Impairments in aromatase expression, reproductive behavior, and sperm quality of male fish exposed to 17β-estradiol

Growing evidence shows that environmental estrogen can reach levels that are high enough to exert adverse reproductive effects on wild fish populations. The authors report different parameters of male reproductive behavior, brain, and gonadal aromatase expression, as well as sperm quality in an internally fertilizing fish species (Jenynsia multidentata, Jenyns) exposed to environmentally relevant concentrations of 17 beta-estradiol (E2). Adult males were exposed to 0, 50, 100, and 250?ng/L E2 over 28?d. The authors' findings demonstrate that E2 exposure resulted in a very clear increase in brain aromatase transcript abundance at all assayed concentrations compared with control; however, no effects on gonadal aromatase expression were observed. Behavioral measures revealed increased sexual activity at 50?ng/L but not 100 or 250?ng/L E2. In contrast to the molecular and behavioral responses, the condition factor, gonadosomatic index, and sperm quality were unaltered by E2 exposure. The results from the present work suggest that E2 affects some aspects of the reproductive biology of J. multidentata. These modifications in the reproductive biology caused by exposure to E2 could potentially lead to long-term effects at population levels that may not always be immediately evident. To the best of the authors' knowledge, this is the first report on the combined effect of E2 on aromatase expression, sexual behavior, and sperm parameters in fish. Environ. Toxicol. Chem. 2012; 31: 935940. (C) 2012 SETAC