Gestational Dibutyl Phthalate Exposure Impairs the Ovarian Reserve in Offspring Mice Through METTL14-m6A-mediated PI3K-AKT-FOXO3a Activation

Dibutyl phthalate (DBP), a common environmental endocrine-disrupting chemical, is known to impair female reproduction, yet its specific effects on ovarian reserve and underlying epigenetic mechanisms are not fully understood. Here, using gestational exposure models ( in vivo ) and fetal ovarian culture models ( in vitro ), we show that gestational DBP exposure disrupts the ovarian reserve through a dual assault: impairing primordial follicle formation ("input") and, more critically, driving primordial follicle premature activation ("output"). Mechanistically, DBP induces METTL14-dependent m⁶A hypermethylation, which activates the PI3K-AKT-FOXO3a signaling axis to promote aberrant follicular activation. Knockdown of Mettl14 rescues this pathway activation and the follicular disruption. Long‑term follow‑up revealed that such precocious activation leads to progressive ovarian reserve depletion, culminating in a premature ovarian insufficiency (POI)-like phenotype with hormonal dysfunction, reduced oocyte quality, and compromised fertility in adult offspring. Collectively, these findings indicate that gestational DBP exposure activates the PI3K-AKT-FOXO3a signaling pathway via METTL14-mediated m⁶A modification, causing impaired follicle formation, follicular over-activation, and ultimately ovarian reserve depletion and a POI-like phenotype in offspring. This study reveals a novel m⁶A‑mediated epigenetic mechanism in plasticizer-induced ovarian toxicity, advancing our understanding of POI etiology and highlighting a significant environmental risk to female fertility.