Docosahexaenoic Acid Modulates Oxidative Stress and Monoamines Levels in Brain of Streptozotocin-Induced Diabetic Rats

The prevalence of diabetes mellitus (DM) is increasing in many countries. A lower prevalence of DM type 2 and other glucose metabolism disorders was observed in populations consuming larger amounts of n-3 polyunsaturated fatty acids, existing mainly in fish. Docosahexaenoic acid (DHA) is an important signaling molecule required for the central nervous system continuous maintenance of brain funcntioning. The aim of this research is to highlight the role of DHA in controlling glycemic measures and modulating the oxidant/antioxidant status and levels of neurotransmitters in brains of diabetic rats. Diabetes was induced with a single s.c. injection of streptozotocin (STZ) (6.0 mg / 0.5 ml /100 g body weight). Experimental male Wister rats (n = 40) were randomly divided into four groups: control group, DHA, STZ-diabetic, and STZ + DHA. All rats were decapitated after 30 days to evaluate glucose and insulin levels, brain oxidative stress and also to estimate monoamines levels. DHA administration significantly improved fasting blood glucose and insulin levels compared to the DHA+STZ group and decreased 8-hydroxy-2'-deoxyguanosine level in their urine. In addition, DHA treatment to STZ-treated rats showed a decrease in malondialdehyde content and advanced oxidation protein product and significantly increased glutathione content in brains of DHA + STZ-treated rats, and decreased the level of monoamines in rat's brain. To conclude: DHA modulated the elevated oxidative stress and neurotransmitters levels, and also acetylcholinesterase activity in diabetic rat brain via enhancing insulin level in serum.