Preterm Labour: Mechanisms and Risks

Andrés López Bernal, University of Oxford, Oxford, UK

Published online: April 2001

DOI: 10.1038/npg.els.0002141

Preterm labour (the occurrence of labour before 37 completed weeks of pregnancy) complicates millions of pregnancies throughout the world and accounts for a disproportionately high percentage of perinatal deaths and long-term handicap of the surviving infants. Research efforts must focus on the prediction and accurate diagnosis of this condition and the development of better, more selective, therapy.

Keywords: preterm labour; myometrium; uterine contractility; second messengers; tocolysis

Figure 1. Regulation of contractility in myometrial cells. Stimulatory agonists bind to seven-transmembrane-domain receptors coupled to heterotrimeric (, , ) G proteins. Activation of phospholipase C (PLC) generates the second messenger inositol 1,4,5-triphosphate (IP3) which releases  Ca2+ from internal stores.  Ca2+ also enters the cells through voltage-operated membrane channels (not shown). The enzyme myosin light-chain kinase (MLCK) is activated by  Ca2+ and phosphorylates myosin light chains (MLC20), leading to contraction. When the level of  Ca2+ decreases, MLC20 is dephosphorylated and the muscle relaxes. Small guanosine triphosphate (GTP)-binding proteins such as Rho can sustain contractions: Rho-activated kinase phosphorylates MLC20 and inhibits myosin phosphatase. This pathway enhances contractility in a  Ca2+-independent manner. GDI (guanosine diphosphate (GDP) dissociation inhibitor) is an inhibitory guanosine diphosphate GDP/GTP exchange protein.
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    Sanborn BM, Yue C, Wang W and Dodge KL (1998) G protein signalling pathways in myometrium: affecting the balance between contraction and relaxation. Reviews of Reproduction 3: 196–205.

Related Sub-Topics:

Intracellular and Extracellular Signalling
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Article Title: Preterm Labour: Mechanisms and Risks
 
How to Cite close
Bernal, Andrés López(Apr 2001) Preterm Labour: Mechanisms and Risks. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1038/npg.els.0002141]