Influence of follicular atresia on LH-induced cAMP and steroid synthesis by bovine thecae interna.
The aim of the present study was to examine the interrelationships between the luteinizing hormone (LH) receptor, the LH-induced changes in adenosine cyclic 3', 5'-monophosphate (cAMP) and steroid synthesis in theca interna tissue of large antral follicles (greater than or equal to 8 mm diameter) from oestrous cycling cows. Three distinct types of theca interna were identified (types I, II and III), all of which contained an LH receptor: type I was capable of secreting increased amounts of cAMP dehydroepiandrosterone, androstenedione and testosterone when exposed to LH; type II was capable of secreting increased amounts of cAMP and progesterone but not the androgens when exposed to LH; type III was incapable of cAMP or steroid synthesis when exposed to LH. Follicles with type I thecae contained: a full complement of granulosa cells; high intrafollicular concentrations of oestradiol; and granulosa cells with a high capacity to metabolise testosterone to oestradiol. These follicles were considered to be non-atretic structures. Follicles with types III thecae contained: fewer granulosa cells; low intrafollicular concentrations of oestradiol; and granulosa cells with a low capacity to metabolise testosterone to oestradiol. Moreover, follicles with type III thecae contained the highest concentrations of progesterone and the lowest concentrations of androstenedione and testosterone. These follicles were considered to be severely atretic structures. Follicles with type II thecae contained granulosa cell populations and progesterone, and androgen concentrations which were intermediate between those with thecae of types I and III. These follicles were considered to be at an intermediate stage of atresia.(ABSTRACT TRUNCATED AT 250 WORDS)
McNatty
K P
KP
Lun
S
S
Heath
D A
DA
Kieboom
L E
LE
Henderson
K M
KM
D000735:Androstenedione / Q000096:biosynthesis; D000818:Animals; D002417:Cattle; D006063:Chorionic Gonadotropin / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis*; D003687:Dehydroepiandrosterone / Q000096:biosynthesis; D005260:Female; D005496:Follicular Atresia; D005498:Follicular Phase; D007986:Luteinizing Hormone / Q000494:pharmacology*; D011284:Pregnenolone / Q000096:biosynthesis; D011374:Progesterone / Q000096:biosynthesis; D013256:Steroids / Q000096:biosynthesis*; D013739:Testosterone / Q000096:biosynthesis; D013799:Theca Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
D006063:Chorionic Gonadotropin; D013256:Steroids; D013739:Testosterone; D000735:Androstenedione; D003687:Dehydroepiandrosterone; D011374:Progesterone; D011284:Pregnenolone; D007986:Luteinizing Hormone; D000242:Cyclic AMP