Molecular mechanism of hippocampal apoptosis of mice following exposure to titanium dioxide nanoparticles

Previous studies demonstrate that the exposure to titanium dioxide nanoparticles (TiO2 NPs) damages the central nervous system of mice; however, very little is known about the effects of TiO2 NPs on hippocampal apoptosis or its molecular mechanism. The present study investigated the molecular mechanism associated with hippocampal apoptosis in mice induced by intragastric administration of TiO2 NPs for consecutive 60 days. Our findings indicate that TiO2 NPs accumulate in the mouse hippocampus, and this accumulation, in turn, led to hippocampal apoptosis and impairment in spatial recognition memory in mice. In addition, TiO2 NPs significantly activated caspase-3 and -9, inhibited Bcl-2, and promoted the levels of Bax and cytochrome c. Furthermore, TiO2 NPs induced accumulation of reactive oxygen species in the mouse hippocampus. These findings suggest that TiO2 NP-induced apoptosis in the mouse hippocampus may result from an intrinsic pathway, and workers and consumers should take great caution when handling nanomaterials.