(94) Maternal consumption of environmentally relevant atrazine concentrations impairs the biosynthesis of 10 testicular steroids in male offspring

D.F. Ahern¹; M. Zahid²; E.G. Rogan^2,3; S.E. Bartelt-Hunt⁴; B. R. White⁵; S. J. Sillman¹; A.T. Desaulniers¹

¹School of Veterinary Medicine & Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 

²Department of Environmental, Agricultural and Occupational Health, College of Public Health, University of Nebraska Medical Center, Omaha, NE

³Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha NE

⁴Department of Civil and Environmental Engineering, University of Nebraska-Lincoln, Lincoln, NE

⁵Department of Animal Science, University of Nebraska-Lincoln, Lincoln, NE 

Abstract Text:

Over the last 50 years, sperm counts of men have declined by >50%, demonstrating a male fertility crisis. These deficits may be due, in part, to developmental programming of the testis. Testicular development is extensive and malleable during both fetal and early post-natal life. Perturbations during these critical periods alter the trajectory of gonadogenesis and impair future fertility. Atrazine is an herbicide heavily used in U.S. corn production and an endocrine-disrupting chemical. Atrazine concentrations over 20 µg/L have been detected in groundwater of agricultural states, exceeding the Environmental Protection Agency limit (3 µg/L). Epidemiological and rodent data suggest many adverse effects of atrazine on reproductive development and/or function. However, these results have inherent limitations (estimated exposure and supraphysiological doses, respectively). Furthermore, few studies have evaluated the effects of atrazine in swine, a preeminent biomedical model. The objective of the present study is to evaluate if maternal consumption of environmentally relevant atrazine concentrations affect testicular steroidogenesis – a key driver of testicular development – in exposed piglets.  Pregnant littermate gilts drank water containing either atrazine (20 µg/L; n = 4) or vehicle control [0.002% (v/v) ethanol; n = 3)] ad libitum from 28 days of gestation through parturition (~127 days total). After farrowing, atrazine-exposed (ATZ; n = 24) and control (n = 12) boars nursed their respective dams ad libitum prior to necropsy on post-natal day 10. Serum was isolated and subjected to high performance liquid chromatography tandem mass spectrometry using the AbsoluteIDQ Stero17 Panel. Data were analyzed via the MIXED procedure of SAS with treatment as the fixed effect and boar as the experimental unit. Serum concentrations of glucocorticoids (cortisol, 11-deoxycorticosterone, corticosterone, and 11-deoxycortisol) were unaffected by ATZ treatment, except for cortisone (an inactive glucocorticoid) that was reduced (P < 0.05) in ATZ boar serum compared to controls. Overall, these data suggest that adrenal steroidogenesis is largely unaffected by ATZ treatment. Gonadal steroids, however, were dramatically affected by ATZ treatment, including progestogens, androgens, and estrogens. Regarding progestogens, serum concentrations of progesterone did not differ by treatment (P = 0.3475) but 17α-hydroxyprogesterone was reduced by 33% in ATZ boars compared to controls (P = 0.0025). Regarding estrogens, estrone tended (P = 0.0934) to be affected by treatment (21% reduction) whereas 17β-estradiol was reduced (P = 0.0318) by 29% in serum of ATZ boars. Of note, all seven androgens examined were reduced (P < 0.05) in ATZ exposed animals compared to control boars including testosterone (27%), dihydrotestosterone (67%), dehydroepiandrosterone (DHEA; 39%), DHEA sulphate (34%), androstenedione (45%), androsterone (57%), and etiocholanolone (49%). Overall, these results indicate that testicular steroidogenesis – particularly androgen production – is significantly impaired by maternal ATZ consumption. Steroids produced during the first few weeks of life, a period called mini-puberty, regulate testicular development (e.g., Sertoli cell proliferation) and brain masculinization. Thus, ATZ-mediated inhibition of testicular steroidogenesis during mini-puberty may have long-term fertility consequences. Ultimately, these data have negative implications for human and animal reproductive health. Atrazine in groundwater of agricultural states may hinder the reproductive development of infants and subsequent fertility of men. Likewise, early-life atrazine exposure may compromise fertility of breeding boars, thereby posing an underappreciated threat to reproductive efficiency in the swine industry.