Effect of pubertal nano-TiO2 exposure on testosterone synthesis and spermatogenesis in mice

Titanium dioxide nanoparticles (nano-TiO2) are frequently used in cosmetics, paints, sunscreens and the like. Recent studies have demonstrated that nano-TiO2 might be deleterious for the male reproductive function. However, the effects of pubertal nano-TiO2 exposure on testosterone (T) synthesis and spermatogenesis remained to be elucidated. Here, we investigated the effect of pubertal nano-TiO2 exposure on the synthesis of T and spermatogenesis. Nano-TiO2 was orally administered daily to Kunming male mice from 28th postnatal day (PND 28) to PND 70. The percentage of spermatozoa abnormality in epididymides was markedly increased in mice exposed to nano-TiO2; decreased layers of spermatogenic cells and vacuoles in seminiferous tubules were also observed in the nano-TiO2 treated group. In addition, pubertal nano-TiO2 exposure significantly decreased the serum T levels in male mice. Moreover, mice exposures to nano-TiO2 significantly reduced the expression of 17 beta-hydroxysteroid dehydrogenase and P450 17 alpha-hydroxysteroid dehydrogenase in the testis of mice, while the expression of cytochrome P450-19, a key enzyme for the translation of T to estradiol (E2), was increased. Taken together, these results indicated that nano-TiO2 could influence the levels of serum T through changes in both the synthesis and translation of T. Furthermore, the decreased serum T synthesis might contribute to the reduced spermatogenesis in mice exposed to nano-TiO2.