Secretory and cytosolic phospholipase A2 activities and

MARIANA GABRIELA FARINA ANA MARIA FRANCHI; SILVIA BILLI; GUSTAVO LEGUIZAMÓN; CARINA WEISSMANN; TAMARA GUADAGNOLI; MARIA LAURA RIBEIRO; ANA MARIA FRANCHI

Reproduction

High Wire Press

Año: 2007 vol. 134 p. 355 - 364

1470–1626

The release of arachidonic acid from membrane glycerophospholipids through the action of phospholipases (PLs) is the first step in the biosynthesis of prostaglandins (PGs). In reproductive tissues, the most important PLs are cytosolic PLA2 (cPLA2) and types IIA and V of the secretory isoform (sPLA2). The aim of this work was to investigate the role of ovarian steroid hormones and oxytocin (OT) in the regulation of rat uterine PLA2 activity and expression during pregnancy and labor. The activity of sPLA22 (cPLA2) and types IIA and V of the secretory isoform (sPLA2). The aim of this work was to investigate the role of ovarian steroid hormones and oxytocin (OT) in the regulation of rat uterine PLA2 activity and expression during pregnancy and labor. The activity of sPLA22). The aim of this work was to investigate the role of ovarian steroid hormones and oxytocin (OT) in the regulation of rat uterine PLA2 activity and expression during pregnancy and labor. The activity of sPLA22 activity and expression during pregnancy and labor. The activity of sPLA2 increased near labor, whereas cPLA2 activity augmented towards the end of gestation. The levels of sPLA2 IIA and cPLA2 mRNA showed an increase before labor (P!0.05, day 21), whereas sPLA2 V mRNA was not regulated during pregnancy. The administration of atosiban (synthetic OT antagonist) together with tamoxifen (antagonist of estrogen receptors) was able to decrease cytosolic and secretory PLA2 activities, diminish the expression of sPLA2 IIA and cPLA2, as well as decrease PGF2a2 activity augmented towards the end of gestation. The levels of sPLA2 IIA and cPLA2 mRNA showed an increase before labor (P!0.05, day 21), whereas sPLA2 V mRNA was not regulated during pregnancy. The administration of atosiban (synthetic OT antagonist) together with tamoxifen (antagonist of estrogen receptors) was able to decrease cytosolic and secretory PLA2 activities, diminish the expression of sPLA2 IIA and cPLA2, as well as decrease PGF2aP!0.05, day 21), whereas sPLA2 V mRNA was not regulated during pregnancy. The administration of atosiban (synthetic OT antagonist) together with tamoxifen (antagonist of estrogen receptors) was able to decrease cytosolic and secretory PLA2 activities, diminish the expression of sPLA2 IIA and cPLA2, as well as decrease PGF2a2 activities, diminish the expression of sPLA2 IIA and cPLA2, as well as decrease PGF2a production before the onset of labor (P!0.01). The ovarian steroid did not affect PLA2 during pregnancy. Collectively, these findings indicate that in the rat uterus, both 17b-estradiol and OT could be regulating the activity and the expression of the secretory and the cytosolic isoforms of PLA2, thus controlling PGF2a synthesis prior to the onset of labor.P!0.01). The ovarian steroid did not affect PLA2 during pregnancy. Collectively, these findings indicate that in the rat uterus, both 17b-estradiol and OT could be regulating the activity and the expression of the secretory and the cytosolic isoforms of PLA2, thus controlling PGF2a synthesis prior to the onset of labor.b-estradiol and OT could be regulating the activity and the expression of the secretory and the cytosolic isoforms of PLA2, thus controlling PGF2a synthesis prior to the onset of labor.2, thus controlling PGF2a synthesis prior to the onset of labor.