Abstract
We investigated the effect of n-6 polyunsaturated fatty acids (PUFAs) on prostaglandin (PG) production by the uterus. A mixed population of endometrial cells (epthelium and stroma) from late-gestation ewes were cultured in defined medium containing linoleic acid (LA, 18:2, n-6), gamma-linolenic acid (GLA, 18:3, n-6) or arachidonic acid (AA, 20:4, n-6) in concentrations of 0 (control), 20 or 100 microM. After 45 h in test medium with or without added PUFAs, cells were challenged with control medium (CM), oxytocin (OT, 250 nM), lipopolysaccharide (LPS, 0.1 micro g/ml) or dexamethasone (DEX, 5 microM) for 22 h in the continued presence of the same concentration of PUFA and the medium was collected for measurement of PGF(2alpha) and PGE(2). Supplementation with LA inhibited the production of PGF(2alpha) but did not alter PGE(2), whereas GLA and AA increased production of both PGs. All PUFA supplements thus increased the ratio of PGE(2) to PGF(2alpha) (E:F ratio) two- to threefold. In control cells, OT and LPS challenges stimulated the production of PGF(2alpha) and PGE(2). In all challenge groups, the concentrations of PGF(2alpha) in response to PUFAs followed the same pattern - LA<control<GLA<AA - but there were significant alterations in responsiveness as a result of PUFA treatment. In the cells supplemented with 100 microM AA, there was no further increase in PGF(2alpha) output in the presence of OT or LPS and when 100 microM GLA was present neither LPS nor OT stimulated PGE(2) significantly. When LPS was given to AA-supplemented cells, the E:F ratio was increased. DEX did not change PGE(2) production in control or LA-treated cells, but the cells produced significantly less PGF(2alpha), so the E:F ratio was increased. In contrast, in GLA- and AA-treated cells, DEX reduced the production of both PGF(2alpha) and PGE(2), so the E:F ratio was unaltered. In summary, the study showed altered production of PGs in the presence of different PUFAs according to their position in the n-6 metabolic pathway. The type of PUFA present affected responsiveness to OT, LPS and DEX and also changed the ratio of PGE(2) to PGF(2alpha) produced. The possible implications of this work are discussed in relation to the effect of diet on term and pre-term labour, which both require upregulation of the endometrial PG synthetic pathway.
Highlights
Cardiovascular disease is the principal cause of death among the human population of developed countries, with the saturated fat content of the diet identified as one of the major risk factors (Department of Health 1995)
LA supplementation did not alter the production of PGE2 significantly, the PGE2 concentration was slightly lower in cells treated with 100 μM LA
In this study we investigated the effect of n-6 polyunsaturated fatty acids (PUFAs) supplementation on the production of prostaglandin by ovine endometrial cells from late-gestation ewes, and examined how PUFA treatment affected the responsiveness to a variety of treatments known to influence www.endocrinology.org prostaglandin synthesis
Summary
Cardiovascular disease is the principal cause of death among the human population of developed countries, with the saturated fat content of the diet identified as one of the major risk factors (Department of Health 1995). This finding has promoted a trend to reduce dietary intakes of meat and dairy products in favour of a substantial increase in vegetable oils, which are high in n-6 polyunsaturated fatty acids (PUFAs), notably linoleic acid (LA, 18:2, n-6). Dietary PUFAs provide energy and components for cell membranes They act as the precursors for a variety of signalling molecules and influence many fundamental cell processes. LA is an essential fatty acid, which is metabolised in the body to GLA, dihomo- -linolenic acid (DGLA, 20:3, n-6) and arachidonic acid (AA, 20:4, n-6) by the position-specific
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