title: 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.
authors.affiliation: Department of Biochemistry and Molecular Biology, Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan.
authors.forename: Agnes L
authors.initials: AL
authors.lastname: Karmaus
authors.affiliation: Department of Biochemistry and Molecular Biology, Center for Integrative Toxicology, Michigan State University, East Lansing, Michigan.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Zacharewski
mesh_terms: D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000818:Animals; D001280:Atrazine / Q000633:toxicity*; D045744:Cell Line, Tumor; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D052244:Endocrine Disruptors / Q000633:toxicity*; D006540:Herbicides / Q000633:toxicity*; D007985:Leydig Cells / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D010726:Phosphodiesterase Inhibitors / Q000633:toxicity; D010766:Phosphorylation; D015290:Second Messenger Systems / Q000187:drug effects; D013739:Testosterone / Q000096:biosynthesis*; D013997:Time Factors
chemical_list: D006063:Chorionic Gonadotropin; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D052244:Endocrine Disruptors; D006540:Herbicides; D010726:Phosphodiesterase Inhibitors; D013739:Testosterone; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D001280:Atrazine
keywords: Atrazine; Leydig cell; phosphodiesterase; steroidogenesis; testosterone