A comparative study of experimental rat models of renal calcium oxalate stone formation.

Purpose: The aim of this study was to design a simple and convenient rat model with significant calcium oxalate crystal deposition in the kidney. Materials and Methods: Sprague-Dawley rats were divided into seven groups of 30 rats each. One group of rats was untreated to serve as controls. Two of the groups of rats were provided with drinking water supplemented with 1% ethylene glycol (EG), and of these two groups, one group was also administered vitamin D. Two groups of rats received intraperitoneal injections of EG, and of these two groups, one group also received vitamin D. Two groups of rats received intraperitoneal injections of glyoxylate, and of these two groups, one group also received vitamin D. We analyzed 24-hour urine samples for urinary constituents for all experimental groups, including calcium, oxalate, citrate, uric acid, pH, and urine volume. The kidneys were examined for crystal deposition using histologic examination and for osteopontin expression using immunohistochemical staining. Results: Calcium-oxalate crystals were found in all rats injected with glyoxylate after 1 week. The degree of crystal deposition in rats injected with glyoxylate for 1 week was significantly increased compared with rats fed EG for 4 weeks. Conclusions: Intraperitoneal injection of glyoxylate is a faster, more exact, and more reliable method to produce calcium oxalate crystal deposition in the kidney than previous urolithiasis animal models.