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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
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.
ISSN: 0022-0795
Source: Journal Of Endocrinology[ISSN 0022-0795],v. 133 (2), p. 237-243
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