Prostaglandin Parturition

Prostaglandins are involved, along with oxytoxin and steroids, in control of parturition. They result in contraction of the uterine muscles and dilation of the cervix (the neck of the womb). This effect is very powerful since the maximum dilation is an increase in diameter of about 10 cm. Prostaglandins were first used for induction of abortion in the UK in 1972. 

Lfterine Delayed parturition, dystocia PGE2,PGF2 ,and other prostaglandins are involved cervical ripening, uterine contractions COX-2... 

Release of oxytocin at this stage of parturition promotes prostaglandin production, particularly of the E and F series, within the decidua these prostaglandins are powerful myometrial stimulants and thus further enhance uterine contractions. The prostaglandin concentration in maternal serum and amniotic fluid increases with the progression of labor. 

N. Yoshida, T. Tanaka, M. Katsuyama, K. Hasumoto, T. Murata, M. Hirata, F. Ushikubi, M. Negishi, A. Ichikawa, S. Narumiya, Failure of parturition in mice lacking the prostaglandin F receptor. Science 277 (1997) 681. 

Studies with knockout mice have confirmed a role for prostaglandins in reproduction and parturition. COX-l-derived PGF2K appears important for luteolysis, consistent with delayed parturition in COX-l-deficient mice. A complex interplay between PGF2E and oxytocin is critical to the onset of labor. EP2 receptor-deficient mice demonstrate a preimplantation defect, which underlies some of the breeding difficulties seen in COX-2 knockouts. 

The prostaglandins occur in all tissues but in very small amounts. They act on loci in the same cells as those in which they are synthesized, and their biological roles are diverse e.g., they function in the female reproductive system during ovulation, menstruation, pregnancy, and parturition, and they stimulate uterine muscle contraction. 

Many reproductive processes (ovulation, fertilization, implantation, decidualization, and parturition) depend on prostaglandin ligand-receptor interactions. It is therefore not surprising that selective COX-2 inhibition has a negative local effect on ovulation, resulting in delayed follicular rupture and infertility, without affecting peripheral hormonal cyclicity (122,123). 

The prostaglandin analog fluprostenol (250-500 jjLg i.m.) results in unpredictable delivery times and variability in the time from injection to foaling. In addition, pony mares not close to spontaneous parturition that were treated with fluprostenol delivered premature and weak foals that died shortly after delivery and treatment was associated with dystocia and retained fetal membranes. In contrast, when fluprostenol was given to mares that were close to spontaneous delivery, normal viable foals were bom (Bristol 1982). 

Bristol F 1982 Induction of parturition in near-term mares by prostaglandin F2 , Journal of Reproduction and Fertility Supplements 32 644... 

Keelan JA, Blumenstein M, Helliwel RJA, et al. Cytokines, Prostaglandins and Parturition—A Review. Placenta 2003 17 S33-S46. 

Prostaglandins increase smooth muscle contraction in the uterus. Administration of NSAIDs thus can adversely affect parturition and labor. 

Leaver, H., E Lytton, H. Dyson, M. Watson, and D. Mellon 1986. The effect of dietary omega-3 and omega-6 polyunsaturated fatty acids on gestation, parturition and prostaglandin E2 in intrauterine tissues and the kidney. Prog. Lipid Res. 25 143-146. 

Whittle, W.L., Patel, F.A., Alfaidy, N., Holloway, A.C., Fraser, M., Gyomorey, S., Lye, S.J., Gibb, W., and Challis, J.R. (2001) Glucocorticoid Regulation of Human and Ovine Parturition The Relationship Between Fetal Hypothalamic-Pituitary-Adrenal Axis Activation and Intrauterine Prostaglandin Production, Biol. Reprod. 64,1019-1032. 

NSAIDs soon found novel use in many clinical conditions. Patency of the ductus arteriosus in neonates, mastocytosis, dysmenorrhoea and other conditions are often remarkably improved by these drugs. At the same time, many adverse effects of NSAIDs can be interpreted as due to inhibition of prostaglandin synthesis. In gynaecology, for example, NSAIDs were thus found to delay parturition and cause haemorrhagic complications in the mother, and to induce premature closure of the ductus arteriosus in the infant (for reviews see refs. 79 and 80). 

There is no direct evidence that a-linolenic acid (18 3w3) is essential in man, and it can only cure some of the signs of essential fatty acid-deficiency in animals. Rats fed a-linolenic acid as the only source of essential fatty acids have normal reproduction except for a deficient process of parturition [408]. This is possibly due to insufficiency of the uterine prostaglandin production. It should also be noted that long chain derivatives of the w3 series are found in high concentration in brain and retinal phospholipids, implying a specific role in brain function and in vision [413,414]. 

Prostaglandins (PG) produced by the uterus have several roles in reproduction, for example, luteolysis, menstruation, implantation and parturition. Up to 1976, all the experimental evidence indicated that the major prostaglandin produced by the uterus was PGFgQ (1). However, studies on the pseudopregnant rat uterus around that time revealed that 6-oxo-PGF 0, now known to be the more stable metabolite of prostacyclin (PGI c ),was the major prostaglandin synthesised by the broken cell preparation (2). For our studies on the uterus, therefore, it became essential to develop an assay for measuring 6-oxo-PGF accurately and precisely. This paper described the development of a radioimmunoassay (RIA) for measuring 6-oxo-PGF Parts of this work have been reported previously (3,4). 

Prostaglandins are intimately involved in many reproductive processes, from ovulation and fertilization to parturition and labour. It has been shown that local control of prostaglandin synthesis and degradation occurs in the fetal membranes, myometrium and placenta. The enzymes sPLA, cPLA, COX-1 and COX-2 have all been identified in pregnant uterus however, only sPLA and COX-2 expression were found to significantly increase with gestational age and labour. Increased concentrations of PGE and POF have been observed during labour, and these prostanoids have been used extensively for... 

Slater, DM, Zervou, S and Thornton, S (2002) Prostaglandins and prostanoid receptors in human pregnancy and parturition. J Soc Gynecol Investig, 9,118-124. 

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