Immunoreactive cytochrome P-450(17 alpha) in rat and guinea-pig gonads, adrenal glands and brain.
The cytochrome P-450(17 alpha)-hydroxylase, 17----20 lyase (P-450(17 alpha)) is the key enzyme responsible for the biosynthesis of androgens in steroidogenic organs. Its cellular localization has been examined with an immunohistochemical technique. In immature rat ovary, P-450(17 alpha) was first detected in sparse interstitial cells on postnatal Day 8. The number of immunoreactive interstitial cells increased thereafter and the intensity of P-450(17 alpha) staining in these cells was highest at 3 weeks of age. The intensity of staining then started to decline and was very faint at Day 35. From 6 weeks on, the distribution of immunoreactive P-450(17 alpha) was of the adult type: it was detected exclusively in the thecal cells of the large antral, preovulatory, follicles. P-450(17 alpha) was not detectable during pregnancy except on the day of parturition, when thecal cells were transiently immunoreactive. The staining had vanished 24 h after delivery. Human chorionic gonadotrophin (hCG), injected into immature females on Days 24 to 26, induced P-450(17 alpha) prematurely in thecal cells. When injected on Days 12 to 14 of pregnancy, hCG also induced P-450(17 alpha) in the thecal cells surrounding the largest follicles, whereas the interstitial and luteal cells were not immunostained. The antiprogestin RU486, injected on Day 16 of pregnancy, reinstated P-450(17 alpha) (and P-450scc) immunoreactivity in the thecal cells. Oestradiol selectively suppressed P-450(17 alpha) expression in the thecal cells of RU486-treated females. In immature guinea-pig ovary, P-450(17 alpha) was immunostained in thecal cells, not in interstitial cells, although the interstitial cells expressed the delta 5-3 beta-hydroxysteroid dehydrogenase. P-450(17 alpha) was also immunolocalized in the Leydig cells of rat and guinea-pig testes, and in the guinea-pig adrenal cortex (zonae fasciculata and reticularis), but not in the rat adrenal cortex. P-450(17 alpha) was not detectable in the brain of either rat or guinea-pig.
Le Goascogne
C
C
INSERM U33, Communications Hormonales, Université Paris-sud, Bicêtre, France.
Sananès
N
N
Gouézou
M
M
Takemori
S
S
Kominami
S
S
Baulieu
E E
EE
Robel
P
P
D000302:Adrenal Cortex / Q000201:enzymology*; D000818:Animals; D001921:Brain / Q000201:enzymology; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006168:Guinea Pigs; D007150:Immunohistochemistry; D007985:Leydig Cells / Q000201:enzymology; D008297:Male; D015735:Mifepristone / Q000494:pharmacology; D010053:Ovary / Q000201:enzymology*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012741:Sexual Maturation / Q000502:physiology; D013254:Steroid 17-alpha-Hydroxylase / Q000032:analysis*; D013737:Testis / Q000201:enzymology*; D013799:Theca Cells / Q000187:drug effects / Q000201:enzymology
D006063:Chorionic Gonadotropin; D015735:Mifepristone; D004958:Estradiol; D013254:Steroid 17-alpha-Hydroxylase