Testicular 3 beta-hydroxysteroid dehydrogenase/delta 5-4 isomerase in the hypophysectomized rat: effect of treatment with 5 alpha-dihydrotestosterone.

Abstract

The in-vivo regulatory effect of androgens on steroidogenesis was investigated. Adult (2 to 3 months old) hypophysectomized rats were treated intratesticularly with increasing doses of 5 alpha-dihydrotestosterone (DHT; 10-200 micrograms/100 g body weight) or vehicle (50 microliters dimethyl sulphoxide; DMSO) in the contralateral testis. Intratesticular testosterone concentrations were extremely low in hypophysectomized rats 15-20 days after surgery. Treatment with DHT caused a dose-dependent inhibition of testicular 3 beta-hydroxysteroid dehydrogenase/delta 5-4 isomerase (3 beta-HSD) 2 h later, and this effect was apparent at the dose of 20 micrograms/100 g body weight (P less than 0.01). The inhibitory effect of 3 beta-HSD was not due to a possible interference of DHT in the enzyme assay, since various concentrations of the androgen (0.1-100 mumol/l) were ineffective as inhibitors of 3 beta-HSD. The highest dose of DHT used in this study (200 micrograms/100 g body weight) resulted in a rapid (1-2 h) and transient (4-6 h) inhibition (approximately 80%) of 3 beta-HSD activity. Pretreatment of rats with the antiandrogen cyproterone acetate (5 mg/rat) or the protein synthesis inhibitor cycloheximide (10 mg/rat) did not affect the enzyme activity of testes injected with DMSO, but counteracted the inhibitory effect of DHT on 3 beta-HSD activity in the contralateral testis. The results presented suggest that the inhibitory effect of the non-aromatizable androgen DHT is receptor-mediated and involves the synthesis of a factor(s) that modulates 3 beta-HSD activity.

• Authors: L F Fanjul, J Quintana, J González, P Santana, F Estévez, C M Ruiz de Galarreta
• Journal: The Journal of endocrinology (J Endocrinol) Vol. 133 Issue 2 Pg. 237-43 (May 1992) ISSN: 0022-0795 [Print] England
• PMID: 1613426 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• 3 beta-hydroxysteroid oxidoreductase-delta(5) 3-ketosteroid isomerase
• Androgens
• Multienzyme Complexes
• Dihydrotestosterone
• Progesterone Reductase
• Steroid Isomerases

Topics

• Androgens (physiology)
• Animals
• Dihydrotestosterone (pharmacology)
• Dose-Response Relationship, Drug
• Hypophysectomy
• Male
• Multienzyme Complexes (antagonists & inhibitors, metabolism)
• Progesterone Reductase (antagonists & inhibitors, metabolism)
• Rats
• Rats, Inbred Strains
• Steroid Isomerases (antagonists & inhibitors, metabolism)
• Testis (enzymology)