Enhancement of endocrine pancreatic secretions by essential fatty acids

Recent studies have suggested the beneficial effects of essential fatty acids in postoperative patients receiving total parenteral nutrition. While there is abundant information on the role of glucose and amino acids on insulin release, the effect of essential fatty acids on endocrine pancreatic secretions is not clear. Since linoleic and linolenic acids are constituents of TPN solutions as well as dietary fat, our aim was to examine their effect on the endocrine pancreatic function, using isolated islets. In each experiment, six islets microdissected from three mice were preperifused at the rate of 1 ml/min with Krebs—Ringer bicarbonate (KRB) buffer pH 7.4 containing 2% bovine albumin and 5.5 m M glucose (basal) with continuous supply of 95% 5% , O 2 CO 2 for 1 hr, after which basal samples were collected on ice every minute. The perifusion was continued for 20 min after the addition of a mixture of 10 m M linoleic acid and 5 m M linolenic acid to the KRB. During each perifusion phase, effluent samples were also collected for insulin and glucagon assay. The mean integrated area under the curve/ 20 min showed an increase in both insulin and glucagon secretions with the addition of fatty acids. Hence insulin increased from a basal 3154.8 ± 953.7 to 8393.0 ± 2073.1 pg ( P < 0.025, n = 6) and glucagon increased from 193.7 ± 46.9 to 1566.1 ± 411.2 pg ( P < 0.0025, n = 5). The fatty-acid-induced insulin but not glucagon secretion was blocked by the addition of 2 m M palmoxirate an inhibitor of fatty acid oxidation. In conclusion our data clearly show that linoleic acid and linolenic acid simultaneously enhance insulin and glucagon secretions and suggest different mechanisms for their insulinotropic and glucagonotropic effects.