RESUMO
Diabetic nephropathy [DN] is a microvascular complication of diabetes that represents a major cause of morbidity and mortality in diabetic subjects and is a leading cause of end-stage renal disease in the western countries. Hyperglycemia and tissue injury increase tissue angiotensin II [Ang II] that stimulates the proliferation of kidney cells and the expression of growth factors or cytokines, which may directly or indirectly contribute to the renal 'changes seen in diabetes. The current study aimed to investigate the effect of caffeic acid phenethyester [CAPE] an active component of bee propolis, on diabetic renal injury via examining its effect on renal and plasma AngH levels, blood glucose and insulin levels, proteinurea, albuminurea, and kidney functions in diabetic rats. This study was performed on 30 male Wister rats [300-325g] in weight. Diabetes was induced in 20 rats using 60mg/kg i.p streptozotocin [STZ] in 20 [microl of 0.05 M sodium citrate, pH 4.5. Ten control healthy rats [Group 1] were injected i.p with - 20 microl of the buffer. Diabetic animals studied in this work were divided into 2 experimental groups [n=10 in each] namely, Group 2 that received no treatment and Group 3 that was injected daily with CAPE 10 microl/kg i.p for 4 weeks. Body weight and blood glucose level were measured at the beginning of the study and then every week for all animals. Blood and 24 hrs urine samples and, kidney tissue were collected at the end of the study for measurement of plasma and kidney tissue Ang II levels, serum insulin, urea and creatinine levels. Proteins, albumin and creatinine levels were also measured in urine. Untreated diabetic rats showed significant increase in blood glucose, and significant decrease in serum insulin levels and they fail to gain weight by the end of the study. In addition they showed significant increase in renal and plasma angiotensin II levels and significant increase in urinary protein and albumin loss with a significant increase in serum urea and creatinine levels in comparison to control rats. CAPE treatment for 4weeks was able to significantly decreased plasma and renal Ang II, and significantly increase serum insulin, and decreased blood glucose levels. In addition both urinary protein and albumin loss decreased significantly in the treated rats. CAPE treatment was able to decrease blood glucose, plasma and renal Ang II levels and to increase serum insulin levels and to ameliorate the manifestations of renal impairment associated with diabetes in rats. This may be through its antioxidant, antiproliferative and anti-inflammatory effects. These findings help us to suggest that supplementation of CAPE as an adjuvant therapy to diabetic persons may be promising in helping a better glycemic control and decreasing the renal complications of this wide spread metabolic disorder