Evaluation of the oxidative effect of long-term repetitive hyperbaric oxygen exposures on different brain regions of rats.

Hyperbaric oxygen (HBO(2)) 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 HBO(2) 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 HBO(2) 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.

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 -1ß and tumor necrosis factor-α were decreased in the VHB, VO, and VOHB groups; transforming growth factor-ß 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.

Inhibition of iNOS reduces the therapeutic effects of ozone in acute necrotizing pancreatitis: an in vivo animal study.

OBJECTIVE: Previously, it was shown that ozone and S-methylthiourea (SMT) treatments had ameliorative effects on experimental models of acute necrotizing pancreatitis (ANP). It is possible that the combination of ozone and SMT may be more effective than either therapy. Therefore, we investigated the efficacy of combination therapy with ozone and SMT in an experimental rat model of ANP. MATERIAL AND METHODS: Sprague-Dawley rats were divided into five experimental groups. Groups were designed as Sham-operated, ANP, ANP + Ozone, ANP + SMT and ANP + Ozone + SMT. A model of ANP was induced by injection of sodium taurocholate into the common biliopancreatic duct. Four days after induction, blood and tissue samples were obtained for biochemical, microbiological and histopathological analysis. RESULTS: Survival rates, serum amylase, lipase and neopterin levels, tissue oxidative stress parameters, bacterial translocation and tissue injury scores were better in the ozone and SMT groups than in the ANP group. There was no bacterial translocation in the ozone-treated groups. Tissue injury scores in the ozone group were better compared to all ANP induced groups. Ozone and SMT treatment in combination did not have better biochemical, microbiological and histological data compared to ozone or SMT treatments separately in experimental ANP. CONCLUSIONS: The combination of ozone and SMT did not provide any therapeutic advantage in ANP possibly because SMT inhibited nitric oxide synthesis which was needed for ozone action.

Evaluation of effects of s-methyl isothiourea and melatonin on intestinal ischemia/reperfusion injury in rats.

The present study was designed to evaluate whether the administration of s-methylisothiourea and melatonin has protective potential in intestinal ischemia/reperfusion injury. Forty male Sprague-Dawley rats were divided into five groups. Ileal specimens were obtained to determine the levels of malondialdehyde, protein carbonyl content, levels of antioxidant enzymes and evaluation of histologic changes. Combination of s-methylisothiourea and melatonin, led to a statistically significant increase in activities of antioxidant enzymes with a decrease in malondialdehyde and protein carbonyl content and intestinal mucosal injury scores. It was shown; combination of SMT and melatonin may exert more promised results.

Synergistic effects of hyperbaric oxygen and granulocytecolony stimulating factor on postoperative adhesion formation in a rat cecal abrasion model.

PURPOSE: We investigated the synergistic effect of hyperbaric oxygen (HBO) and granulocyte-colony stimulating factor (G-CSF) on adhesion formation in rats. METHODS: 40 adult male Sprague-Dawley rats (250-350 g) were divided into 4 groups. In group-1, no further management was undertaken. Group-2 received HBO therapy, group-3 was treated with 50 ug/kg subcutaneous G-CSF once daily for 7 days following laparatomy and cecal abrasion and group-4 was given both G-CSF and HBO therapies. On the 7th day, all rats were sacrificed and adhesions were scored. Tissue samples from adhesions and peritonea and cecum wall were examined both pathologically and biochemically for tissue hydroxyproline content. RESULTS: No mortality occurred in study groups. When the groups were evaluated according to the adhesion numbers and grades, there was a statistically significant difference between the control and groups 3 and 4 (P < 0.001). There was no statistically significant difference between groups 1 and 2 (p > 0.05). HBO + G-CSF group was significantly different from control, HBO and G-CSF groups, regarding hydroxyproline contents (p = 0.005). Inflammation and fibrosis did not differ significantly among the groups (p = 0.248), (p = 0.213). CONCLUSION: HBO treatment could not reduce the adhesion formation alone. Combined use of HBO and G-CSF, has a markedly preventive effect on postoperative adhesion formation (Tab. 1, Fig. 2, Ref. 57).

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. METHODS: A total of 28 Sprague-Dawley male rats were used and divided into four groups. In the first phase of the study, pinealectomy (PINX) was performed on half the animals. An incision was made and sutured in the cecum of all experimental animals in all groups 15 days after the PINX procedure. Some animals were given melatonin orally at a dose of 5 mg/kg daily following the adhesion operation and continued for 15 days. The rats were anesthetized and the abdomen opened after the 15th day (on day 30 of the study). After adhesion scoring based on macroscopic inspection, tissue samples were obtained from the sutured region of the cecum to measure malondialdehyde and hydroxyproline. RESULTS: Peritoneal adhesion density was significantly higher in the PINX group compared to the control animals; exogenously administered melatonin significantly reduced adhesion formation. The degree of adhesion was also significantly lower in the intact rats given melatonin compared to the control group. CONCLUSION: Antioxidant activity increases in the oxidative process. We conclude that melatonin may be an important molecule in preventing peritoneal adhesions.

Effects of aminoguanidine and melatonin on intestinal ischemia/reperfusion injury in rats: An assessor-blinded, controlled experimental study.

BACKGROUND: The reactive oxygen and nitrogen species generated during reperfusion of tissue are characteristic of intestinal ischemia and reperfusion (IIR) injury. OBJECTIVE: This study was designed to assess whether the administration of aminoguanidine (AG), a selective nitric oxide synthase inhibitor, and/or melatonin has protective potential in IIR injury. METHODS: Male Wistar albino rats (age, 3-4 weeks; weight, 100-150 g) were divided in a nonrandom fashion into 5 groups of equal size: group 1, IIR injury + AG 100 mg/kg; group 2, IIR injury + melatonin 10 mg/kg; group 3, IIR injury + AG 100 mg/kg + melatonin 10 mg/kg; group 4, sham operation; and group 5, IIR injury alone. Sixty minutes of intestinal ischemia and 4 hours of reperfusion were carried out in all but the sham-operation group. Ileal specimens were obtained from all rats to determine the extent of histologic changes, measure tissue concentrations of malondialdehyde (MDA) and protein carbonyl (PC), and assess the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Specimens were also assessed and scored by a pathologist blinded to the experiment and the data. RESULTS: Forty rats were divided into 5 groups of 8 each; all 40 survived until study end. In the IIR injury-alone group, mean (SD) MDA concentration and PC content were significantly higher than that of the sham-operation group, and SOD and GPx activity were significantly lower: MDA concentration, 0.86 (0.03) versus 0.54 (0.01) mmol/g protein, respectively; PC content, 0.60 (0.02) versus 0.34 (0.01) mmol/g protein; SOD activity, 104.33 (43.14) versus 2954.72 (109.55) U/g protein; and GPx activity, 10.44 (0.63) versus 24.34 (1.77) U/g protein (all, P < 0.001). Administration of AG, melatonin, and the AG/melatonin combination was associated with significantly higher SOD (1802.31 [102.35], 1776.50 [58.41], and 1924.28 [98.10] U/g protein, respectively) and GPx (17.36 [1.23], 15.96 [1.08], and 18.06 [1.72] U/g protein) activity and significantly lower MDA concentration (0.62 [0.02], 0.64 [0.02], and 0.56 [0.01] mmol/g protein) and PC content (0.53 [0.03], 0.51 [0.01], and 0.49 [0.02] mmol/g protein) compared with the IIR injury-alone group (P < 0.001). Mean intestinal mucosal injury scores were significantly lower in the 3 treatment groups (2.12 [0.35], 1.75 [0.46], and 1.12 [0.35]) compared with the IIR injury-alone group (3.87 [0.35]; all, P < 0.001). CONCLUSION: In this study, AG, melatonin, or both administered in combination were associated with improvements in oxidative markers in this rat model of IIR injury.

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.

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.

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.

Correlation between hyperbaric oxygen exposure pressures and oxidative parameters in rat lung, brain, and erythrocytes.

OBJECTIVES: The oxygen toxicity risk of hyperbaric oxygen (HBO) treatment has long been of interest. However, there are no comprehensive articles describing the relationship between HBO protocols and oxidative parameters used clinically. The purpose of this study was to determine the effects of various HBO pressure modalities on the oxidative values of rat lung, brain, and erythrocytes. DESIGN AND METHODS: A total of 64 male Sprague-Dawley rats was randomly divided into 7 groups. Group A was used as a control. Groups C to G were subjected to 100% oxygen at a pressure of 1, 1.5, 2, 2.5, and 3 ATA (atmosphere absolute), respectively, for 2 h. Group B was exposed to normal atmospheric air at 3 ATA for the same duration. The rat's lung, brain, and blood were taken immediately after the exposure and thiobarbituric acid reactive substances (TBARS) and superoxide dismutase (SOD) levels were determined. RESULTS: Both TBARS levels and SOD activity increased concordantly with the pressure increase. Although a statistically significant change in TBARS levels started from 100% oxygen exposure at 1 ATA (normobaric), SOD activity was affected after 2 ATA. A significant correlation exists between exposure pressure and the aforementioned parameters. Ambient air exposure at 3 ATA did not affect any parameters besides the brain TBARS levels. CONCLUSIONS: It is clear that HBO exposure causes oxidative stress. The main reason for this effect seems to be exposure to pure oxygen, since pure high pressure has no significant effect on the aforementioned parameters. However, clinicians should use as low pressures as possible since all oxidative parameters appear to be directly proportional to the extent of HBO exposure.

Exogenously administered and endogenously produced melatonin reduce hyperbaric oxygen-induced oxidative stress in rat lung.

Hyperbaric oxygen (HBO) is a widely used treatment modality in many diseases. A known side effect of HBO is the production of reactive oxygen species. Many antioxidants such as vitamins C and E, riboflavin and selenium have been used successfully to scavenge the reactive oxygen species caused by HBO administration. In this study, we aimed to see if melatonin, a newly discovered antioxidant, has a protective effect against the overproduction of reactive oxygen species produced by HBO in rat lung tissue. Sixty male Sprague-Dawley rats were divided into 5 groups as follows: control, daytime HBO (3 ATA, 120 min), daytime HBO plus melatonin (10 mg/kg), nighttime HBO and nighttime HBO (under light exposure). The MDA, SOD and CAT levels of daytime and nighttime HBO (under light exposure) increased significantly. This significance was not found in the daytime HBO plus melatonin and nighttime HBO groups when compared with the control. In this study, HBO caused oxidant stress, and melatonin decreased the levels of MDA, SOD and CAT. Moreover, endogenous melatonin was found to be a more effective antioxidant than exogenous 10 mg/kg melatonin.

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.

Exposure time related oxidative action of hyperbaric oxygen in rat brain.

Hyperbaric oxygen (HBO) is known to cause oxidative stress in several organs and tissues. Due to its high rate of blood flow and oxygen consumption, the brain is one of the most sensitive organs to this effect. The present study was performed to elucidate the relation of HBO exposure time to its oxidative effects in rats' brain cortex tissue. For this purpose, 49 rats were randomly divided into five groups. Except the control group, study groups were subjected to three atmospheres HBO for 30, 60, 90, and 120 min. Their cerebral cortex layer was taken immediately after exposure and used for analysis. Thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and nitrate-nitrite (NOX) levels were determined. TBARS and SOD levels were found to increase in a time-dependent manner. GSH-Px activity reflected an inconsistent course. NOX levels were found to be increased only in the 120 min exposed group. The results of this study suggests that HBO induced oxidative effects are strongly related with exposure time.

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.

Alpha-tocopherol, beta-carotene and melatonin administration protects cyclophosphamide-induced oxidative damage to bladder tissue in rats.

Cyclophosphamide (CP) has potential urotoxicity such as hemorrhagic cystitis (HC). 2-Mercaptoethane sulfonate (mesna) has been widely used as an effective agent against CP-induced cystitis, but significant HC has still been encountered clinically. In recent studies, mesna was shown to be more effective if combined with antioxidants. The purpose of this study was to evaluate the effects of antioxidants, alpha-tocopherol, beta-carotene and melatonin on CP-induced bladder damage in rats, even if used without mesna administration. Male Sprague-Dawley rats weighing 180-210 g were divided into 5 groups. Four groups received a single dose of CP (100 mg/kg) intraperitoneally with the same time intervals. Group 2 received CP only, group 3 received beta-carotene (40 mg/kg/day), group 4 received alpha-tocopherol (40 mg/kg/day) and group 5 received melatonin (10 mg/kg/day) both before and the day after CP injection. Group 1 served as control. Bladder histopathology, as well as malondialdehyde (MDA) and iNOS levels, and excretion of nitrite-nitrates (NO(x)) in urine were evaluated. CP injection resulted in severe histological changes and macroscopic hematuria. alpha-Tocopherol and melatonin showed meaningful protection against bladder damage. Protection by beta-carotene was also significant but weaker. MDA levels increased significantly with CP injection and all antioxidants ameliorated this increase in bladder tissue. CP also elevated the NO(x) level in urine and iNOS activity in bladder. Only melatonin was able to decrease these parameters. In conclusion, there is no doubt that oxidants have a role in the pathogenesis of CP-cystitis. Antioxidants, especially melatonin and alpha-tocopherol, may help to ameliorate bladder damage induced by CP.

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 efficiency of hyperbaric 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 severity of colitis. Hyperbaric oxygen may have a promising place in the treatment of inflammatory bowel disease.

Peroxynitrite may be involved in bladder damage caused by cyclophosphamide in rats.

PURPOSE: It was previously shown that nitric oxide (NO) produced by inducible NO synthase (iNOS) is responsible for cyclophosphamide (CP) induced cystitis. In this study we evaluated whether peroxynitrite is also responsible for CP induced bladder damage in rats. MATERIALS AND METHODS: A total of 38 male albino Wistar rats were divided into 4 groups. Group 1 served as controls and was given 2 ml saline, while 3 groups received a single dose of CP (200 mg/kg) at the same intervals. Group 2 received CP only, group 3 received the selective iNOS inhibitor aminoguanidine (AG) (100 mg/kg) and group 4 received the peroxynitrite scavenger ebselen (2-phenyl-1,2-benzisoselenazol-3[2H]-one) (20 mg/kg). RESULTS: CP injection resulted in severe cystitis with continuous macroscopic hemorrhage, strong edema, inflammation and ulceration. Moreover, bladder tissue malondialdehyde levels, iNOS activation and urine nitrite-nitrate levels were dramatically increased. AG histologically protected bladder against CP damage and decreased urine nitrite-nitrate levels, bladder malondialdehyde and iNOS induction. Ebselen showed results similar to those of AG without changing the urinary nitrite-nitrate level and iNOS activity. CONCLUSIONS: These results suggest that not only nitric oxide, but also peroxynitrite may be important in the pathogenesis of CP induced cystitis.