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Test substance VP SVCG LABC GP COWS Androgen agonists MT 8 8 8 8 8 TREN 3 3 3 3 3 Androgen antagonists PRO 5 5 5 4 5 VIN 8 8 8 7 8 LIN 3 4 4 1 3 DDE 9 9 9 9 9 5[alpha]-Reductase inhibitor FIN 4 4 4 3 4 Times a single tissue was 4 3 0 0 1 the most sensitive end point Times the tissue was equally 30 27 29 13 23 sensitive with at least one other tissue Times tissue was not 1 (a) 0 1 (a) 7 (a) 1 (a) statistically significant by either approach (a) One common instance was laboratory 6 with LIN.
Nine laboratories assessed the detection of the weak androgen antagonist DDE.
Four laboratories assessed the detection of this androgen antagonist using doses of 3, 10, 30, and 100 mg PRO/kg bw/day coadministered with 0.
Four laboratories assessed the detection of this weak androgen antagonist using doses of 3, 10, 30, and 100 mg LIN/kg bw/day coadministered with 0.
Then, the assay was adapted for androgen antagonists such as flutamide (FLU) (Peets et al.
The protocols have been refined, and the next phases of the OECD validation program will test the protocol with selected doses of weak androgen agonists, androgen antagonists, a 5[alpha]-reductase inhibitor, and chemicals having no androgenic activity.
The objectives of the first phase of the OECD validation of the Hershberger bioassay were to a) demonstrate the reproducibility and sensitivity of the responses of five male sex accessory tissues to the action of a reference androgen, TP, hereafter phase 1A; b) assess the utility, reproducibility, and sensitivity of various other measured end points within and among participating laboratories in response to the action of TP; c) study the interaction of reference TP doses with a reference androgen antagonist, FLU, on the sex accessory tissues and other end points, hereafter phase 1B; and d) select standard reference doses of TP and FLU for future studies with weakly potent agonists, antagonists, and nonandrogenic test substances.
For the androgen antagonists (VCZ and p,p'-DDE), 0.
This finding demonstrates that no significant differences exist regarding the use of SD and Wistar rats in the Hershberger assay for the detection of androgen antagonists.