Comparative hypoglycemic and nephroprotective effects of tocotrienol rich fraction (TRF) from palm oil and rice bran oil against hyperglycemia induced nephropathy in type 1 diabetic rats

Abstract

Diabetic nephropathy (DN) is a serious complication confronted by patients with diabetes. Available data indicate that the development of DN is linked to hyperglycemia. Tocotrienol rich fraction (TRF) from palm oil (PO) and rice bran oil (RBO) has been shown to lower the blood glucose level in patients and preclinical animal models. This study was designed to investigate if TRF from PO and RBO could improve the renal function in DN by the virtue of their hypoglycemic and antioxidant activities. Male Wistar rats having an average body weight (bw) 250 g were divided into four groups of six each .The first group served as diabetic control [injected with 55 mg/kg bw of streptozotocin (STZ), intraperitoneally], while the second and third group received PO-TRF and RBO-TRF, respectively, by gavage at a dose of 200 mg/kg bw/day, over a period of 8 weeks post-induction of diabetes. The fourth group comprised of age-matched male Wistar rats that received single intraperitoneal injection of normal saline only and served as control. After 8 weeks of STZ injection and TRF treatment, 24 h urine was collected and animals were sacrificed. Fasting blood glucose, glycosylated hemoglobin, biochemical markers of renal function and oxidative stress were evaluated in serum, urine and kidney tissue. The results show that treatment with PO-TRF as well as RBO-TRF significantly improved the glycemic status and renal function in type 1 diabetic rats but PO-TRF afforded greater efficiency at similar dose as compared to RBO-TRF. In conclusion, PO-TRF was found to be more effective hypoglycemic and nephroprotective agent in DN than RBO-TRF.