Antiandrogenic pesticides disrupt sexual characteristics in the adult maleguppy (Poecilia reticulata)

Environmental contaminants have been identified as endocrine disruptors thr ough their antiandrogenic activity. Thus, as androgen receptor antagonists, the fungicide vinclozolin and the principal DDT metabolite p,p ' -DDE have been demonstrated to induce demasculinization in rats. Whether this is als o the case in fish remains to be demonstrated. For a period of 30 days, gro ups of adult male guppies were exposed to vinclozolin, p,p ' -DDE, or the t herapeutic antiandrogen flutamide (used as positive control) applied to the fodder at concentrations between 0.1 and 100 mug/g fodder. Subsequently, s exual characteristics of relevance to the male reproductive capacity were m easured and compared with untreated control fish. All three chemicals cause d profound alterations at increasing levels of biological organization, eve n in these fully matured males. At the cellular level, the three compounds induced a significant reduction in the number of ejaculated sperm cells. At the organ level, the sexually attractive orange-yellow coloration was redu ced in area and discolored, and treated fish also had smaller testes. Furth er, at the organismal level, computer-aided behavior analyses demonstrated a severe disruption in male courtship behavior. We conclude that this demas culinization is consistent with an antiandrogenic action of vinclozolin and p,p ' -DDE and is likely to compromise reproductive capability in this fis h.