(Anti-) androgenic reactions in the rat prostate and seminal vesicle: Validation of proliferation markers and androgen receptor staining pattern and the effects of the „xenoestrogen“ BPA in the Wistar rat.

Androgenic effects of xenoestrogens are now in the focus of research: Therefore, the aim of this study was to validate proliferating activities using immunohistochemistry and morphometry for the evaluation of androgen-like effects of the xenoestrogen bisphenol A. Bisphenol A is an industrial monomer used in the production of polycarbonate plastics and epoxy resins. Orchiectomized Wistar rats (the negative control group), (n=13) were treated p.o. with 3, 50, 200, 500mg/kg bw/day for seven days. The positive control group was treated s.c. with 1mg/kg bw/day testosterone propionate (TP). Flutamide (3mg/kg bw/day p.o.) was used to antagonize possible androgen effects of the „high dose“ of BPA. Immunohistochemical staining and proliferating activity were determined morphometrically using the Axiophot of Zeiss-Vision (KS 300, KS 100, KS RUN). For the densitometric evaluation of the androgen receptor staining we used a polyclonal antibody (sc-815, Santa Cruz) as well as a monoclonal antibody (No. 554224, BD PharMingen). For the evaluation of the proliferation we used two different primary antibodies from DakoCytomation (Ki-67 antigen, Clone MIB-5) and from Novocastra (PCNA, Clone PC10). Counting the number of immunoreactive cells (N=1000 per [13] sections) in prostate the following data were achieved: 1. PCNA: Intact 90%, Orchiectomized 10%, TP substituted orchiectomized rats 88%, 3mg/kg bw BPA 3%, 50mg/kg bw BPA 4%, 200mg/kg bw BPA 3%, 500mg/kg bw BPA 5%, 500+FL BPA 5% immunoreactive cells. 2. MIB-5: Intact 85%, Orchiectomized 8%, TP substituted orchiectomized rats 90%, 3mg/kg bw BPA 11%, 50mg/kg bw BPA 9%, 200mg/kg bw BPA 3%, 500mg/kg bw BPA 2%, 500+FL BPA 1% immunoreactive cells. In view of the validation of the proliferation markers analyzed and the reaction of the androgen receptor it can be concluded that the proliferation markers proofed to indicate androgenic reactions stimulating proliferation activity more sensitive. BPA showed in all doses tested no stimulation of the proliferating activity on prostate cells compared with the castrated control.