Regulation of endometrial prostaglandin synthesis during early pregnancy in cattle: effects of phospholipases and calcium in vitro.
In experiment 1, endometrial explants from 3 cyclic (Day 17) cows were incubated with arachidonic acid (AA), phospholipase A-2 (PLA-2) and calcium ionophore A23187 (CaI) or control. AA (0.2 mg), PLA-2 (1 U/ml) and CaI (4 micrograms/ml) increased PGF and PGE secretion. In experiment 2, endometrial explants from cyclic (n = 4) and pregnant (n = 3) cows were incubated +/- Ca++ and with either: control, AA, PLA-2, CaI, PLA-2 + CaI, or AA + CaI. PG secretion was higher in cultures with Ca++. In presence of Ca++, PGF secretion was lower for pregnant than cyclic endometrium. AA with Ca++ stimulated PGF and PGE secretion, indicating that AA availability may limit PG secretion. The stimulatory effect of PLA-2 on PGF and PGE secretion was greater in pregnant than cyclic endometrium. However, CaI inhibited the PLA-2 response of pregnant, but not cyclic endometrium. In experiment 3, endometrium (4 cyclic cows) failed to convert 3H-PGF2 alpha to PGE2 or 3H-PGE2 to PGF2 alpha. Responsiveness of PG secretion to PLA-2, and CaI is altered by reproductive status suggesting that these factors may be involved in the differential regulation of PG production during early pregnancy in cattle.
Danet-Desnoyers
G
G
Department of Dairy and Poultry Sciences, University of Florida, Gainesville, USA.
Meyer
M D
MD
Gross
T S
TS
Johnson
J W
JW
Thatcher
W W
WW
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D015237:Dinoprost / Q000096:biosynthesis / Q000378:metabolism; D004717:Endometrium / Q000378:metabolism*; D005260:Female; D010740:Phospholipases / Q000378:metabolism / Q000494:pharmacology*; D010741:Phospholipases A / Q000378:metabolism / Q000494:pharmacology; D011247:Pregnancy; D011453:Prostaglandins / Q000096:biosynthesis* / Q000378:metabolism; D010738:Type C Phospholipases / Q000378:metabolism / Q000494:pharmacology
D011453:Prostaglandins; D016718:Arachidonic Acid; D000001:Calcimycin; D015237:Dinoprost; D010740:Phospholipases; D010741:Phospholipases A; D010738:Type C Phospholipases; D002118:Calcium