Effect of the mycotoxin zearalenone on the testis of mice and the protective role of vitamin E: Histological and toxicological study

ABSTRACT

Zearalenone [ZEN] is a non steroidal mycotoxin produced by several species of Fusarium fungi. It is frequently detected in cereals used for human food stuffs and animal feeds such as wheat, maize and rice. Zearalenone and its metabolites constitute an important class of endocrine disruptors which causes estrogenic effects and can alter reproduction. The aim of the present work was to evaluate the histological and biochemical toxic effects of Zearalenone on the testicular tissue of mice and the possible role of vitamin E in preventing such effects. The study was carried out on forty adult male mice classified into three groups; a control group which comprised three subgroups; [negative control that received no treatment and two positive controls receiving intraperitoneal injection of either olive oil or vitamin E], ZEN-treated group where zearalenone intoxication was induced by daily intraperitoneal injection in a dose of 20 mg/kg b.wt for 3 days, while the protected group received vitamin E by intraperitoneal injection in a dose of 100 mg/kg b.wt daily for 3 days, simultaneously with zearalenone in a similar dose to that of ZEN-treated group. By the end of the experimental period, blood samples were collected for estimation of serum testosterone level. The mice were then sacrificed and fresh specimens were taken from the testis and processed for light and electron microscopic examinations. Biochemical analysis of serum testosterone demonstrated significant decrease in the hormonal level in the ZEN-treated group compared to the control group, while vitamin E-protected group revealed nearly normal levels with no significant difference from the control subgroups. Light microscopic examination of ZEN- treated group revealed loss of normal architecture of the testicular tissue as several seminiferous tubules showed disorganization of the spermatogenic cells and dissolution of the intercellular connections. Ultrastructural examination of the same group revealed many degenerated cells with electron dense cytoplasm and dense irregular nuclei, multiple apoptotic spermatogenic cells, spermatids with various degrees of degeneration and failure of acrosomal cap formation together with multiple abnormal spermatozoa with irregular heads. Extensive exfoliation of spermatids together with other degenerated cells were frequently depicted in the lumen. Many Leydig cells appeared degenerated with irregular nuclei. On the other hand, vitamin E-protected group showed amelioration of most of the degenerative changes depicted in the ZEN treated group. Exposure to the mycoloxin zearalenone demonstrated a considerable risk on the testicular structure and function of mice. Simultaneous administration of vitamin E was efficient in preventing most of such toxic effects. Therefore, mycological analysis should be regular for food stuffs especially cereals. Whereas, vitamin E can be recommended for protecion against zearalenone intoxication