Steroid biosynthetic enzyme activities in leachate-exposed female perch [An article from: Science of the Total Environment, The]

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Description:
Studies have shown that adult female perch in a freshwater lake, Molnbyggen, Sweden, have a reproductive disorder caused by unidentified endocrine disrupting compounds (EDCs) leaching from a local refuse dump. The adverse effects include shallow open sores, low ratio of sexually mature individuals, low gonadosomatic index and low circulating levels of androgens. We hypothesised that the low androgen levels could be a result of impaired production and/or stimulated excretion of androgens by EDCs. From October 2000 to November 2001, at time-points important in the perch reproductive cycle, adult female perch were collected in Molnbyggen and in the reference lake, Djursjon. The activities of three key enzymes in androgen biosynthesis: 17@a-hydroxylase (17OHlase), 17,20-lyase (lyase) and 17@b-hydroxysteroid dehydrogenase (17@bHSD) were determined in head kidney or ovary. The relationship between enzyme activities and plasma steroid concentrations was examined. Ovarian histopathology and the determination of brain aromatase activity were also included in the study. Similar 17OHlase, 17@bHSD and aromatase activities were found in Molnbyggen females and reference fish throughout the year. Head kidney 17OHlase showed a positive correlation to cortisol levels (r=0.754; p