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ABSTRACT
The purpose of this study was to investigate the apoptosis-related cytotoxic effects and molecular mechanisms of individual isomers of profenofos (PFF) on primary hippocampal neurons at 1.0 to 20 mg L−1. The cell viability and lactate dehydrogenase (LDH) efflux indicated that (−)PFF exposure was associated with more toxic effects than (+)PFF above the concentration of 5 mg L−1 (P < 0.5). Flow cytometric results showed that the percentages of apoptotic cells incubated with 20 mg L−1 (−)PFF, (+)PFF and rac-PFF for 24 h reached 23.4%, 9.2% and 14.2% (P < 0.01), respectively. Hippocampal neurons incubated with (−)PFF, (+)PFF and rac-PFF exhibited a dose-dependent accumulation of intracellular reactive oxygen species (ROS) and malondialdehyde (MDA) and a dose-dependent inhibition of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activity, implying that the defense system of the tests induces oxidative damage. A statistically significant difference was observed between the two enantiomers at 5 mg L−1 and above. Moreover, the results showed that (−)PFF exposure caused a significant loss in mitochondrial transmembrane potential (MMP), an upregulation of Ca2+ and Bax protein expression, a downregulation of Bcl-2 protein expression, and the activation of caspase-3 and caspase-9 in a dose-dependent manner; (+)PFF and rac-PFF exhibited these effects to a lesser degree. All results suggest that PFF induced apoptosis in rat hippocampal neurons via the mitochondria-mediated pathway, and oxidative stress is one of the factors of PFF-induced apoptosis. In addition, (−)PFF appears to play an important role in oxidative stress and apoptosis, indicating that enantioselectivity should be considered when assessing ecotoxicological effects and health risks of chiral pesticides.
Funding
This work was supported by the National Natural Science Foundation of China (No 21307023, 21407038, 21407051).