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Titolo:
THE EFFECTS OF PROGESTERONE, 4,16-ANDROSTADIEN-3-ONE AND MK-434(TM) ON THE KINETICS OF PIG TESTIS MICROSOMAL TESTOSTERONE-4-ENE-5-ALPHA-REDUCTASE ACTIVITY
Autore:
COOKE GM; POTHIER F; MURPHY BD;
Indirizzi:
UNIV OTTAWA,REPROD BIOL UNIT,2202D1 TUNNEYS PASTURE OTTAWA ON K1A 0L2CANADA UNIV OTTAWA,DEPT PHYSIOL OTTAWA ON K1A 0L2 CANADA HLTH CANADA,BANTING RES CTR,FOOD DIRECTORATE,BUR CHEM SAFETY,TOXICOL RES DIV OTTAWA ON K1A 0L2 CANADA UNIV LAVAL ST FOY PQ G1K 7P4 CANADA UNIV MONTREAL,FAC MED VET,DEPT ANAT & PHYSIOL ANIM,CTR RECH & REPROD ANIM ST HYACINTHE PQ J2S 7C6 CANADA
Titolo Testata:
Journal of steroid biochemistry and molecular biology
fascicolo: 5-6, volume: 60, anno: 1997,
pagine: 353 - 359
SICI:
0960-0760(1997)60:5-6<353:TEOP4A>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
PROSTATIC HYPERTROPHY; C19 STEROIDS; ANDROGEN; METABOLISM; SKIN; DIHYDROTESTOSTERONE; 5-ALPHA-REDUCTASE; DEHYDROGENASE; TESTOSTERONE; EPIDIDYMIS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
36
Recensione:
Indirizzi per estratti:
Citazione:
G.M. Cooke et al., "THE EFFECTS OF PROGESTERONE, 4,16-ANDROSTADIEN-3-ONE AND MK-434(TM) ON THE KINETICS OF PIG TESTIS MICROSOMAL TESTOSTERONE-4-ENE-5-ALPHA-REDUCTASE ACTIVITY", Journal of steroid biochemistry and molecular biology, 60(5-6), 1997, pp. 353-359

Abstract

The enzyme 3-oxo-steroid: NADPC(+) 4-oxidoreductase (EC 1.3.1.22; 5 alpha-reductase) was assayed in testicular microsomes of pigs of 3, 20 and 24 weeks of age. The activity was very low in 3-week-old animals and approximately 10-fold higher in 5- and 6-month-old pigs. The pH optimum was 6.3 in 6-month-old animals, 5.7 in 5-month-old animals, but could not be reliably determined in 3-week-old animals. The kinetic parameters for 5 alpha-reductase in testis microsomes from g-month-old animals were; K-m(app), 8.0 mu mol/l, V-max(app), 6.7 nmoles/90 min/mg protein. Progesterone was a competitive inhibitor of testosterone 5 alpha-reduction with an apparent K-i(app) of 0.86 mu mol/l. However, 4,16-androstadien-3-one (dienone), which undergoes 5 alpha-reduction in the biosynthesis of the pheromonally active 16-androstenes, was a comparatively poor inhibitor with a K-i(app) of 4.9 mu mol/l. Similarly, MK434, which is a selective inhibitor of the human type 2 5 alpha-reductase, but which inhibits both types 1 and 2 in the rat, was also a poor competitive inhibitor of testosterone 5 alpha-reductase in the pig testis (K-i(app), 3.1 mu mol/l. It would appear from these studies that the pig testis microsomal 5 alpha-reductase corresponds to a type 1 isozyme that is not capable of reducing dienone other than under conditions where the dienone concentration would be in considerable excess of testosterone. It is, therefore, probable that substrate-specific 5 alpha-reductases exist in the pig testis for the 5 alpha-reduction of testosterone and dienone. (C) 1997 Elsevier Science Ltd.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/11/20 alle ore 09:52:21