Control of steroidogenesis in small and large bovine luteal cells.
Evidence was cited to show that: (1) prostacyclin (PGI2) plays a luteotrophic role in the bovine corpus luteum and that products of the lipoxygenase pathway of arachidonic acid metabolism, especially 5-hydroxyeicosatetraenoic acid play luteolytic roles; (2) oxytocin of luteal cell origin plays a role in development, and possibly in regression, of the bovine corpus luteum; and (3) luteal cells arise from two sources; the characteristic small luteal cells at all stages of the oestrous cycle and pregnancy are of theca cell origin; the large cells are of granulosa cell origin early in the cycle, but a population of theca-derived large cells appears later in the cycle. Results of in vitro studies with total dispersed cells and essentially pure preparations of large and small luteal cells indicate that: (1) the recently described Ca2+-polyphosphoinositol-protein kinase C second messenger system is involved in progesterone synthesis in the bovine corpus luteum; (2) activation of protein kinase C is stimulatory to progesterone synthesis in the small luteal cells; (3) activation of protein kinase C has no effect on progesterone synthesis in the large luteal cells; and (4) protein kinase C exerts its luteotrophic effect in total cell preparations, in part at least, by stimulating the production of prostacyclin. The protein kinase C system may cause down regulation of LH receptors in the large cells.
Hansel
W
W
Department of Physiology, New York State College of Veterinary Science, Cornell University, Ithaca 14853.
Alila
H W
HW
Dowd
J P
JP
Yang
X Z
XZ
D000818:Animals; D003338:Corpus Luteum / Q000166:cytology / Q000378:metabolism*; D003339:Corpus Luteum Hormones / Q000096:biosynthesis*; D011464:Epoprostenol / Q000502:physiology*; D005260:Female; D011247:Pregnancy; D011493:Protein Kinase C / Q000502:physiology; D013799:Theca Cells / Q000378:metabolism
D003339:Corpus Luteum Hormones; D011464:Epoprostenol; D011493:Protein Kinase C