Academy of Medical Sciences of I.R. Iran Archives of Iranian Medicine 1029-2977 13 2 2010 02 01 Pre- and Post-Treatment of Streptozocin Administered Rats with Melatonin: Effects on Some Hepatic Enzymes of Carbohydrate Metabolism 105 110 EN Masoumeh Akmali Robab Ahmadi Mahmood Vessal Journal Article <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <meta name="ProgId" content="Word.Document"> <meta name="Generator" content="Microsoft Word 12"> <meta name="Originator" content="Microsoft Word 12"> <link rel="File-List" href="file:///C:%5CUsers%5Camir%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_filelist.xml" /> <link rel="themeData" href="file:///C:%5CUsers%5Camir%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_themedata.thmx" /> <link rel="colorSchemeMapping" href="file:///C:%5CUsers%5Camir%5CAppData%5CLocal%5CTemp%5Cmsohtmlclip1%5C01%5Cclip_colorschememapping.xml" /><style type="text/css">  </style> </meta> </meta> </meta> </meta> Background: Melatonin, found in high concentrations in the pineal gland, organs within the digestive system and in some plants and fungi, acts as an antioxidant which decreases reactive oxygen species in streptozocin-induced diabetic rats, raises insulin secretion by the pancreatic β-cells and increases the number of insulin receptors on hepatocyte membranes. <o:p></o:p> Materials and Methods: The protective and therapeutic effects of melatonin feeding in streptozocin-induced diabetic rats were studied. Streptozocin administered rats were gavaged with melatonin, pre- and post-treatment, at a level of 5 mg/kg body weight daily for a period of 15 days. Levels of plasma glucose, cholesterol, triacylglycerol, oral glucose tolerance test, and some hepatic enzymes of carbohydrate metabolism including insulin inducible glucokinase, hexokinase and glucose 6-P dehydrogenase were measured using standard methods and compared with the values in normoglycemic and diabetic control groups.<o:p></o:p> Results: Both pre- and post-treatment of the streptozocin administered rats with melatonin normalized plasma glucose, cholesterol, and triacylglycerol, improved oral glucose tolerance test and increased hepatic glucokinase, hexokinase and glucose 6-P dehydrogenase specific activities to the levels seen in normal rats.<o:p></o:p> Conclusion: Melatonin pre-treatment prevents the injurious effects of streptozocin in rats. In streptozocin induced diabetic animals, post-treatment with this antioxidant normalizes both blood and liver constituents which were ameliorated by streptozocin.