Activity, synthesis, storage, and messenger RNA of cyclooxygenase in intrauterine tissues of guinea pigs near term and during labor

Prostaglandin H2 synthase‐1 and ‐2 expression in guinea pig gestational tissues during late pregnancy and parturition

“…3). PTGS regulation at the protein synthesis level has been suggested in a former study by Schellenberg et al (2003), who assessed de novo PTGS synthesis rates in amnion explants pretreated with aspirin and concluded that the PTGS enzyme accumulates in the amnion in vivo during late gestation. Thus, regulation of mRNA and protein synthesis collectively leads to increased PTGS1 and decreased PTGS2 abundance in the gestational tissues by term, resulting in the dominance of PTGS1 over PTGS2 around the time of labour.…”

“…It has been shown that PGE 2 and PGF 2α production increases in the amnion and the placenta of guinea pigs by late gestation, and the activity of PTGS, the committing and rate limiting enzyme of the PG biosynthetic pathway, rises dramatically in guinea pig amnion before and during labour (Moussard et al 1986; Moussard et al 1987; Schellenberg & Kirkby, 1997). PTGS2 mRNA has been detected in the amnion, but its level did not change at term (Schellenberg et al 2003). Our results are in agreement with these findings and extend them to PTGS2 protein abundance, which was either unchanged or decreased to low levels in the four gestational tissues by late pregnancy and labour.…”

“…The guinea pig gestational tissues (amnion, visceral yolk sac, placenta and myo‐endometrium) produce labour‐promoting PGs (PGE 2 and PGF 2α ), and the PG output of the placenta and the amnion increases with advancing pregnancy (Moussard et al 1986; Schellenberg & Kirkby, 1997). Schellenberg and colleagues have demonstrated that the predominant intrauterine source of PGs is the amnion membrane and that PTGS activity in the amnion rises before and during labour as a result of increased enzyme synthesis (Schellenberg & Kirkby, 1997; Schellenberg et al 2003). They have detected both PTGS1 and ‐2 mRNAs in the guinea pig amnion, but found no change in PTGS2 mRNA abundance during the last third of gestation.…”

15-Hydroxyprostaglandin Dehydrogenase Expression and Localization in Guinea Pig Gestational Tissues During Late Pregnancy and Parturition

“…We have previously shown that functional progesterone withdrawal in women and guinea pigs around the time of labor may be mediated by changes in myometrial progesterone receptor (PR) expression. 19,20 We and others have also reported that intrauterine prostaglandin synthesis in the pregnant guinea pig occurs predominantly in the amnion [21][22][23] and that the capacity for prostaglandin synthesis increases with advancing gestation via an increase in PTGS expression. 21 Expression and activity of PTGS likewise increase in the human amnion at term labor, 1,24 further illustrating the similarities in the hormonal regulation of pregnancy between women and guinea pigs and the usefulness of the guinea pig as an experimental model.…”