Rat gastric hydrophobic barrier: modulation of phosphatidylcholine molecular species by dietary lipids.
Phospholipids protect the gastric mucosa by forming a proton-repellent hydrophobic layer on its luminal surface. We have recently shown that two molecular species of phosphatidylcholine (PC), PC16:0/18:1, and PC16:0/18:2, but not PC16:0/16:0, are predominantly released into gastric mucus. We investigated whether these molecular species in mucus are modified by dietary fat. Rats were fed (for three weeks) a diet supplemented with either 10% cod liver, palm, or sunflower oil, or 10% corn starch as a control. In tissue, cod liver oil decreased PC16:0/20:4 and PC18:0/20:4. Cod liver oil and palm oil increased PC16:0/18:1, whereas sunflower oil decreased PC16:0/18:1. Palm oil additionally decreased PC16:0/18:2, whereas the other diets had no effect on PC16:0/18:2. In mucus, however, PC16:0/18:1 and PC16:0/18:2 were not significantly altered by any diet. They were increased over tissue values and comprised 37.6 +/- 3.3 and 33.1 +/- 1.4 mol% in controls. PC16:0/16:0 was lower in mucus than in mucosa and even decreased by cod liver oil (1.2 +/- 0.2 vs. 2.7 +/- 0.3 mol%; P < 0.01). We conclude that PC16:0/18:1 and PC16:0/18:2 are modified by dietary fat in tissue. In gastric secretions, however, PC16:0/18:1 and PC16:0/18:2 are kept constant and together comprise 70 mol% of the released PC species, whereas PC16:0/16:0 does not play a role for the gastric hydrophobic barrier under any dietary treatment. Additionally, cod liver oil decreases the content of PC16:0/20:4 and PC18:0/20:4 in gastric mucosa, thereby possibly decreasing the formation of eicosanoids.
Bernhard
W
W
Department of General Pharmacology, Hannover Medical School, Germany.
Postle
A D
AD
Linck
M
M
Sewing
K F
KF
D000818:Animals; D003060:Cod Liver Oil / Q000494:pharmacology*; D004041:Dietary Fats; D005227:Fatty Acids / Q000032:analysis*; D005753:Gastric Mucosa / Q000187:drug effects / Q000502:physiology*; D008297:Male; D000073878:Palm Oil; D010713:Phosphatidylcholines / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D010938:Plant Oils / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D000074242:Sunflower Oil; D007507:Therapeutic Irrigation
D004041:Dietary Fats; D005227:Fatty Acids; D010713:Phosphatidylcholines; D010938:Plant Oils; D000074242:Sunflower Oil; D000073878:Palm Oil; D003060:Cod Liver Oil