5-methoxyindole-3-carboxaldehyde attenuates alveolar type II epithelial cell senescence induced by exposure to polystyrene microplastics in pulmonary fibrosis via PI3K/AKT/mTOR signaling pathway

Mice were divided into two groups: (1) Sham/Control group receiving sterile saline, and (2) PS-MPs group receiving 2 mg/kg of 5 um polystyrene microplastics (Zhongke Leiming, Beijing, China). Under light anesthesia (4% isoflurane), animals received daily intranasal instillation of their respective treatments (100 uL volume) for 28 consecutive days. Body weight was monitored twice weekly throughout the experimental period. On day 29, all mice were euthanized via intraperitoneal injection of pentobarbital sodium (150 mg/kg). Lung tissues and bronchoalveolar lavage fluid (BALF) were collected immediately for subsequent analysis.