Metformin attenuates valproic acid-induced developmental cardiotoxicity through activation of the AMPK/PGC-1α axis and restoration of mitochondrial and redox homeostasis in zebrafish embryos.

Prenatal valproic acid (VPA) exposure is strongly linked to developmental cardiotoxicity, yet no targeted pharmacological countermeasure exists. Converging mechanistic evidence indicates that VPA cardiotoxicity centers on AMPK/PGC-1α suppression, positioning the AMPK activator metformin (MET) as a rational candidate for in vivo protection. We examined MET's protective effects against VPA-induced developmental cardiotoxicity in zebrafish embryos. Embryos were randomly allocated to four groups (Control, VPA 0.1 mM, MET 10 mM, VPA + MET) immediately after fertilization and chronically exposed until 96 hpf. Oxidative stress biomarkers (MDA, NO, SOD, GSH) and the expression of cardiac (nkx2.5, vmhc, amhc), AMPK (prkaa2, acaca), and mitochondrial/energy-related genes (ppargc1a, cpt1b, pck1, atp5pb, mt-nd1) were quantified. Compared with controls, VPA reduced nkx2.5 (p < 0.01) and elevated amhc (p < 0.05), triggered pericardial edema (p < 0.0001), suppressed prkaa2, ppargc1a, and atp5pb (p < 0.05, p < 0.001, and p < 0.0001, respectively), upregulated acaca (p < 0.0001), increased MDA and NO (p < 0.0001), and lowered SOD and GSH (p < 0.0001 and p < 0.001, respectively). Relative to the VPA group, MET co-treatment restored nkx2.5 expression (p < 0.001), attenuated pericardial edema (p < 0.0001), increased prkaa2 (p < 0.05), ppargc1a (p < 0.01), and atp5pb (p < 0.0001), suppressed acaca (p < 0.0001), and normalized MDA (p < 0.05), NO (p < 0.0001), SOD, and GSH (both p < 0.0001). The restoration of prkaa2/ppargc1a, mitochondrial, and antioxidant capacity by MET suggests that the AMPK/PGC-1α axis may serve as a central target in VPA cardiotoxicity.