Abstract

Abstract
Epidemiologic studies have linked dioxins exposure to ischemic heart disease induced mortality. This study aimed
to investigate the effect of subchronic combined exposure to tetra chloro dibenzodioxin (TCDD) and dibenzofuran (DF)
on left ventricular myocardium of male rats; and the possible underlying mechanism. Moreover, this work aimed to
determine the ameliorative effect of antioxidant vitamins (A, E) supplementation. Fifty animals were classified into four
groups: control group (I); group (II) received vitamins only; group (III) included twenty animals received a dose of 1/10
of LD50 of combined TCDD/DF and group (IV) was included ten animals that received vitamins A and E in combination
with TCDD/DF. Left ventricular myocardium was examined using histological study, immunohistochemical detection of
Aryl Hydrocarbon Receptors (AHR) and mRNA expression of cytochrome P450 gene. Also, oxidant antioxidant markers
in tissue homogenate were detected. Progressive cardiomyopathy, myocardial necrosis, interstitial and perivascular
fibrosis were evident in a time related manner after dioxins treatment. This was associated with increased immunohistochemical
expression of AHR and mRNA expression of CYP1A1. Oxidative stress was evident in left ventricle of
dioxins treated group. These results suggested that combined TCDD/DF exposure has a potent cardio toxic effect
which could be ameliorated by simultaneous supplementation with vitamins A and E.

Keywords: Dioxins; Rat; Cardiomyocyte; Histology; Immunohistochemistry