Prophylactic role of β-carotene against acrylonitrile-induced testicular toxicity in rats: Physiological and microscopical studies

Acrylonitrile (ACN) is an aliphatic nitrile product which is extensively used in various synthetic chemical industries. ACN is known to exert toxic actions to human beings as well as experimental animals. The present study was designed to examine the ability of β-carotene, a naturally occurring antioxidant, to attenuate ACN-induced testicular toxicity in adult albino rats. Daily oral administration of ACN at a dose level of 30 mg/kg b.w. (7.2 mg/animal) to male rats for a period of 5 days significantly reduced the levels of serum testosterone (T), androsterone, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) which indicate injury to the testis function. Also, it decreased serum and testicular glutathione (GSH) content and glutathione-Stransferase (GST) activity. While, ACN induced lipid peroxidation as indicated by markedly increased malondialdehyde (MDA). ACN intoxication also induced marked alterations in most of the seminiferous tubules including germ cell depletion, tubular atrophy, maturation arrest, complete necrosis as well as multinucleated giant cell formation. Expansion of intertubular spaces and interstitial haemorrhage were also illustrated. Ultrastructural examination of the seminiferous tubules revealed thickened boundary tissue, pyknosis of Sertoli cell nuclei, damaged mitochondria and smooth endoplasmic reticulum-derived vacuoles. Spermatogenic cells also demonstrated altered cytoplasmic organelles, vacuoles of varying sizes and deformed spermatids. Mitochondrial disruption and a decrease in the amount of smooth endoplasmic reticulum were observed in Leydig cells. Compared to ACN-treated animals, pretreatment with β-carotene and its co-administration with ACN once daily at a dose of 40 mg/kg b.w. (9.6 mg/animal) for 30 days induced a remarkable degree of improvement in the levels of endocrine parameters including T, androsterone, FSH and LH. Also, it mitigates serum and testicular GSH content, GST activity and MDA level. Moreover, it protects testicular tissues and cell structures. In conclusion, the present results clearly demonstrate the prophylactic role of β-carotene against ACN-induced testicular toxicity in rats.