Glyphosate exposure and epigenetic-environmental interactions in ASD: The role of circTiam1

Glyphosate (Gly), the most widely used agrochemical, is epidemiologically linked to escalating autism spectrum disorder (ASD) prevalence, yet mechanisms remain elusive. A mouse model of gestational and lactational glyphosate-based herbicide (GBH) exposure (0.10-1.00%) was established to assess ASD-like neurodevelopmental effects. Neural and microglial cell lines (mouse BV2, human HMC3) were used to elucidate mechanisms of GBH-induced neurodevelopmental deficits. GBH induced dose-dependent ASD-like behaviours, including stereotyped repetitive actions and social impairments, without anxiety-like alterations. These behavioral changes were accompanied by neuronal injury and synaptic loss in the medial prefrontal cortex (mPFC). Mechanistically, GBH selectively upregulated CACNA2D3 in microglia, but not neurons, elevating microglial Ca²⁺ levels, promoting pro-inflammatory cytokines, and activating NF-κB signaling, while impairing phagocytosis. High-throughput circular RNA (circRNA) sequencing identified upregulated circTiam1, which sponges miR-128-3p to derepress CACNA2D3, confirmed by knockdown/overexpression and binding assays. Serum circTiam1 was elevated in children with ASD and positively correlated with Childhood Autism Rating Scale and Social Responsiveness Scale scores. These findings delineate a novel circTiam1/miR-128-3p/CACNA2D3 axis mediating microglial dysfunction, possibly contributing to ASD-like behaviors following GBH exposure, underscoring critical epigenetic-environmental interactions. Future studies using in vivo, microglia-targeting models and independent clinical cohorts are needed to determine the mechanistic, biomarker, and translational relevance of circTiam1.