Tea catechins, a class of
flavonoids, are suggested to have
biological effects, possibly mediated through their antioxidative properties. Recent data indicated that
tea catechins suppressed proliferative changes in glomeruli and inhibited the development of glomerulosclerosis in partially nephrectomized rats. We thus sought to determine whether
tea catechins may protect against renal dysfunction in
streptozotocin-induced diabetic rats. Four groups of male Sprague-Dawley rats (n=11-15 per group), with and without
streptozotocin-induced diabetes, were treated with and without catechins (5 mg/day) administered in the
drinking water for 12 weeks. At the end of the treatment period, 24-hour urinary
albumin excretion rate (AER), serum
lipid peroxides as
thiobarbituric acid reactive substrates (
TBARS) and blood pressure were measured. Renal glomerular volume and interstitial
fibrosis were assessed morphologically.
Albuminuria developed progressively in untreated diabetic rats, resulting in a mean AER of 559+/-124 (mean+/-SE) versus 63+/-7 microg/day/100 g
body weight in non-diabetic rats at 12 weeks (P<0.001).
Catechin treatment significantly reduced AER to 287+/-56 microg/day/100 g
body weight in diabetic rats (P=0.017 versus untreated diabetic rats). Increased interstitial
fibrosis in the kidney, observed in untreated diabetic rats, was completely normalized with
catechin treatment. Serum levels of
TBARS and blood pressure were comparable among the four groups. In conclusion, administration of
tea catechin retards the progression of functional and morphological changes in the kidney of
streptozotocin-induced diabetic rats.