Nanoparticles and nanomaterials as inevitable modern toxic agents. Review. Part 3. Influence of nanoparticles on brain and behavior. Conclusions and unsolved problems

Abstract

The final part of the review focuses on the existing methods and results of studying the effects of nanoparticles (NPs) on the brain and behavior. The types of behavioral tests used to assess changes in the behavior of NP-treated animals are described. The data accumulated in the literature on the negative influence of NPs on animal brains exposed to NPs in adulthood are considered. The signs of different cellular and tissue damage are presented, such as development of oxidative stress in the brain, inflammation and swelling, disturbances in the structure of cells, and an increase in the permeability of the bloodbrain barrier. Disturbances in spatial memory, working, and long-term reference memory, decreased propensity for social interactions, inhibition of exploratory behavior, depression and anxiety, and impaired motor coordination, were found after various types and duration of contact of animals with NPs. The accumulated information about the negative consequences of prenatal and early postnatal, during lactation, for example, contact with NPs for mature offspring, is also described. Various cellular and tissue damage is found in the brain of young animals, such as the inhibition of cell proliferation, an increase in the number of cells undergoing apoptosis, edema and vascular degeneration, a decrease in the expression of genes associated with neurogenesis, and numerous signs of the development of oxidative stress. Behavioral disturbances in adult animals that had contact with NPs in early ontogenesis are considered, such as manifestations of depressive behavior or increased anxiety and suppression of spatial and short-term memory. Contradictory results of studies about contact with NPs in both adulthood and early ontogenesis are also presented. In conclusion, unresolved issues are highlighted, and general conclusions on the review are given.