Assessment of serum biotin levels and its association with blood glucose in gestational diabetes mellitus.

Aim: The incidence of gestational diabetes mellitus is increasing worldwide. Biotin is shown to improve glycemic status in diabetes mellitus. We wanted to study whether there is a difference in biotin levels between mothers with and without gestational diabetes mellitus (GDM), association of biotin with blood glucose, and with the outcome of GDM. Methods: We recruited 27 pregnant mothers with GDM and 27 pregnant mothers without GDM. We measured the biotin levels using enzyme linked immunosorbent assay (ELISA). We measured the blood glucose during OGTT and fasting insulin levels in the study participants. Results: We found that biotin levels were slightly decreased in mothers with GDM [271 (250,335)] as compared to control mothers [309 (261,419)], though it was not statistically significant (p = 0.14). Blood glucose levels were found to be significantly higher in GDM mothers as compared to control mothers during fasting, 1 h and 2 h plasma sample obtained during OGTT. Biotin was not significantly associated with blood glucose in pregnant mothers. Logistic regression analysis showed that biotin (OR = 0.99, 95 % CI = 0.99-1.00) has no association with the outcome of GDM. Conclusion: Ours is the first study to compare the biotin levels in GDM mothers and control mothers. We found that the biotin levels were not significantly altered in GDM mothers as compared to control mothers and biotin levels have no association with the outcome of GDM.

Melatonin protects against tenofovir-induced nephrotoxicity in rats by targeting multiple cellular pathways.

Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection and chronic hepatitis B infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to its better tolerance, and a more effective treatment can be achieved. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats and to determine its cellular targets. Rats were divided into groups and treated as follows. Group I (control): Rats in this group (n = 6) received sterile water only by gavage for 35 days. Group II: Rats (n = 6) in this group received 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group III: Rats (n = 6) in this group received once daily 20 mg/kg bodyweight melatonin i.p. 2 h before the administration of 600 mg/kg body weight TDF in sterile water by gavage for 35 days. Group IV: Rats were pretreated daily with 20 mg/kg body weight melatonin i.p. 2 h before the administration of sterile water by gavage. All the rats were sacrificed on the 36th day, after overnight fast. Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced, oxidative stress, nitrosative stress, mitochondrial pathway of apoptosis, PARP overactivation and preserved proximal tubular function (p < 0.01). This suggests that melatonin may be useful in ameliorating TDF nephrotoxicity.

NF-κB-iNOS-COX2-TNF α inflammatory signaling pathway plays an important role in methotrexate induced small intestinal injury in rats.

Although methotrexate is widely used in clinics as an anticancer agent, it's utility is limited by its gastrointestinal toxicity, the mechanism of which is unclear. The role of NFκB inflammatory pathway in MTX induced mucositis was investigated in the present study. GI injury was induced in adult Wistar rats by the administration of 3 consecutive i.p . injections of MTX. On the fourth day, the rats were sacrificed and the small intestine was removed; A piece was used for light microscopy, immunohistochemistry, immunofluorescence studies . The mucosa was collected and used for the analysis of protein and mRNA expressions of NFκB and its target genes by the western blot, RT-PCR respectively. MTX treatment resulted in NFκB activation and nuclear translocation as evidenced by immunofluorescence, immunohistochemistry , and western blot. NFκB mRNA was also increased. There was increased protein and mRNA expressions of NFκB target genes, TNF-α, iNOS, COX-2, PLA2, HO-1, HSP70, MMPs 2 and 9 . Aminoguanidine pretreatment (30mg/ 50mg /kg body wt.) attenuated MTX induced activation of NFκB and its proinflammatory target genes and improved MTX induced morphological changes. Aminoguanidine has protective effects against MTX induced gastrointestinal mucositis in rats.

Activation of the mitochondrial apoptotic pathway contributes to methotrexate-induced small intestinal injury in rats.

The efficacy of methotrexate (MTX), a commonly used chemotherapeutic drug, is limited by intestinal injury. As the mechanism of MTX-induced small intestinal injury is not clear, there is no definitive treatment for MTX-induced gastrointestinal injury. The present study investigates the role of mitochondrial apoptotic pathway in MTX-induced small intestinal injury and examines whether aminoguanidine is effective in preventing the damage. Eight Wistar rats were administered 3 consecutive i.p. injections of 7 mg/kg body wt. MTX. Some rats were pretreated with 30 mg or 50 mg/kg body wt. of aminoguanidine (n = 6 in each group). Protein expressions of cytochrome c, caspases 3 and 9, and PARP-1 were determined in the small intestines by immunohistochemistry and western blot. Mitochondrial pathway of apoptosis was activated in the small intestines of MTX-treated rats as evidenced by intense immunostaining for cyt c, caspases 9 and 3, and PARP-1 and mitochondrial release of cyt c, activation of caspases, and PARP-1 cleavage by Western blot. Immunofluorescence revealed increased nuclear localization of PARP-1. Aminoguanidine pretreatment ameliorated MTX-induced small intestinal injury in dose-dependent manner and inactivated the mitochondrial apoptotic pathway. Aminoguanidine may possess beneficial intestinal protective effects as an adjuvant co-drug against MTX intestinal toxicity during cancer chemotherapy. As the mechanism of MTX-induced small intestinal injury is not clear, there is no definitive treatment for MTX-induced gastrointestinal injury. The results of the present study show that the mitochondrial pathway of apoptosis plays a role in MTX-induced small intestinal injury as evidenced by cytochrome c release, activation of caspases 9 and 3, PARP-1 cleavage, and DNA fragmentation. Aminoguanidine (AG) pretreatment attenuates the severity of small-intestinal injury induced in rats by MTX treatment. The mechanisms of action of AG involve inhibition of iNOS, and mitochondrial pathway of apoptosis. It is suggested that aminoguanidine may possess beneficial intestinal protective effects as an adjuvant co-drug against MTX intestinal toxicity during cancer chemotherapy.

Aminoguanidine pretreatment prevents methotrexate-induced small intestinal injury in the rat by attenuating nitrosative stress and restoring the activities of vital mitochondrial enzymes.

BACKGROUND: One of the major toxic side effects of methotrexate (MTX) is enterocolitis, for which there is no efficient standard treatment. Nitric oxide overproduction has been reported to play an important role in MTX-induced mucositis. This study was designed to investigate whether pretreatment with aminoguanidine (AG) - a selective iNOS inhibitor - prevents MTX-induced mucositis in rats. METHODS: Rats were pretreated with AG (30 and 50 mg/kg body weight) i.p. daily 1 h before MTX (7 mg/kg body weight) administration for 3 consecutive days. After the final dose of MTX, the rats were killed, and the small intestines were used for analysis. RESULTS: The small intestines of MTX-treated rats showed moderate to severe injury. Pretreatment with AG had a dose-dependent protective effect on MTX-induced mucositis. AG pretreatment reduced iNOS protein levels, mucosal nitric oxide levels, and protein tyrosine nitration. AG pretreatment also restored the activities of electron transport chain (ETC) complexes, vital tricarboxylic acid (TCA cycle) enzymes, and mitochondrial antioxidant enzymes. CONCLUSIONS: These findings suggest that AG is beneficial in ameliorating MTX-induced enteritis in rats.

Role for NF-κB inflammatory signalling pathway in tenofovir disoproxil fumarate (TDF) induced renal damage in rats.

Nephrotoxicity due to tenofovir treatment of HIV patients has been reported. However, the mechanism of tenofovir nephrotoxicity is not clear. NFκB is an important proinflammatory transcription factor that plays a pivotal role in oxidative stress-induced inflammation. We hypothesized that NFκB proinflammatory signalling pathway may play a role in tenofovir induced renal damage. Renal damage was induced in adult male Wistar rats by the oral administration of 600 mg/kg body wt. daily for 5 consecutive weeks. Kidneys were removed and used for histological and biochemical analysis. The protein and mRNA expressions of NFκB and its target genes namely iNOS, COX-2 and TNFα, and its inhibitor IκB-alpha were analysed by immunohistochemical methods, western blot and quantitative RT PCR. NFκBp65 activity was determined by ELISA. The protein and mRNA expressions of NFκB p65, iNOS, COX-2 and TNFα were increased in the kidneys of TDF treated rats. The activity of NFκBp65 was increased by 28 fold in the nuclear fractions of the TDF treated rat kidneys. Pretreatment with melatonin, a NFκB inhibitor attenuated TDF induced renal damage. It is concluded that the activation of NFκB and its downstream proinflammatory target genes iNOS, COX-2, and TNF-α may contribute to the pathophysiology of TDF induced renal damage.

Methotrexate administration induces differential and selective protein tyrosine nitration and cysteine nitrosylation in the subcellular organelles of the small intestinal mucosa of rats.

Gastrointestinal toxicity is one of the most frequent dose limiting side effects of methotrexate (MTX), a commonly used chemotherapeutic drug. Peroxynitrite (PON) overproduction is reported to contribute to MTX induced gastrointestinal mucositis. However, the consequence of PON overproduction i.e. protein tyrosine nitration and protein cysteine nitrosylation, the subcellular distribution of these modified proteins and their molecular weights have not been investigated yet. Mucositis was induced in Wistar rats by the administration of 3 consecutive i.p. injections of MTX. Tyrosine nitrated proteins and cysteine nitrosylated proteins were determined in the subcellular organelles fractions of mucosa using immunoprecipitation and western blot. The proteins in the subcellular fractions were separated by 1D electrophoresis, and probed with anti -nitrotyrosine antibody and anti-nitrosocysteine antibody. After MTX treatment, a general increase in protein tyrosine nitration as well as a change in the spectrum of proteins that underwent nitration was observed. The relative densities of the 3 nitrotyrosine protein adducts were as follows: Mitochondria > cytosol > microsomes > nucleus. In the mitochondrial fraction increased nitration of 12 kDa, 25 kDa 29Kda, 47 kDa, and 62Kda proteins, in the cytosol increased nitration of 12 kDa, 19 kDa, 45 kDa, and 60 kDa proteins and in the nuclear fraction increased nitration of 17 kDa, 35 kDa, and 58 kDa proteins was observed. On the other hand, MTX treatment resulted to a general decrease in protein cysteine nitrosylation in all the subcellular fractions. These results suggest that MTX induced, PON mediated small intestinal injury is mediated by differential nitration and nitrosylation of proteins in the subcellular organelles with increased protein tyrosine nitration and decreased cysteine nitrosylation. In addition MTX treatment results in selective nitration and nitrosylation of proteins in the intestinal mucosa. This differential nitrosative modifications may contribute to MTX induced small intestinal injury.

Mitochondrial dysfunction and electron transport chain complex defect in a rat model of tenofovir disoproxil fumarate nephrotoxicity.

The long-term use of tenofovir, a commonly used anti-HIV drug, can result in renal damage. The mechanism of tenofovir disoproxil fumarate (TDF) nephrotoxicity is not clear, although it has been shown to target proximal tubular mitochondria. In the present study, the effects of chronic TDF treatment on the proximal tubular function, renal mitochondrial function, and the activities of the electron transport chain (ETC) complexes were studied in rats. Damage to proximal tubular mitochondria and proximal tubular dysfunction was observed. The impaired mitochondrial function such as the respiratory control ratio, 2-(4,5-dimethyl-2-thiazolyl)-3,5-diphenyl-2H-tetrazolium bromide (MTT) reduction, and mitochondrial swelling was observed. The activities of the electron chain complexes I, II, IV, and V were decreased by 46%, 20%, 26%, and 21%, respectively, in the TDF-treated rat kidneys. It is suggested that TDF induced proximal tubular mitochondrial dysfunction and ETC defects may impair ATP production, resulting in proximal tubular damage and dysfunction.

Preclinical efficacy of melatonin in the amelioration of tenofovir nephrotoxicity by the attenuation of oxidative stress, nitrosative stress, and inflammation in rats.

Abstract Background: Nephrotoxicity is a dose-limiting side effect of long-term use of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of human immunodeficiency virus (HIV) infection. Identifying an agent that prevents tenofovir disoproxil fumarate (TDF)-induced renal injury can lead to better tolerance to TDF, and a more effective treatment can be achieved in HIV infected patients. Recent studies show that oxidative stress, nitrosative stress, and inflammation play a role in TDF nephrotoxicity. The present study is aimed at investigating whether melatonin, a potent antioxidant and anti-inflammatory agent, protects against TDF nephrotoxicity in rats. Methods: Adult male rats were used for the study. Some rats received 600 mg/kg body weight TDF by gavage for 35 days, while others received once daily 20 mg/kg body weight melatonin i.p. 2 h before TDF administration. All the rats were sacrificed on the 36th day, after overnight fast. Results: Melatonin pretreatment protected the rats against TDF nephrotoxicity both histologically and biochemically. Biochemically, melatonin pretreatment attenuated TDF-induced renal oxidative stress, nitrosative stress, and inflammation and preserved proximal tubular function. Histologically, melatonin pretreatment prevented TDF-induced proximal tubular injury and mitochondrial injury such as swelling, disruption of cristae, and deposition of amorphous material in the matrix. It restored the lysosomal and mitochondrial numbers in the proximal tubules also. Conclusions: Melatonin pretreatment protects rats from tenofovir-induced damage to proximal tubular mitochondria by attenuating oxidative stress, nitrosative stress, and inflammation. This suggests that it may be useful in ameliorating TDF nephrotoxicity in humans.

Depletion of the cellular antioxidant system contributes to tenofovir disoproxil fumarate - induced mitochondrial damage and increased oxido-nitrosative stress in the kidney.

BACKGROUND: Nephrotoxicity is a dose limiting side effect of tenofovir, a reverse transcriptase inhibitor that is used for the treatment of HIV infection. The mechanism of tenofovir nephrotoxicity is not clear. Tenofovir is specifically toxic to the proximal convoluted tubules and proximal tubular mitochondria are the targets of tenofovir cytotoxicity. Damaged mitochondria are major sources of reactive oxygen species and cellular damage is reported to occur after the antioxidants are depleted. The purpose of the study is to investigate the alterations in cellular antioxidant system in tenofovir induced renal damage using a rat model. RESULTS: Chronic tenofovir administration to adult Wistar rats resulted in proximal tubular damage (as evidenced by light microscopy), proximal tubular dysfunction (as shown by Fanconi syndrome and tubular proteinuria), and extensive proximal tubular mitochondrial injury (as revealed by electron microscopy). A 50% increase in protein carbonyl content was observed in the kidneys of TDF treated rats as compared with the control. Reduced glutathione was decreased by 50%. The activity of superoxide dismutase was decreased by 57%, glutathione peroxidase by 45%, and glutathione reductase by 150% as compared with control. Carbonic Anhydrase activity was decreased by 45% in the TDF treated rat kidneys as compared with control. Succinate dehydrogenase activity, an indicator of mitochondrial activity was decreased by 29% in the TDF treated rat kidneys as compared with controls, suggesting mitochondrial dysfunction. CONCLUSION: Tenofovir- induced mitochondrial damage and increased oxidative stress in the rat kidneys may be due to depletion of the antioxidant system particularly, the glutathione dependent system and MnSOD.

A preclinical study on the protective effect of melatonin against methotrexate-induced small intestinal damage: effect mediated by attenuation of nitrosative stress, protein tyrosine nitration, and PARP activation.

PURPOSE: One of the major toxic side effects of methotrexate (MTX) is enterocolitis. To date, there is no efficient standard treatment for this side effect. Nitrosative stress is reported to play a critical role in MTX-induced mucositis. The purpose of this study is to investigate whether pretreatment with melatonin, an inhibitor of nitro-oxidative stress, prevents MTX-induced mucositis in rats. METHODS: Rats were pretreated with melatonin (20 and 40 mg/kg body weight) i.p. daily 1 h before MTX (7 mg/kg body weight) administration for three consecutive days. After the final dose of MTX, the rats were killed and the small intestines were used for analysis. RESULTS: The small intestines of MTX-treated rats showed moderate to severe injury. The villi were distorted, blunted, and atrophied and focally absent in various segments of the small intestines. Crypt abscesses were also found, suggesting an inflammatory response. Pretreatment with melatonin had a dose-dependent protective effect on MTX-induced mucositis. Morphology was saved to a moderate extent with 20 mg melatonin pretreatment, and near-normal morphology was achieved with 40 mg melatonin pretreatment. Damage to the villi and crypt abscess was reduced. The villi/crypt ratio was almost restored. Melatonin pretreatment protected the small intestines from MTX-induced damage by attenuating nitrosative stress, protein tyrosine nitration and PARP expression. CONCLUSION: Because of its versatility in protecting against nitro-oxidative stress and reducing inflammation, we suggest that melatonin could be beneficial in ameliorating MTX-induced enteritis in humans.

Preclinical efficacy of melatonin to reduce methotrexate-induced oxidative stress and small intestinal damage in rats.

BACKGROUND: Methotrexate is widely used as a chemotherapeutic agent for leukemia and other malignancies. The efficacy of this drug is often limited by mucositis and intestinal injury, which are the major causes of morbidity in children and adults. AIM: The present study investigates whether melatonin, a powerful antioxidant, could have a protective effect. METHOD: Rats were pretreated with melatonin (20 and 40 mg/kg body weight) daily 1 h before methotrexate (7 mg/kg body weight) administration for three consecutive days. After the final dose of methotrexate, the rats were sacrificed and the small intestine was used for light microscopy and biochemical assays. Intestinal homogenates were used for assay of oxidative stress parameters malondialdehyde and protein carbonyl content, and myeloperoxidase activity, a marker of neutrophil infiltration as well as for the activities of the antioxidant enzymes. RESULT: Pretreatment with melatonin had a dose-dependent protective effect on methotrexate (MTX)-induced alterations in small intestinal morphology. Morphology was saved to some extent with 20 mg melatonin pretreatment and near normal morphology was achieved with 40 mg melatonin pretreatment. Biochemically, pretreatment with melatonin significantly attenuated MTX-induced oxidative stress (P < 0.01 for MDA, P < 0.001 for protein carbonyl content) and restored the activities of the antioxidant enzymes (glutathione reductase P < 0.05, superoxide dismutase P < 0.01). CONCLUSION: The results of the present study demonstrate that supplementation by exogenous melatonin significantly reduces MTX-induced small intestinal damage, indicating that it may be beneficial in ameliorating MTX-induced enteritis in humans.

Aminoguanidine, a selective nitric oxide synthase inhibitor, attenuates cyclophosphamide-induced renal damage by inhibiting protein nitration and poly(ADP-Ribose) polymerase activation.

BACKGROUND: Cyclophosphamide (CP) is an antineoplastic agent that is used for the treatment of many neoplastic diseases. Renal damage is one of the dose-limiting side effects of CP. Recent studies show that nitrosative stress plays an important role in CP-induced renal damage. AIM: The purpose of our study was to investigate whether aminoguanidine (AG), a selective inducible nitric oxide synthase inhibitor, protects against CP-induced nitrosative stress and renal damage. METHOD: Renal damage was induced in rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 h before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 h after the administration of CP or saline. Pretreatment with AG prevented CP-induced nitration of protein tyrosine and poly(ADP-ribose) polymerase (PARP) activation. RESULT: Pretreatment with AG attenuated CP-induced renal damage. The present study demonstrates that AG is effective in preventing CP-induced renal damage and also that the protective effect is from its ability to inhibit nitric oxide-induced protein nitration and PARP activation. CONCLUSION: The present study shows that AG can prevent CP-induced renal damage by inhibiting protein tyrosine nitration and PARP activation. Thus, a more efficient and comfortable therapy can be achieved for patients in need of CP treatment. AG appears to be a promising drug for the prevention of nephrotoxicity of CP.

Protective effect of aminoguanidine against cyclophosphamide-induced oxidative stress and renal damage in rats.

BACKGROUND: Cyclophosphamide (CP) is widely used in the treatment of tumors and B-cell malignant disease, such as lymphoma, myeloma, chronic lymphocytic leukemia, and Waldenstrom's macroglobulinemia. Renal damage is one of the dose-limiting side effects of CP. Oxidative stress is reported to play important roles in CP-induced renal damage. AIM: To find out whether aminoguanidine (AG) protects against CP-induced oxidative stress and renal damage. METHOD: Renal damage was induced in the rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 hour before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 hours after the administration of CP or saline. The kidneys were used for histological examination by light microscopy and biochemical assays--malondialdehyde, protein carbonyl content, reduced glutathione (GSH), and the activities of antioxidant enzymes including glutathione peroxidase (GPx), glutathione S transferase (GSTase), catalase, glutathione reductase, and myeloperoxidase (MPO), a marker of neutrophil infiltration. RESULTS: Pretreatment with AG attenuated CP-induced renal damage histologically. Pretreatment with AG prevented CP-induced lipid peroxidation, protein oxidation, depletion of reduced GSH, and loss of activities of the antioxidant enzymes including GPx, catalase, and GSTase and also MPO activity. CONCLUSION: The results of the present study reveal that AG can prevent CP-induced renal damage by inhibiting oxidative stress. Thus, AG may be useful for prevention of the nephrotoxicity of CP.

Ultrastructural changes in the rat kidney after single dose of cyclophosphamide--possible roles for peroxisome proliferation and lysosomal dysfunction in cyclophosphamide-induced renal damage.

Electron microscopy was used to examine changes in the subcellular organelles of the rat kidney at different time intervals after a single exposure to cyclophosphamide (CP). The morphological changes were studied at different time points (6 hrs, 16 hrs and 24 hrs) after a single-dose administration of CP. Six rats were killed at each time intervals after the administration of CP. Saline-treated rats served as controls. CP administration resulted in alterations in various subcellular organelles including peroxisomes, lysosomes, mitochondria, and the endoplasmic reticulum (ER) of the renal tubular epithelium as well as damage to the glomerulus. The basement membrane of the glomerulus was thickened. Many podocytes were destroyed. The nucleoplasm of the endothelial cell showed fewer granularities. The tubules were distorted and the brush border was destroyed. Two striking features in the renal tubular cells are increase in number and size of the peroxisomes (peroxisome proliferation) and decrease in the number of lysosomes. The mitochondria were elongated and the number was increased in the tubules of CP-treated rats. The ER was dilated. Cell necrosis was also seen. This study is an evidence of changes in morphology of rat kidney after induction of renal damage by a single dose of CP. Since transmission electron microscopy is the highest magnification tool at present, it can be useful in estimating the degree of injury and outcome of alternative treatment strategies in the management of CP-induced renal damage after establishing a scoring system.

Oral glutamine attenuates cyclophosphamide-induced oxidative stress in the bladder but does not prevent hemorrhagic cystitis in rats.

Cyclophosphamide (CP) is widely used in the treatment of cancer and non-malignant disease states such as rheumatoid arthritis. Hemorrhagic cystitis is a major dose-limiting side effect of CP. The incidence of this side effect is related to the dosage and can be as high as 75%. Elimination of the side effects of CP can lead to better tolerance of the drug, and a more efficient therapy can be achieved for patients in need of CP treatment. Several studies have demonstrated that oxidative stress and neutrophil infiltration play important roles in CP-induced bladder damage. Glutamine is utilized under clinical conditions for preventing chemotherapeutic drug-induced side effects, based on its ability to attenuate oxidative stress. The aim of the study is to verify whether glutamine prevents CP-induced oxidative stress and bladder damage using a rat model. Adult male rats were administered 150 mg/kg body weight of CP intraperitoneally. Glutamine pretreated rats were administered 1 g/kg body weight of glutamine orally 2 h before the administration of CP. Vehicle/glutamine-treated rats served as controls. All the rats were killed 16 h after the dose of CP/vehicle. The urinary bladders were removed and used for light microscopic and biochemical studies. The markers of oxidative stress including malondialdehyde content, protein carbonyl content, protein thiol, and myeloperoxidase activity, a marker of neutrophil infiltration, were measured in bladder homogenates. CP treatment induced hemorrhagic cystitis in the rats. Pretreatment with glutamine significantly reduced CP-induced lipid peroxidation (p < 0.01), protein oxidation (p < 0.01), and increase in myeloperoxidase activity (p < 0.05). However, it did not prevent CP-induced bladder damage. The results of the present study show that glutamine pretreatment does not attenuate CP-induced hemorrhagic cystitis, although it prevents CP-induced oxidative stress and neutrophil infiltration significantly. It is therefore necessary to clarify the utility of glutamine as a chemoprotective agent before it is recommended in the market as a nutrient supplement.

The effects of oral glutamine on cyclophosphamide-induced nephrotoxicity in rats.

Nephrotoxicity is one of the adverse side effects of cyclophosphamide (CP) chemotherapy. In a recent study, we have demonstrated that oxidative stress and glutathione depletion play important roles in CP-induced renal damage. The aim of the study was to verify whether glutamine, the precursor for glutathione synthesis, prevents CP-induced oxidative stress and renal damage using a rat model. Adult male rats were administered a single dose of 150 mg/ kg body weight of CP intraperitoneally. The glutamine-pretreated rats were administered 1 gm/kg body weight of glutamine orally 2 h before the administration of CP. Vehicle/glutamine-treated rats served as controls. All the rats were killed 16 h after the dose of CP/vehicle. The kidneys were removed and used for light microscopic and biochemical studies. The markers of oxidative stress including malondialdehyde content, protein carbonyl content, protein thiol, reduced glutathione and myeloperoxidase activity, a marker of neutrophil infiltration, were measured in kidney homogenates. CP treatment-induced damage to kidney involved the glomeruli and the tubules. Pretreatment with glutamine reduced CP-induced glutathione depletion and increased myeloperoxidase activity. However, it did not prevent CP-induced lipid peroxidation, protein carbonylation and renal damage. The results of the present study suggest that glutamine pretreatment does not prevent CP-induced lipid peroxidation and renal damage, although it prevents CP-induced glutathione depletion and neutrophil infiltration significantly. It is suggested that mechanisms other than oxidative stress may also be involved and/or oxidative stress may be consequence and not the cause of CP induced renal damage.

Melatonin attenuates methotrexate-induced oxidative stress and renal damage in rats.

Nephrotoxicity is an adverse side effect of methotrexate (MTX) chemotherapy. The present study verifies whether melatonin, an endogenous antioxidant prevents MTX-induced renal damage. Adult rats were administered 7 mg/kg body weight MTX intraperitoneally for 3 days. In the melatonin pretreated rats, 40 mg/ kg body weight melatonin was administered daily intraperitoneally 1 h before the administration of MTX. The rats were killed 12 h after the final dose of MTX/vehicle. The kidneys were used for light microscopic and biochemical studies. The markers of oxidative stress were measured along with the activities of the antioxidant enzymes and myeloperoxidase activity in the kidney homogenates. Pretreatment with melatonin reduced MTX induced renal damage both histologically and biochemically as revealed by normal plasma creatinine levels. Melatonin pretreatment reduced MTX induced oxidative stress, alteration in the activity of antioxidant enzymes as well as elevation in myeloperoxidase activity. The results suggest that melatonin has the potential to reduce MTX induced oxidative stress, neutrophil infiltration as well as renal damage. As melatonin is an endogenous antioxidant and is non-toxic even in high doses it is suggested that melatonin may be beneficial in minimizing MTX induced renal damage in humans.

Nitrosative stress, protein tyrosine nitration, PARP activation and NAD depletion in the kidneys of rats after single dose of cyclophosphamide.

OBJECTIVES: Cyclophosphamide (CP) and its structural analogue ifosfamide are highly effective cytostatic drugs. While both cyclophosphamide and ifosfamide have severe urotoxic side effects, only ifosfamide is thought to be nephrotoxic. The nephrotoxicity of CP in generally overlooked because of normal plasma creatinine levels. Therefore, little information is available regarding the pathogenic mechanism of renal damage by CP. In the present study, we investigated the role of nitrosative stress in CP-induced renal damage. METHODS: The experimental rats received a single i.p. of 150 mg/kg body weight CP in saline and were killed 6 h or 16 h later. The control rats received saline. The kidneys were used for histological and biochemical analysis. Nitrotyrosine and poly (ADP-ribose) polymerase (PARP) were localized immunohistochemically as indicators of protein nitration and DNA damage, respectively. Nitrite, NAD and superoxide dismutase (SOD) activity were assayed in the kidney homogenates. RESULTS: The nitrite level in the kidneys of CP-treated rats was elevated twofold. The kidneys of CP-treated rats stained strongly for nitrotyrosine as well as for PARP. Significant decrease in oxidized NAD levels was also observed in the kidneys of CP-treated rats. The activity of the peroxynitrite sensitive enzyme SOD was significantly reduced in the kidneys of CP-treated rats. CONCLUSION: The results of the present study reveal that nitrosative stress may play an important role in CP-induced renal damage. It is suggested that protein nitration, PARP activation and NAD +/- depletion may play a critical role in the pathogenesis of cyclophosphamide induced renal damage.