title: In vitro secretion of progestins by rat luteal cells and their 20 alpha-hydroxysteroid dehydrogenase activity.
abstract: Functionally active or regressing corpora lutea were harvested from pseudopregnant (psp) rats between days 5-8 of psp or day 15 of psp, respectively. They were enzymatically dispersed and cultured for 24 h to assess progestins in the medium and 20 alpha-hydroxysteroid dehydrogenase [20 alpha-HSD, catalyzing the conversion of progesterone to 20 alpha-dihydroprogesterone (20 alpha-OH-P)] activity in the cell. Though the active luteal cells retained low 20 alpha-HSD activity, they secreted 6-7 times more 20 alpha-OH-P than progesterone as the regressing luteal cells did. There was no significant difference between the total amounts of progestins in the 2 groups. When increasing doses of pregnenolone were added to the media, progesterone secretion from the active luteal cells was promoted and the progesterone to 20 alpha-OH-P ratio became comparable to the circulating progestins ratio during the mid-luteal phase. In contrast, from the regressing luteal cells only 20 alpha-OH-P secretion was promoted. These results indicate that an insufficient precursor supply results in the catabolism of a large part of synthesized progesterone before its release from luteal cells and suggest the presence of a high affinity but low capacity 20 alpha-HSD in active corpora lutea.
authors.forename: K
authors.initials: K
authors.lastname: Naito
authors.forename: M
authors.initials: M
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Homma
mesh_terms: D015089:20-Hydroxysteroid Dehydrogenases / Q000378:metabolism*; D004092:20-alpha-Dihydroprogesterone / Q000378:metabolism*; D043607:20-alpha-Hydroxysteroid Dehydrogenase; D000818:Animals; D002478:Cells, Cultured; D003338:Corpus Luteum / Q000187:drug effects / Q000378:metabolism*; D003470:Culture Media; D005260:Female; D011284:Pregnenolone / Q000494:pharmacology; D011374:Progesterone / Q000031:analogs & derivatives* / Q000378:metabolism*; D011555:Pseudopregnancy; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D003470:Culture Media; D004092:20-alpha-Dihydroprogesterone; D011374:Progesterone; D011284:Pregnenolone; D015089:20-Hydroxysteroid Dehydrogenases; D043607:20-alpha-Hydroxysteroid Dehydrogenase