Biomaterial Database

Inhibition of testosterone synthesis in the canine testis in vitro. 1983

D E Pittaway

Testicular 17 beta-hydroxysteroid oxidoreductase (17 beta-HOR) is one of the several enzymes necessary for the synthesis of testosterone, but is not required for either glucocorticoid or mineralocorticoid synthesis. Since specific inhibition of the testicular enzyme has potential contraceptive and experimental uses, the inhibitory effect of twenty steroids on 17 beta-HOR activity was examined in microsomal preparations of canine testes. Six steroids inhibited testosterone formation, but only 4-estrene-3,17-dione (KI = 2.4 microM) and 5-androstene-3,17-dione (KI = 6.8 microM) had significant inhibitory activity. The data suggest the following molecular characteristics necessary for competitive inhibition of 17 beta-HOR activity: (a) requirement for 17-keto group, (b) relative requirement for 3-keto group, (c) decreased inhibition with unsaturation in position 5-6, and (d) marked loss of inhibitory activity with 6 beta-, 11 beta- or 19- hydroxylation, and A-ring aromatization.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008861	Microsomes	Artifactual vesicles formed from the endoplasmic reticulum when cells are disrupted. They are isolated by differential centrifugation and are composed of three structural features: rough vesicles, smooth vesicles, and ribosomes. Numerous enzyme activities are associated with the microsomal fraction. (Glick, Glossary of Biochemistry and Molecular Biology, 1990; from Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)	Microsome
D004285	Dogs	The domestic dog, Canis familiaris, comprising about 400 breeds, of the carnivore family CANIDAE. They are worldwide in distribution and live in association with people. (Walker's Mammals of the World, 5th ed, p1065)	Canis familiaris,Dog
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013256	Steroids	A group of polycyclic compounds closely related biochemically to TERPENES. They include cholesterol, numerous hormones, precursors of certain vitamins, bile acids, alcohols (STEROLS), and certain natural drugs and poisons. Steroids have a common nucleus, a fused, reduced 17-carbon atom ring system, cyclopentanoperhydrophenanthrene. Most steroids also have two methyl groups and an aliphatic side-chain attached to the nucleus. (From Hawley's Condensed Chemical Dictionary, 11th ed)	Steroid,Catatoxic Steroids,Steroids, Catatoxic
D013737	Testis	The male gonad containing two functional parts: the SEMINIFEROUS TUBULES for the production and transport of male germ cells (SPERMATOGENESIS) and the interstitial compartment containing LEYDIG CELLS that produce ANDROGENS.	Testicles,Testes,Testicle
D013739	Testosterone	A potent androgenic steroid and major product secreted by the LEYDIG CELLS of the TESTIS. Its production is stimulated by LUTEINIZING HORMONE from the PITUITARY GLAND. In turn, testosterone exerts feedback control of the pituitary LH and FSH secretion. Depending on the tissues, testosterone can be further converted to DIHYDROTESTOSTERONE or ESTRADIOL.	17-beta-Hydroxy-4-Androsten-3-one,17-beta-Hydroxy-8 alpha-4-Androsten-3-one,8-Isotestosterone,AndroGel,Androderm,Andropatch,Androtop,Histerone,Sterotate,Sustanon,Testim,Testoderm,Testolin,Testopel,Testosterone Sulfate,17 beta Hydroxy 4 Androsten 3 one,17 beta Hydroxy 8 alpha 4 Androsten 3 one,8 Isotestosterone
D015067	17-Hydroxysteroid Dehydrogenases	A class of enzymes that catalyzes the oxidation of 17-hydroxysteroids to 17-ketosteroids. EC 1.1.-.	17 beta-Hydroxysteroid Dehydrogenases,Testosterone Dehydrogenases,17-Ketosteroid Reductases,17 Hydroxysteroid Dehydrogenases,17 Ketosteroid Reductases,17 beta Hydroxysteroid Dehydrogenases,Dehydrogenases, 17 beta-Hydroxysteroid,Dehydrogenases, 17-Hydroxysteroid,Dehydrogenases, Testosterone,Reductases, 17-Ketosteroid