The effects of acetamiprid exposure on osteoporosis: inducing imbalanced bone remodeling by disrupting the equilibrium of adipogenic/osteoblast/osteoclast differentiation.

Acetamiprid (ACE), a widely used neonicotinoid insecticide, has raised increasing concerns regarding its potential health risks; however, its effects on bone metabolism remain unclear. Here, computational toxicology, network toxicology, molecular docking, and molecular dynamics simulations were integrated with in vivo and in vitro experiments to investigate the impact of ACE and its primary metabolite N-desmethyl-acetamiprid (N-dm-ACE) on bone remodeling. The results show that long-term ACE exposure significantly reduced trabecular bone mineral density and bone mass, impaired trabecular microarchitecture, decreased serum procollagen type I N-terminal propeptide (PINP), increased C-terminal telopeptide of type I collagen (CTX-I), and elevated inflammatory cytokines. Network toxicology identified peroxisome proliferator-activated receptor gamma (PPARγ) as a key target, which was supported by stable binding of ACE and N-dm-ACE to PPARγ in molecular docking and dynamics analyses. Mechanistically, ACE exposure upregulated PPARγ and CCAAT/enhancer-binding protein alpha (C/EBPα) while suppressing runt-related transcription factor 2 (RUNX2), thereby promoting adipogenic differentiation and inhibiting osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs), while reducing the osteoprotegerin (OPG)/receptor activator of nuclear factor κB ligand (RANKL) ratio to enhance osteoclast differentiation. Silencing Pparg markedly reversed these effects. These findings demonstrate that ACE and N-dm-ACE disrupt bone remodeling through activation of the PPARγ pathway, promoting osteoporosis.