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http://hdl.handle.net/10553/53518
Title: | Testicular 3-Beta-Hydroxysteroid Dehydrogenase Delta-5-4 Isomerase In The Hypophysectomized Rat - Effect Of Treatment With 5-Alpha-Dihydrotestosterone | Authors: | Fanjul, Lf Quintana, J Gonzalez, J Santana, P Estevez, F Degalarreta, Cmr |
Keywords: | Corticotropin-Releasing Factor Human Chorionic-Gonadotropin Leydig-Cell-Function Luteinizing-Hormone Androgen Biosynthesis, et al |
Issue Date: | 1992 | Publisher: | 0022-0795 | Journal: | Journal of Endocrinology | 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-mu-g/100 g body weight) or vehicle (50-mu-l 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-mu-g/100 g body weight (P < 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-mu-mol/l) were ineffective as inhibitors of 3-beta-HSD. The highest dose of DHT used in this study (200-mu-g/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. | URI: | http://hdl.handle.net/10553/53518 | ISSN: | 0022-0795 | Source: | Journal Of Endocrinology[ISSN 0022-0795],v. 133 (2), p. 237-243 |
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