Effects of two fungicides with multiple modes of action on reproductive endocrine function in the fathead minnow (Pimephales promelas).
Many chemicals that adversely affect reproduction and/or development do so through multiple pathways within the reproductive tract and hypothalamic-pituitary-gonadal axis. Notable in this regard are fungicides, such as prochloraz or fenarimol, which in mammals have the potential to impact endocrine function through inhibition of CYP enzymes involved in steroid metabolism, as well as through antagonism of the androgen receptor(s). The objective of our studies was to assess the effects of prochloraz and fenarimol on reproductive endocrine function in a model small fish species, the fathead minnow (Pimephales promelas), using both in vitro and in vivo assays. The two fungicides inhibited in vitro CYP19 aromatase activity in brain and ovarian homogenates from the fish, with prochloraz exhibiting a greater potency than fenarimol. Prochloraz and fenarimol also bound competitively to the cloned fathead minnow androgen receptor expressed in COS-1 cells. The two fungicides significantly reduced fecundity of the fish in a 21-day reproduction assay at water concentrations of 0.1 (prochloraz) and 1.0 (fenarimol) mg/l. The in vivo effects of prochloraz on plasma steroid (17beta-estradiol, testosterone, 11-ketotestosterone) and vitellogenin (an estrogen-responsive protein) concentrations, as well as on gonadal histopathology, were consistent with inhibition of steroidogenesis. Fenarimol also affected several aspects of endocrine function in vivo; however, the suite of observed effects did not reflect either aromatase inhibition or androgen receptor antagonism. These studies contribute to a better mechanistic understanding of the extrapolation of effects of endocrine-disrupting chemicals across vertebrate classes.
Ankley
Gerald T
GT
U.S. Environmental Protection Agency, ORD, NHEERL, Mid-Continent Ecology Division, Duluth, Minnesota 55804, USA. ankley.gerald@epa.gov
Jensen
Kathleen M
KM
Durhan
Elizabeth J
EJ
Makynen
Elizabeth A
EA
Butterworth
Brian C
BC
Kahl
Michael D
MD
Villeneuve
Daniel L
DL
Linnum
Ann
A
Gray
L Earl
LE
Cardon
Mary
M
Wilson
Vickie S
VS
D000818:Animals; D001141:Aromatase / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D019556:COS Cells; D002522:Chlorocebus aethiops; D003530:Cyprinidae; D004958:Estradiol / Q000097:blood; D005260:Female; D005298:Fertility / Q000187:drug effects; D005496:Follicular Atresia / Q000187:drug effects; D005659:Fungicides, Industrial / Q000633:toxicity*; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000378:metabolism; D007093:Imidazoles / Q000633:toxicity*; D008297:Male; D015741:Metribolone / Q000378:metabolism; D010053:Ovary / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D011743:Pyrimidines / Q000633:toxicity*; D011944:Receptors, Androgen / Q000378:metabolism; D013737:Testis / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood; D014819:Vitellogenins / Q000097:blood
D005659:Fungicides, Industrial; D007093:Imidazoles; D011743:Pyrimidines; D011944:Receptors, Androgen; D014819:Vitellogenins; D015741:Metribolone; D013739:Testosterone; D004958:Estradiol; C045362:prochloraz; D001141:Aromatase; C003600:11-ketotestosterone; C033789:fenarimol