Although titanium dioxide nanoparticles (TiO2 NPs) have been demonstrated to accumulate in organs resulting in toxicity, there is currently only limited data regarding male reproductive toxicity by TiO2 NPs. In this study, testicular damage and alterations in gene expression profiles in male mice induced by intragastric administration of 2.5, 5, and 10mg/kg body weight of TiO2 NPs for 90 consecutive days were examined. Our findings showed that TiO2 NPs can cross the blood-testis barrier to reach the testis and accumulate therein, which, in turn, results in testicular lesions, sperm malformations, and alterations in serum sex hormone levels. Furthermore, microarray analysis showed that 70 genes with known functions were up-regulated, while 72 were down-regulated in TiO2 NPs-exposed testes. Of the altered gene expressions, Ly6e, Adam3, Tdrd6, Spata19, Tnp2, and Prm1 are involved in spermatogenesis, whereas Sc4mol, Psmc3ip, Mvd, Srd5a2, Lep, and Cyp2e1 are associated with steroid and hormone metabolism. Hence, the production and application of TiO2 NPs should be carried out cautiously, especially by humans of reproductive age.
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