This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by TEZON, J. G. Articles by BLAQUIER, J. A. Search for Related Content PubMed PubMed Citation Articles by TEZON, J. G. Articles by BLAQUIER, J. A.

Androgens Control Androgen-Binding Sites in Rat Epididymis^*

JORGE G. TEZON and JORGE A. BLAQUIER

Institute de Biologia y Medicina Experimental, Laboratorio de Esteroides Obligado 2490, 1428 Buenos Aires, Argentina

Abstract

Previous results suggested that the number of androgen-binding sites in rat epididymis was controlled by androgens. Using an exchange technique for receptor determination, we now report that cytoplasmic receptor number decreased to about half the control value after 4 days of castration and reached its lowest level (30% of the control value) after 12 days of castration. The Kd for [³H]methyltrienolone for cytoplasmic receptor varied from 2.8 x 10^–9 M in controls to 0.6 x 10^–9 M (P < 0.001) after 6 or more days of castration. Nuclear binding sites were reduced to 17% of the control value from the second day of castration on, but no change in the affinity for methyltrienolone was noted.

The administration of testosterone propionate (400 µg/day) to rats castrated for 20 days significantly increased the number of nuclear and cytoplasmic binding sites from the second and third days of treatment, respectively. Labeled thymidine incorporation into DNA rose significantly after a 4-day latency period. The proportion of total binding sites capable of translocation into the nucleus was elevated during the early phase (2–4 days) of androgen treatment. These results also suggest the heterogeneity of the cytoplasmic binding site population.

Control epididymides were composed of 61.5% receptor-containing epithelial cells, and this proportion was significantly reduced to 53.2% after 20 days of castration. Androgen administration elevated this percentage after an 8-day latency period.

Proteolytic activity in cytosol was increased over control values after castration (for 20 days) and until the fourth day after the onset of androgen treatment. However, this activity does not seem to be an important factor in the decrease in binding sites caused by orchidectomy. (Endocrinology 113:1025, 1983)

Footnotes

^* This work was supported by the National Research Council (Argentina) and Ford Foundation Grant 780-0349.

Research Career Awardee, National Research Council (Argentina). To whom requests for reprints should be addressed.

Received September 16, 1982.

This article has been cited by other articles:

				N. A. Henderson, G. M Cooke, and B. Robaire Region-specific expression of androgen and growth factor pathway genes in the rat epididymis and the effects of dual 5{alpha}-reductase inhibition. J. Endocrinol., September 1, 2006; 190(3): 779 - 791. [Abstract] [Full Text] [PDF]

				L. O'Donnell, K. M. Robertson, M. E. Jones, and E. R. Simpson Estrogen and Spermatogenesis Endocr. Rev., June 1, 2001; 22(3): 289 - 318. [Abstract] [Full Text] [PDF]

				X. Fan and B. Robaire Orchidectomy Induces a Wave of Apoptotic Cell Death in the Epididymis Endocrinology, April 1, 1998; 139(4): 2128 - 2136. [Abstract] [Full Text] [PDF]