Sex-specific cardiac remodeling and metabolic reprogramming in IUGR F2 fetuses following glyphosate or glyphosate-based herbicide exposure.

We previously demonstrated that perinatal exposure to a glyphosate-based herbicide (GBH) or pure glyphosate (Gly) induces intrauterine growth restriction (IUGR) in second-generation (F2) rats. Given the association between IUGR and fetal cardiac remodeling, we investigated whether ancestral exposure programs structural, mitochondrial, and metabolic alterations in F2 fetal hearts. Pregnant F0 rats received GBH or Gly (3.88 and 3.83 mg glyphosate/kg/day, respectively) from gestational day (GD) 9 to F1 weaning. F1 females were subsequently mated and euthanized at GD19 to collect male and female F2 fetal hearts. Both treatments increased relative heart weight in males, while GBH induced left ventricle dilation in both sexes, compatible with a globular phenotype. In males, Gly reduced cardiomyocyte proliferation and Dio2 expression, and both treatments increased Vcam1 expression. GBH also decreased mitochondrial DNA copy number while upregulating Nd1 and mitochondrial biogenesis markers, suggesting a compensatory response. In females, GBH increased Pdk4 and Pgc1-α expression, and Gly increased Pparα and Acadl expression, indicating a metabolic reprogramming. Autofluorescence lifetime imaging revealed sex- and treatment-dependent alterations in NAD(P)H and FAD lifetimes. Overall, effects were more pronounced in GBH-exposed lineage and in males, whereas Gly induced subtler alterations. These findings identify the fetal heart as a multigenerational target of herbicide exposure and highlight the contribution of co-formulants to developmental toxicity.