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Abstract

Background Early-life exposure to exogenous chemicals can disrupt neurodevelopment. Perfluorohexanesulfonic acid (PFHxS), a legacy PFAS widely used and detected globally, remains poorly studied for its neurotoxicity. Methods CD-1 mice (n = 90 dams) were exposed to human-relevant dose of PFHxS from gestational day (GD) 0–17. PFHxS levels were measured in maternal plasma and foetal/offspring medial prefrontal cortex (mPFC) (GD 18, postnatal weeks [PNW] 4 and 10) using liquid chromatography tandem mass-spectrometry (LC-MS/MS). Offspring social behaviour was assessed with the Three-Chamber social test. Neurotransmitters in mPFC of PNW 10 offspring were profiled by LC-MS/MS, transcriptomics was performed on GD 18 and PNW 4 mPFC, GABAergic neurons were quantified by immunofluorescence, and glutamate decarboxylase (GAD) expression by western blotting. PFHxS-GAD interactions were examined via molecular docking and microscale thermophoresis (MST). Findings Maternal plasma reached 5.1 ± 0.1 ng/mL, equivalent to human biomonitoring data, and PFHxS accumulated in foetal mPFC (68.1 ± 4.1 pg/g). PFHxS exposure induced social deficits at PNW 4 and 10, which were more pronounced in males. The mPFC of PFHxS exposed offspring exhibited an excitatory-tilted neurotransmitter profile, feature with reduced γ-aminobutyric acid (GABA, 90.6 ± 12.2 vs. 70.2 ± 4.3 μg/g, p = 0.008). The differentially expressed genes were enriched in GABAergic and synaptic signalling pathways. Despite unchanged percentage of GABAergic neuron and GAD expression, metabolite GABA/glutamate ratio was attenuated, suggesting impaired GAD function. Both molecular docking and MST suggested moderate-to-strong binding affinity between PFHxS and GAD, affecting GABA synthesis. Interpretation Gestational PFHxS exposure at human-relevant levels impairs offspring social behaviour, likely via disruption of GAD-mediated imbala