As a consequence of improved life expectancies, the world population is increasing and the worldwide prevalence of age-related diseases, such as neurodegenerative diseases, is also rising (Jaul and Barron, 2017). Numerous studies have reported that neurodegeneration has been partly associated with pesticide exposure (Flores-Gutierrez et al., 2023; Rodrigues et al., 2022). Among these, fipronil is an N-phenylpyrazole insecticide widely used in agriculture, veterinary science, and households to control pests (Goncalves et al., 2022). The insect-selective toxicity of fipronil is due to its tight binding to gamma-amino butyric acid (GABA) receptors of insects, compared to mammal GABA receptors (Hainzl et al., 1998). Therefore, the usage of fipronil is more preferred than that of older generation insecticides. However, accumulation of fipronil in environment has been reported, so that public health threats have become an issue (Chen et al., 2022; Hainzl et al., 1998). In the body, fipronil can accumulate in adipose tissues and in the brain, so there has been increasing research to understand its potential neurotoxicity to humans (Cravedi et al., 2013; Schmitz et al., 2021).

Fipronil has been demonstrated to induce lipid peroxidation in PC12 neuronotypic cells, (Lassiter et al., 2009) as well as to cause mitochondrial injury and apoptotic cell death in SH-SY5Y neuroblastoma cells through increasing oxidative stress (Vidau et al., 2011). However, the use of antioxidant could not entirely protected SH-SY5Y cells from fipronil-induced cell death (Ki et al., 2012; Lee et al., 2011; Park et al., 2016), reflecting the contribution of other mechanism(s), in addition to oxidative stress, to the neuronal cytotoxicity of fipronil. Identification of the non-oxidative stress mechanisms might be of benefit in preventing neuronal damage induced by fipronil exposure.

Study of changes in global protein expression or proteome in cells or tissues and analysis of toxicant-induced proteomic changes has been proven to be a helpful strategy in the discovery of toxicant mechanism (Alugubelly et al., 2021; Ford et al., 2017; Kennedy, 2002; Tatjana et al., 2021). The term “toxicoproteomics” has been used to describe the application of proteomics to research in toxicology and pathology (Suman et al., 2016; Wetmore and Merrick, 2004). This differs from regular mechanistic studies which are restricted to the effect of the toxicant on single genes or proteins in a chosen model. One of the primary areas of functional proteomics is protein-protein interactions (PPI), namely physical interactions involving two or more proteins, which are indicative of intricate biological processes. Analysis of the role of PPI's has shown significant promise in identifying the main contributor to a specific toxic mechanism, as well as a neurodegenerative event (Calabrese et al., 2022).

In this report, we explored the proteomic changes in SH-SY5Y human neuronal cell line upon treatment with fipronil, so as to illustrate comprehensive mechanism(s) and possible key events in fipronil-induced degeneration of neuronal cells. Additionally, we also explored the mode of cell death in fipronil-treated cells and the effect of antioxidant pretreatment on impairment of neurite outgrowth and cell death.