Thermal Adaptation Inhibits the Wnt Signaling Pathway Regulating Autophagy and Improving the Development of Embryos

Heat stress impairs the reproductive capacity of organisms. In contrast, thermal adaptation can have beneficial effects. In this study, we investigated the mechanism through which thermal adaptation (39°C for 1 h followed by recovery at 37°C for 3 h) improves the quality of in vitro cultured mouse morula-stage embryos. Thermal adaptation resulted in several key changes: increased expression of genes associated with embryo quality (Cdh1, Gja1, Dnmt1); decreased expression of Wnt and mTOR genes and proteins; and upregulated expression of GSK3β and autophagy-related markers (LC3B, Beclin-1). Consequently, thermal adaptation increased the blastocyst rate and improved embryo quality. These findings suggest that thermal adaptation during early embryo development enhances developmental competence by inhibiting the Wnt signaling pathway and activating autophagy.