Raised dietary n-6 polyunsaturated fatty acid intake increases 2-series prostaglandin production during labour in the ewe.
Preterm labour is the major cause of perinatal morbidity and mortality in humans. The incidence is around 10% and the causes are often unknown. Consumption of dietary n-6 polyunsaturated fatty acids (PUFAs) in western societies is increasing. These are metabolized to arachidonic acid, the precursor for 2-series prostaglandins (PGs), major signalling molecules during labour. This study investigated the effect of dietary supplementation with linoleic acid (LA, 18: 2, n-6) on parturition. Ewes were fed a control or LA-supplemented diet from 100 days gestation. Labour was induced using a standardized glucocorticoid challenge (dexamethasone, Dex) to the fetus, starting on day 139. Electromyographic (EMG) activity and fetal and maternal circulating PG concentrations were monitored. One third of LA-fed ewes delivered early (pre-Dex) although basal uterine EMG activity preceding Dex was higher in control ewes (P < 0.05). A steep increase in EMG activity occurred 18-38 h after the start of Dex infusion. Twice basal EMG activity (defined as established labour) occurred on average 7 h earlier in the LA-supplemented ewes (P < 0.05). The basal concentrations of maternal and fetal PGFM and fetal PGE(2) were approximately doubled in LA-supplemented ewes before the start of Dex infusion (P < 0.01). The rise in fetal PGE(2) and maternal oestradiol concentrations post-Dex occurred earlier in the LA-supplemented ewes. All PG measurements remained significantly higher in the LA-supplemented ewes during labour onset. This study suggests that consumption of a high LA diet in late pregnancy can enhance placental PG production and may thus increase the risk of preterm labour.
Elmes
M
M
Reproduction and Development Group, Royal Veterinary College, Hawkshead Lane, North Mymms, Hatfield, Herts AL9 7TA, UK.
Green
L R
LR
Poore
K
K
Newman
J
J
Burrage
D
D
Abayasekara
D R E
DR
Cheng
Z
Z
Hanson
M A
MA
Wathes
D C
DC
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000502:physiology; D001806:Blood Urea Nitrogen; D003907:Dexamethasone / Q000494:pharmacology; D004032:Diet; D004576:Electromyography; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D005323:Fetal Monitoring; D005333:Fetus / Q000502:physiology; D006728:Hormones / Q000097:blood; D007328:Insulin / Q000097:blood / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D007743:Labor, Obstetric / Q000187:drug effects / Q000502:physiology*; D010120:Oxytocics / Q000494:pharmacology; D011247:Pregnancy; D011453:Prostaglandins / Q000096:biosynthesis* / Q000097:blood; D011863:Radioimmunoassay; D012756:Sheep
D005231:Fatty Acids, Unsaturated; D006728:Hormones; D007328:Insulin; D010120:Oxytocics; D011453:Prostaglandins; D007334:Insulin-Like Growth Factor I; D003907:Dexamethasone