Integrating network toxicology, transcriptomics and experimental validation to elucidate the potential mechanisms of fluoride-induced neurotoxicity in zebrafish.

Fluorine is a halogen element that is widely distributed in the environment and highly reactive. Fluoride concentrations in surface water typically remain below 0.3 mg/L (Nayeri et al., 2025; Li et al., 2021). However, due to the excessive use of pesticides and chemical fertilizers, coupled with wastewater pollution from the metallurgical and semiconductor industries, fluoride concentrations in water bodies have surged dramatically in some regions. In certain high-fluoride areas, levels have even reached 10–20 mg/L (Jiang et al., 2025). The safety standard for fluoride concentration is 1.5 mg/L, but in polluted rivers of some Asian countries, concentrations far exceed this standard, in industrial wastewater, concentrations can be hundreds of times higher (Jin et al., 2024). Such severe fluoride contamination has severely undermined the sustainable development of aquaculture and poses a significant challenge to the balance of aquatic ecosystems (Ho et al., 2023). Fluoride readily binds to bone tissue and can cause spinal developmental abnormalities at elevated concentrations within the body. Furthermore, fluoride exposure can also cause other disorders, such as skeletal fluorosis, decreased bone mineral density, or impaired bone remodeling (Veneri et al., 2023; Srivastava and Flora, 2020). However, research on the mechanisms underlying its neurotoxicity at environmentally relevant concentrations remains limited. Fish inhabiting areas with severe fluoride contamination inevitably ingest fluoride through various pathways—including drinking water, food, and industrial wastewater—thereby adversely affecting their neurological development (Jin et al., 2024; Wang et al., 2025a). The accumulation of fluoride can disrupt neural development and synaptic transmission, leading to behavioral deficits such as impaired swimming ability and reduced migration capacity, thereby threatening the survival of the population (Guth et al., 2020).

Fluoride can cross the blood-brain barrier and accumulate in brain tissue, exerting significant neurotoxic effects at high concentrations (Zwierello et al., 2023). Neuroinflammation is both a defensive response of the central nervous system to injury and a pathological feature of pollutant-induced neuronal damage (Shi and Yong, 2025). Research indicates that due to characteristics such as the immaturity of the blood-brain barrier during early life stages, the risk of cognitive impairment and neurodegenerative diseases caused by fluoride exposure is significantly higher in young individuals than in adults (Choi et al., 2012; Qiu et al., 2025; Wang et al., 2023). Chen et al. found that long-term exposure to high concentrations of fluoride induces neurotoxicity via the gut-brain axis and leads to behavioral abnormalities (Chen et al., 2025). Cao et al. observed that fluoride exposure caused learning and memory impairments in APP/PS1 transgenic mice, accompanied by reduced protein expression, increased oxidative stress, and Alzheimer’s disease-like neuropathological progression (Cao et al., 2019). Research by Green et al. indicates that exposure to environmentally relevant concentrations of fluoride causes neurological damage in mother mice and their offspring, leading to neurological dysfunction manifested as significantly impaired learning and memory abilities (Green et al., 2019; Li et al., 2022). In summary, these studies indicate that fluoride can activate inflammation-related pathways within brain tissue, disrupting the balance of the nervous system and impairing learning and memory capabilities (Zhang et al., 2022; Chen et al., 2017). The pollution of aquatic ecosystems by fluoride compounds is becoming increasingly severe, necessitating an urgent assessment of their toxicological effects on aquatic organisms.

Zebrafish (Danio rerio) are widely used in toxicological research due to their rapid development, well-defined genetic background, and sensitivity to environmental pollutants, providing an ideal experimental model for studying the effects of environmental contaminants on the nervous system (MacRae and Peterson, 2023; Garcia et al., 2016; MacRae and Peterson, 2015). In this study, we employed zebrafish as an experimental model and systematically investigated the potential mechanisms underlying neuroinflammation and brain tissue damage induced by environmental-level fluoride exposure through the integrated application of network toxicology, transcriptomics, and experimental validation. Our findings reveal that TLR4/NF-_kB/NLRP3 pathway-mediated neuroinflammation constitutes a core component of fluoride-induced neurotoxicity, providing a potential target for intervention against fluoride neurotoxicity.