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() Effects of estradiol and atrazine on testicular ultrastructure in Xenopus laevis.

Hecker, M.¹, Kim, W. J.², Park, J.-W.¹, Villeneuve, D.³, Murphy, M.¹, Jones, P.¹, Solomon, K.⁴, van der Kraak, G.⁴, Kendall, R.⁵, Giesy, J.¹, ¹ Michigan State University, East Lansing, Michigan, USA² Soonchunhyang University, Asan-si, Chungcheongnam-do, Korea³ Oregon State University, Corvallis, Oregon, USA⁴ University of Guelph, Guelph, Ontario, Canada⁵ Texas Tech University, Lubbock, Texas, USA

ABSTRACT- Adult male African clawed frogs (Xenopus laevis) were exposed to either estradiol (0.1g/L) or atrazine (10 or 100g/L) to examine potential ultrastructural alterations of testicular cells by use of electron microscopy. Results from ultrastructural analyzes were compared to concentrations of steroid hormones testosterone (T) and estradiol (E2) in plasma and gonad growth expressed as the gonado-somatic index (GSI). Exposure to E2 caused significant changes both at the sub-cellular and biochemical level. Exposure to E2 resulted in significantly fewer sperm cells, inhibition of meiotic division of germ cells, increase in lipid droplets that are storage compartments for the sex steroid hormone precursor cholesterol, and reduced plasma T concentrations (control: 13.8ng/ml; E2: 0.7ng/ml; p<0.05). E2 concentrations in plasma increased in response to exposure to estradiol in water (control: 3.4ng/ml; E2: 9.2ng/ml; p<0.05). Exposure to neither concentration of atrazine caused effects on germ cell development, testicular aromatase activity or plasma hormone concentrations. These results suggest that atrazine does not affect testicular function. In contrast, exposure of male X. laevis to E2 led to sub-cellular events that are indicative of disruption of testicular development, and demasculinization processes (decrease of androgen hormone titers).

Key words: testicular ultrastructure, atrazine, amphibians, aromatase