Myocardial ischemia/reperfusion (I/R) injury has been associated with ferroptosis, which is characterized by an iron-dependent accumulation of lipid peroxide to lethal levels. Gossypol acetic acid (GAA), a natural product taken from the seeds of cotton plants, prevents oxidative stress. However, the effects of GAA on myocardial I/R-induced ferroptosis remain unclear. This study investigated the ability of GAA to attenuate I/R-induced ferroptosis in cardiomyocytes along with the underlying mechanisms in a well-established rat model of myocardial I/R and isolated neonatal rat cardiomyocytes. H9c2 cells and cardiomyocytes were treated with the ferroptosis inducers erastin, RSL3, and Fe-SP. GAA could protect H9c2 cells against ferroptotic cell death caused by these ferroptosis inducers by decreasing the production of malondialdehyde and reactive oxygen species, chelating iron content, and downregulating mRNA levels of Ptgs2. GAA could prevent oxygen-glucose deprivation/reperfusion-induced cell death and lipid peroxidation in the cardiomyocytes. Moreover, GAA significantly attenuated myocardial infarct size, reduced lipid peroxidation, decreased the mRNA levels of the ferroptosis markers Ptgs2 and Acsl4, decreased the protein levels of ACSL4 and NRF2, and increased the protein levels of GPX4 in I/R-induced ex vivo rat hearts. Thus, GAA may play a cytoprotectant role in ferroptosis-induced cardiomyocyte death and myocardial I/R-induced ferroptotic cell death.

Bone marrow-derived mesenchymal stem cells (BMSCs) maintain skeletal homeostasis by balancing adipogenic and osteogenic differentiation, yet clinically used drugs that bias this fate choice and their mechanisms remain incompletely defined. Here, we investigated whether dextromethorphan (DXM), a widely used antitussive, modulated lineage commitment in rat BMSCs and interrogated candidate upstream signaling modules. Rat BMSCs were induced with adipogenic medium or osteogenic medium in the presence of DXM (30 μM). Adipogenesis and osteogenesis were quantified using Oil Red O and Alizarin Red S staining with elution-based quantification, and lineage markers were measured by RT-qPCR. Intracellular Ca²⁺ and ROS were analyzed using flow cytometry, and the levels of p-AKT and p-ERK were assessed through Western blotting analysis. Under adipogenic induction, DXM increased lipid droplet accumulation and the mRNA levels of Pparγ and Fabp4. Although DXM elevated Ca²⁺ and ROS, the chelation of intracellular Ca²⁺ and pharmacological inhibition of Sig-1R/PLC–IP3R signaling, redox/ROS, NMDA receptors, AKT/ERK, Kv channels, bitter taste receptor-related signaling, and mTOR did not attenuate the DXM-enhanced adipogenesis. DXM reduced p-ERK without increasing p-AKT; U0126 lowered basal adipogenesis but did not block the DXM effect. Under osteogenic induction, DXM reduced matrix mineralization and downregulated Runx2 and Bglap mRNA levels, while Wwtr1 mRNA levels were not significantly changed. DXM also partially reversed the osteogenic induction-associated reduction in Mtor mRNA. Separately, under adipogenic induction, rapamycin attenuated baseline adipogenesis but did not prevent the additional lipid accumulation induced by DXM. Collectively, DXM shifted the osteogenic–adipogenic balance toward adipogenesis through a non-canonical mechanism.