Effects of melatonin on liver, skeletal muscle and myocard of rats with hyperthyroidism: The Light and electron microscopic study

ABSTRACT The aim of this study was to investigate light and electron microscopically structural changes that occurred in liver, skeletal muscle and myocard of rats with hyperthyroidism and effect of Melatonin on these changes. In this study, rats were divided into 3 groups; Group I was designated as control, group II was injected with 3,3%5-Trnodo-L-Thyronine (T3), group in was injected with T3+ Melatonin. In the end of study, the tissue specimens of liver, skeletal muscle and myocard of removed from rats were examined with light and electron microscopy. In skeletal muscle of T3 injected rats were observed decrease in muscle fiber diamater, splitting of fiber, collections of adipose tissue in perimysium, gathering of nuclei in central and increase of mast cells when compared to the control In the electron microscopic study was observed that mytochondries were dilate and I band was the less clear. In T3 + Melatonin injected group, the structure of fiber was simüiar to control The structure of myocard in group II and HI was similiar to control except from larged membranous structure. In the liver of T3 injected group, dilatasyon in sinusoids, increase in the amount of Kupffer cell and glycogen were observed. In adition to, some hepatocyte cytoplasm was stainless. In group HI, glycogen and amount of Kupffer cell were similiar to group E, the other structures were similiar to control. In electron microscopic examination, the hepatocyte structure of group II was similiar to control. In the hepatocyte structure of T3 + Melatonin enjected group, the amount of microvillus increased, Disse space enlarged, the amount of lipid droples of ito cells increased, Kupffer cell was more active. In conclusion, this study showed that T3 injection caused structural changes in liver and skeletal muscle, Melatonin hormone showed positive effect on these changes however some changes were observed in liver. But myocard didn't showed significant changes in the light and electron microscopical level