Can Spermatogenesis Be Maintained Quantitatively in Intact Adult Rats with Exogenously Administered Dihydrotestosterone?

HAOLIN CHEN, VARADARAJ CHANDRASHEKAR, BARRY R. ZIRKIN

Research output: Contribution to journalArticlepeer-review

Abstract

ABSTRACT: It is well established that testosterone (T) is required to maintain spermatogenesis in the mammalian testis, presumably acting through a receptor mechanism, as elsewhere. It is puzzling, however, that the T concentration that is required to maintain spermatogenesis quantitatively in intact adult rats (15–20 ng/ml) is well in excess of the concentration required to saturate testicular androgen receptors. If, indeed, T regulation of spermatogenesis is mediated through the androgen receptor, 5α‐dihydrotestosterone (DHT) would be expected to more effectively maintain spermatogenesis than T because of its greater affinity for, and slower rate of dissociation from, the androgen receptor. To test this hypothesis experimentally, the quantitative relationship between the intratesticular concentration of exogenously administered DHT and the maintenance of germ cell production was examined in intact rats in which endogenous T production was suppressed. To this end, rats received increasing doses of DHT via polydimethylsiloxane implants of 6–36 cm in length for 8 weeks. In each DHT‐treated rat, serum luteinizing hormone (LH) concentration was reduced to below the limit of detectability by radioimmunoassay (RIA), and intratesticular T concentration was reduced by >90%. Serum and intratesticular DHT concentrations increased with increasing implant size. The serum and intratesticular concentrations of 5α‐androstane‐3α, 17β‐diol (3α‐Diol) were consistently higher than DHT concentrations because of conversion of DHT to 3α‐Diol. Spermatogenesis was maintained qualitatively in some rats that received implants of 6 cm, in most rats that received implants of 12 cm, and in all rats that received implants of 18 cm. Spermatogenesis was maintained quantitatively in most rats that received implants of 24 cm and 36 cm. The minimal average intratesticular concentration of DHT associated with the quantitative maintenance of spermatogenesis was approximately 50% of the T concentration shown previously to be minimally required. These results indicate that DHT, with its greater affinity for, and slower rate of dissociation from, the androgen receptor, more effectively maintains spermatogenesis than T at comparable intratesticular concentrations. 1994 American Society of Andrology

Original languageEnglish (US)
Pages (from-to)132-138
Number of pages7
JournalJournal of andrology
Volume15
Issue number2
DOIs
StatePublished - 1994

Keywords

  • DHT
  • Maintenance of spermatogenesis
  • androgen receptor

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Reproductive Medicine
  • Endocrinology
  • Urology

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