IMMUNOHISTOCHEMISTRY AND IN-SITU HYBRIDIZATION OF THE ANDROGEN RECEPTOR IN THE DEVELOPING HUMAN PROSTATE

As it is suggested that the androgen receptor mechanism is required fo r prostatic development, we attempted to determine the appearance, exp ression and distribution of the androgen receptor in embryonic, infant ile and pubertal prostate. Using mono- and polyclonal antibodies and a digoxigenin-labeled 713 bp riboprobe, the androgen receptor expressio n in paraffin sections of fetal, infantile, and pubertal prostates was studied at the protein and RNA level. Under highly standardized condi tions, application of the polyclonal antibodies resulted in a weak cyt oplasmic and nuclear labeling of the epithelium of fetal glands. No im munoreaction was obtained with monoclonal antibodies. Applying the pol yclonal antibody to pubertal and adult specimens? immunoreactivity of the androgen receptor was positive in nuclei of adluminal and basal ep ithelial cells, in interstitial and vascular smooth muscle cells and v ascular endothelium, whereas ganglionic cells and enteroendocrine cell s were negative. In situ hybridization with the digoxigenin-labeled ri boprobe gave clear positive results already in epithelium of very youn g fetal specimens. A semiquantitative visual evaluation of in situ hyb ridizations showed that intermediate intensity of expression was incre ased in pubertal and adult specimens, whereas strong expression was re duced in prostatic epithelium. Conclusions: The essential findings are : (1) an early expression of androgen receptor mRNA in the fetal prost ate; (2) no immunoreaction of monoclonal antibodies against the androg en receptor in the same specimens, (3) a decrease of androgen receptor mRNA expression, but increase in immunoreactivity of the androgen rec eptor protein with the onset of glandular maturation during puberty.