Immunohistochemical localization of steroid 5 alpha-reductase 2 in the human male fetal reproductive tract and adult prostate.

Abstract

The activity of the type 2 isozyme of steroid 5 alpha-reductase is crucial for normal development of the external genitalia and prostate in human males. We used immunohistochemistry to localize type 2 isozyme expression in the human male fetal reproductive tract and adult prostate. In fetal tissue, the stroma of the seminal vesicles, corpus cavernosum, corpus spongiosum, dorsal vein complex, scrotal skin, and prostate expressed the enzyme. In addition, the epithelial cells of the fetal urethra and proximal prostatic ducts stained positively. The type 2 isozyme could not be detected in epithelial cells of the fetal prostatic acini, seminal vesicles, prostatic utricle, ejaculatory ducts, epididymides, and Cowper's glands. Adult prostate specimens were derived from transurethral prostatectomies performed for benign prostatic hyperplasia. Enzyme expression in these benign prostatic hyperplasia samples localized to the stroma and epithelial cells of the urethra and proximal ducts. No staining was detected in the acinar (luminal and basal) epithelial cells. Double staining with an antismooth muscle actin antibody localized type 2 isozyme expression to the stromal fibroblast cells of the prostate. Double staining with an androgen receptor antibody localized AR expression to the acinar epithelial cells and stromal fibroblasts. These data indicate that 5 alpha-reductase type 2 is expressed throughout the developing male genitourinary tract and functions as both an autocrine and a paracrine mediator of growth and differentiation.

Anatomical and cellular localization of neuroactive 5α/3α‐reduced steroid‐synthesizing enzymes in the spinal cord

“…The study was possible thanks to the availability of highly specific antisera against 5␣-R1, 5␣-R2, and 3␣-HSD, which have already been used successfully to localize these enzymes in various steroidogenic tissues (Smithgall and Penning, 1988;Andersson and Russell, 1990;Pawlowski et al, 1991;Thigpen et al, 1993;Jez et al, 1996;Levine et al, 1996). The preabsorption experiments performed on SC sections as internal control in this work confirmed the specificity of 5␣-R1, 5␣-R2, and 3␣-HSD immunoreactions.…”

“…Although the specificity of 5␣-R1, 5␣-R2, and 3␣-HSD antisera has previously been demonstrated extensively (Smithgall and Penning, 1988;Andersson and Russell, 1990;Pawlowski et al, 1991;Thigpen et al, 1993;Jez et al, 1996;Levine et al, 1996), internal control experiments were performed in the present work to confirm the specificity of immunoreactions observed in the SC. These control experiments were 1) the substitution of 5␣-R1, 5␣-R2, or 3␣-HSD antiserum with PB; 2) replacement of each antiserum with nonimmune rabbit serum; and 3) preincubation of each antibody with purified corresponding antigen.…”

“…The peptidic fragments used as immunogens correspond to highly conserved regions in the amino acid sequences of rat and human 5␣-R1 and 5␣-R2 isozymes (Andersson and Russell, 1990). The specificity and effectiveness of these antisera have already been extensively demonstrated in rat and human prostate and gonadal tissues by immunoblotting, Western blotting, and immunohistochemical experiments (Andersson et al, 1989;Andersson and Russell, 1990;Thigpen et al, 1993;Silver et al, 1994;Levine et al, 1996).…”

“…Although previous studies have thoroughly shown the specificity and effectiveness of the three antisera in various nonneural tissues (Smithgall and Penning, 1988;Andersson and Russell, 1990;Pawlowski et al, 1991;Thigpen et al, 1993;Jez et al, 1996;Levine et al, 1996), control experiments were performed with the SC sections. Preincubation of 5␣-R1, 5␣-R2, and 3␣-HSD antisera with the respective antigen (10 g/ml) resulted in a disappearance of the immunoreaction in the SC of intact female, male, GDX/ADX, or sham-operated rats (Fig.…”

Expression of the androgen receptor and 5α-reductase type 2 in the developing human fetal penis and urethra

“…To improve our understanding of the role of androgens in human male fetal urethral development, it is necessary to know the distribution of the AR and 5α-reductase type 2 in the developing external genitalia. Several studies have been performed in animals (Veyssiere et al 1985;Cooke et al 1991;Tsuji et al 1994;Bentvelsen et al 1995;Tian and Russell 1997); however, complete data are lacking in human tissues, and prior studies have not focused on urethral development in the human fetus (Kalloo et al 1993;Levine et al 1996).…”