Efficacy of melatonin in restoring the antioxidant status in the lens of diabetic rats induced by streptozotocin
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Melatonin is a well-known free radical scavenger. The present study aimed to investigate the effects of melatonin treatment on the antioxidant status in the lenticular tissue of streptozotocin (STZ)-induced diabetic rats.
Thirty-four male rats were randomly divided into four groups as follows: healthy control rats (group 1, n = 10); diabetic control rats (group 2, n = 10); melatonin-treated (5 mg/kg·day) diabetic rats (group 3, n = 10) and melatonin-treated (5 mg/kg·day) healthy rats (group 4, n = 4). Diabetes was induced by injection of streptozotocin (50 mg/kg, ip). Following 8-weeks of melatonin treatment, all rats were killed and the blood plasma and their lenses were stored at −70 °C for antioxidant enzyme activities assay and biochemical determination.
The plasma glucose and lens malondialdehyde (MDA) increased significantly in the rats of group 2 as compared to the group 1. Also, a significant decrease in the levels of catalase (CAT) and glutathione reductase (GR) activities in the lenses and plasma reduced glutathione (GSH) was found. However, the levels of lenticular MDA (not significant) and the plasma glucose significantly decreased in the rats of group 3 compared to the group 2. Besides, the levels of CAT, GR in the rats lens and plasma GSH increased significantly.
Diabetes mellitus induced hyperglycemia and oxidative stress, whereas melatonin decreased the blood glucose levels and lipid peroxidation and increased the activities of antioxidant enzymes in diabetic rat lenses.
KeywordsAntioxidant enzymes Diabetes Melatonin Oxidative stress Streptozotocin
Reactive oxygen species
β-Nicotinamide adenine dinucleotide phosphate-reduced form
1, 1, 3, 3-tetra ethoxy propane
5, 5′-dithiobis-(2-nitrobenzoic acid)
Reduced nicotinamide adenine dinucleotide phosphate
Reactive nitrogen species
Bovine serum albumin, Non-insulin-dependent diabetes mellitus (NIDDM)
The authors thank from the biochemistry department of Shiraz University of Medical Sciences for technical assistance in this work.
Masoumeh Akmali contributed to the design the study, and drafted the manuscript, Masoumeh Akmali, Marjan Khorsand and Morteza Akhzari conducted the analysis, wrote and revised manuscript, Marjan Khorsand performed the biochemical analysis and animal treatment.
The Shahid Sadoughi University of Medical Sciences (Yazd, Iran) and Shiraz University of Medical Sciences (Shiraz, Iran) funded this study, which is derived from the student thesis of Marjan Khorsand by grant number 1083.
Compliance with ethical standards
Ethics approval and consent to participate
All experiments in this study performed according to the guidelines of “Animal Care Ethics Committee” of Shiraz University of Medical Sciences, Shiraz, Iran (IR.SUMS.REC).
Conflict of interest
There is no financial or personal conflict of interest.
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