Comparative analysis of the protective effects of melatonin and vitamin E on streptozocin‐induced diabetes mellitus

Abstract

There is a clearly documented link between diabetic complications and lipid peroxidation. Hyperglycemia causes a reduction in levels of protective endogenous antioxidants and increases generation of free radicals. The present study was carried out to compare the protective effects of melatonin and vitamin E against streptozocin (STZ)-induced diabetes in rats. Melatonin was administered s.c. (100 microg/kg) whereas vitamin E was given i.p. (100 mg/kg) after induction of diabetes with STZ (60 mg/kg). Plasma total cholesterol, triglyceride and low density lipoprotein (LDL) levels were increased in STZ group while both melatonin and vitamin E injection caused a significant decrease in the levels of all these parameters. The lipid lowering effect of melatonin was greater than that of vitamin E. Melatonin caused a significant decrease in brain, liver and kidney tissue malondialdehyde (MDA) levels which were increased because of STZ-induced diabetes. Vitamin E also reduced elevated MDA concentrations in diabetic rat tissues, but the effect of melatonin was more potent than that of vitamin E. Furthermore, treatment of diabetic rats with melatonin increased brain and kidney glutathione peroxidase (GSH-Px) activity to the levels below that of control rats. Vitamin E was found to be less effective on GSH-Px activity levels in brain and kidney than melatonin whereas it was more potent than melatonin in liver. In summary, melatonin prevents many diabetic complications by reducing oxidative stress and protects organisms from oxidative damage and dyslipidemia. Considering the much lower molar concentration of melatonin compared with vitamin E, melatonin seems to be a more potent antioxidant, especially in the brain and kidney.

Effects of Lycopene Alone or Combined with Melatonin on Methotrexate-Induced Nephrotoxicity in Rats

“…A number of studies have shown that Mel is significantly better than the classic antioxidants in resisting free radical-induced molecular destruction (Gultekin et al, 2001;Baydas et al, 2002). Beneficial antioxidant effects of Mel have been recently shown in clinical settings for several chronic diseases, including patients with rheumatoid arthritis (Forrest et al, 2007), elderly patients with primary essential hypertension (KedzioraKornatowska, 2008), and females with infertility.…”

The Effects of Melatonin on Oxidative Stress Parameters and DNA Fragmentation in Testicular Tissue of Rats Exposed to Microwave Radiation

“…Melatonin acts as antioxidant [12] and immunostimulant, and regulates mRNA levels for some specific proteins. It plays a role in the prevention of cancer, neurodegenerative diseases and diabetes complications [13].…”

The effect of melatonin and/or complex vitamin B1,B6,B12 in modulating epinephrine-induced stress in male rats

“…MT administration prevented the changes in the MDA induced by Fe administration that generated the oxidative stress in chronic hemodialysis patients to treat anemia (José et al 2001). MT caused a significant decrease in the brain, liver and kidney tissue MDA levels, which were increased because of streptozotocin-induced diabetes (Baydas et al 2002). Sahin et al (2004) found that the levels of MDA in serum, liver, heart and kidney was markedly increased in heat-stressed quail, and the levels significantly decreased by the MT supplementation.…”