SHORT-TERM, LOW-DOSE GLYPHOSATE EXPOSURE IN MICE TRIGGERS INFLAMMATION AND EXACERBATES ALZHEIMER’S DISEASE PATHOGENESIS DETECTED BY INCREASES IN BLOOD NFL

Glyphosate (GLY) is a ubiquitously used broad-spectrum herbicide. Despite widespread human exposure, as evidenced by its detection in human biofluids, the neurobiological consequences of GLY remain poorly understood. We were the first to demonstrate that GLY penetrates the brain and increases inflammatory cytokines in young C57BL/6J mice following short-term exposure at the No Observed Adverse Effect Level. We have reported persistent detection of the primary GLY-derived metabolite, aminomethylphosphonic acid, in brain tissue after prolonged exposure and washout periods, accompanied by increased Alzheimer’s disease (AD)-like pathology and neuroinflammation. GLY exposure produced dose-dependent increases in plasma neurofilament light chain (NfL), a biomarker of neuroaxonal injury, consistent with emerging human data. However, it remains unclear whether exposure at the U.S. Environmental Protection Agency’s chronic reference dose (cRfD; 1.75 mg/kg/day) produces similar effects. To address this gap, 3xTg-AD and NonTg mice were exposed to GLY for 30 days at the mouse-equivalent cRfD. Plasma was analyzed for NfL and inflammatory cytokines while hippocampal tissue was assessed for cytokines and AD-like pathology. GLY exposure significantly increased circulating NfL and elevated pro-inflammatory cytokines in both genotypes. In 3xTg-AD mice, GLY further increased amyloid-β and phosphorylated tau levels. Plasma NfL was positively correlated with amyloid and tau pathology. These findings demonstrate that short-term GLY exposure at regulatory-relevant doses induces measurable inflammatory and neurodegenerative changes. These results raise important concerns regarding widespread GLY exposure and support the combined use of NfL, GLY, and AMPA as biomarkers for monitoring GLY-associated neurotoxicity in at-risk populations.