Effect of Prolonged Melatonin Application on Metabolic Parameters and Organ Weights in Young Male and Female Sprague-Dawley rats

The question of the introduction of melatonin as a drug remains still open. Especially the long term melatonin administration have to be analysed and discussed. The aim of present study was to analyze the effect of low doses of melatonin (4 g/ml of tap water) administered for 70 days, daily from 15.00 to 08.00 h (from 08.00 to15.00 h animals were drinking tap water) on selected metabolic parameters in male and female Sprague-Dawley rats. In addition to concentration/content of triacylglycerols, phospholipids, cholesterol, malondialdehyde, glucose and glycogen in the serum and tissues, serum corticosterone and insulin, weights of selected organs, periovarial and epididymal fat and body weight were recordered. Melatonin was not administered to control groups. Oral glucose tolerance tests were carried out before melatonin administration and 9 weeks thereafter.