Combined exposure to low levels of Pb2 + and 1-nitropyrene induces damage to the hypothalamic–pituitary–ovarian axis in mice via the hippo pathway and pyroptosis

High concentrations of divalent lead (Pb²⁺) in the environment induce damage to the hypothalamic–pituitary–ovarian axis (HPOA) axis, whereas 1-nitropyrene (1-NP) not only damages the brain but also leads to female reproductive toxicity. However, the effects of combined exposure to low levels of Pb²⁺ and 1-NP on the HPOA damage remain unexplored. In this study, mice were simultaneously exposed to both environmental chemicals for 21 days through free water ingestion of Pb²⁺ and intraperitoneal administration of 1-NP. Additionally, HPOA was exposed to low levels of Pb²⁺ and 1-NP for 7 days in vitro using a multi-organ co-culture approach. The results showed that the combined exposure to 0.008 mg/L Pb²⁺ (which complies with some hygiene standards) and ≥ 0.02 mg/kg 1-NP caused tissue damage and decreased the function of HPOA in vivo. In vitro, the same changes were induced by 0.008 mg/L Pb²⁺ combined with 0.3 μM 1-NP in the culture medium. Both in vivo and in vitro, the damaged HPO exhibited decreased levels of YAP and increased levels of LATS1, pYAP, NLRP3, ASC, cleaved CASPASE-1, and GSDMD. These findings suggest that simultaneous exposure to low levels of Pb²⁺ and 1-NP can induce HPOA damage in mice. The potential molecular mechanism may be that low levels of Pb²⁺ and 1-NP synergistically activate the Hippo signaling pathway, leading to the upregulation of the NLRP3/GSDMD axis. This, in turn, regulates inflammation-mediated pyroptosis, ultimately triggering organ damage.