Premature onset of labor, neonatal patent ductus arteriosus, and prostaglandin synthetase antagonists--a rat model of a human problem

Altered expression of Notch signaling, Tlr receptors, and surfactant protein expression after prostaglandin inhibition may be associated with the delayed labor in LPS-induced mice

PURPOSE

This study aims to investigate whether indomethacin (IND) delays preterm birth by regulating the Notch pathway, Tlr receptors, and Sp-A in the placenta in lipopolysaccharide (LPS)-induced preterm labor (PTL) model.

METHODS

CD-1 mice were distributed to the pregnant control (PC), Sham, PBS, IND (2 mg/kg; i.p.), LPS (25 μg/100 μl; intrauterine), and LPS + IND groups. The injections were performed on day 14.5 of pregnancy. Placentae were collected on day 15.5 of pregnancy, and immunohistochemical analyzes were performed. Differences in staining intensities between the Cox-1, Notch-1 (N1), Dll-1, Jagged-2 (Jag-2), Tlr-2, and Tlr-4 proteins were compared.

RESULTS

Preterm labor rates were 100% and 66% (preterm delivery delayed 5 h) in the LPS and LPS + IND groups, respectively. In LPS-treated mice, a general morphological deterioration was observed in the placenta. Total placental mid-sagittal measurement was significantly reduced in the LPS-treated group, while it was similar to the PC group in the LPS + IND group. Cox-1 expression in the LZ increased, and Sp-A expression decreased after LPS injection, and IND administration diminished this increase. N1 expression increased in the labyrinth zone (LZ) and the junctional zone (JZ). Dll-1 and Jag-2 expression increased in the JZ after LPS injection (p < 0.0001). IND administration diminished Tlr-2 expression in the LZ and Tlr-4 expression in the JZ after LPS injection.

CONCLUSION

In conclusion, PG (prostaglandin) inhibition may alter Notch signaling, Tlr, and Sp-A protein expression and may be associated with delayed labor in LPS-induced mice.

Relationship of Notch Signal, Surfactant Protein A, and Indomethacin in Cervix During Preterm Birth: Mast Cell and Jagged-2 May Be Key in Understanding Infection-mediated Preterm Birth

Although it is thought that there is a close relationship between Notch signal and preterm birth, the functioning of this mechanism in the cervix is unknown. The efficacy of surfactants and prostaglandin inhibitors in preterm labor is also still unclear. In this study, 48 female CD-1 mice were distributed to pregnant control (PC), Sham, PBS, indomethacin (2 mg/kg; intraperitoneally), lipopolysaccharides (LPS) (25 μg/100 μl; intrauterine), LPS + IND, and Surfactant Protein A Block (SP-A Block: SP-A B; the anti-SP-A antibody was applied 20 µg/100μl; intrauterine) groups. Tissues were examined by immunohistochemistry, immunofluorescence, and Western blot analysis. LPS administration increased the expression of N1 Dll-1 and Jagged-2 (Jag-2). Although Toll-like receptor (Tlr)-2 significantly increased in the LPS-treated and SP-A-blocked groups, Tlr-4 significantly increased only in the LPS-exposed groups. It was observed that Jag-2 is specifically expressed by mast cells. Overall, this experimental model shows that some protein responses increase throughout the uterus, starting at a specific point on the cervix epithelium. Surfactant Protein A, which we observed to be significantly reduced by LPS, may be associated with the regulation of the epithelial response, especially during preterm delivery due to infection. On the contrary, prostaglandin inhibitors can be considered an option to delay infection-related preterm labor with their dose-dependent effects. Finally, the link between mast cells and Jag-2 could potentially be a control switch for preterm birth.

Indomethacin and the fetal renal nonfunction syndrome

A pregnancy during which both beta-adrenergics and indomethacin were administered in order to stop preterm uterine contractions is reported. After 8 wk of therapy a Caesarean section was performed. The female neonate had all the characteristics of a Potter's facies, was anuric and died after 47 h of extra-uterine life. A possible relationship between this perinatal death and the prolonged intra-uterine exposure to indomethacin is discussed.

Patent ductus arteriosus in premature infants: a review of current management

Problems related to the ductus arteriosus confront the pediatrician more than any other isolated cardiac defect. Due to increased awareness of the problems of prematurity, the reported frequency of patent ductus arteriosus increased threefold between 1970 and 1975. Aggressive therapy directed toward closure of the ductus is indicated within the first week of life in the very immature infant. Pharmacologic closure of the PDA with indomethacin is effective about half the time.

Indomethacin--placental transfer, cytotoxicity, and teratology in the rat

Aspirin is a well-known teratogen in laboratory animals and is an inhibitor of prostaglandin synthesis. To further investigate the inhibition of prostaglandin synthesis as a mechanism of teratogenesis, we examined the teratologic potential, cytotoxic potential, and placental transfer of indomethacin in the rat. Indomethacin was not teratologic, not cytotoxic to cells in the embryonic hindlimb bud, and did not cross the placenta in physiologically significant amounts on days 11 to 12 of gestation. Near parturition, however, indomethacin crossed the placenta in pharmacologically significant amounts. The pharmacokinetics of placental drug transfer are discussed.