Strain sensitivity differences in the Hershberger assay

The Hershberger assay is a test method for detecting androgenic or antiandrogenic properties based on alterations in the weights of accessory sex organs in castrate male animals. We performed this study to examine strain sensitivity differences in the Hershberger assay. Flutamide (FLU) at a dose of 3.2 mg/kg was administered to castrated F344, SD, or Wistar rats, in addition to testosterone propionate (TP) administered at a dose of 0.4 mg/kg. Although FLU significantly attenuated the TP-induced increase in glans penis weight in SD and Wistar rats, this attenuation was not observed in F344 rats. Statistical analysis showed differences among the strains in all sex accessory organ weights. The interaction in the ventral prostate, seminal vesicle, and glans penis weights was significant between SD and F344 rats, and between Wistar and F344 rats, but not between SD and Wistar rats. F344 rats were less suitable than SD or Wistar rats for detecting FLU-induced changes.