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Saudi Journal of Kidney Diseases and Transplantation
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ORIGINAL ARTICLE  
Year : 2011  |  Volume : 22  |  Issue : 6  |  Page : 1181-1186
Simvastatin ameliorates gentamicin-induced renal injury in rats


1 Department of Nephrology, Rasool Akram Hospital, Iran Medical University, Tehran, Iran
2 Clinical Research Department, Nikan Research Institute, Tehran, Iran

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Date of Web Publication8-Nov-2011
 

   Abstract 

Gentamicin nephrotoxicity is one of the most common causes of acute renal failure. Simvastatin is one of the antioxidative drugs, which has anti-inflammatory and anabolic effects and modulates the immune system. The present study was conducted to assess the effect of simvastatin on ameliorating the gentamicin-induced renal injury in 87 Sprague-Dawley rats, which were allocated randomly to 11 study groups: (A) and (B) groups with only gentamicin in 2 dosages; (C), (D), and (E) gentamicin 50 mg/kg/day and simvastatin with different dosage; (F), (G), and (H) gentamicin 80 mg/kg/day and simvastatin with different dosage; (I) only simvastatin; (J) Injected normal saline; (K) control (no gentamicin and no simvastatin) group. Our study intervention period for injection of drugs was 12 days. Serum creatinine level and clearance were measured in all groups. At the end of the study, the rats were killed and both kidneys were removed and processed for histopathologic examination using the standard methods. The 50 mg/kg/day dose was utilized because it induces a mild form of renal toxicity, whereas the 80 mg/kg/day dose cause a more severe degree of renal injury. Morphologic examination of specimens from all rats was qualitatively assessed with blindness to treatment groups and proximal tubular profiles that were presented in each file were counted. The results demonstrated amelioration of gentamicin-induced renal toxicity in rats by simvastatin due to its antioxidant drug dose-related effect.

How to cite this article:
Jabbari M, Rostami Z, Jenabi A, Zahedi-Shoolami L, Mooraki A. Simvastatin ameliorates gentamicin-induced renal injury in rats. Saudi J Kidney Dis Transpl 2011;22:1181-6

How to cite this URL:
Jabbari M, Rostami Z, Jenabi A, Zahedi-Shoolami L, Mooraki A. Simvastatin ameliorates gentamicin-induced renal injury in rats. Saudi J Kidney Dis Transpl [serial online] 2011 [cited 2019 Nov 17];22:1181-6. Available from: http://www.sjkdt.org/text.asp?2011/22/6/1181/87229

   Introduction Top


Gentamicin nephrotoxicity is one of the most common causes of acute renal failure. [1] Although the change in gentamicin dosing from multiple-daily to once-daily doses has reduced the risk of nephrotoxicity, the incidence of gentamicin induced acute renal failure still remains high. [2] There may be several mechanisms by which gentamicin induces renal injury. These include binding to anionic phospholipids and altering the function and structure of cellular and intra-cellular membranes. [3],[4],[5] Gentamicin may also cause ATP depletion from either mitochondrial damage or direct inhibition of mitochondrial oxidative phosphorylation, [6],[7] and it may cause oxidative injury. [8],[9]

Simvastatin is one of the antioxidative drugs, which has anti-inflammatory and anabolic effects and modulates the immune system. [10],[11] Simvastatin inhibits HMG-CoA in the metabolic cycle of acetyl CoA and decreases cholesterol and low-density lipoprotein, and its oxidative form, oxidative low-density lipoprotein, is one of the lipid peroxidation indices that increases in gentamicin nephrotoxicity and decreases with simvastatin usage. [12],[13]

The aim of our study is to assess the effect of simvastatin on ameliorating the gentamicin-induced renal injuries.


   Materials and Methods Top


Our study is a randomized controlled trial (R-CT), approved by the ethical board of Iran Medical University.

Study samples

Study samples included 87 Sprague-Dawley rats with a weight range of 140-320 g. The animal experimentation was conducted in accordance with the National Institute of Health guide for the careful use of laboratory animals. The rats were kept in an animal research facility, and they were provided with rat chow and tap water after a 5 days period of adaptation to the environment. They were allocated randomly to 11 groups. There were 8 rats in each group except the third group, which had 7 participants. Each group of rats was given one injection and oral gavage at noon.

The study groups were assigned the following regimens:

  1. Gentamicin 50 mg/kg/day for 8 days.
  2. Gentamicin 80 mg/kg/day for 8 days.
  3. Gentamicin 50 mg/kg/day for 8 days and simvastatin 2 mg/kg/day for 12 days starting 4 days before gentamicin injection.
  4. Gentamicin 50 mg/kg/day for 8 days and simvastatin 10 mg/kg/day for 12 days starting 4 days before gentamicin injection.
  5. Gentamicin 50 mg/kg/day for 8 days and simvastatin 20 mg/kg/day for 12 days starting 4 days before gentamicin injection.
  6. Gentamicin 80 mg/kg/day for 8 days and simvastatin 2 mg/kg/day for 12 days starting 4 days before gentamicin injection.
  7. Gentamicin 80 mg/kg/day for 8 days and simvastatin 10 mg/kg/day for 12 days starting 4 days before Gentamicin injection.
  8. Gentamicin 80 mg/kg/day for 8 days and simvastatin 20 mg/kg/day for 12 days starting 4 days before gentamicin injection.
  9. Simvastatin 20 mg/kg/day for 12 days.
  10. Injected with normal saline once daily for 12 days.
  11. Control (no gentamicin and no simvastatin), Thus the daily normal saline injection and simvastatin oral gavage were commenced 4 days before the onset of gentamicin and were continued for the entire 8 days of the gentamicin prescription.
Preparation of the gavage solution

Three tablets of simvastatin (60 mg) were diluted in 10 mL water, and then 2 mL from that was diluted in 10 mL water. All the injections were administered intraperitoneally, between 14:30 and 15:00 hours every day. Blood samples were drawn on the 13th day from the carotid vessels and collected into heparin red tubes and centrifuged at 1000 g at 4°C and plasma was then frozen. Blood drawings were obtained between 14:30 and 15:00 hours on the 13th day and in groups A and B on the 8th day. Twenty-four hours urine collections were obtained between 14:30 and 15:00 hours on the 12th day and in groups A and B on 8th day for urine volume and urinary creatinine (3-4 mL urine were kept in −4°C).

Preparing the histopathologic specimens

On the 13th day after anesthesia with ketamine-xylocaine, the rats were sacrificed. The abdominal cavity was opened after minimal dissection; both kidneys were removed and fixed in neutral formalin (10%) and then processed for histopathologic examination by standard methods.

The morphologic examination of kidney histologic sections from all rats was qualitatively assessed with blindness for treatment groups. Proximal tubular profiles that were presented in each file were counted. Four categories of injuries were were distinguished: 0 (no alteration), one plus (1+) (isolated cell necrosis, apoptotic bodies and or disruption of cell membrane and loss of nuclear stain), 2 plus (2+) (several necrotic cells in a tubular profile, and 3 plus (3+) (complete or almost complete necrosis of tubular profiles).


   Statistical Analysis Top


Statistical analysis was done by SPSS for Windows version 14. Quantitative variables were presented by central indices, and quailtative variables were presented by frequency tables. Chi-square and independent sample t tests were used for data analysis. Two-tailed significance level of 0.05 was used to detect the difference between variables.


   Results Top


The mean of weight in all samples was 170.17 ± 24.13 g, and the lowest weight was in group F (163.12 ± 17.48 g), while the highest was in group H (177.5 ± 20.46 g). The highest level of creatinine in samples was in group F (0.7263 mg/dL) and lowest was in the control group (0.4650 mg/dL). The highest level of creatinine clearance was in the control group (0.01936 mL/min) and the lowest was in group K (0.00848 mL/min).

[Table 1] summarizes the results of the study and shows the means of the serum creatinine levels, creatinine clearances, and frequencies of the pathologic lesions of the different groups of the study. Comparison of the means of creatinine levels, clearances, and pathologic lesions did not show significant differences between the control groups (groups J and K). The means of serum creatinine levels in group B was significantly higher than group A (P = 0.001). The creatinine clearances and pathologic lesions were different between these two groups, but the differences were not statistically significant (P >0.05). The means of serum creatinine levels and creatinine clearances and pathologic lesions in group I (simvastatin group) were different from the control groups (P = 0.708), but this difference was not statistically significant (P > 0.05). The means of the serum levels of creatinine in the simvastatin group had significant differences from those in groups A, B, F, G, and H (P < 0.0001) and nonsignificantly different from those in groups C (P = 0.15), (P = 0.18), E (P = 0.2), J (P = 0.37), and K (P = 0.71). The means of the creatinine clearances in simvastatin group were significantly different from those in groups A (P = 0.005), B (P = 0.002), D (P = 0.01), E (P = 0.008), F (P = 0.018), and H (P = 0.008); however, they were not statistically significantly different from those in groups C, G, J, and K (P > 0.05).
Table 1: Serum creatinine, creatinine clearance, and pathologic situation in patients of our study.

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The pathologic lesions were the same in group I and the control groups. In combination groups, the increase in the dose of simvastatin from 2 to 10 mg/kg/day, the creatinine levels decreased from a mean of 0.52 to 0.49 mg/dL, while changing the simvastatin dose from 2 to 20 mg/kg/day, the creatinine levels increased from a mean of 0.4943 to 0.5037 mg/dL. However, these differences in the means of the serum levels of creatinine were not statistically significant.

The means of the serum levels of creatinine decreased in groups C (P = 0.032), D (P = 0.5) and E (P = 0. 046) in comparison with group A, and the means of the creatinine clearances increased in groups C (P = 0.05), D (P = 0.5), and E (P = 0.18). The pathologic lesions in groups C (P = 0.01), D (P = 0.029), and E (P = 0.002) were significantly lower than those in group A.

The means of the serum levels of creatinine in group F were higher than those in group B (P > 0.05), while the means of the serum levels of creatinine in groups G (P = 0.04) and H (P = 0.002) were significantly lower than group B, and the means of the creatinine clearances improved in the samples of groups F (P > 0.05), G (P = 0.001), and H (P > 0.05) in comparison with group B. The pathologic lesions were different in groups F (P = 0.29), G (P = 0.10), and H (P = 0.02) in comparison with those of group B.

The means of the serum levels of creatinine in group F were significantly higher than those in groups J and K (P < 0.001). The means of the creatinine clearances in group F were lower than those in groups J (P = 0.018) and K (P = 0.017). The frequency of the pathologic lesions in group F were significantly different from those in groups J and K (P = 0.01). The means of the serum levels of creatinine in group G were significantly higher than those in groups J and K (P < 0.001). The means of the creatinine clearances in group G were lower than those in groups J and K (P > 0.05). The frequency of pathologic lesions in group F was significantly different than that in groups J (P = 0.01) and K (P = 0.00). The mean of the serum levels of creatinine in group H was significantly higher than those in groups J and K (P < 0.001). The means of the creatinine clearances in group H were lower than those in groups J and K (P > 0.05). The frequency of the pathologic lesions in group H was significantly different from that in groups J and K (P = 0.00).


   Discussion Top


The results of the present study indicate that simvastatin can ameliorate gentamicin-induced renal toxicity in rats. Two different doses of gentamicin were used to induce renal toxicity. The 50 mg/kg/day dose was utilized because it induces a mild form of renal toxicity, whereas the 80 mg/kg/day dose causes a more severe degree of renal injury. The doses were given for eight days because this period is needed to cause renal injury with insufficiency with the large gentamicin dose.

Gentamicin was considered to be an important drug against life-threatening infections, although the mechanism for the nephrotoxic adverse effects is still not very well elucidated. [14] Some studies reported that gentamicin-induced reactive oxygen species, which has a major role in the mechanism of nephrotoxicity of gentamicin. [9],[15]

Gentamicin is still one of the main antibiotics in use against gram-negative bacteria. Therefore, we are still concerned about the strategies to ameliorate its nephrotoxicity.

Antioxidant drugs are one of the drugs with the best nephroprotection. It seems that antioxidants possess the highest potential for clinical use. [16] The simvastatin doses of 2, 10, and 20 mg/kg/day were selected to examine whether there is any dose-dependent response to protect against gentamicin nephrotoxicity. Simvastatin was started 4 days prior to gentamicin injection to assure adequate tissue simvastatin levels, when renal tissue is exposed by gentamicin. Interperitoneal injection of 80 mg/kg/day gentamicin and to a lesser extent, the 50 mg/kg/day gentamicin induced renal injury, as indicated by the renal histopathology and function tests. The 80 mg/kg/day as compared with 50 mg/kg/day was clearly associated with a greater loss of renal function as indicated by generally greater serum levels of creatinine and lower rate of creatinine clearances and more severe histopathology as shown by the histologic analyses of the renal cortical tissue obtained at the end of the 12 th day.

The present data indicate that the daily oral gavage of simvastatin, especially with the 10 mg/kg/day and especially in groups receiving gentamicin 50 mg/kg/day ameliorated the degree of renal injury. The rats given gentamicin revealed a significantly lower serum creatinine, higher creatinine clearance, and lesser percentage of 3+ and greater percentage of 1+ proximal tubular necrosis; not significantly different from the control group.

Those rats receiving only simvastatin 20 mg/kg/day compared with the rats that did not receive simvastatin and/or gentamicin displayed histopathologic improvement, lower serum creatinine concentration and paradoxically significant lower creatinine clearance. Therefore, simvastatin 20 mg/kg/day probably had an adverse effect on kidneys, or this discrepancy reflects the low sample size or high variance in createnine clearance.

Also the rats that received gentamicin 80 mg/kg/day with simvastatin 2, 10, and 20 mg/kg/day compared with the rats given no simvastatin displayed lower serum creatinine concentration and higher creatinine clearance.

Both the rat groups injected with gentamicin 50 and 80 mg/kg/day, increasing simvastatin dosage from 2 to 10 mg/kg/day correlated with parallel improvement in histopathology and renal function test. Increasing simvastatin from 2 to 10 mg/kg/day resulted in a linear dose-response correlation, but increasing simvastatin from 10 to 20 mg/kg/day did not disclose further linear dose-response correlation. The discrepancy is not clear.

In summary, we have five possible hypotheses in the present study:

  1. Simvastatin may be renoprotective and capable of clearing and detoxifying; however, the ability of simvastatin to potentiate myoglobinuria, which increases serum creatinine clearance, suggests high dose of simvastatin itself or synergistically with gentamicin high dose may be harmful, which initially negatively affected creatinine clearance.
  2. Probably time may have been too short to cause detectable difference, and gradually with the accumulation of simvastatin in renal tissue harmful effect or beneficial effect of simvastatin will be displayed significantly.
  3. It may be demonstrated that amelioration in histopathologic damages is not enough to cause changes in renal function tests.
  4. Simvastatin is capable of tubular cell repair, but tubular function improvement requires more time.
  5. The experiments were performed in rats weighting 140-230 g with a wide range of distribution. Of course, low-weight rats were more susceptible to nephrotoxicity. According to these hypotheses, we need future studies for confirmation of these hypotheses.


 
   References Top

1.Kaloyanides G, Bosmans JL, De Broe M. Antibiotic and immunosuppression-related renal failure. Schrier R, Gottschalk C, eds. Diseases of the kidney & urinary tract 1 (2007):1037 .   Back to cited text no. 1
    
2.Ferriols-Lisart R, Alos-Alminana M. Effectiveness and safety of once-daily aminoglycosides: a meta-analysis. Am J Health Syst Pharm 1996; 53(10):1141-50.  Back to cited text no. 2
    
3.Chung L, Kaloyanides G, McDaniel R, McLaughlin A, McLaughlin S. Interaction of gentamicin and spermine with bilayer membranes containing negatively charged phospholipids. Biochemistry 1985;24(2):442-52.  Back to cited text no. 3
    
4.Ramsammy LS, Kaloyanides GJ. Effect of gentamicin on the transition temperature and permeability to glycerol of phosphatidylinositol-containing liposomes. Biochem Pharmacol 1987; 36(7):1179-81.  Back to cited text no. 4
    
5.Kirschbaum B. Interactions between renal brush border membranes and polyamines J Pharmacol Exp Ther 1984;229:409-16.  Back to cited text no. 5
    
6.Weinberg JM, Harding PG, Humes HD. Mechanisms of gentamicin-induced dysfunction of renal cortical mitochondria. II. Effects on mitochondrial monovalent cation transport. Arch Biochem Biophys 1980;205(1):232-9.  Back to cited text no. 6
    
7.Weinberg JM, Humes HD. Mechanisms of gentamicin-induced dysfunction of renal cortical mitochondria. I. Effects on mitochondrial respiration. Arch Biochem Biophys 1980;205(1): 222-31.  Back to cited text no. 7
    
8.Baliga R, Ueda N, Walker PD, Shah SV. Oxidant mechanisms in toxic acute renal failure. Am J Kidney Dis 1997;29(3):465-77.  Back to cited text no. 8
    
9.Walker PD, Barri Y, Shah SV. Oxidant mechanisms in gentamicin nephrotoxicity. Ren Fail 1999;21(3-4):433-42.  Back to cited text no. 9
    
10.Colio MB, Tunon J, Venetura J. Antiinflamatory and immunomodulatory effects of statins. Kidney Int 2003;63(1):12.  Back to cited text no. 10
    
11.von Stechow D, Fish S, Yahalom D. Does simvastatin stimulate bone formation in vivo. BMC Musculoskelet Disord 2003;4(8).  Back to cited text no. 11
    
12.Ramsammy L, Ling KY, Josepovitz C, Levine R, Kaloyanides GJ. Effect of gentamicin on lipid peroxidation in rat renal cortex. Biochem Pharmacol 1985;34(21):3895-900.  Back to cited text no. 12
    
13.Josepovitz C, Levine R, Lane B, Kaloyanides GJ. Contrasting effects of Gentamicin and mercuric chloride on urinary excretion of enzymes and phospholipids in the rat. Lab Invest 1985;52(4):375-86.  Back to cited text no. 13
    
14.Ali BH. Gentamicin nephrotoxicity in humans and animals: Some recent research. Gen Pharmacol 1995;26(7):1477-87.   Back to cited text no. 14
    
15.Britti A, Sarro D. A role for superoxide in gentamicin mediated nephropathy in rats. Eur J Pharmacol 2002;450:67-76.  Back to cited text no. 15
    
16.Badreldin H. Ali, AlMoundhri MS. Agents ameliorating or augmenting the nephrotoxicity of cisplatin and other platinum compounds: A review of some recent research. Food Chem Toxicol 2006;44:1173-83.  Back to cited text no. 16
    

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Correspondence Address:
Mosadegh Jabbari
Nikan Research Institute, No 9, Third Bahar Street, Ashrafi Esfahani highway, Pounak Square, P. O. Box 1476995579, Tehran
Iran
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PMID: 22089778

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