Immunolocalization of Steroid 5.ALPHA.-Reductase Type 2 in Human Prostate, Seminal Vesicle and Vas Deferens. Light and Electron Microscopic Immunohistochemistry.

Abstract

Localization of steroid 5α-reductase type 2 in human prostate, seminal vesicle and vas deferens was investigated by light and electron microscopic immunohistochemistry using a rabbit polyclonal antiserum raised against a synthetic peptide fragment representing amino acids 225-240 of the human 5α-reductase type 2 enzyme. Under light microscope, the enzyme was localized in the cytoplasm of basal epithelial and stromal cells of the prostate. Secretory epithelial cells were negative. There was no immunoreaction in cell nuclei. Double immunostaining for 5α-reductase and muscle specific actin indicated that all smooth muscle cells had 5α-reductase type 2. However, a few type 2-positive cells did not react with a muscle specific actin antibody. Electron microscopic immunocytochemistry revealed that the cytoplasm of smooth muscle cells and of a few fibroblasts had immunoreaction products for this enzyme. In the seminal vesicle and vas deferens, basal and smooth muscle cells were positive for the type 2 enzyme. These findings indicate that the major sites of the DHT production are basal epithelial cells and stromal smooth muscle cells in human prostate, seminal vesicle and vas deferens. These cells may play a role in maintaining the functional activity of these male accessory sex organs through the production of DHT.