Neurotoxicity of Mn 3 O 4 nanoparticles: Apoptosis and dopaminergic neurons damage pathway.

Mn ₃ O ₄ nanoparticles (NPs) are used increasingly in various fields due to their excellent physiochemical properties. Previous studies have documented that Mn-based nanomaterials resulted in excess reactive oxygen species (ROS) generation and dopamine (DA) reduction both in vivo and in vitro experiments. However, little is known about the mechanism of ROS production and DA decrease induced by Mn-based nanomaterials. The present study was carried out to elucidate the mechanism of the co-incubation model of dopaminergic neuron PC12 cells and the synthesized Mn ₃ O ₄ NPs. The results demonstrated that exposure to Mn ₃ O ₄ NPs reduced cell viability, increased level of lactate dehydrogenase (LDH), triggered oxidative stress and induced apoptosis. Notably, the level of ROS was remarkably increased (>10-fold) with Mn3O4 NPs exposure. We also found that mitochondrial calcium Ca ²⁺ uniporter (MCU) was up-regulated and the mitochondrial Ca ²⁺ concentration ([Ca ²⁺ ] _mito ) increased induced by Mn ₃ O ₄ NPs in PC12 cells. Furthermore, the MCU inhibitor RuR significantly attenuated Mn ₃ O ₄ NPs-induced [Ca ²⁺ ] _mito , ROS production and apoptosis. In PC12 cells, the decrease of DA content was mainly due to the downregulation of DOPA decarboxylase (DDC) expression caused by Mn ₃ O ₄ NPs treatment. The expression of proteins related to DA storage system was not significantly affected by treatment.
(Copyright © 2019. Published by Elsevier Inc.)