Inhibition of thyroid hormone release from cultured amphibian thyroid glands by methimazole, 6-propylthiouracil, and perchlorate.

Thyroid gland explant cultures from prometamorphic Xenopus laevis tadpoles were evaluated for their utility in assessing chemicals for thyroid hormone (TH) synthesis disruption. The response of cultured thyroid glands to bovine thyroid stimulating hormone (bTSH) and the TH synthesis inhibitors methimazole, 6-propylthiouracil, and perchlorate was determined. Thyroid glands continuously exposed for 12 days to graded concentrations of bTSH released thyroxine (T4) in a dose-dependent manner.

Development of quantitative real-time PCR assays for fathead minnow (Pimephales promelas) gonadotropin beta subunit mRNAs to support endocrine disruptor research.

Fathead minnows (Pimephales promelas) are a widely-used small fish model for regulatory ecotoxicology testing and research related to endocrine disrupting chemicals (EDCs). Quantitative real-time PCR assays for measuring fathead minnow gonadotropin (GtH) beta subunit transcripts were developed and "baseline" transcript levels in pituitary tissue were examined over a range of age classes and spawning states. Among females, GtHbeta transcripts did not vary significantly with gonadal-somatic index or gonad stage.

Evaluation of the methoxytriazine herbicide prometon using a short-term fathead minnow reproduction test and a suite of in vitro bioassays.

Prometon is one of the most consistently detected herbicides in the U.S. environment.

Reproductive and developmental toxicity and bioconcentration of perfluorooctanesulfonate in a partial life-cycle test with the fathead minnow (Pimephales promelas).

Perfluorooctanesulfonate (PFOS) is a widespread environmental contaminant emanating from the production and/or metabolism of fluorinated chemicals with a variety of applications. The goal of this work was to assess the toxicity and bioconcentration of PFOS in the fathead minnow (Pimephales promelas). Sexually mature fish were exposed via the water for 21 d to 0 (control), 0.

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.