Histological and immunohistochemical study on the effect ofaflatoxin B1 on the left ventricular muscle of adult male rabbitwith reference to the protective role of melatonin

IntroductionAflatoxins are naturally occurring mycotoxins produced by mold. They grow onwhole grains such as corn, rice, and wheat as well as on peanuts, almonds, walnuts,sunflower seeds, and spices such as black pepper. Aflatoxins can contaminate thesefood products during processing, storage, or transport. Humans are exposed to theireffect through ingestion of contaminated diet.AimThe aim of this work was to study the effect of aflatoxin on the left ventricularmuscle of adult male rabbit and evaluate the role of concomitant melatonin (MEL)administration.Materials and methodsSixteen adult male rabbits weighing 1.8–2.2 kg were used. They were divided intofour groups, four animals each. Group I was the control. Group II received MEL orallyat a dose 5 mg/kg body weight daily. Group III received aflatoxin B1 (AFB1) orallyat a dose 30 μg/kg body weight daily. Group IV received MEL concomitant withAFB1 at the same doses as the previous groups. All animals were kept for 8 weeks,and then specimens were taken from their left ventricles and stained for histologicalexamination and immunohistochemical study for desmin expression with quantitativeanalysis of optical density of desmin immunoexpression.ResultsLight microscopic examination of left ventricle of AFB1-treated rabbits showedfibrillolysis with sarcoplasmic vacuolation. The nuclei showed pyknosis andperipheralization with congested dilated myocardial blood vessels and mononuclearcellular infilteration. Immunohistochemical study revealed areas of increaseddesmin expression alternating with areas of decreased desmin expression. Electronmicroscopic examination revealed extensive destruction and degeneration of themyofibrils with discontinuous intercalated discs. Some mitochondria appeareddegenerated with disrupted cristae. The sarcoplasm showed dilated smoothendoplasmic reticulum and rarefaction with discontinuous sarcolemma in the samegroup. MEL coadministration improved the previous histological changes.ConclusionThese findings proved that AFB1 has adverse effects on the left ventricular musclesof rabbits, which were ameliorated by coadministration of MEL.