OECD validation of the Hershberger assay in Japan: phase 2 dose response of methyltestosterone, vinclozolin, and p,p'-DDE.

Abstract

The Organisation for Economic Co-operation and Development has initiated the development of new guidelines for the screening and testing of potential endocrine disruptors. The Hershberger assay is one of the assays selected for validation based on the need for in vivo screening to detect androgen agonists or antagonists by measuring the response of five sex accessory organs and tissues of castrated juvenile male rats: the ventral prostate, the seminal vesicles with coagulating glands, the levator ani and bulbocavernosus muscle complex, the Cowper's glands, and the glans penis. The phase 1 feasibility demonstration stage of the Hershberger validation program has been successfully completed with a single androgen agonist and a single antagonist as reference substances. The phase 2 validation program employs a range of additional androgen agonists and antagonists as well as 5alpha-reductase inhibitors. Seven Japanese laboratories have contributed phase 2 validation studies of the Hershberger assay using methyltestosterone, vinclozolin, and 2,2-bis (4-chlorophenyl)-1,1-dichloroethylene (p,p'-DDE). The methyltestosterone doses were 0, 0.05, 0.5, 5, and 50 mg/kg/day, and the vinclozolin and p,p'-DDE doses were 0, 3, 10, 30, and 100 mg/kg/day. All chemicals were orally administered by gavage for 10 consecutive days. In the antagonist version of the assay using vinclozolin and p,p'-DDE, 0.2 mg/kg/day of testosterone propionate was coadministered by subcutaneous injection. All five accessory sex preproductive organs and tissues consistently responded with statistically significant changes in weight within a narrow window. Therefore, the Japanese studies support the Hershberger assay as a reliable and reproducible screening assay for the detection of androgen agonistic and antagonistic effects.

Cumulative Effects of In Utero Administration of Mixtures of “Antiandrogens” on Male Rat Reproductive Development

“…These pesticides, or their metabolites, competitively inhibit the binding of androgens to AR, which leads to inhibition of androgen-dependent gene expression in vitro and in vivo (Kelce and Wilson 1997). Vinclozolin and procymidone both act as AR antagonists in the Hershberger assay (castrated-immature androgen-and pesticide-treated male rats), an effect replicated in several laboratories (Ashby et al 2004;Charles et al 2005;Kang et al 2004;Kennel et al 2004;Owens et al 2007;Shin et al 2007;Yamasaki et al 2003).…”

Analysis of the effects of androgens and training on myostatin propeptide and follistatin concentrations in blood and skeletal muscle using highly sensitive Immuno PCR

“…The Hershberger assay was performed according to the guidelines of the rodent Hershberger assay (Yamasaki et al 2003). The rats were orchiectomised under anesthesia (Rompun / Ketanest).…”

The Antiandrogenic Activity of the Fungicide N-(3, 5-Dichlorophenyl) Succinimide in In Vivo and In Vitro Assays

“…Based on the in vitro assay results, we further tested the antiandrogenic activity of NDPS by in vivo Hershberger assay, a powerful tool for EDC screening that is recommended by EDSTAC [19,26] and the Organisation for Economic Co-operation and Development (OECD) [27]. NDPS remarkably reduced the weights of sex accessory tissues including the seminal vesicle, ventral prostate, dorsolateral prostate, levator ani/bulbocavernosus muscle, and Cowper's glands (Table 4).…”