The synergistic effect of dietary cholesterol with fruit tannins in forming kidney stones

Abstract

Prevalence of kidney stones has increased continously over several decades worldwide, the major causes of which are largely unknown. To explore the dietary causes of kidney stones, and reveal mechanisms underlying dietary risk factors inducing kidney stones, animal experiments using mice as the disease model were performed. Eight-week old male CD-1 mice were treated by ethylene glycol, cholesterol or/and apple tannins for 3 d, respectively. In the present study, the crystalline analysis in urine and kidney tissues, HE staining kidney sections as well as observation of micro-stones, tannins and cholesterol deposition in kidneys of mice in different groups were conducted. We found that gavage with ethylene glycol, cholesterol and tannins resulted in mice urine solute supersaturation in renal tubules and forming kidney stones. Significant cholesterol and tannin deposits in mouse kidney were observed by laser confocal microscopy and crystals were shown either adhered with or co-deposited with cholesterol and tannin deposits. The primary crystals were found in renal cortex, medullar, especially papilla in the kidney sections under polarized microscope. These findings demonstrate that interaction of cholesterol and tannins in kidney plays a critical role in the formation of kidney stones.

Keywords

• polyphenol
• condensed tannins
• cholesterol
• kidney stones
• synergistic effect.