Similar toxicity potential of glyphosate and glyphosate-based herbicide on cerebellar development after maternal exposure in rats.

ABSTRACT

Studies on the effects of glyphosate (GlyP) and glyphosate-based herbicides (GBHs) on cerebellar development are extremely limited. This study examined the effects of maternal exposure to GlyP and GBH on rat cerebellar development in male offspring. From day 6 of gestation until day 21 postpartum at weaning, dams were given GlyP at 1.5% or 3.0% in diet or GBH at 1.0% in drinking water (corresponding to 0.36% GlyP). At weaning, GBH exposure was linked to increased numbers of DCX+ migrating granule cells in the cortex and TUNEL+ apoptotic cells in the internal granular layer (IGL), suggesting the disappearance of mismigrated granule cells via apoptosis. GBH also upregulated Nr4a3 and downregulated Cdk5 in the cerebellar vermis, suggesting a causal relation with the impaired granule cell development at this time. GlyP (3.0%) tended to increase in the number of DCX+ migrating granule cells in the IGL and upregulated Nr4a3 at weaning. Both compounds also upregulated genes related to granule cell migration (Astn1, Astn2, Nfia, and/or Nfix) at weaning and in adulthood, which might be an ameliorative response to delayed granule cell migration. Moreover, GBH induced Purkinje cell misalignment at weaning, which could be the result of delayed granule cell migration. In adulthood, GBH was associated with upregulation of the reelin signaling-related genes Reln, Dab1, and Efnb1, suggesting a compensatory response to Purkinje cell misalignment. GlyP induced the same gene expression changes. These results suggest that GBH reversibly disrupts cerebellar development, primarily by targeting granule cell migration and differentiation, whereas GlyP exhibited similar toxic potential as GBH.