Immunolocalization of steroidogenic enzymes P450scc, 3 beta HSD, P450c17 and P450arom in the corpus luteum of the Hokkaido brown bear (Ursus arctos yesoensis) in relation to delayed implantation.
The objective was the immunocytochemical localization of steroidogenic enzymes in the corpus luteum of Hokkaido brown bears during the period of delayed implantation. Cholesterol side-chain cleavage cytochrome P450 (P450scc), 3 beta-hydroxysteroid dehydrogenase (3 beta HSD), 17 alpha-hydroxylase cytochrome P450 (P450c17) and aromatase cytochrome P450 (P450arom) were localized as biosynthetic sites of pregnenolone, progesterone, androgens, and oestrogens, respectively. Ovaries containing corpora lutea were obtained from three mature bears during the expected delayed implantation period and ovarian sections were immunostained by the avidin-biotin-peroxidase complex method using polyclonal antibodies generated against steroidogenic enzymes of mammalian origin. P450scc and 3 beta HSD were localized in all luteal cells, whereas P450c17 (0.4-5.1% of 1000 cells) and P450arom (7.1-11.2% of 1000 cells) were localized in only a few luteal cells. These data suggest that luteal cells contain steroidogenic enzymes required for progesterone synthesis but also have a minimum capability for synthesizing androgen and oestrogen during the delayed implantation period in Hokkaido brown bears.
Tsubota
T
T
Department of Animal Sciences, University of Illinois, Urbana 61801.
Nitta
H
H
Osawa
Y
Y
Mason
J I
JI
Kita
I
I
Tiba
T
T
Bahr
J M
JM
D015096:3-Hydroxysteroid Dehydrogenases / Q000032:analysis*; D000818:Animals; D001141:Aromatase / Q000032:analysis; D002786:Cholesterol Side-Chain Cleavage Enzyme / Q000032:analysis; D003338:Corpus Luteum / Q000201:enzymology*; D003577:Cytochrome P-450 Enzyme System / Q000032:analysis*; D010065:Embryo Implantation, Delayed / Q000502:physiology*; D005260:Female; D007150:Immunohistochemistry; D011247:Pregnancy; D013254:Steroid 17-alpha-Hydroxylase / Q000032:analysis; D001503:Ursidae / Q000378:metabolism*
D003577:Cytochrome P-450 Enzyme System; D015096:3-Hydroxysteroid Dehydrogenases; D001141:Aromatase; D013254:Steroid 17-alpha-Hydroxylase; C022433:pregnenolone 17-alpha-hydroxylase; D002786:Cholesterol Side-Chain Cleavage Enzyme