Androgen receptors in bone-forming tissue

Androgen receptors (AR) were stained in sections of normal human growth pla te 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 obtain ed from the femora of 3 male patients undergoing orthopaedic surgery for os teoarthritis. 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 c ompletely devoid of AR or only contained a few. Less-differentiated chondro blasts, perichondrial cells and hypertrophic chondrocytes contained few or no AR. Osteoblasts land osteocytes) contained numerous AR and almost all we re in the cytoplasm. Normal human osteoblasts, in their second or third pas sage, were grown on coverslips either in a medium with no added androgen or in the presence of 5 alpha-dihydrotestosterone or methyltrienolone for a p eriod of 24 h or longer. In control cultures, with vehicle and no added and rogen, nearly all AR were found in the cytoplasm, with hardly any in the nu cleus. In the presence of added androgen some osteoblasts from two of the s pecimens 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 osteoblasti c cells derived from osteoarthritic subjects. However, the ability to trans locate may depend on the state of differentiation of the osteoblast and on culture conditions.