310. Oestrogen receptor alpha and beta in the prostate of the brushtail possum (Trichosurus vulpecula)

Abstract

Oestrogen plays a physiological role in the growth of the prostate and has been implicated in the development of prostate disease in man. Both oestrogen receptors are present in the normal human prostate with oestrogen receptor alpha (ERα) localised in stromal cells and oestrogen receptor beta (ERβ) in epithelial cells. However, in benign prostatic hyperplasia (BPH) ERα is found in both stromal and epithelial cells. The study of human prostate growth is complicated by the lack of a suitable animal model. The brushtail possum (Trichosurus vulpecula), however, may provide a novel model for such studies. It has a prostate that is structurally similar to that in man and also exhibits seasonal hyperplasia and regression. This study investigated the localisation of ERα and ERβ in the possum prostate. Male possums were killed throughout the year including the breeding season when the prostate is enlarged and the non-breeding season. Each prostate was divided into central and posterior regions and either fixed in Bouins fluid or snap frozen. The presence of both ERα and ERβ were determined using Western blotting with the Novocastra antisera NCL-ER-6F11 (ERα) and NCL-ER-beta (ERβ). Immunohistochemical localisation of the receptors was determined using the same antisera for ERα on paraffin sections, and for ERβ on frozen sections. Western blotting demonstrated immunoreactive bands of ~60 kDa for ERα and ERβ protein in the central and posterior prostate in the breeding and non-breeding periods. ERα was localised to the nuclei of both epithelial and stromal cells in central and posterior regions of the prostate throughout the year. ERβ was localised to the nuclei of stromal cells in the central and posterior prostate throughout the year. This study confirms the presence of ERα and ERβ in the possum prostate. The distribution of ERα is similar to that seen in prostatic tissue from men with BPH.