Effect of superoxide dismutase treatment on gentamicin nephrotoxicity in rats

The nephroprotective potential of selected synthetic compound against gentamicin induced nephrotoxicity

BACKGROUND

Nephrotoxicity, the rapid impairment of kidney function caused by harmful drugs and chemicals, affects about 20% of cases and is projected to become a leading cause of death by reactive oxygen species (ROS). Gentamicin (GM), an aminoglycoside antibiotic is one of the well know drugs/chemicals to cause nephrotoxicity both in humans and animals.

METHODS

A study on the effects of a synthetic phenolic compound, called 5-a, on GM-induced nephrotoxicity in male Wistar albino rats was conducted. The rats were grouped into five groups: normal control (NC), GM control (GM), positive control (GM + Dexa), treatment I (GM + 5-a 5 mg/kg) and treatment II (GM + 5-a 10 mg/kg). Throughout the experiment, the rats' weights were monitored, and at its conclusion, their serum and kidney tissues were analyzed for renal function indicators and inflammatory markers. The study also included histopathological evaluations, molecular docking studies, blood and urine analyses for electrolyte changes, and behavioural assessments for central nervous system impact.

RESULTS

2-{5-[(2-hydroxyethyl)-sulfanyl]-1,3,4-oxadiazol-2-yl} phenol (5-a) significantly protected against renal damage by reducing inflammatory markers, improving antioxidant defences, and decreasing kidney injury, particularly at higher doses. The findings suggest that compound 5-a, due to its anti-inflammatory and antioxidant properties, could be a promising therapeutic option for reducing gentamicin-induced nephrotoxicity and potentially for other kidney disorders in the future.

CONCLUSION

These findings highlight the therapeutic effects of compound 5-a in alleviating gentamicin-induced nephrotoxicity.

Investigation the effects of 2-aminoethoxydiphenyl borate (2-APB) on aminoglycoside nephrotoxicity

Investigation the protective effect of transient receptor potential channel modulator 2-Aminoethoxydiphenyl Borate (2-APB) on aminoglycoside nephrotoxicity caused by reactive oxygen species, calcium-induced apoptosis and inflammation was aimed. Forty Wistar rats were divided (n=8) as follows: Control group; DMSO group; 2-APB group; Gentamicin group (injected 100 mg/kg gentamicin intramuscularly for 10 days); Gentamicin+ 2-APB group (injected 2 mg/kg 2-APB intraperitoneally, then after 30 minutes 100 mg/kg gentamicin was injected intramuscularly for 10 days). Blood samples were collected for biochemical analyses, kidney tissue samples were collected for light, electron microscopic and immunohistochemical investigations. In gentamicin group glomerular degeneration, tubular dilatation, vacuolization, desquamation of tubular cells and hyaline cast formation in luminal space and leukocyte infiltration were seen. Disorganization of microvilli of tubular cells, apical cytoplasmic blebbing, lipid accumulation, myelin figure like structure formation, increased lysosomes, mitochondrial swelling and disorganization of cristae structures, apoptotic changes and widening of intercellular space were found. TNF-α, IL-6 and caspase 3 expressions were increased. BUN and creatinine concentrations were increased. Increase in MDA levels and decrease in SOD activities were determined. Even though degeneration still continues in gentamicin+2-APB treatment group, severity and the area it occupied were decreased and the glomerular and tubule structures were generally preserved. TNF-α, IL-6, caspase 3 immunoreactivities and BUN, creatinine, MDA concentrations were reduced and SOD activities were increased markedly compared to gentamicin group. In conclusion, it has been considered that 2-APB can prevent gentamicin mediated nephrotoxicity with its anti-oxidant, anti-apoptotic and anti-inflammatory effects.

Effects of atorvastatin on biomarkers of acute kidney injury in amikacin recipients: A pilot, randomized, placebo-controlled, clinical trial

BACKGROUND

The most common clinical indication of aminoglycosides (AG) is the treatment of serious Gram-negative infections. The aim of this study was to evaluate plausible effects of atorvastatin on the biomarkers of acute kidney injury (AKI) in patients receiving amikacin.

MATERIALS AND METHODS

In this double-blinded randomized clinical trial, fifty patients (25 in each group) receiving amikacin (15 mg/kg/day) were randomly assigned to either atorvastatin (40 mg/day) or placebo (40 mg/day) groups for 7 days. Blood urea nitrogen (BUN), serum creatinine (SCr), and urinary neutrophil gelatinase-associated lipocalin (NGAL) levels were measured at days 0, 1, and 7 of amikacin treatment.

RESULTS

During the study period, 4 (8%) patients including two patients in each atorvastatin and placebo group experienced AKI. Urine NGAL/urine Cr did not change significantly between and within placebo and atorvastatin groups during the study period. Similarly, the mean changes in SCr, BUN, and urine NGAL/urine Cr values did not differ significantly between and within patients with and without AKI.

CONCLUSION

Our data suggested that the changing pattern of urine NGAL/urine Cr ratio did not differ significantly between the atorvastatin and placebo groups during the early phase of amikacin treatment.

A systematic meta-analysis on the efficacy of pre-clinically tested nephroprotectants at preventing aminoglycoside nephrotoxicity

Nephrotoxicity limits the use of aminoglycoside antibiotics. Kidney damage is produced mainly in the renal tubule due to an inflammatory and oxidative process. At preclinical level, many drugs and natural products have been tested as prospective protectors of aminoglycoside nephrotoxicity. The main objective of this work was to make a systematic literature review of preclinical studies about aminoglycoside nephrotoxicity protection and a statistical analysis based on the meta-analysis methodology. Studies published up to January 2016 were identified. After applying inclusion criteria, 54 studies were chosen. The size of the experimental groups, means and standard deviations of data on renal function (i.e. plasma creatinine and blood urea nitrogen [BUN] concentrations) were extracted and registered in a database. The studies were grouped according to the mechanism of nephroprotection and their route of administration. The Mean Difference (95% confidence interval) was calculated for each study and group. 40 of 54 products tested produced an amelioration of aminoglycoside nephrotoxicity based on creatinine results. Also a dose dependent protective effect was observed (both in creatinine and BUN). Products orally administered were more effective than via i.p. Products with attributed antioxidant activity were the most used and those which proved statistically significant nephroprotection as a class effect. Aminoglycoside tubular reuptake inhibitors, excretion inducers and calcium channel blockers also showed a promising and rather homogeneous class tendency towards nephroprotection, although more research is necessary to obtain solid and conclusive results, based on a larger number of studies.

Time dependent effect of gentamicin on enzymes of carbohydrate metabolism and terminal digestion in rat intestine

Gentamicin (GM) is an aminoglycoside antibiotic commonly used against life threatening gram negative bacterial infections, however, nephrotoxicity remains the major concern for its long term use. Although its effects on kidney are well characterized but there have been no studies regarding its effects on intestine. We hypothesize that GM causes adaptive coordinated effect on enzymes of carbohydrate metabolism and terminal digestion/ absorption in rat intestine. Rats were administerd a nephrotoxic dose of GM (80 mg /kg body weight) daily for 15 days and a time dependent effect was observed on various enzyme activities. Activities of lactate (LDH), malate (MDH) and isocitrate (ICDH) dehydrogenases, significantly increased and peaked at different time intervals of GM treatment. Whereas LDH activity remained higher, MDH and ICDH activity slowly declined from their peak values. Activities of fructose-1,6-bisphosphatase, glucose-6-phosphatase and glucose-6-phosphate dehydrogenase increased but malic enzyme decreased in a time dependent manner. Activity of alkaline phosphatase and sucrase significantly increased but γ-glutamyl transpeptidase activity decreased. GM administration increased lipid peroxidation, glutathione peroxidase but decreased superoxide dismutase and catalase activities. The results indicate that GM treatment selectively upregulated certain enzymes of carbohydrate metabolism and terminal digestion/absorption and perturbed antioxidant defenses. Human & Experimental Taxicology, ( 2007) 26, 587—593.

Protective effect of selected calcium channel blockers and prednisolone, a phospholipase-A2 inhibitor, against gentamicin and carbon tetrachloride-induced nephrotoxicity

The ameliorative effect of calcium channel blockers (CCBs) and a phospholipase-A2 inhibitor in drug-/chemical-induced nephrotoxicity was investigated. Rats were divided into 7 groups of 5 rats in each group. In the gentamicin model, group I rats were pretreated with normal saline (10 ml kg−1), while groups II–VII rats were pretreated with normal saline (10 ml kg−1), ascorbic acid (10 mg kg−1), nifedipine (0.86 mg kg−1), verapamil (4.3 mg kg−1), diltiazem (3.43 mg kg−1), and prednisolone (0.57 mg kg−1), respectively, perorally 1 h before intraperitoneal (i.p.) injection of gentamicin (40 mg kg−1) for 14 days. In the carbon tetrachloride (CCl4) model, rats were pretreated with CCBs and prednisolone for 7 days before inducing nephrotoxicity with 20% CCl4 (1.5 ml kg−1). Rats were thereafter killed and blood and tissue samples were collected for assessments. I.p. injections of gentamicin and CCl4 caused significant hypernatremia, hypokalemia, hypocalcemia, hypophosphatemia, and hyperchloremic alkalosis and reduced renal tissue levels of antioxidants. Also, significant reductions in the hemoglobin, packed cell volume, red blood cells, and platelet indices were observed. Pretreatments with nifedipine (0.86 mg kg−1), verapamil (4.3 mg kg−1), diltiazem (3.43 mg kg−1), and prednisolone (0.57 mg kg−1) significantly ameliorated the deleterious effects of gentamicin and CCl4 possibly via antioxidant and anti-lipoperoxidation mechanisms. The results obtained in this study suggest potential clinical usefulness of tested CCBs and prednisolone in drug-/chemical-induced nephrotoxicity.

Comparative protective effect of N-acetyl cysteine and tetramethylpyrazine in rats with gentamicin nephrotoxicity

Gentamicin (GM) is used against serious and life-threatening infections, but its use is limited by the occurrence of nephrotoxicity, which involves the generation of free radicals. In this work we tested the effect of a compound with antioxidant properties, tertamethylpyrazine (TMP), a major constituent of the Chinese medicinal plant Lingusticum wallichi, on GM-induced nephrotoxicity, and compared it with an established anti-oxidant compound N-acetyl cysteine (NAC). Six groups of rats were studied: (1) control, treated orally (p.o.) and intraperitoneally (i.p.) with saline; (2) treated i.p. with GM (80 mg kg(-1) per day for 6 days); (3) TMP, given p.o. (100 mg kg(-1) per day for 10 days) + GM (same dose as above during the last 6 days); (4) NAC, given i.p. (500 mg kg(-1) per day for 10 days) + GM as above; (5) TMP (100 mg kg(-1) per day for 10 days) + saline; (6) NAC (500 mg kg(-1) per day for 10 days) + saline. GM nephrotoxicity was characterized by reduced creatinine clearance, increased creatinine and urea concentrations in plasma, increased urinary excretion of N-acetyl-beta-d-glucosaminidase (NAG) and total protein. These functional and structural alterations were prevented or ameliorated by NAC treatment, while TMP had only a slight mitigating effect that was less marked than that produced by NAC. The concentration of GM in the renal cortex of the rats given GM + NAC (but not TMP) was lower than that found in rats treated with GM alone by about 25%. The mechanism by which NAC and, to a lesser extent TMP, protected against GM-induced nephrotoxicity may be related, at least in part, to the decrease in oxidative stress in renal cortex.

Spirulina platensis protects against gentamicin-induced nephrotoxicity in rats

The present study aimed to investigate the protective effect of Spirulina platensis (SP) on gentamicin sulphate (GS)-induced changes in the levels of lipid peroxidation and endogenous antioxidants in the kidney of rats. Sprague-Dawley rats were treated in separate groups as follows for 7 consecutive days: control (C), gentamicin sulphate (100 mg/kg i.p.) (GS), Spirulina platensis (1000 mg/kg orally) (SP) and Spirulina platensis (1000 mg/kg orally) plus gentamicin sulphate (100 mg/kg i.p.) (SP + GS). The degree of protection was evaluated by determining the effects of Spirulina platensis on malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GPX) and nitric oxide (NO), and plasma creatinine and urea levels were estimated in kidney homogenates to evaluate antioxidant activity, and the kidney was histologically examined as well. Spirulina platensis elicited significant nephroprotective activity by decreasing lipid peroxidation (MDA) and elevated the levels of GSH, SOD, GPX, NO, creatinine and urea. Furthermore, these biochemical observations were supplemented by histological examination of the rat kidneys. In conclusion, the present study indicates a very important role of reactive oxygen species (ROS) and the relation to renal dysfunction and point to the therapeutic potential of Spirulina platensis in gentamicin sulphate induced nephrotoxicity.

Effects of co-supplementation of vitamins E and C on gentamicin-induced nephrotoxicity in rat

Gentamicin (GM) is an effective antibiotic against severe gram-negative infections. However it can produce nephrotoxicity in human. Reactive oxygen species (ROS) have been proposed as the causative factors of the renal side effects the drug. This study was performed to investigate the protective role of antioxidant vitamins against GM-mediated nephropathy in an in situ model of isolated rat kidney. Male Sprague-Dawley rats were randomly assigned to one of the following groups of seven rats: group 1 (Control) was perfused with Tyrode solution; group 2 (GM), 200 microg ml(-1) GM was added to the perfusate; group 3 (GM + Vit C), as group 2 with vitamin C added to the drinking water for 3 days (200 mg l(-1)) and to the perfusate (100 mg l(-1)); group 4 (GM + Vit E), as group 2 with vitamin E (100 mg (100 g body weight)(-1), i.m.) injected 12 h before the start of the experiment; group 5 (GM + Vit C + Vit E) as group 2 with vitamin E and C co-administered (concentrations and conditions as in groups 3 and 4). To compare the groups, urinary lactate dehydrogenase (LDH), N-acetyle-beta-D-glucosaminidase (NAG) and alkaline phosphatase (ALP) activities, inulin clearance (glomerular filtration rate, GFR) and renal tissue glutathione (GSH) content were measured. GM caused a significant nephrotoxicity demonstrated by an increase in urinary LDH, NAG and ALP activities. Reduction in GSH content and a marked decrease in GFR were observed compared to controls. Vitamin C inhibited the GM-induced increase in urinary enzyme activities but did not show a significant effect on the GSH content or GFR. Vitamin E prevented the GM-induced reduction in GSH level without a significant improvement in GFR. Co-administration of vitamins C and E significantly prevented the GM-induced nephrotoxicity demonstrating by preservation of GFR and GSH levels and prevention of increase in urinary enzyme activities. We conclude that co-administration of moderate doses of vitamins C and E has beneficial effects on renal preservation in GM-induced nephrotoxicity.

Protective effect of ebselen, a selenoorganic drug, against gentamicin-induced renal damage in rats

Gentamicin is an antibiotic that is widely used against serious and life-threatening gram-negative infections. However, its clinical use is limited by its nephrotoxicity. Oxidative stress and nitrosative stress are reported to play important role in gentamicin nephrotoxicity. In the present study we investigated whether ebselen, an inhibitor of oxidative stress and nitrosative stress prevents or reduces gentamicin-induced renal damage in the rat. For this purpose male Wistar rats were divided into five groups and treated as follows. Group 1 (control group): dimethyl sulphoxide, intraperitoneally, Group 2: Gentamicin 100 mg/kg b.wt. subcutaneously, Group 3: 5 mg/g b.wt. ebselen intraperitoneally, Group 4: 2.5 mg/kg b.wt. ebselen followed by 100 mg/kg b.wt. gentamicin subcutaneously one hour later, and Group 5: 5 mg/kg b.wt. of ebselen followed by 100 mg/kg b.wt. gentamicin one hour later for four consecutive days. Nephrotoxicity was evaluated histopathologically by light microscopy, and biochemically by the measurement of the plasma creatinine and urea levels. Parameters of oxidative stress such as reduced glutathione, malondialdehyde, and activities of superoxide dismutase and glutathione peroxidase were measured in the kidney. Serum nitrite and nitrate were measured as indicators of nitrosative stress. Treatment of rats with gentamicin resulted in statistically significant reduction in reduced glutathione levels (51%) and the activities of antioxidant enzymes superoxide dismutase (56%) and glutathione peroxidase (39%) as compared with the controls in the kidneys. Renal malondialdehyde level was increased significantly (43%) as compared with the controls. Plasma creatinine levels, urea levels and nitrite levels were significantly increased (4, 4.5 and 160% times respectively) as compared with the controls. Histologically, damage to the renal cortex and medulla was observed moderate to severe tubular necrosis and glomerular congestion. Pretreatment with 2.5 mg/kg b.wt. ebselen prevented gentamicin induced damage to medulla; however, renal cortex showed mild damage and biochemically indicators of oxidative stress and nitrosative stress were significantly reduced. Pretreatment with 5 mg/kg b.wt. ebselen prevented gentamicin-induced oxidative damage and nitrosative damage and renal damage almost completely in 78% of the rats, in the other 22% of the rats, ebselen pretreatment reduced gentamicin-induced renal damage. The results of the present study suggest that ebselen may be useful as a nephroprotective agent.

Parachlorophenylalanine Exacerbates Oxidative Stress Induced by Gentamicin in Rats

The present work studies the effect of parachlorophenylalanine (PCPA, 200 mg/kg intraperitoneally/48 hr for 7 days) on the oxidative stress and nephropathy induced by gentamicin (80 mg/kg intraperitoneally/daily for 7 days) in Wistar rats. The effect of PCPA on lipid peroxidation products and reduced glutathione content in renal and brain tissue, as well as on 5HT content in brain was assessed. Catalase and superoxide dismutase activities were determined in brain tissue. Blood urea nitrogen and creatinine in plasma and total protein content in urine were also measured. Gentamicin caused significant increases in proteinuria, non-protein nitrogen compounds and lipid peroxidation markers, together with decreases in both reduced glutathione content in renal and brain tissue and enzymatic activities in brain homogenates. PCPA harnessed the effect of gentamicin in the brain and the kidney, while PCPA alone induced brain oxidative stress. These results support the prooxidant action of PCPA in brain tissue and its capacity to exacerbate the oxidative stress and renal dysfunction induced by gentamicin, as well as the possible antioxidant property of serotonin.

Protective Effect of L-Arginine Intake on the Impaired Renal Vascular Responses in the Gentamicin-Treated Rats

The purpose of this study was to investigate the effect of gentamicin (100 mg/kg/day, i.p.) treatment on endothelium-dependent and -independent vasodilation in isolated perfused rat kidney, and the effect of amino acid L-arginine (in the drinking water, 2.25 g/l) on renal dysfunction induced by gentamicin. When gentamicin-treated groups were compared with the control group, it was observed that BUN and creatinine levels increased significantly. Also, the relaxant responses induced by acetylcholine, sodium nitroprusside and pinacidil decreased. Histopathological examination indicated acute tubular necrosis in this group. In animals treated with gentamicin together with L-arginine, there was a significant amelioration in the BUN and creatinine levels. The vasodilator responses were similar to those of the control group. Histopathological examination indicated only hydropic degeneration in tubular epithelium of kidney. Co-administration of L-NG-nitroarginine methyl ester (L-NAME) (112.5 mg/l), an inhibitor of nitric oxide synthase, and L-arginine to rats treated with gentamicin did not change the protective effect of L-arginine. In rats receiving L-NAME alone, the level of BUN and creatinine and vasodilation to acetylcholine were not significantly different when compared to those of the control group, while relaxant responses to sodium nitroprusside and pinacidil were increased. These results suggest that gentamicin leads to an impairment in vascular smooth muscle relaxation in addition to acute tubular necrosis in the rat kidney. Supplementation of L-arginine has an important protective effect on gentamicin-induced nephropathy.

Effect of tempol (4-hydroxy tempo) on gentamicin-induced nephrotoxicity in rats

We investigated the effects of tempol (4-hydroxy tempo), a membrane-permeable radical scavenger, on gentamicin-induced renal failure in rats. The rats were given gentamicin (100 mg/kg/day, i.p., once a day); and gentamicin (100 mg/kg/day, i.p.) and tempol (3.5, 7 or 14 mg/kg/day, i.p., once a day). At the end of 7 days, the gentamicin group produced the remarkable nephrotoxicity, characterized by a significantly decreased creatinine clearance and increased serum creatinine, blood urea nitrogen (BUN) and daily urine volume when compared with controls. In control the BUN value was 21.2 +/- 0.07 (mg/100 mL); in comparison, it was 96.9 +/- 6.03 in gentamicin group (P < 0.05). Renal histopathologic examination confirmed acute tubular necrosis in this group. In rats treated with gentamicin and tempol a partial improvement in biochemical and histologic parameters was observed. BUN values were 96.9 +/- 6.03 and 36.3 +/- 2.39 in gentamicin, and gentamicin plus tempol (14 mg/kg) treated groups, respectively (P < 0.05). These results suggest that the administration of tempol may have a protective effect on gentamicin-induced nephrotoxicity in rats.

Agents ameliorating or augmenting experimental gentamicin nephrotoxicity: some recent research

Despite its nephrotoxic potential, the aminoglycoside antibiotic gentamicin (GM) is still considered to be an important agent against life-threatening infections. The goal of reducing or protecting against its nephrotoxicity has attracted much effort and attention during the last decade. This article reviews some of the literature published during the last decade on the effects of agents that ameliorate or augment GM nephrotoxicity. Notable among the ameliorating agents are antioxidant agents. These include different classes of compounds that include beta blockers (e.g. carvedilol), superoxide dismutase mimetic agents (e.g. M40403), hormones (e.g. melatonin), iron chelators (e.g. deferrioxamine), vitamins (vitamin C and E) and medicinal plants (e.g. garlic). Other ameliorating agents include antibiotics (e.g. ceftriaxone), antiplatelet drugs (e.g. trapidil) and Ca++ agents that may augment GM nephrotoxicity include cyclosporin and the Ca++-channel blocker verapamil.

Aged garlic extract attenuates gentamicin induced renal damage and oxidative stress in rats

Gentamicin (GM) is an antibiotic whose clinical use is limited by its nephrotoxicity. Experimental evidences suggest a role of reactive oxygen species in GM-induced nephrotoxicity. Therefore, we investigated if aged garlic extract (AGE), an antioxidant, has a protective role in this experimental model. Four groups of male Wistar rats were studied: 1) Control (CT), injected subcutaneously (s.c.) and intraperitoneally (i.p.) with saline, 2) GM, treated s.c. with GM (70 mg/kg/12 hours/4 days), 3) AGE, treated i.p with AGE (1.2 mL/kg/12 hours/6 days), and 4) GM + AGE treated with GM and AGE. The treatment with AGE started two days before the first dose of GM (GM + AGE group) or saline (AGE group). Animals were sacrificed on day 5, and blood, urine, and kidneys were obtained. Nephrotoxicity was made evident by: 1) the increase in blood urea nitrogen and plasma creatinine, 2) the decrease in plasma glutathione peroxidase (GPx) activity and the urinary increase in N-acetyl-beta-D-glucosaminidase activity and total protein, and 3) necrosis of proximal tubular cells. These alterations were prevented or ameliorated by AGE treatment. Furthermore, AGE prevented the GM-induced increase in the renal levels of oxidative stress markers: nitrotyrosine and protein carbonyl groups and the decrease in manganese superoxide dismutase (Mn-SOD), GPx, and glutathione reductase (GR) activities. The protective effect of AGE was associated with the decrease in the oxidative stress and the preservation of Mn-SOD, GPx, and GR activities in renal cortex. These data suggest that AGE may be a useful agent for the prevention of GM-nephrotoxicity.

Antioxidant S-allylcysteine prevents gentamicin-induced oxidative stress and renal damage

Acute renal failure (ARF) is a major complication of gentamicin (GM) treatment, which is effective against gram-negative infections. Since experimental evidence suggests a role of reactive oxygen species (ROS) in GM-induced ARF, in this work we studied the effect of a garlic-derived compound, S-allylcysteine (SAC), which is a free radical scavenger, on GM-induced nephrotoxicity. In rats treated with GM (70 mg/kg/12 h/4 days/s.c.), ARF was evident by the: (i) decrease in creatinine clearance and increase in blood urea nitrogen, (ii) decrease in blood glutathione peroxidase (GPx) activity and increase in urinary excretion of N-acetyl-beta-D-glucosaminidase and total protein, and (iii) necrosis of proximal tubular cells. These alterations were prevented by SAC treatment (250 mg/kg/i.p. 24 h before the first dose of GM and 125 mg/kg/12 h/4 days along GM-treatment). Furthermore, SAC prevented the GM-induced oxidative stress (protein carbonyl groups) and the decrease in manganese superoxide dismutase (Mn-SOD), GPx, and glutathione reductase (GR) activities in renal cortex. In conclusion, SAC ameliorates the GM-induced ARF by a mechanism related, at least in part, to its ability to decrease oxidative stress and to preserve antioxidant enzymes activity in renal cortex.

A role for superoxide in gentamicin-mediated nephropathy in rats

Gentamicin is an antibiotic effective against Gram-negative infection, whose clinical use is limited by its nephrotoxicity. Oxygen free radicals are considered to be important mediators of gentamicin-mediated nephrotoxicity, but the exact nature of the radical in question is not known with certainty. We have investigated the potential role of superoxide in gentamicin-induced renal toxicity by using M40403, a low molecular weight synthetic manganese containing superoxide dismutase mimetic, which selectively removes superoxide. Administration of gentamicin at 100 mg/kg, s.c. for 5 days to rats induced a marked renal failure, characterised by a significant decrease in creatinine clearance and increased plasma creatinine levels, fractional excretion of sodium, lithium, urine gamma glutamyl transferase (gamma GT) and daily urine volume. A significant increase in kidney myeloperoxidase activity and lipid peroxidation was also observed in gentamicin-treated rats. M40403 (10 mg/kg, i.p. for 5 days) attenuated all these parameters of damage. Immunohistochemical localisation demonstrated nitrotyrosine formation and poly(ADP-ribose) synthetase (PARS) activation in the proximal tubule of gentamicin-treated rats. Renal histology examination confirmed tubular necrosis. M40403 significantly prevented gentamicin-induced nitrotyrosine formation, poly(ADP-ribose) synthetase activation and tubular necrosis. These results confirm our hypothesis that superoxide anions play an important role in gentamicin-mediated nephropathy and support the possible clinical use of low molecular weight synthetic superoxide dismutase mimetics in those conditions that are associated with over production of superoxide.

Effect of trapidil, an antiplatelet and vasodilator agent on gentamicin-induced nephrotoxicity in rats

This study was carried out to evaluate the effect of trapidil, an antiplatelet and vasodilator drug, on the nephrotoxicity by an aminoglycoside, gentamicin, in rats. Forty female Wistar rats were divided into six different groups. One group served as a control group and the other groups were treated as follows: gentamicin (50 mg kg(-1) twice daily)-treated, gentamicin plus trapidil (4 or 20 mg kg(-1) daily)-treated and only trapidil-treated (4 or 20 mg kg(-1) daily) groups. Serum urea, creatinine and nitrite/nitrate levels were measured. Moreover, histopathological as well as electron microscopic examinations were performed. At a lower dose (4 mg kg(-1)) trapidil did not prevent the development of renal tubular damage by gentamicin. However, a higher dose of trapidil (20 mg kg(-1)) inhibited the ability of gentamicin to increase the levels of creatinine and urea. Furthermore, both light and electron microscopic evaluation confirmed the nephroprotective effect of the higher dose of trapidil. The level of the stable nitric oxide (NO) metabolite, nitrite, was also increased by trapidil. In conclusion, trapidil at a higher dose may protect against gentamicin nephrotoxicity. The mechanism underlying trapidil nephroprotection is not known, but may result from the antagonism of platelet-derived growth factor (PDGF), vasodilatation, inhibition of trombosit aggregation, and/or NO release.

Garlic ameliorates gentamicin nephrotoxicity: relation to antioxidant enzymes

Reactive oxygen species are involved in gentamicin (GM) nephrotoxicity, and garlic is effective in preventing or ameliorating oxidative stress. Therefore, the effect of garlic on GM nephrotoxicity was investigated in this work. Four groups of rats were studied: (i) fed normal diet (CT), (ii) treated with GM (GM), (iii) fed 2% garlic diet (GA), and (iv) treated with GM and 2% garlic diet (GM + GA). Rats were placed in metabolic cages and GM nephrotoxicity was induced by injections of GM (75 mg/kg every 12 h) for 6 d. Lipoperoxidation and enzyme determinations were made in renal cortex on day 7. GM nephrotoxicity was made evident on day 7 by (i) tubular histological damage, (ii) enhanced BUN and urinary excretion of N-acetyl-beta-D-glucosaminidase, and (iii) decreased creatinine clearance. These alterations were prevented or ameliorated in GM + GA group. The rise in lipoperoxidation and the decrease in Mn-SOD and glutathione peroxidase (GPx) activities observed in the GM group, were prevented in the GM + GA group. Cu, Zn-SOD activity and Mn-SOD and Cu,Zn-SOD content did not change. CAT activity and content decreased in the GM, GA, and GM + GA groups. CAT mRNA levels decreased in the GM group. The protective effect of garlic is associated with the prevention of the decrease of Mn-SOD and GPx activities and with the rise of lipoperoxidation in renal cortex.

Carvedilol: a beta blocker with antioxidant property protects against gentamicin-induced nephrotoxicity in rats

Gentamicin is an antibiotic effective against gram negative infections, whose clinical use is limited by its nephrotoxicity. Since the pathogenesis of gentamicin-induced nephrotoxicity involves oxygen free radicals, the antioxidant carvedilol may protect against gentamicin-induced renal toxicity. We therefore tested this hypothesis using a rat model of gentamicin nephrotoxicity. Carvedilol (2 mg/kg) was administered intraperitoneally 3 days before and 8 days concurrently with gentamicin (80 mg/kg BW). Estimations of urine creatinine, glucose, blood urea, serum creatinine, plasma and kidney tissue malondialdehyde (MDA) were carried out, after the last dose of gentamicin. Kidneys were also examined for morphological changes. Gentamicin caused marked nephrotoxicity as evidenced by increase in blood urea, serum creatinine and decreased in creatinine clearance. Blood urea and serum creatinine was increased by 883% and 480% respectively with gentamicin compared to control. Carvedilol protected the rats from gentamicin induced nephrotoxicity. Rise in blood urea, serum creatinine and decrease in creatinine clearance was significantly prevented by carvedilol. There was 190% and 377% rise in plasma and kidney tissue MDA with gentamicin. Carvedilol prevented the gentamicin induced rise in both plasma and kidney tissue MDA. Kidney from gentamicin treated rats, histologically showed necrosis and desquamation of tubular epithelial cells in renal cortex, whereas it was very much comparable to control with carvedilol. In conclusion, carvedilol with its antioxidant property protected the rats from gentamicin-induced nephrotoxicity.

Protective effects of vitamin e and probucol against gentamicin-induced nephrotoxicity in rats

Gentamicin (GM) is widely used as a bactericidal agent for the treatment of severe gram negative infections, however, its clinical use is partially limited due to its nephrotoxicity. Recent evidence suggests a role of reactive oxygen metabolites in GM nephrotoxicity. The present study was designed to investigate a possible potential protective role of vitamin E and/or probucol against GM nephrotoxicity. GM was administered to rats in a single dose of (150 mg kg(-1)i.p.), while vitamin E (250 mg kg(-1)i.m.) and/or probucol (60 mg kg(-1)i.m.) were given once daily for 3 consecutive days prior to GM administration. GM-induced nephrotoxicity was evidenced by marked elevations in serum urea and creatinine levels, urinary activity of N-acetyl-beta- d -glucosaminidase (NAG) and gamma-glutamyl-transferase (gamma-GT). Also, GM caused significant increases in kidney content of malondialdehyde (MDA), and significant decreases in kidney content of reduced non-protein sulphydryls (NPSH) and superoxide dismutase (SOD) activity. Vitamin E pretreatment significantly lowered the elevated serum urea and creatinine levels, and urinary activity of NAG and gamma-GT. In addition, vitamin E ameliorated the rise in renal content of MDA and enhanced the renal NPSH content as well as SOD activity. Similarly, probucol significantly inhibited the elevations in urea and creatinine levels and enhanced renal NPSH content and SOD activity. Simultaneous use of vitamin E and probucol was more effective in mitigating disturbances in the assessed parameters. The present work indicates that, due to their antioxidant activity, vitamin E and probucol have potential protective effects against GM nephrotoxicity.

Gentamicin nephrotoxicity in humans and animals: some recent research

It would appear from the literature cited in this article, that interest in gentamicin nephrotoxicity is still thriving. Despite extensive studies, the mechanism(s) of the nephrotoxicity is uncertain. Several clinical and experimental strategies have been employed in order to ameliorate or abolish the signs of gentamicin nephrotoxicity. Most of these were unsuccessful, impractical or unsafe. Therefore there is still a need for further studies to elucidate the mechanism(s) of action of the drugs nephrotoxicity, and to discover safe, practical and effective agents to ameliorate the nephrotoxicity in patients at risk.