Dietary fish oil dose-response effects on ileal phospholipid fatty acids and contractility.
We have reported that dietary fish oil (FO) leads to the incorporation of long-chain n-3 PUFA into the gut tissue of small animal models, affecting contractility, particularly of rat ileum. This study examined the FO dose response for the incorporation of n-3 PUFA into ileal tissue and how this correlated with in vitro contractility. Groups of ten to twelve 13-wk-old Wistar-Kyoto rats were fed 0, 1, 2.5, and 5% FO-supplemented diets balanced with sunflower seed oil for 4 wk, after which ileal total phospholipid FA were determined and in vitro contractility assessed. For the total phospholipid fraction, increasing the dietary FO levels led to a significant increase first evident at 1% FO, with a stepwise, nonsaturating six-fold increase in n-3 PUFA as EPA (20:5n-3), DPA (docosapentaenoic acid, 22:5n-3), and DHA, but mainly as DHA (22:6n-3), replacing the n-6 PUFA linoleic acid (18:2n-6) and arachidonic acid (20:4n-6) over the dosage range. There was no difference in KCl-induced depolarization-driven contractility. However, a significant increase in receptor-dependent maximal contractility occurred at 1% FO for carbachol and at 2.5% FO for prostaglandin E2, with a concomitant increase in sensitivity for prostaglandin E2 at 2.5 and 5% FO. These results demonstrate that significant increases in ileal membrane n-3 PUFA occurred at relatively low doses of dietary FO, with differential receptor-dependent increases in contractility observed for muscarinic and prostanoid agonists.
Patten
Glen S
GS
CSIRO Human Nutrition, Adelaide, South Australia. glen.patten@csiro.au
Adams
Michael J
MJ
Dallimore
Julie A
JA
Abeywardena
Mahinda Y
MY
D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D004042:Dietary Fats, Unsaturated / Q000494:pharmacology*; D015232:Dinoprostone / Q000494:pharmacology; D004281:Docosahexaenoic Acids; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000032:analysis / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000032:analysis / Q000378:metabolism; D005395:Fish Oils / Q000494:pharmacology*; D007082:Ileum / Q000187:drug effects* / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism; D009119:Muscle Contraction / Q000187:drug effects; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D011921:Rats, Inbred WKY; D018160:Receptors, Cytoplasmic and Nuclear / Q000187:drug effects / Q000378:metabolism
D004042:Dietary Fats, Unsaturated; D005227:Fatty Acids; D015525:Fatty Acids, Omega-3; D005395:Fish Oils; D008563:Membrane Lipids; D010743:Phospholipids; D018160:Receptors, Cytoplasmic and Nuclear; D004281:Docosahexaenoic Acids; D011189:Potassium Chloride; D002217:Carbachol; D015232:Dinoprostone