Androgen receptors in bone-forming tissue.

Androgen receptors (AR) were stained in sections of normal human growth plate of the costo sternal junction obtained at postmortem from one 4-day-old and two 5-day-old male infants, and in osteoblasts, grown in culture obtained from the femora of 3 male patients undergoing orthopaedic surgery for osteoarthritis. In the growth plate AR were found mostly in a narrow band of chondrocytes occupying an area about midway between the proximal and distal end of the epiphysis. Nearly all AR were in the cytoplasm and appeared in a granular form; there was no diffuse staining and the nuclei were either completely devoid of AR or only contained a few. Less-differentiated chondroblasts, perichondrial cells and hypertrophic chondrocytes contained few or no AR. Osteoblasts (and osteocytes) contained numerous AR and almost all were in the cytoplasm. Normal human osteoblasts, in their second or third passage, were grown on coverslips either in a medium with no added androgen or in the presence of 5alpha-dihydrotestosterone or methyltrienolone for a period of 24 h or longer. In control cultures, with vehicle and no added androgen, nearly all AR were found in the cytoplasm, with hardly any in the nucleus. In the presence of added androgen some osteoblasts from two of the specimens demonstrated a clear translocation of AR into the nucleus, whilst osteoblasts from a third specimen failed to translocate. These preliminary results indicate that AR translocation to the nucleus occurs in osteoblastic cells derived from osteoarthritic subjects. However, the ability to translocate may depend on the state of differentiation of the osteoblast and on culture conditions.