Résumé
Malathion is one of the organophosphorus insecticides that are widely used in agriculture and have been reported to cause multiple organ damage. Vitamin C has been proposed as an antioxidant because it reduces oxidative stress. This work aimed to study the possible histological, immunohistochemical, and ultrastructural changes of gonadotrophs and somatotrophs of the pars distalis of the anterior pituitary gland associated with chronic sublethal malathion administration and assess the possible beneficial role of vitamin C in ameliorating these possible changes. Forty adult female albino rats were divided into four groups. Group I served as the control group. Group II received vitamin C at a dose of 20 mg/100 g/day. Group III animals were treated with malathion at a dose of 100 mg/kg/day. Groups IV animals received vitamin C and then malathion after 2 h at the previous doses. The treatments were given orally to the rats for 2 months. The rats were then sacrificed and specimens from the anterior pituitary gland were taken for light and electron microscopic examination. Light microscopic examination of rats treated with malathion revealed that gonadotrophs exhibited vacuolated degranulated cytoplasm and pyknotic nuclei, whereas somatotrophs appeared shrunken with dense nuclei. Immunohistochemically, there was a decrease in the immunoreactivity of follicle stimulating hormone, luteinizing hormone, and growth hormone-secreting cells. Ultrastructurally, gonadotrophs and somatotrophs showed disintegration of cellular organelles and apoptosis of the nuclei. Coadministration of malathion with vitamin C showed a slight improvement in some gonadotrophs and somatotrophs that looked normal in both light microscopic and electron microscopic examination; however, still others were markedly affected, showing signs of degeneration and apoptosis. The results showed that malathion in chronic doses induces histological, immunohistochemical, and ultrastructural changes in gonadotrophs and somatotrophs because of oxidative stress, and the use of vitamin C partially improves the malathion-induced toxicity