Effect of betamethasone with or without gentamicin on renal scarring in rat model of pyelonephritis

ABSTRACT

To evaluate the effect of betamethasone in preventing renal scarring in rat model of pyelonephritis. Material and Sixty three female Sprague-Dawley rats were divided into seven equal groups [A-G]. After exposing the left kidney under general anesthesia, direct inoculation of colonies of mannose-sensitive E.coli was done in groups C-G and normal saline in group B. No injection was done in group A. After 48 hours of bacterial inoculation, intramuscular [IM] injections of gentamicin [3 mg/kg/ day for 10 days] was used in groups C, E and F. Betamethasone [0.3 mg/kg/day IM] was used after two days [group D and E] and 5 days [group F] of bacterial inoculation. Normal saline as daily IM injections for 10 days in group B and no IM injection in group G was done. After 8 weeks of bacterial inoculation, the rats were sacrificed and the volume of renal scar was determined using a point- counting technique. Changes in the weight and volume of the kidneys were not statistically significant. No scar was detected in group A, but all the other groups with intrarenal injections [including group B with no bacterial inoculation] had scarring. The volume density and absolute volume of the scar in groups C-G were significantly more than group B [p < 0.001], but no statistically significant difference was observed in groups C-G. Betamethasone with or without gentamicin, when used 48 hours or more after induced pyelonephiritis is not effective to prevent renal scar