SiO2 nanoparticles cause depression and anxiety-like behavior in adult zebrafish

The extensive employment of engineered nanoparticles (NPs) makes it inevitable that the environment would be exposed to nano-materials. As a result, their biological effects on the ecosystem and living organisms are gaining attention. Here, we report that both nano-silica (SiO2-NPs) and reserpine can elicit depression-like behavior in adult zebrafish in a novel tank test. Nano-silica or reserpine induce the depressive phenotype by decreasing locomotion, inhibiting exploratory behavior, aggravating the depressive phenotype and disturbing swimming patterns. Immunohistochemistry reveals that the dampened locomotion induced by nano-silica and reserpine is associated with the reduced expression of tyrosine hydroxylase. Inhibited exploratory behavior, aggravated depressive phenotypes, and disturbed spatiotemporal swimming path patterns are related to the increased expression of serotonin. These findings imply that the similar behavioral and depression-inducing effect of nano-silica and reserpine may share a common physiological mechanism. In summary, our results suggest that exposure to silica nanoparticles in the nervous system is a possible depression-inducing factor.