Effects of pinealectomy and exogenous melatonin on rat hearts.
The effects of pinealectomy and administration of melatonin, the major secretory product of the pineal gland, which is a direct free radical scavenger and an indirect antioxidant, were studied in rat hearts on the basis of cardiac morphology and biochemical findings. Three groups of Wistar rats were used: one group was the sham-operated control, one group consisted of pinealectomized rats and one group consisted of pinealectomized rats that were treated with melatonin. Serum cholesterol, tissue levels of malondialdehyde (MDA) and reduced glutathione (GSH), and heart weight were determined. Histochemical staining with the Van Gieson, PAS/Alcian blue at pH 2.5 and Masson's trichrome methods were performed in addition to hematoxylin-eosin staining. Levels of serum cholesterol and tissue MDA, and heart weight were increased in pinealectomized rats whereas GSH levels did not change. Melatonin administration reversed these effects. Microscopically, myocardial fibrosis and myxomatous degeneration of cardiac valves were detected in all pinealectomized rats. It can be concluded that pinealectomy of rats causes morphological changes in rat hearts, and short-term application of melatonin does not reverse these changes.
Mizrak
Bülent
B
Department of Pathology, Faculty of Medicine, T. Ozal Medical Center, Inonu University, 44069, Malatya, Turkey. bmizrak@inonu.edu.tr
Parlakpinar
Hakan
H
Acet
Ahmet
A
Turkoz
Yusuf
Y
D000818:Animals; D001011:Aorta / Q000473:pathology; D002784:Cholesterol / Q000097:blood; D005260:Female; D005355:Fibrosis / Q000473:pathology; D005978:Glutathione / Q000032:analysis; D006321:Heart / Q000187:drug effects*; D006351:Heart Valves / Q000473:pathology; D008315:Malondialdehyde / Q000032:analysis; D008550:Melatonin / Q000494:pharmacology*; D009206:Myocardium / Q000737:chemistry* / Q000473:pathology; D009929:Organ Size / Q000187:drug effects; D010870:Pineal Gland / Q000502:physiology* / Q000601:surgery; D051381:Rats; D017208:Rats, Wistar
D008315:Malondialdehyde; D002784:Cholesterol; D005978:Glutathione; D008550:Melatonin