Research Article THE EFFECT OF FISH OIL ON OXIDANT/ANTIOXIDANT STATUS IN DIABETIC RATS THROUGH THE REDUCTION OF ARACHIDONIC ACID IN THE CELL MEMBRANE JIHAN SEID HUSSEIN 1* , ZAKARIA EL-KHAYAT 1 , SAFAA MORSY 1 , FATMA ORABY 1 , GAMAL SINGER 2 1 Medical Biochemistry Department, National Research Center, 2 Chemistry/Biochemistry Department, Faculty of Science, Helwan University, Cairo, Egypt. Email: jihan_husein@yahoo.com Received: 06 Jan 2014, Revised and Accepted: 22 Feb 2014 ABSTRACT Background: Dietary omega-3 fatty acids directly affect arachidonic acid (AA) metabolism because they displace AA from membranes and compete with it for the enzymes that catalyze the biosynthesis of thromboxanes, prostaglandins and leukotrienes. Objective: This study aimed to evaluate the role of fish oil supplementation in reducing the free radicals production through the reduction of arachidonic acid level in erythrocyte membrane in experimental diabetic rats. Methods: Forty eight male albino rats were used in this study and divided into four groups :control, fish oil, diabetic and treated groups. Fish oil and treated groups were administered fish oil in a dose of 1.2 ml /kg bw/day orally for 8 weeks. Urinary 8-hydroxyguanosine and erythrocyte membrane arachidonic acid were estimated by HPLC. Also, urinary isoprostanes and erythrocyte membrane superoxide dismutase were determined. Results: Our results indicated that hyperglycemia in diabetic rats significantly increased urinary 8-hydroxyguanosine and isoprostanes and erythrocyte membrane arachidonic acid, whereas, supplementation of fish oil significantly decreased these values in treated group. Conclusion: Fish oil supplementation has an important role in attenuating the elevation of arachidonic acid (omega-6) in cell membrane phospholipids resulting in a reduction in free radicals production. Keywords: Fish oil, Diabetes Mellitus, 8-hydroxyguanosine, Isoprostanes, Arachidonic acid. INTRODUCTION During diabetes, persistent hyperglycemia causes increased production of free radicals especially reactive oxygen species (ROS), for all tissues from glucose auto-oxidation and protein glycosylation [1]. Abnormally high levels of free radicals and simultaneous decline of antioxidant defense systems can lead to the damage of cellular organelles and enzymes, increased lipid peroxidation and development of complications of diabetes mellitus [2]. Isoprostanes are a proposed biomarker of oxidative stress, they are produced by nonenzymatic peroxidation of arachidonic acid (AA; 20:4x6), esterified to phospholipids and subsequently released, possibly by a phospholipase. They circulate in the blood stream and are finally excreted in urine [3]. Also oxidative modified DNA in the form of 8- Hydroxy-2-Deoxyguanosine (8-OHdG) can be quantified to indicate the extent of DNA damage [4]. Urinary 8-OHdG an oxidative damage nucleoside, has been widely used as a marker for evaluating in vivo oxidative stress [5]. Food derived antioxidants have a strong potential for long term use as chemo-preventive agents in disease states involving oxidative stress [6]. It was found that, dietary omega-3 fatty acids directly affect AA metabolism because they displace AA from membranes and compete with it for the enzymes that catalyze the biosynthesis of thromboxanes, prostaglandins and leukotrienes [7]. So, consuming food enriched in omega-3 fatty acids (such as fish oil) is diminished potential for cells like monocytes, neutrophils and esinophils to synthesize these powerful arachidonic acid–derived mediators of inflammation and a diminished potential for platelets to produce the prothrombotic agent thromboxane A2 [8]. From this light, we aimed to evaluate the role of fish oil supplementation in reducing the free radicals production through the reduction of arachidonic acid level in erythrocyte membrane in experimental diabetic rats. MATERIALS AND METHODS Materials, Chemicals Streptozotosin (STZ) and 8-hydroxyguanosine & arachidonic acid standards (high performance liquid chromatography (HPLC) grade) were purchased from Sigma Chemicals Co. (Munih, Germany). All other chemicals were HPLC grade and purchased from ALDRICH, Germany. Experimental animals Male albino rats weighting 180 to 200 g were obtained from the animal house of National Research Center, Giza, Egypt. Methods The guidelines of the ethical care and treatment of the animals followed the regulations of the ethical committee of the National Research Center (NRC). Induction of diabetes mellitus STZ was dissolved in 50 mM sodium citrate (pH 4.5) solution containing 150 mM NaCl. The solution (6.0 mg/0.5 ml/100 g body weight (bw)) was subcutaneously administrated in rats, fasting blood sugar was estimated after 3 days to confirm the development of diabetes mellitus [9]. Experimental design Forty eight male albino rats were housed in individual suspended stainless steel cages in a controlled environment (22 to 25°C) and 12 h light/12 h dark with food and water freely available, and were divided randomly into four groups ; 12 rats in each group as follow: 1. Group I (control group): healthy rats received 1.2 ml corn oil/kg bw/day orally. 2. Group II (fish oil group): healthy rats received 1.2 ml fish oil/kg bw/day orally. 3. Group III (diabetic group): diabetic rats received 1.2 ml corn oil/kg bw/day orally. 4. Group IV (treated group): diabetic rats received 1.2 ml fish oil/kg bw/day orally [10]. After the experimental period (8 weeks), 24 h urine was collected from each animal for estimation of urinary 8-hydroxyguanosine, F2 isoprostane and creatinine. International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-149 Vol 6, Issue 2, 2014 Academic Sciences