (MDA) levels and urinary nitrite–nitrate excretion were encountered in the CP‐only group leading to severe cystitis. Melatonin exhibited significant protection against CP‐induced cystitis by diminishing bladder oxidative stress and blocking iNOS and peroxynitrite production. Oxidants may have a major role in the pathogenesis of CP‐induced cystitis and iNOS is an important mediator leading to peroxynitrite production. Melatonin ameliorates bladder damage induced by CP.

The efficacy of ozone therapy in experimental caustic esophageal burn.

INTRODUCTION Ozone has been proposed as an antioxidant enzyme activator, immunomodulator and cellular metabolic activator. This study was designed to investigate the efficacy of ozone therapy in the prevention of esophageal damage and stricture formation developed after esophageal caustic injuries in the rat. MATERIALS AND METHODS Forty-five rats were allocated into three groups; sham-operated, un-treatment and treatment groups. Caustic esophageal burn was created by instilling 15% NaOH in the distal esophagus. The rats were left untreated or treated with 1 mg/kg/day ozone intraperitoneally. All rats were sacrificed at 28 days. Efficacy of the treatment was assessed by measuring the stenosis index (SI) and histopathologic damage score, and biochemically by determining tissue hydroxyproline content (HP), superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA) and protein carbonyl content (PCC) in esophageal homogenates. RESULTS Whereas seven (47%) rats died in the un-treatment group, all rats in the sham-operated and the treatment group survived during the study. SI, the histopathologic damage score, was significantly lower in the ozone-therapy group than the un-treatment group. HP levels were significantly higher in the un-treatment group than the group treated with ozone. Caustic esophageal burn increased MDA and PCC levels and also decreased SOD and GPx enzyme activities. In contrast, ozone therapy decreased the elevated MDA and PCC levels and also increased the reduced SOD and GPx enzyme activities. CONCLUSION Ozone has a preventive effect in the development of fibrosis by decreasing tissue damage and increasing the antioxidant enzyme activity in an experimental model of corrosive esophageal injury.

Oxidative Stress Levels in Rats Following Exposure to Oxygen at 3 atm for 0 - 120 min

BACKGROUND Hyperbaric oxygen (HBO) is known to cause oxidative stress in several organs and tissues. We previously defined the pressure-related oxidative effects of HBO in several tissues of rats. This study was performed to elucidate the relationship of HBO exposure time to its oxidative effects. METHODS A total of 49 rats were randomly divided into 5 groups. Study groups were subjected to 3 atm HBO for 30, 60, 90, and 120 min except the control group. Their blood and lungs were removed immediately after exposure and used for analysis. Thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), and glutathione peroxidase (GSH-Px) levels were determined to reflect oxidant and antioxidant status. RESULTS TBARS levels were found to increase in a time-dependent manner in both erythrocytes [median (min-max); from 0.65 (0.39-0.84) with 30 min HBO exposure up to 1.26 (1.00-1.44) nmol x g(-1) hemoglobin after 120 min] and lung tissue [from 2140 (1550-2510) up to 5465 (5090-5950) nmol x g(-1) protein]. Similarly, SOD activity also presented a dose-dependent course from 0.06 (0.05-0.10) to 0.18 (0.14-0.26) U x g(-1) hemoglobin in erythrocytes and from 16,660 (3479-25,994) to 52,522.5 (41,362-65,799) U x g(-1) protein in lung tissue. In contrast, GSH-Px activity reflected an irregular trend; its levels were mostly found to be increased, but they were decreased at one stage (in the erythrocytes of 30-min exposed rats). CONCLUSIONS The results of this study exhibited a clear relationship of HBO-induced oxidative action to exposure time. This action was most pronounced from 90 to 120 min of exposure.

Hyperbaric oxygen enhances the efficiency of 5-aminosalicylic acid in acetic acid-induced colitis in rats.

The aim of this study was to assess the efficienchyperbaric oxygen alone and in combination with 5-aminosalicylic acid in THE acetic acid–induced colitis model, a well-known experimental model of inflammatory bowel disease in rats. Rats were randomly divided into FIVE groups. In the noncolitis control group, rats were given isotonic saline, while in the other groups rats were treated by intracolonic administration of 4% acetic acid. In group 2, the untreated control group, no additional therapy was applied. In groups 3, 4, and 5 hyperbaric oxygen, 5-aminosalicylic acid. and 5-aminosalicylic acid + hyperbaric oxygen therapies were applied, respectively. Administration of acetic acid caused an inflammatory response in all animals. Histopathologic score was significantly higher in group 2 than in any other group. 5-Aminosalicylic acid and hyperbaric oxygen significantly decreased the histopathologic score (P < 0.05). Myeloperoxidase activity was also reduced significantly by 5-aminosalicylic acid (P < 0.05) but not by hyperbaric oxygen. The most prominent ameliorative effect, however, was seen in group 5 and the histopathologic score and myeloperoxidase activity were significantly lower than in groups 3 (P < 0.05) and 4 (P < 0.001). Hydroxyproline level also increased significantly in group 5, but not in groups 3 and 4 (P < 0.001). These findings indicate that hyperbaric oxygen therapy is effective in reducing the extent of colitis induced by acetic acid, although it is not as potent as 5-aminosalicylic acid. The combination of hyperbaric oxygen and 5-aminosalicylic acid, however, led to a much more prominent reduction in the severitcolitis. Hyperbaric oxygen may have a promising place in the treatment of inflammatory bowel disease.

Effects of Poly(ADP-Ribose) Polymerase Inhibition in Bladder Damage Caused by Cyclophosphamide in Rats

It was previously shown that nitric oxide produced by inducible nitric oxide synthase (iNOS) and peroxynitrite are responsible for cyclophosphamide (CP)-induced cystitis. Since endogenous production of peroxynitrite is known to lead to poly(ADP-ribose) polymerase (PARP) activation, in this study, the aim was to evaluate whether the PARP activation pathway is also included in the pathogenesis of CP-induced bladder ulceration in rats. A total of 48 male albino Wistar rats were divided into 5 groups. Group 1 served as control and was given 2 ml saline; four groups received a single dose of CP (200 mg/kg) with the same time intervals. Group 2 received CP only; Group 3, selective iNOS inhibitor 1400W (20 mg/kg); Group 4, peroxynitrite scavenger ebselen (30 mg/kg); and Group 5, PARP inhibitor 3-aminobenzamide (20 mg/kg). CP injection resulted in severe cystitis with continuous macroscopic hemorrhage, strong edema, inflammation, and ulceration. Moreover, bladder iNOS activation and urine nitrite-nitrate levels were dramatically increased. Histologically, 1400W protected bladder against CP damage and decreased urine nitrite-nitrate levels and bladder iNOS induction. Ebselen has shown similar histologic results with 1400W without changing urinary nitrite-nitrate level and iNOS activity. Furthermore in the 3-aminobenzamide group, beneficial effects had also occurred including decreased ulceration. These results suggest that PARP activation involves pathogenesis of CP-induced bladder ulceration. Furthermore, PARP is not only important for ulceration but also for bladder edema, hemorrhage, and inflammation because of broken uroepithelial cellular integrity.

Evaluation and Comparison of the Effects of Hyperbaric Oxygen and Ozonized Oxygen as Adjuvant Treatments in an Experimental Osteomyelitis Model

BACKGROUND We evaluated and compared the efficacy of ozone (O(3)) and hyperbaric oxygen (HBO) therapies in an experimental rat model of osteomyelitis. MATERIALS AND METHODS Forty-eight male Sprague-Dawley rats were divided into sham, osteomyelitis (control), vancomycin (V), vancomycin + HBO (VHB), vancomycin + O(3) (VO), and vancomycin + HBO + O(3) (VOHB) groups. Osteomyelitis was induced by a bone injection of 10(8) CFU/mL methicillin-resistant Staphylococcus aureus. HBO was administered daily at 2.8-atm pressure for 90 min; O(3) therapy was provided as intraperitoneal injections of 0.7 mg/kg O(3)/O(2) gas mixture once daily. Treatments were continued from d 7 to 21 after induction of osteomyelitis. Bone tissues and blood samples were harvested for biochemical, histopathologic, and microbiologic analyses. RESULTS Rats in the sham, VO, and VOHB groups gained weight but those in the control, V, and VHB groups did not. Levels of malondialdehyde, superoxide dismutase, and glutathione peroxidase were lower in the VHB, VO, and VOHB groups than in V and control groups. Levels of interleukin-10 and -1β and tumor necrosis factor-α were decreased in the VHB, VO, and VOHB groups; transforming growth factor-β was increased in these groups compared with V and control groups (P ≤ 0.001). Bacteria counts in VOHB were significantly lower than those in group of V (P = 0.012). Histopathologic scores in group VO were significantly lower than those in group V (P = 0.046). CONCLUSIONS O(3) was as effective as HBO in decreasing oxidative parameters and inflammatory cytokines. Rats in the VO and VOHB groups gained more weight than did the other groups. Bacteria counts were significantly decreased in group VOHB compared with the other groups. Histopathologic scores in group VO were significantly decreased compared with the other groups.

Melatonin prevents peritoneal adhesions in rats

Background and Aim:  Intra‐abdominal adhesions are important postoperative complications following abdominal surgery. The adhesions that develop form the basis of more advanced pathology such as intestinal obstruction or infertility. Melatonin is secreted from the pineal gland in a circadian pattern; this molecule has potent antioxidant characteristics and has beneficial effects in many models of inflammation. The aim of this study was to evaluate the effects of melatonin on peritoneal adhesions created in rats.

Poly(ADP-ribose) polymerase inhibition modulates experimental acute necrotizing pancreatitis-induced oxidative stress, bacterial translocation and neopterin concentrations in rats

Various studies have been performed to find out novel treatment strategies for acute necrotizing pancreatitis (ANP). Inhibition of poly(ADP-ribose) polymerase (PARP) is shown to reduce inflammation in several pathological conditions. We aimed to evaluate the efficacy of benzamide, a PARP inhibitor, in an experimental model of ANP. Thirty Sprague–Dawley rats were divided into three groups: sham-operated, ANP and ANP + benzamide groups. All groups except the sham-operated group were subjected to the ANP procedure, induced by infusing of 1 mL/kg of 3% sodium taurocholate into the common biliopancreatic duct. The ANP + benzamide group received 100 mg/kg/day benzamide intraperitoneally for a total of three days after induction of pancreatitis. The surviving animals were killed at the fourth day and the pancreas was harvested for biochemical, microbiological and histological analysis. Blood samples were also obtained from the animals. In the ANP group, a significant increase was observed in concentrations of serum amylase and neopterin and tissue oxidative stress indices (malondialdehyde, superoxide dismutase and glutathione peroxidase). Almost all of these changes were found to be reversed to near their normal values in the ANP + benzamide group. Histological injury scores were significantly higher in the ANP group than in the sham group (P < 0.05, ANP versus sham), and were significantly lower in the ANP + benzamide group than in the ANP group (P < 0.05, ANP + benzamide versus ANP). Evaluation of bacterial translocation identified significantly fewer infected sites in the ANP + benzamide group than in the ANP animals (P < 0.01). We observed that inhibition of PARP with benzamide reduced the severity, the mortality, the bacterial translocation rates and the neopterin concentrations in an experimental ANP model in rats. These findings suggest that it may be possible to improve the outcome of ANP by using PARP inhibitors.

Retroperitoneal lymph node mapping with intratesticular injected patent blue dye in rats

OBJECTIVES Endolymphatic injection of several dyes have been previously studied to identify retroperitoneal lymphatic structure in animals and humans with malignant diseases. However, there have been no studies, to our knowledge, that demonstrate the utility of injecting patent blue dye into the testicular parenchyma to detect retroperitoneal lymphoid structure. The aim of this experimental study was to investigate whether intratesticular patent blue dye injection is feasible and is an accurate method for retroperitoneal lymph node mapping in rats. MATERIALS AND METHODS Twenty male albino Wistar rats were included in the study and divided over two equal groups. The first group underwent patent blue violet (PBV) injection into the spermatic funiculus, while the second group underwent PBV injection into the testicular parenchyma. After the injection, the color changes in the retroperitoneal lymphatic structures and the urinary bladder were anticipated. The time interval between the injection and the staining of lymphatic structures and urinary bladder was measured for each intervention. Blue stained retroperitoneal nodal tissues were dissected and removed. These nodal tissues were examined histologically. RESULTS After PBV injection, intense staining of the ipsilateral spermatic cord lymphatics was seen and anticipated color changes in the retroperitoneal lymphatic structures and urinary bladder were evaluated visually. Both application routes of dye resulted in the same distribution of retroperitoneal lymph nodes in the same time frame. All retroperitoneal nodular tissues removed were noted histologically to be lymph nodes and were found to be consistent with the ipsilateral lumbar lymph and the ipsilateral suprarenal lymph nodes according to the staining order in both groups. No toxic effects were observed histologically. There were no statistically significant differences in the time intervals between the two groups. CONCLUSIONS We demonstrated that both funicular and intratesticular injections of patent blue dye are feasible and accurate methods for retroperitoneal lymph node mapping in rats. This shows that intralymphatic dye injection is not absolutely necessary to detect retroperitoneal lymphatic structures and may have applications beyond testis cancer.

Evaluation of the Oxidative Effect of Long-Term Repetitive Hyperbaric Oxygen Exposures on Different Brain Regions of Rats

Hyperbaric oxygen (HBO2) exposure affects both oxidative and antioxidant systems. This effect is positively correlated with the exposure time and duration of the treatment. The present study aims enlightening the relation of HBO2 with oxidative/antioxidant systems when administered in a prolonged and repetitive manner in brain tissues of rats. Sixty rats were divided into 6 study (n = 8 for each) and 1 control (n = 12) group. Rats in the study groups were daily exposed 90-min HBO2 sessions at 2.8 ATA for 5, 10, 15, 20, 30 and 40 days. One day after the last session, animals were sacrificed; their whole brain tissue was harvested and dissected into three different regions as the outer grey matter (cortex), the inner white matter and cerebellum. Levels of lipid peroxidation and protein oxidation and activities of superoxide dismutase and glutathione peroxidase were measured in these tissues. Malondialdehyde, carbonylated protein and glutathione peroxidase levels were found to be insignificantly increased at different time-points in the cerebral cortex, inner white matter and cerebellum, respectively. These comparable results provide evidence for the safety of HBO treatments and/or successful adaptive mechanisms at least in the brain tissue of rats, even when administered for longer periods.