In Vivo Constriction of the Fetal and Neonatal Ductus Arteriosus by a Prostanoid EP4-Receptor Antagonist in Rats

Abstract

Indomethacin is used to constrict the patent ductus arteriosus in premature infants. To clarify possible prostanoid receptor antagonists that can constrict the ductus, we studied in vivo constriction of the fetal and neonatal ductus arteriosus by AE3-208, a prostanoid EP4-receptor antagonist, in rats. Following quick cesarean section of near-term pregnant rats (21 d), neonates were incubated in room air at 33°C. The inner diameter of the ductus was measured with a microscope and a micrometer following rapid whole-body freezing of the fetus and neonate, and sectioning of the thorax in the frontal plane on a freezing microtome. In the control, the ductus arteriosus constricted quickly after birth, and the inner diameter was 0.80 mm in the fetus and 0.06 mm at 90 min after birth. AE3-208, administered orogastrically to the dam, constricted the fetal ductus dose dependently. Maximal ductal constriction was observed 4 h after administration, and the ductal diameters were 0.06 mm and 0.26 mm after administration of 10 mg/kg and 10 ng/kg of AE3-208, respectively. In neonatal rats, AE3-208 injected subcutaneously at 30 min after birth, inhibited dilatation of the ductus by PGE1 dose dependently. PGE1 (10 g/kg) was injected subcutaneously to the 1-h-old neonatal rat, and the ductal diameters were 0.53 mm and 0.19 mm without and with pretreatment of AE3-208 (10 g/kg), respectively. These results indicate the major role of EP4 in the fetal and neonatal ductus and show that an EP4 antagonist can be used to constrict the patent ductus of premature infants. Indomethacin has been used to constrict the PDA in premature babies (1,2) by inhibiting prostaglandin synthesis (3). However, it exhibits serious side-effects, such as suppression of renal function and gastrointestinal dysfunction (4). Recently, EP1, EP2, EP3, and EP4 were identified as receptors for PGE (5), and their specific distribution in tissues and organs has been studied (6 -10). More recently, agonists and antagonists for these receptors have been developed (10). Theoretically, these agonists and antagonists can be clinically useful because they have fewer side-effects (11). The dilator receptor for PGE in the neonatal DA has been reported as being EP4 in rabbits, mice, and humans (11-13), and as EP2 in pigs and lambs (14,15). In this study, we report in vivo constriction of the fetal and neonatal ductus arteriosus in rats by an EP4 antagonist, AE3-208 (6). METHODSDrugs. PGE1 (PGE 1 CD, M r 354) and AE3-208 (EP4 antagonist, M r 404) were supplied by Ono Pharmaceutical Co. (Osaka, Japan). PGE1 dissolved in saline and AE3-208 dissolved in 5% glucose were kept at -20°C until used. Indomethacin (M r 358, Sigma Chemical Co., St. Louis, MO) was purchased from Iwai Chemicals (Tokyo, Japan).Animals. Virgin Wistar rats (pregnancy period 21.5 d) were mated overnight from 1700 to 0900 h; the presence of sperm in vaginal smears fixed d 0 of pregnancy. The rats were housed in an environmentally controlled room, acclimatized to a 12-h light/12-h dark cycle, and maintained on co...

Prostaglandin E-Prostanoid 4 Receptor Mediates Angiotensin II–Induced (Pro)Renin Receptor Expression in the Rat Renal Medulla

“…The animal protocols were approved by the Animal Care and Use Committee at Sun Yat-sen University, China. Rats randomly received either sham operation, AngII infusion (Human AngII, Sigma, St. Louis, MO) via a subcutaneous osmotic minipump (Alzet model 2002, Alza, Palo Alto, CA) at a rate of 100 ng/min, or co-administered with ONO-AE3-208 (ONO) (MedChemexpress LLC, Princeton, NJ) 20 at 0.2 mg/kg/d for 14 days. Under isoflurane anesthesia, the minipump was subcutaneously implanted in the back of the neck area.…”

The Prostanoid EP4 Receptor and Its Signaling Pathway

“…The EP4 agonists ONO-AE1-437 and ONO-4819 exhibited a potent dilatory effect on the rat fetal ductus arteriosus against O 2 ×2 or indomethacininduced contractions in a concentration-dependent manner both in vivo and in vitro . Another EP4 agonist, ONO-AE1-329, inhibited rat neonatal ductus arteriosus contractions (Momma et al, 2005b), whereas its antagonist, ONO-AE3-208, promoted rat fetal and neonatal ductus arteriosus contractions in vivo (Momma et al, 2005a). Thus, the EP4 receptor maintains the opening of the ductus arteriosus.…”

Changing Expression of Cyclooxygenases and Prostaglandin Receptor EP4 During Development of the Human Ductus Arteriosus

“…Among them, the EP4 receptor has been shown to be the most potent mediator of PGE2 vasodilatating effect on the DA in fetal life (7)(8)(9). It induces relaxation of smooth muscle cells via G protein-coupling and intracellular cyclic adenosine monophosphate (cAMP) increase (7).…”