D-limonene in diabetic rats

Introduction: Diabetes mellitus (DM) is a multi-factorial condition associated with oxidative stress. Limonene, as a plant-derived antioxidant, can be used for treating DM. Objectives: An investigation on antioxidant effects in diabetic rats exposed to D-limonene. Materials and Methods: Sixty male Wistar rats were categorized into six groups as follows: control (healthy rats), diabetic control (untreated diabetic rats), sham glibenclamide, diabetic glibenclamide, sham limonene, and finally diabetic limonene. Alloxan (100 mg/dL) was infused intraperitoneally to induce type 1 diabetes in rats. Rats in certain groups were given limonene (100 mg/dL) and glibenclamide (10 mg/dL) orally for 8 weeks. Subsequently, animals were killed, and their kidneys were removed. Serum levels of biochemical factors (including serum creatinine, urea, and glucose) were determined, and factors such as nitric oxide (NO), malondialdehyde (MDA), glutathione (GSH), and myeloperoxidase (MPO) were measured in kidney tissue homogenate. The gene expression and enzymatic activity of glutathione peroxidase (GPx), catalase (CAT), and superoxide dismutase (SOD) in the kidney were measured by real-time polymerase chain reaction (real-time PCR) and spectrophotometry, respectively. Results: Limonene treatment significantly decreased serum glucose, creatinine, and urea. Additionally, MDA, MPO, and NO significantly decreased while GSH increased after treatment with limonene. Real-time RT-PCR showed significant elevation (P<0.05) in mRNA levels of GPx, CAT, and SOD in the limonene-treated compared with the diabetic control group. Conclusion: Our results demonstrated that limonene as an herbal antioxidant had better effects on antioxidant markers compared to glibenclamide in rat models of diabetes.