The effect of epigallocatechin-3-gallate on the renal dysfunction in the obstructed kidney in the rat.

INTRODUCTION: Epigallocatechin-3-gallate (EGCG) is the most active catechin polyphenol extracted from the green tea. EGCG has protective effects in various renal and non-renal conditions. The aim of this study was to investigate the effect of EGCG on the alterations in renal functional parameters following reversible unilateral ureteral obstruction (UUO) in the rat.

METHODS: Wistar rats underwent reversible left UUO for 72 hours. Group-EGCG (n=10) received intraperitoneal 50 mg/kg/day of EGCG whereas Group-Vx (n=10) had only normal saline. Five days post UUO reversal, renal functions of both kidneys were measured using clearance techniques and the gene expression of some of kidney injury markers (KIM-1 and NGL) and the pro-inflammatory mediator (TNF-α) were determined using real time PCR.

RESULTS: Renal blood flow, glomerular filtration rate, urine volume and urinary sodium excretion were still altered 5 days post-UUO reversal. Fractional sodium excretion had returned to baseline values by that time. EGCG did not significantly affect any of the renal functional parameters of the obstructed kidney (P>0.05 for all). However, it significantly decreased the gene expressions of KIM-1, NGAL and TNF-α in the left obstructed kidney in Group-EGCG compared to Group-Vx (28±27 vs. 286±107, 1.1±0.2 vs. 10.9±4.3, and 0.8±0.1 vs. 1.5±0.2, P<0.05 for all).

CONCLUSION: EGCG appears to have no significant protective effect on the haemodynamic or tubular glomerular functions when measured as early as five days post reversal of UUO despite the attenuation of some of the kidney injury markers and pro-inflammatory mediators.