Microglial gp91phox-mediated neuroinflammation and ferroptosis contributes to learning and memory deficits in rotenone-treated mice

Abstract

Apart from dopaminergic neurotoxicity, exposure to rotenone, a commonly used insecticide in agriculture, also adversely affects hippocampal and cortical neurons, resulting in cognitive impairments in mice. We recently established a role of microglia-mediated neuroinflammation in rotenone-elicited deficits of cognition, yet the mechanisms remain elusive. Here, we investigated the involvement of NADPH oxidase 2 (NOX2) catalytic subunit gp91^phox in rotenone-induced cognitive deficits and the associated mechanisms. Our study demonstrated that rotenone exposure elevated expression of gp91^phox and phosphorylation of the NOX2 cytosolic subunit p47^phox, along with NADPH depletion in the hippocampus and cortex of mice, indicating NOX2 activation. Specific knockdown of gp91^phox in microglia via adeno-associated virus delivery resulted in reduced microglial activation, proinflammatory gene expression and improved learning and memory capacity in rotenone-intoxicated mice. Genetic deletion of gp91^phox also reversed rotenone-elicited cognitive dysfunction in mice. Furthermore, microglial gp91^phox knockdown attenuated neuronal damage and synaptic loss in mice. This intervention also suppressed iron accumulation, disruption of iron-metabolism proteins and iron-dependent lipid peroxidation and restored the balance of ferroptosis-related parameters, including GPX4, SLC711, PTGS2, and ACSL4 in rotenone-lesioned mice. Intriguingly, pharmacological inhibition of ferroptosis with liproxstatin-1 conferred protection against rotenone-induced neurodegeneration and cognitive dysfunction in mice. In summary, our findings underscored the contribution of microglial gp91^phox-dependent neuroinflammation and ferroptosis to learning and memory dysfunction in rotenone-lesioned mice. These results provided valuable insights into the pathogenesis of cognitive deficits associated with pesticide-induced Parkinsonism, suggesting potential therapeutic avenues for intervention.

Keywords: Ferroptosis; Gp91phox; Microglia; NADPH oxidase; Parkinson's disease; Rotenone.