Effect of lithium on cyclosporin induced nephrotoxicity in rats

Psychoactive drugs provide essential intervention in the care of transplant recipients, yet little is known of their interaction with immunosuppressants such as cyclosporin (CSA). Lithium (Li) is an invaluable drug for the treatment of manic disorders in organ transplant patients. As both these drugs are known to produce renal toxicity, the concomitant use of CSA and Li may be potentially harmful. The present study was undertaken to investigate the effect of CSA and Li chloride individually and in combination on renal structure and function of rats. Male Sprague-Dawley rats were divided into the following eight groups of seven animals each: group I, control (vehicle only); group 2, Li (2 mEq/ kg i.p.) alone; group 3, CSA 12.5 mg/kg (subcutaneous); group 4, CSA 25 mg/kg; group 5, CSA 50 mg/kg; group 6, CSA 12.5 mg/kg + Li; group 7, CSA 25 mg/kg + Li; and group 8, CSA 50 mg/kg + Li. The drugs were given once a day for seven days; Li being administered 30 min before CSA. Twenty four hours after the last dose of drugs the animals were sacrificed and blood samples were analyzed for blood urea nitrogen (BUN), serum creatinine (SCr), CSA and Li levels. The left kidney was analyzed for malondialdehyde (MDA) and conjugated dienes (CD) levels and right kidney was used for histopathological studies. Our results showed that Li alone did not produce any significant renal toxicity, whereas CSA dose dependently caused structural and functional changes in kidneys. However, significantly higher structural and functional impairment was observed in the animals treated with Li plus CSA as compared to CSA alone treated animals. Several fold increase in blood Li level was also noticed in the rats concomitantly treated with CSA and Li. A significant increase in MDA and CD in the rats treated with CSA plus Li suggests the role of oxidative stress in drug induced nephrotoxicity. These findings clearly demonstrate that even non toxic doses of Li may significantly exacerbate CSA induced nephrotoxicity in rats. The enhanced nephrotoxicity following concomitant use of these drugs may be attributed to significant increase in the bioavailability of Li and enhanced oxidative stress. Further clinical studies are warranted to investigate the interaction of these nephrotoxic drugs in human subjects.     

Mercury exacerbates cyclosporin nephrotoxicity in rats

Background The use of cyclosporin (CsA) in the presence of other nephrotoxic drugs poses a great challenge to physicians. This study was designed to address the effect of concomitant administration of mercury and cyclosporin on nephrotoxicity of rats. Methods Male Sprague-Dawley rats (weighing 230±20 g) were divided into the following 8 groups of 7 animals each: group 1, control; group 2, mercury alone; group 3, cyclosporin 12.5 mg/kg; group 4, cyclosporin 25 mg/kg; group 5, CsA 50 mg/kg; group 6, CsA 12.5 mg/kg+mercury; group 7, CsA 25 mg/kg+mercury; and group 8, CsA 50 mg/kg+mercury. Mercury (1 mg/kg) was given by subcutaneous injection, and CsA, by oral gavage; drugs were given once a day for 7 days. Twenty-four hours after the last dose of drugs, the animals were killed, and blood samples were assayed for BUN, serum creatinine, and CsA levels. The left kidney was analyzed for malondialdehyde, lipid hydroperoxides, vitamin E, and glutathione levels, and histopathologic analysis was done on the right kidney. Results Mercury significantly exacerbated CsA-induced nephrotoxicity. There was a highly significant increase in oxidative stress in animals treated with the combination of CsA and mercury. Mercury also increased the bioavailability of CsA in rats. Conclusions Concomitant treatment of mercury with CsA produced severe nephrotoxicity. The enhanced nephrotoxicity may be attributed to the increased bioavailability of CsA and an increase in lipid peroxidation after concomitant use of these drugs.     

Aluminum exacerbates cyclosporin induced nephrotoxicity in rats

Cyclosporin (CSA) has been universally used as an immunosuppressant for the management of allotransplantation and autoimmune diseases. However, nephrotoxicity of CSA limits its use to optimum level. Aluminum (Al) is an extensively distributed element in the environment and human exposure to this metal is unavoidable. Recent studies suggest that even a slight impairment of renal function may increase the Al body burden significantly, which may lead to neurotoxicity, nephrotoxicity, osteodystrophy or hypochromic anemia. In the present study, an attempt was made to study the effect of concomitant use of Al and CSA on structure and function of kidney in rats. This study was undertaken in two steps. In the first set of experiments, the effect of single dose of Al (1% Al2(SO4)3 18H2O) on the nephrotoxicity of multiple doses of CSA (12.5 mg/kg, 25 mg/kg and 50 mg/kg) was studied, where as in the second set of experiments the effect of multiple doses of Al (0.25%, 0.5% and 1%) on single dose of CSA (50 mg/kg) was undertaken. Male Sprague-Dawley rats (weighing 230 +/- 20 g) were used in this study. CSA was given once a day by gavage for seven days, where as Al was given in drinking water for the same period. Twenty four hours after the last dose of CSA, animals were sacrificed and blood and kidney were collected for biochemical and histopathological studies. The bio-chemical parameters included blood urea nitrogen (BUN), serum creatinine (SCr), CSA and Al levels. The kidney homogenates were assayed for malondialdehyde (MDA) and lipid hydroperoxides (LPH). Treatment of rats with CSA alone produced dose-dependent structural and functional changes in kidney. Although Al alone failed to produce any deleterious effect on renal function, it significantly increased the bioavailability and nephrotoxicity of CSA. Al also exacerbated CSA induced increase in oxidative stress (as evident by increased MDA and LPH). Thus, the exacerbation of CSA nephrotoxicity by Al may be attributed to increased bioavailability of CSA and excessive generation of free radicals following concomitant use of these drugs.     

Effect of tacrolimus and cyclosporine on renal microcirculation and nitric oxide production

OBJECTIVES: Cyclosporine (CSA) and tacrolimus (TAC) frequently induce nephrotoxicity and similar pathologic changes. Acute CSA-induced nephrotoxicity has been reported to be mediated by activation of vasoconstrictors such as endothelin. The purpose of the present study was to investigate the acute effects of TAC and CSA on the renal microcirculation and upon a vasodilator such as nitric oxide (NO) production. METHODS: Renal blood flow (RBF) in the microcirculation was measured by a Laser Doppler flow meter in uninephrectomised rats. RBF, mean arterial pressure (MAP), and renal vascular resistance (RVR) were measured in the following groups: (a) TAC (0.1 to 2.0 mg/kg/h, n = 3 approximately 6); CSA (20 and 50 mg/kg/h, n = 5); (b) L-NAME (10 mg/kg), an NO synthase inhibitor, 8 minutes prior to TAC (0.5 and 1.5 mg/kg/h, n = 5), or CSA (20 and 50 mg/kg/h, n = 5). Stable NO end-products, serum NO(2) and NO(3), were measured by the Griess method (n = 5). RESULTS: None of the parameters were changed by TAC alone, whereas TAC with L-NAME significantly reduced RBF (-28 +/- 7%) and increased RVR (46 +/- 17%) in a dose-dependent manner. CSA alone significantly reduced RBF (-37 +/- 6%) and increased RVR (69 +/- 22%) without any changes in MAP. The effects of CSA were enhanced by L-NAME. Serum concentration of NO(2) + NO(3) was significantly reduced by both L-NAME alone and CSA (50 mg/kg) (P < .05), while there were no changes with TAC (1.5 mg/kg). CONCLUSIONS: Blockade of NO production enhance the vasoconstrictive effect of CSA, and unmasked such an effect of TAC. These results suggest that the nephrotoxicity of CSA and TAC may involve the NO system.     

Modification of experimental nephrotoxicity with fish oil as the vehicle for cyclosporine

Cyclosporine-associated renal dysfunction is well recognized. While renal vasoconstriction appears to be a major pathogenic factor, the precise mechanism responsible for the altered hemodynamics is unclear. To investigate whether alterations in renal eicosanoid metabolism could be involved, we substituted fish oil rich in eicosapentaenoic acid (EPA), an inhibitor of cyclooxygenase metabolites, for the conventional olive oil cyclosporine vehicle. Male rats were pretreated with 1.0 cc fish oil or olive oil by gavage. After 14 days, cyclosporine (12.5 mg/cc vehicle) was added to the oil and animals received cyclosporine 50 mg/kg for an additional 14 days. Pair-fed control animals received fish oil or olive oil alone. Glomerular filtration rate (GFR) was severely reduced in the cyclosporine-in-olive-oil (CSA + OO) group (0.28 +/- .05 ml/min/100 g) vs. olive oil (OO) controls (0.70 +/- .04) (P less than 0.001). While GFR was reduced in the cyclosporine-in-fish oil group (CSA + FO) vs. fish oil (FO) controls (0.47 +/- .07 vs. 0.74 +/- .04), it was significantly higher than in the CSA + OO group (P less than 0.05). Trough whole-blood cyclosporine levels were not significantly different in the two groups. While CSA + OO appeared to elevate renal cortical content of thromboxane B2 (65.7 +/- 7.3 pg/mg tissue vs. 46.9 +/- 5.3 for OO), both the CSA + FO and FO groups had reduced levels (31.1 +/- 2.7 and 29.5 +/- 2.3, respectively). In addition, there was a striking reduction in proximal tubular vacuolar changes in the CSA +/- FO vs. CSA + OO group. We conclude that the use of EPA-rich fish oil as the vehicle for cyclosporine results in improved renal function and morphology and is associated with depressed renal cortical levels of vasoconstrictor thromboxane B2.     

The combined effect of cyclosporine a and gentamicin on enzymuria in the Sprague-Dawley rat

Male Sprague-Dawley rats (8 per group) were administered a single oral dose of cyclosporine A (10, 30 and 50 mg/day) for 5 days or vehicle (corn oil, 1.5 mL/kg) and urinary enzymes excretion was monitored. Only minor changes in enzymuria were observed in the 10 and 30 mg/kg group. However, in the 50 mg/kg group, nephrotoxicity was evident by significant increase in the excretion of N-acetyl-beta-D-glucosaminidase (NAG), glutamate dehydrogenase (GDH), and lactate dehydrogenase (LDH on day 2 of treatment. As chemotherapeutic drug interaction with cyclosporine A (CyA) is thought to aggravate its nephrotoxicity, the effect of combined CyA (30 mg/kg) and the antibiotic gentamicin (50 mg/kg) for 5 days was investigated. Gentamicin alone caused a significant enzymuria, whilst co-treatment of rats with CyA gave rise to increased changes in enzymuria on days 1 and 2, between the groups receiving gentamicin+vehicle and those receiving CyA+gentamicin. This was particularly marked by significant changes in LDH excretion. In contrast these observed differences were not paralleled by changes in serum creatinine and other functional parameters. Treatment with gentamicin, appears to enhance CyA nephrotoxicity, but only in the first 2 days, after this there was no significant differences between the two groups. Our data suggest that urinary enzyme measurements could serve as a valuable non-invasive means of monitoring renal performance in animals or humans who may be exposed to combination of drugs. CyA is found not to potentiate the nephrotoxic effect of gentamicin in the animal model used in this study. It therefore appears safe to use the combined therapy particularly in the treatment of transplant patients.     

THE COMBINED EFFECT OF CYCLOSPORINE A AND GENTAMICIN ON ENZYMURIA IN THE SPRAGUE-DAWLEY RAT

Male Sprague-Dawley rats (8 per group) were administered a single oral dose of cyclosporine A (10, 30 and 50 mg/day) for 5 days or vehicle (corn oil, 1.5 mL/kg) and urinary enzymes excretion was monitored. Only minor changes in enzymuria were observed in the 10 and 30 mg/kg group. However, in the 50 mg/kg group, nephrotoxicity was evident by significant increase in the excretion of N-acetyl-β-D-glucosaminidase (NAG), glutamate dehydrogenase (GDH), and lactate dehydrogenase (LDH on day 2 of treatment. As chemotherapeutic drug interaction with cyclosporine A (CyA) is thought to aggravate its nephrotoxicity, the effect of combined CyA (30 mg/kg) and the antibiotic gentamicin (50 mg/kg) for 5 days was investigated. Gentamicin alone caused a significant enzymuria, whilst co-treatment of rats with CyA gave rise to increased changes in enzymuria on days 1 and 2, between the groups receiving gentamicin + vehicle and those receiving CyA + gentamicin. This was particularly marked by significant changes in LDH excretion. In contrast these observed differences were not paralleled by changes in serum creatinine and other functional parameters. Treatment with gentamicin, appears to enhance CyA nephrotoxicity, but only in the first 2 days, after this there was no significant differences between the two groups. Our data suggest that urinary enzyme measurements could serve as a valuable non-invasive means of monitoring renal performance in animals or humans who may be exposed to combination of drugs. CyA is found not to potentiate the nephrotoxic effect of gentamicin in the animal model used in this study. It therefore appears safe to use the combined therapy particularly in the treatment of transplant patients.     

Investigating the Protective Effects of Astragalus Membranaceus on Nephrotoxicity in Cyclosporine A-treated Rats

The immunosuppressive drug, cyclosporine A (CsA), has been used in patients who were treated for immune diseases and in transplant patients. However, nephrotoxicity due to CsA, remains an important clinical challenge. Although the mechanisms of nephrotoxicity are far from clear, notwithstanding there is evidence that suggests the role of oxidative stress in its pathogenesis. This study was conducted to investigate the protective effect of the Chinese herbal medicine, astragalus membranaceus (AM), in CsA-induced nephrotoxicity in a rat model. Adult Sprague–Dawley rats were treated with olive oil, CsA (25 mg/kg/bw), AM (5 mg/kg/bw), CsA plus AM for 30 days. Renal function, Malondialdehyde (MDA) levels were measured and histopathology, and Immunohistochemical staining for Endothelin was performed. In this study, CsA caused a significant deterioration in renal function, morphology, and also induced oxidative stress, as indicated by increased renal MDA. Administration of AM along with CsA improved the functional and histological parameters of the kidneys, and counteracted the oxidative stress induced by CsA. These results suggested that AM has a protective potential in experimental CsA nephrotoxicity.     

Protective effect of administration of Withania somifera against bromobenzene induced nephrotoxicity and mitochondrial oxidative stress in rats

Background: The present study was conducted to elucidate the protective role of Withania somnifera against bromobenzene induced nephrotoxicity and mitochondrial dysfunction in rats. Methods: In this study, Wistar albino rats of either sex were divided into six groups consisting of six animals each. The first one was control, those in group II received bromobenzene (10?mmol/kg, intragastric intubation) once, but group III and IV animals received W. somnifera (250 and 500?mg/kg, orally), respectively for 8 days followed by bromobenzene once on the 8th day and silymarin (100?mg/kg, orally) was given for 8 days to group V animals and then bromobenzene on the last day. Group VI animals received only W. somnifera (500?mg/kg) for 8 days. Results: The levels of renal lipid peroxidation, lysosomal enzymes and glycoprotein were increased significantly (p?<?0.05) in the bromobenzene alone treated rats and antioxidant status and mitochondrial enzymes were found to be decreased, when compared to the control group. The levels of kidney functional markers (urea, uric acid and creatinine) were also found to be abnormal in serum of bromobenzene alone treated rats. On the other hand, administration of W. somnifera (250 and 500?mg/kg) along with bromobenzene offered a significant dose-dependent protection to the biochemical alterations as observed in the bromobenzene alone treated rats, which was also evidenced by histopathology. Conclusion: Thus, the oral administration of W. somnifera significantly protected against the bromobenzene induced nephrotoxicity and renal mitochondrial dysfunction in rats.     

Attenuation of Cyclosporine-Induced Renal Dysfunction by Catechin: Possible Antioxidant Mechanism

One of great use of immunosuppressant, Cyclosporine-A (CsA) is in the solid organ transplantation; however the extensive use of this is cautionable due to its toxic effect in renal tissue, characterized by the tubular atrophy, interstitial fibrosis, and progressive renal impairment. However, there are many mediators are associated with pathogenesis of nephrotoxicity of CsA, the exact mechanism is still in debate. Recent studies indicate that Reactive Oxygen Species (ROS) induced oxidative stress and lipid peroxidations are the important mechanisms implicated in the pathophysiology of nephrotoxicity with CsA. In the present study we examined effect of dietary flavonoid catechin on oxidative damage in cyclosporine-A induced nephrotoxicity. Chronic administration of CsA (20 mg/kg/day) subcutaneously for 21 days significantly decreased the body weight as compared with vehicle treated rats. CsA (20 mg/kg/day) administration for 21 days significantly decreased the renal function by increase in the serum creatinine, blood urea nitrogen, and decrease in the creatinine and urea clearance as compared with vehicle treated rats. Catechin (100 mg/kg/day) for 21 days along with CsA significantly reversed the changed renal parameters, however lower dose of catechin (50 mg/kg/day) restored only increased serum creatinine levels as compared with CsA alone treated group. Biochemical analysis revealed that chronic administration of CsA (20 mg/kg/day) for 21 days significantly induced lipid peroxidation and decreased the glutathione levels in the kidney homogenate of rats. It is also observed that chronic CsA administered rats showed decrease in antioxidant defense enzyme superoxide dismutase and increase in the catalase activity as compared with vehicle treated rats. Co-administration of catechin (100 mg/kg/day) orally along with CsA for 21 days significantly reduced the lipid peroxidation and restored the decreased glutathione levels as compared with CsA alone group, but lower dose of catechin (50 mg/kg/day) restored only decreased glutathione levels induced by CsA. Co-administration of only higher dose of catechin (100 mg/kg/day) along with CsA significantly increased the superoxide dismutase (SOD) levels as compared with CsA alone treated group. It is also observed that catechin (100 mg/kg/day) along with CsA further increased the catalase levels as compared with CsA alone treated group, but not with lower dose of catechin. Animals administered with catechin (100 mg/kg/day) alone for 21 days showed significant increase in the catalase levels as compared with vehicle treated group. The major findings of the present study suggest that oxidative stress might play a significant role in CsA-induced nephrotoxicity. In conclusion, dietary administration of flavonoid catechin could be a useful component for the prevention/treatment of CsA-induced nephrotoxicity.     

Attenuation of cyclosporine-induced renal dysfunction by catechin: possible antioxidant mechanism

One of great use of immunosuppressant, Cyclosporine-A (CsA) is in the solid organ transplantation; however the extensive use of this is cautionable due to its toxic effect in renal tissue, characterized by the tubular atrophy, interstitial fibrosis, and progressive renal impairment. However, there are many mediators are associated with pathogenesis of nephrotoxicity of CsA, the exact mechanism is still in debate. Recent studies indicate that Reactive Oxygen Species (ROS) induced oxidative stress and lipid peroxidations are the important mechanisms implicated in the pathophysiology of nephrotoxicity with CsA. In the present study we examined effect of dietary flavonoid catechin on oxidative damage in cyclosporine-A induced nephrotoxicity. Chronic administration of CsA (20 mg/kg/day) subcutaneously for 21 days significantly decreased the body weight as compared with vehicle treated rats. CsA (20 mg/kg/day) administration for 21 days significantly decreased the renal function by increase in the serum creatinine, blood urea nitrogen, and decrease in the creatinine and urea clearance as compared with vehicle treated rats. Catechin (100 mg/kg/day) for 21 days along with CsA significantly reversed the changed renal parameters, however lower dose of catechin (50 mg/kg/day) restored only increased serum creatinine levels as compared with CsA alone treated group. Biochemical analysis revealed that chronic administration of CsA (20 mg/kg/day) for 21 days significantly induced lipid peroxidation and decreased the glutathione levels in the kidney homogenate of rats. It is also observed that chronic CsA administered rats showed decrease in antioxidant defense enzyme superoxide dismutase and increase in the catalase activity as compared with vehicle treated rats. Co-administration of catechin (100 mg/kg/day) orally along with CsA for 21 days significantly reduced the lipid peroxidation and restored the decreased glutathione levels as compared with CsA alone group, but lower dose of catechin (50 mg/kg/day) restored only decreased glutathione levels induced by CsA. Co-administration of only higher dose of catechin (100 mg/kg/day) along with CsA significantly increased the superoxide dismutase (SOD) levels as compared with CsA alone treated group. It is also observed that catechin (100 mg/kg/day) along with CsA further increased the catalase levels as compared with CsA alone treated group, but not with lower dose of catechin. Animals administered with catechin (100 mg/kg/day) alone for 21 days showed significant increase in the catalase levels as compared with vehicle treated group. The major findings of the present study suggest that oxidative stress might play a significant role in CsA-induced nephrotoxicity. In conclusion, dietary administration of flavonoid catechin could be a useful component for the prevention/treatment of CsA-induced nephrotoxicity.     

Rutin attenuates gentamicin-induced renal damage by reducing oxidative stress,inflammation, apoptosis,and autophagy in rats

Abstract

Gentamicin is commonly used against gram-negative microorganisms. Its therapeutic use is mainly limited by nephrotoxicity. This study was aimed at evaluating the effect of rutin on oxidative stress, inflammation, apoptosis, and autophagy in gentamicin-induced nephrotoxicity in rats. The rats were treated with saline intraperitoneally (group I), 150?mg/kg of rutin orally (group II), 80?mg/kg of gentamicin intraperitoneally for 8?d (group III), or 150?mg/kg of rutin plus 80?mg/kg of gentamicin (group IV). The serum urea, creatinine, kidney malondialdehyde (MDA), and reduced glutathione (GSH) levels and superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activity and protein concentration were measured, and renal histopathology analysis and immunohistochemical staining were performed. Rutin pretreatment attenuated nephrotoxicity induced by gentamicin by reducing the urea, creatinine, and MDA levels and increasing the SOD, CAT, and GPx activity, and the GSH levels. The rutin also inhibited inducible nitric oxide synthase (iNOS), cleaved caspase-3 and light chain 3B (LC3B), as evidenced by immunohistochemical staining. The present study demonstrates that rutin exhibits antioxidant, anti-inflammatory, anti-apoptotic, and anti-autophagic effects and that it attenuates gentamicin-induced nephrotoxicity in rats.     

Melatonin, a pineal hormone with antioxidant property, protects against gentamicin-induced nephrotoxicity in rats

The present study investigated the effects of melatonin, an antioxidant, on gentamicin-induced nephrotoxicity in rats. Melatonin (5 mg/kg p.o.) was used 3 days before and 8 days simultaneously with gentamicin (80 mg/kg i.p.) Saline-treated animals served as controls. Determinations of urinary creatinine, N-acetyl-beta-D-glucosaminidase, glucose, protein, blood urea, serum creatinine, plasma and kidney tissue malondialdehyde (MDA), and antioxidant enzyme levels in kidney tissue were done after 8 days of gentamicin treatment. The kidneys were also examined for morphological changes using histological techniques. Gentamicin caused nephrotoxicity as evidenced by marked elevation in blood urea and serum creatinine. Mean blood urea and serum creatinine levels were 289+/-50, and 2.5+/-0.5 mg/dl, respectively, in rats treated with gentamicin. Melatonin significantly protected the rats from gentamicin-induced nephrotoxicity; blood urea and serum creatinine levels were 23+/-2.7 and 0.88+/-0.19 mg/dl, respectively. The creatinine clearance was decreased with gentamicin treatment (0.048+/- 0.007 ml/min) as compared with controls (0.41+/-0.08 ml/h/kg). In rats treated with melatonin plus gentamicin, the creatinine clearance was similar to controls (0.41+/-0.08 ml/h/kg). The product of lipid peroxidation (MDA) was markedly increased in plasma (2.10+/-0.15 nmol) and kidney tissue (8.87+/-3.2 nmol/mg protein) with gentamicin treatment. Melatonin prevented the gentamicin-induced rise in plasma MDA (1.03+/-0.27 nmol) and kidney tissue MDA (2.57+/-0.87 nmol/mg protein). An increased excretion of urinary N-acetyl-beta-D-glucosaminidase, glucose, and protein by gentamicin was also prevented by melatonin. Kidneys from gentamicin-treated rats showed tubular epithelial loss with intense granular degeneration involving more than 50% of renal cortex, while there were findings comparable to controls in melatonin plus gentamicin treated rats. The present study indicates that melatonin significantly protects against gentamicin-induced renal toxicity in Wistar rats.     

N-acetylcysteine attenuates cyclosporin-induced nephrotoxicity in rats.

BACKGROUND: Cyclosporin (CsA) has played an important role in the improvement of solid-organ transplant patients and graft survival. However, nephrotoxicity due to CsA remains an important clinical challenge. The renal toxicity of CsA is attributed to reduced renal blood flow which leads to hypoxia reoxygenation injury accompanied by excessive generation of oxygen-derived free radicals (ODFR). N-acetyl-L-cysteine (NAC) is a highly potent antioxidant that has been shown to reduce ODFR injury. In this study an attempt was made to assess the effect of NAC on CsA-induced lipid peroxidation and nephrotoxicity. METHODS: Adult Sprague-Dawley rats were treated orally with CsA (25 and 50 mg/kg) alone and in combination with different doses of NAC (10, 20 and 40 mg/kg) for a period of 3 weeks. Twenty-four hours after the last treatment, animals were sacrificed and blood was analysed for blood urea nitrogen (BUN) and serum creatinine (SCr), and kidney samples were analysed for lipid hydroperoxides, conjugated dienes and glutathione, and histopathological changes. RESULTS: Treatment of rats with CsA produced a significant increase in BUN and SCr level and histological abnormalities. CsA-induced impairment of renal toxicity was accompanied by significant increase in renal oxidative stress. NAC treatment significantly protected animals against CsA-induced structural and functional impairment of kidney. CONCLUSIONS: CsA-induced nephrotoxicity was significantly attenuated by NAC. This study clearly suggests the role of oxidative stress in the pathogenesis of CsA-induced nephrotoxicity. Concomitant use of antioxidants such as NAC to minimize CsA-induced nephrotoxicity in humans warrant further studies.     

Pomegranate Extract Attenuates Gentamicin-Induced Nephrotoxicity in Rats by Reducing Oxidative Stress

Nephrotoxicity is a major complication of gentamicin (GEN), which is widely used in the treatment of severe Gram-negative infections. Reactive oxygen species are important mediators of GEN-induced nephrotoxicity. Because of the strong antioxidant properties of pomegranate extract (PE), we evaluated the protective effect of PE against GEN-induced nephrotoxicity. Thirty-two adult male rats were randomly divided into four equal groups: (1) controls; (2) treated with GEN for 14 consecutive days (100 mg/kg/day); (3) treated with GEN plus distilled water; and (4) treated with GEN plus PE (100 μL). After 15 days, the rats were killed and their kidneys were taken, and blood analysis was performed. Tubular necrosis and interstitial fibrosis scores were determined histopathologically; and biochemically, nitric oxide (NO), malondialdehyde (MDA), and reduced glutathione (GSH) levels in kidneys were determined. Urea, creatinine, Na⁺, and K⁺ levels were investigated in the blood analysis. Statistical analyses were made by the chi-square test and analysis of variance. Serum urea and creatinine levels were significantly higher in rats treated with GEN alone than rats in the control and the GEN + PE-treated groups. The GSH level in renal tissue of only GEN-treated rats was significantly lower than those in the control group, and administration of PE to GEN-treated rats significantly increased the level of GSH. The group that was given GEN and PE had significantly lower MDA levels in kidney cortex tissue than those given GEN alone. There was no significant difference of NO levels between the groups. In rats treated with GEN + PE, despite the presence of mild tubular degeneration and tubular necrosis is less severe, and glomeruli maintained a better morphology when compared with the GEN-treated group. We think that PE prevents kidney damage by decreasing oxidative stress in kidney.     

Effects of nifedipine on cisplatinum-induced nephrotoxicity in rats

The effects of calcium channel blockade with nifedipine (N) on cis-diammine dichloroplatinum II (CDDP)-induced nephrotoxicity were tested in male Sprague-Dawley rats. Renal function was evaluated before and five days after CDDP administration (5 mg/kg). The rats were treated with various doses of N (0.1; 0.3; 0.6 mg/kg/day) 2 days before CDDP administration and throughout the study. The severity of CDDP-induced acute renal failure was markedly modified in N-treated animals according to the daily dosage of N. At 0.3 and 0.6 mg/kg BW/day, N enhanced CDDP nephrotoxicity. Serum creatinine was 637 +/- 45 and 611 +/- 71 mumoles/liter, respectively, 5 days after CDDP administration (vs. 313 +/- 24 mumoles in animals treated with CDDP alone; p less than 0.05). In these animals the plasma potassium level was significantly elevated at day 7 when compared with CDDP-treated and control rats. In contrast, at the dose of 0.1 mg/kg BW/day N attenuated CDDP nephrotoxicity with a serum creatinine of 214 +/- 35 mumoles at the end of the study. The pathologic changes were also more severe in the groups receiving 0.3 and 0.6 mg/kg of nifedipine. We postulate that at the higher doses (0.3 and 0.6 mg/kg) the systemic hemodynamic effects of nifedipine may override the potentially beneficial intrarenal effect which may account for the favorable results recorded with a dosage of 0.1 mg/kg.     

Effect of animal sex on experimental ciclosporin nephrotoxicity

Experimental ciclosporin (CSA) nephrotoxicity is reported to be more severe in male versus female rodents. To investigate these sex differences further, groups of male and female Sprague-Dawley rats were pair fed and given either CSA 50 mg/kg or olive oil vehicle by gavage daily for 5 days. Both groups of treated animals showed azotemia and depression of CIn but there were no sex differences. CSA levels were 5,820 ng/ml in females and 6,480 ng/ml in males (p = NS). Although CSA did not produce enzymuria in either sex, females showed more extensive proximal tubular cell vacuolization. Conclusion: Female Sprague-Dawley rats are equally as susceptible to CSA nephrotoxicity as males. Strain differences or experimental design may account for apparently conflicting results in the literature.     

Prevention of cyclosporine-induced nephrotoxicity with pentoxifylline

Although cyclosporine (CSA) is established in the prevention of allograft rejection, its use has been associated with dose-limiting toxicities, most notably to the kidney and liver. To date, the pathogenesis of the acute form of nephrotoxicity is unclear but may be related to inhibition of vasodilatory prostaglandins resulting in vasoconstriction and ischemia. The present study investigated the coadministration of CSA with a unique hemorheologic agent, pentoxifylline (PTX), in the murine model. A total of 48 rats were orally dosed with CSA 25 mg/kg for 10 days with either PTX 45 mg/kg i.p. or saline every 12 hr. Posttreatment renal function, assessed by creatinine (CCR) and inulin (CIN) clearances and renal electrolyte handling, was compared with baseline data and between groups. In an attempt to assess prostaglandin-mediated changes in enteral absorption, oral CSA pharmacokinetics with and without PTX were compared to the pharmacokinetics of similar groups (N = 8) administered i.v. CSA. Mean CIN of rats coadministered CSA and PTX (942 +/- 214 microliters/min/g KW) was similar to control rats 884 +/- 185 microliters/min/g KW); both were significantly greater than CSA alone (537 +/- 211 microliters/min/g KW; p less than .01). Likewise, percent of baseline CCR was significantly reduced in rats treated CSA (61 +/- 24%) compared to controls 113 +/- 41%) and rats coadministered PTX (117 +/- 75%; p less than .05). No differences in percent change from baseline electrolyte handling were observed among groups. Further, no differences in CSA pharmacokinetics with or without PTX were found.(ABSTRACT TRUNCATED AT 250 WORDS)     

p-Coumaric acid,a common dietary polyphenol,protects cadmium chloride-induced nephrotoxicity in rats

The present study was conducted to elucidate the protective role of p-coumaric acid, a common dietary polyphenol against cadmium induced nephrotoxicity in rats. For the purpose of comparison, a standard reference drug silymarin (50?mg/kg?b.?wt) was used. In this experiment, the animals were divided into four groups, with each consisting of six animals. The animals in Group I animals received saline and served as a control group and those in Group II received cadmium chloride (3?mg/kg b. wt) subcutaneously once daily for 3 weeks, but Group III and IV animals received cadmium chloride followed by p-coumaric acid (100?mg/kg b. wt, oral) and silymarin (50?mg/kg b. wt, oral), respectively, daily for 3 weeks. At the end of the treatment, the animals were sacrificed, and the blood and kidney samples were collected. The results obtained in this study revealed the fact that the levels of lipid peroxidation, lysosomal enzymes, glycoprotein, cadmium and metallothionein were increased in the cadmium chloride alone treated rats and antioxidant status was found to be decreased, when compared to the control group. The levels of kidney functional markers (urea, uric acid and creatinine) were also found to be abnormal in serum and urine of cadmium chloride alone treated rats. On the other hand, the administration of p-coumaric acid along with cadmium chloride significantly protected the biochemical alterations as observed in the cadmium chloride alone treated rats as evidenced by histopathology. Thus, the oral administration of p-coumaric acid significantly protected the cadmium-induced nephrotoxicity in rats.     

Verapamil increases the nephrotoxic potential of gentamicin in rats.

The effect of verapamil on the nephrotoxic potential of gentamicin was examined in rats. Rats were injected with one of the two or both drugs for 6 days and sacrificed 48 h after the last injection. In verapamil-treated rats (5 mg/kg/day), no histological or biochemical evidence of renal injury was detected. In all gentamicin-treated rats (100 mg/kg/day), a significant increase in kidney weight was observed (p less than 0.001). The renal histopathologic lesions were more extensive in rats treated simultaneously with both gentamicin and verapamil. These rats exhibited a decline in body weight earlier (from day 4) than rats injected with gentamicin alone (from day 6). Serum urea nitrogen and creatinine in the latter group of rats were 24.9 +/- 3.7 and 1.1 +/- 0.1 versus 47.4 +/- 8.6 and 1.6 +/- 0.2 mg/dl, respectively, in rats treated with the combined therapy (p less than 0.05). These results indicate that verapamil increases the severity of gentamicin nephrotoxicity. This interaction should be considered as a factor that can potentially increase the nephrotoxic risk associated with gentamicin administration.