The Effects of Estrogen on Calcium Oxalate Crystal Deposition in Rat Kidney

Cheon, Min Woo; Kim, Young Gon

Abstract

PURPOSE: The effect of female sex hormones in urinary stone formation has not been known. Sexual difference in the incidence and crystaline composition of urinary stones in human are well known, especially calcium oxalate stone occurs more frequently in men than women. These findings imply that sex hormone may be related to the pathogenesis of urolithiasis. The present study was conducted to investigate the effects of estrogen on stone formation by using an ethylene glycol (EG) and ammonium chloride-induced urolithiasis model in rat.
MATERIALS AND METHODS
Adult Sprague-Dawley female rats were divided into 3 groups, containing 8 rats each. Group I were fed with normal diet for 7 days. Group II were fed with the 0.8% EG and 1.0% ammonium chloride for 7 days. Group III were oophorectomized and 7 days later were fed with the 0.8% EG and 1.0% ammonium chloride for 7 days more. Right kidneys were used for examining the crystal deposits by polarizing microscope and left kidneys were used for tissue calcium content.
RESULTS
The concentration of estradiol in group III is lower than that of group I and II (p<0.05). There was a significant difference between control (179.03+/-45.46microgram/g) and lithogenic diet groups in tissue calcium contents (p<0.05). Also, there was a significant difference of tissue calcium contents between group II (318.68+/-46.86microgram/g) and group III (703.05+/-121.51microgram/g) (p<0.05).
CONCLUSIONS
These data suggest that estrogen can inhibit calcium oxalate stone formation in EG and ammonium chloride diet rats.