The Suppressive Effect of Selenium on Renal Inflammation in a Rat Model of Pyelonephritis with Delayed Treatment

Yeom, Min Ho; Park, Jae Bok; Park, Jae Shin

Abstract

PURPOSE: Some investigators have noted that the renal scarring that occurs after pyelonephritis is closely related to the inflammation or the free oxygen radicals rather than to direct injury by the bacterial infection. We examined whether delayed administration of the antioxidant agent selenium only or its combined administration with antibiotics suppresses renal scarring in a rat model of pyelonephritis.
MATERIALS AND METHODS
An inoculum of 1x10(8) colony-forming units/ 0.1ml of Escherichia coli was injected directly into the renal parenchyma of both kidneys of 12 rats (n=24). The control group with 2 rats (n=4 kidneys) received injections of isotonic saline instead of bacterial solution. Three days after surgery, the animals were given the following treatment. In the pyelonephritis group, 2 rats (n=4) received isotonic saline intramuscularly twice daily for 5 days. For the antibiotic treatment group (antibiotic only), 3 rats (n=6) were treated with only with an antibiotic, ciprofloxacin (intramuscular injection, 15mg/kg twice daily) for 5 days. For the selenium treatment only group (selenium only), 4 rats (n=8) were treated with selenium (intraperitoneal injection, 0.5mg/kg twice daily). For the combined group (selenium antibiotic), 3 rats (n=6) received selenium (0.5mg/kg, intraperitoneal injection twice daily) and ciprofloxacin (15mg/kg, intramuscular injection twice daily) together. Six weeks after the bacterial inoculation, all the rats were killed and all the kidneys were examined histopathologically for renal scarring by using an OLYMPUS BX 51 microscope and I-solution.
RESULTS
Delayed treatment with antibiotics-only or selenium-only had no effect on scarring compared with the untreated controls. However, the addition of selenium to the delayed antibiotic therapy significantly inhibited renal scarring compared with the pyelonephritis group or the antibiotic treated-only group or the selenium-treated only group (p<0.0001).
CONCLUSIONS
These results suggest that selenium is effective in preventing renal scar formation during pyelonephritis when the initiation of antimicrobial treatment is delayed in this rat model of pyelonephritis.