The global prevalence of diabetes mellitus is on rise. Oxidative stress plays a central role in diabetic tissue damage. Diabetes-induced oxidative stress has been known to affect liver, pancreas, kidney, eyes, kidneys, nerves, heart, and blood vessels. Anti-hyperglycemic and antioxidant activities have been recorded with numerous plants, many of which are used as traditional herbal treatments of diabetes. Spirulinais a microscopic single cell alga which grows in fresh water and contains various antioxidants, especially phycocyanin. The objective of the present study was to investigate antioxidants and oxidative stress markers in the brain of streptozotocin (STZ) induced diabetic ratstreated with Spirulinaplatensis and metformin. 35 male Wistar rats (Weight: 250 ± 20 g) were divided into five groups (n=7), 1: control, 2: Spirulina, 3: Diabetes mellitus (STZ: 45 mg.kg-1 BW,IP), 4: Diabetes mellitus + Spirulinaand 5: diabetes mellitus + metformin. Spirulina concentrate(14 mg.kg-1 BW/ day) and metformin(14 mg.kg-1 BW/ day)were given to rats orally via gavage for 60 days. Total thiol groups, ferric reducing antioxidant power (FRAP) and malondialdehyde (MDA) levels in brain tissue were investigated at the end of study. MDA as a marker of lipid peroxidation, significantly increased in the brain of diabetic rats (p<0.05). Administration of Spirulina and metformin significantly increased FRAP levels in brain (p<0.05). Although, Spirulina had significant reducing effect on MDA in the brain of diabetic rats but metformin did not reduce lipid peroxidation significantly. The results of the present study showed that 2 months administration of Spirulinaat a dose of 14 mg.kg-1 BW/ day in diabetic rats, improve antioxidant capacity of brain tissue to reduce lipid peroxidation caused by diabetes.

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