Atrazine-mediated disruption of steroidogenesis in BLTK1 murine leydig cells

Abstract

Atrazine (ATR) is a broad-spectrum triazine herbicide that disrupts steroidogenesis resulting in reproductive and developmental toxicity at high doses. Mouse BLTK1 Leydig cells were used as a steroidogenic model to investigate the effects of ATR on testosterone (T) biosynthesis. Induction of steroidogenesis by 3 ng/ml recombinant human chorionic gonadotropin (rhCG) induced intracellular 3',5' cyclic adenosine monophosphate (cAMP) approximately 20-fold and T approximately 3-fold at 4 h. Co-treatment with 300 μM ATR super-induced cAMP levels 100-fold yet antagonized rhCG-mediated induction of T approximately 20% at 4 h. ATR inhibited cAMP-specific phosphodiesterase (cPDE) with an IC50 of ≥98 μM, suggesting cPDE inhibition contributes to the super-induction of cAMP. However, concentrations of up to 3 mM db-cAMP did not antagonize rhCG induction of T levels, suggesting cAMP super-induction alone does not decrease T biosynthesis. Western analysis of cAMP-activated protein kinase A (PKA) target proteins identified ATR-mediated concentration-dependent alterations in phosphorylation including phospho-CREB. These results suggest the cPDE inhibition by ATR and super-induction of cAMP are independent of effects on T levels, and that altered phosphorylation of key steroidogenic regulatory proteins may underlie ATR-mediated disruption of steroidogenesis.