Androstenedione and progesterone production in vitro by the inner or the outer theca cells in preovulatory follicles of gonadotropin stimulated calves.
This study reports some of the steroidogenic characteristics of the interna and externa theca cells taken from young and eCG primed calves. These cells were isolated from large healthy follicles. The were separately cultured for 3 days in absence or in presence of steroid substrates. Androstenedione (A4) and progesterone (P4) were measured by radioimmunoassay (RIA). In control conditions, A4 levels, higher in interna than in externa cells (P < 0.001), decreased during cultures (P < 0.01). In both cell types, A4 increased in presence of 17 alpha-hydroxypregnenolone (17OHP5), pregnenolone (P5) and 22R-hydroxycholesterol (22R-chol)(*P < 0.05) but not with P4 or 17 alpha-hydroxyprogesterone (17OHP4)(P > 0.05). The most efficient substrate was dehydroepiandrosterone (DHEA) (P < 0.005). In control conditions, P4 levels increased in both cell types. They were higher in externa than in interna cells on day 1, the reverse was observed on day 3. P4 levels increased after addition of 22 R-chol and P5 (P < 0.005) but not with 17OHP5, 17OHP4 and DHEA (P > 0.05) from day 1 in externa cells and only on day 3 in internal cells. P4 levels measured on day 1 were lower than the quantity of P4 added as a substrate. These results, obtained with theca cells from young calf follicles, indicate: 1/A4 is synthesized by the delta5 pathway and 17 alpha-hydroxylase activity decreases in vitro, 2/externa and interna cells differ by the quantities of A4 and P4 produced, 3/both lack precursors to produce A4 and P4 but their 3 beta-hydroxysteroid dehydrogenase activity subsists, 4/P4 could be metabolized during the first 2 days in both cell cultures.
Laboratoire de Physiologie de la Reproduction des Mammifères Domestiques, Institut National de la Recherche Agronomique, Centre de Tours-Nouzilly, France. mbosc@tours.inra.fr
M J
MJ
Bosc
A
A
Nicolle
D006907:17-alpha-Hydroxypregnenolone / Q000378:metabolism; D000735:Androstenedione / Q000096:biosynthesis*; D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D003687:Dehydroepiandrosterone / Q000378:metabolism; D005260:Female; D006888:Hydroxycholesterols / Q000378:metabolism; D006080:Ovarian Follicle / Q000378:metabolism*; D010060:Ovulation; D011284:Pregnenolone / Q000378:metabolism; D011374:Progesterone / Q000096:biosynthesis*; D013799:Theca Cells / Q000378:metabolism*; D013997:Time Factors
D006063:Chorionic Gonadotropin; D006888:Hydroxycholesterols; C003585:22-hydroxycholesterol; D006907:17-alpha-Hydroxypregnenolone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D011374:Progesterone; D011284:Pregnenolone