Androgen uptake and binding in rat epididymal nuclei, in,vivo

Androgen binding in epididymis was studied in mature rats eviscerated and functionally hepatectomized 18 h after castration. 1,2,6,7-³H-testosterone injected iv was recovered in 105,000 g supernatant and nuclear fractions largely as labeled dihydrotestosterone (³H-DHT) bound to macromolecules. On sucrose density gradients, both epididymal supernatant and nuclear binding components had sedimentation coefficients of 3-4S. Similar nuclear binding components were found in ventral prostate and seminal vesicle but not in kidney or lung. The temporal relationship between binding in epididymal supernatant and nuclear fractions was consistent with the transfer of ³H-DHT-macromolecular complexes from the cytoplasm into the nucleus.