Diabetes mellitus is a common endocrine disease that causes cardiovascular complicati-ons. This study was performed to determine whether melatonin (MEL) could have a protective effect against myocardial injury induced by diabetes in rats. Thirty two adult male albino rats were used in this study and divided into four groups; diabetic rats, diabetic rats injected with different doses of melatonin for 30 days and control rats. Samples from the hearts were processed to study the histolo-gical, apoptotic and ultrastructural changes in the cardiac muscle cells. To reveal the apop-totic changes in the cells, specific damages of DNA were identified by terminal deoxynuc-leotidyl transferase–mediated dUTP-biotin nick end labeling (TUNEL) method and the quanti-tative analysis was performed. Examination of the diabetic cardiac muscle cells showed an increase in the number of the apoptotic cells. Moreover, they had swollen mitochondria, dilated sarcoplasmic reticulum and accumula-ted glycogen granules. Treatment with MEL resulted in a significant improvement in the incidence of apoptotic, histological and ultra-structure figures of the diabetic cardiac muscle cells.
Apoptosis; Ultrastructure; Cardiac muscle cells; Melatonin; Diabetes mellitus