protective effects of salvia officinalis extract against gentamicin-induced nephrotoxicity in rat

background: the aim of this study was to examine the renoprotective effect of hydro alcoholic sage (salvia officinalis: so) leaves extract against gentamicin-induced nephrotoxicity in rats. methods: in this experimental study forty male sprague dawley rats weighing 200-300 g were randomly divided into 5 groups; (1) the rats without treatment (control), (2) intraperitoneally injected with normal saline for one week (sham), (3) gentamicin 80 mg/kg/day, intraperitoneally for 7 days (gen), (4) sage extract at 50 mg/kg/day plus gentamicin (80 mg/kg/day) for one week (gen+so 50) and (5) sage extract at 100 mg/kg/day plus gentamicin (80 mg/kg/day)  for one week (gen+so 100). during the last 6 hours, the rats were transferred to the metabolic cage for urine sampling. at the end of the period, after deep anesthesia with thiopental, blood samples were obtained from aorta and the left kidney were removed for oxidative stress measurement. statistical analyses were made by one way analysis of variance. results: the decrease in the amount of glomerular filtration rate (gfr) induced by gentamicin was relatively improved by sage extract administration which leaded to the decrease in plasma creatinine and urea-nitrogen concentrations. in addition, the relative excretion of sodium and potassium decreased and absolute excretion of potassium increased in the gen+so groups. the degree of oxidative stress that had increased by gentamicin were also significantly lowered by sage extracts administration. conclusion: sage extract exhibits nephroprotective effect in gentamicin induced renal damage probably by its anti-oxidant activity, but further studies on its exact mechanism of action are warranted.