Restoration of spermatogenesis by exogenously administered testosterone in rats made azoospermic by hypophysectomy or withdrawal of luteinizing hormone alone

Caleb A. Awoniyi, Robert L. Sprando, Rosemary Santulli, Varadaraj Chandrashekar, Larry L. Ewing, Barry R. Zirkin

Research output: Contribution to journalArticlepeer-review

65 Scopus citations

Abstract

The major objective of the studies presented herein was to compare the extent to which exogenously administered testosterone is able to restore spermatogenesis in adult rats made azoospermic by withdrawal of all pituitary hormones (hypophysectomy for 4 weeks) vs. withdrawal of LH alone [testosterone- and estradiol-fllled (TE) polydimethylsiloxane implants of 2.5 and 0.1 cm, respectively, for 8 weeks]. In hypophysectornized (Hypox) rats, serum LH and FSH were both undetectable; in the rats that received TE implants, serum LH was undectectable, but FSH was unaffected compared to control values. Seminiferous tubule fluid testosterone concentrations were reduced significantly from their control values of 60-65 to 1.4-1.7 ng/ml in the azoospermic Hypox and TE rats. These rate then received testosterone-filled implants of 4, 12, 18, or 24 cm and were killed 2 months later. In both the Hypox and TE rate, seminiferous tubule fluid testosterone concentrations rose linearly with increasing capsule sizes, and with each of the implant sizes, these concentrations did not differ significantly between the Hypox and TE rats. This made it possible for the first time to examine the effects of comparable intratesticular testosterone concentrations on the numbers of advanced spermatids per testis that could be restored in the azoospermic testes of rats lacking all pituitary factors vs. those lacking only LH. The results that we present demonstrate that the numbers of restored advanced spermatids were consistently and significantly lower in Hypox than in TE rats despite equivalent seminiferous tubule fluid testosterone concentrations. These results provide quantitative conclusive evidence to support the contention that pituitary factors in addition to LH are required for the quantitative restoration of spermatogenesis in the adult rat testis.

Original languageEnglish (US)
Pages (from-to)177-184
Number of pages8
JournalEndocrinology
Volume127
Issue number1
StatePublished - Jul 1990
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology

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