Chronic Fluoride Exposure Disrupts Calcium-Dependent Neurodevelopmental Signalling and Brain Proteomic Architecture: Multi-Target Modulation by Naringin.

Abstract

Long-term exposure to fluoride during early development is associated with impairments in neurobehavioral functions, oxidative stress, and molecular alterations in the developing brain. However, the mechanisms by which fluoride disrupts neurodevelopment, as well as the potential of natural flavonoids such as naringin to counteract these effects, are not well characterised. This study aimed to investigate the neurodevelopmental harms of fluoride and evaluate the multi-target neuroprotective efficacy of naringin using behavioural, biochemical, antioxidant, proteomic, and gene expression approaches in rats. Adult male and female Wistar rats and their offspring were exposed to sodium fluoride with or without naringin throughout development. Neurodevelopmental and behavioural assessments were performed along with estimation of serum and urine fluoride levels. Brain oxidative stress markers and biochemical parameters were analysed, followed by proteomic profiling (LC-MS/MS), functional enrichment analysis, and PCR validation of selected molecular markers. Fluoride exposure did not significantly affect most neonatal reflexes but produced selective impairments in specific sensorimotor parameters and pronounced behavioural deficits during post-weaning stages. Rats exposed to fluoride exhibited increased oxidative stress, altered antioxidant enzyme activities, and elevated fluoride levels in both serum and urine, highlighting systemic and neuronal toxicity. Proteomic analysis indicated a dysregulation of pathways linked to mitochondrial function, calcium signalling (including pathways associated with CALM2), synaptic plasticity, and apoptosis. PCR analysis confirmed alterations in key neuronal and stress-related genes. Co-treatment with naringin significantly alleviated behavioural impairments, restored antioxidant balance, reduced fluoride accumulation, mitigated dysregulation across multiple molecular pathways, and lessened changes in both proteomic and transcriptional markers. Fluoride exposure was associated with neurodevelopmental toxicity involving oxidative imbalance, mitochondrial dysfunction, calcium-related signalling disturbances, and alterations in synaptic pathways. Naringin attenuated many behavioural, biochemical, and molecular alterations, indicating a protective effect across multiple targets. These findings support further investigation of naringin as a potential protective compound against fluoride-induced neurodevelopmental alterations.