UNSATURATED FATTY-ACIDS ALTER THE INSULIN-SECRETION RESPONSE OF THE ISLETS OF LANGERHANS IN-VITRO

The aim of the present study is to examine the influence which differe nt concentrations of free fatty acids (FFAs) have on the insulin secre tion response of the islets of Langerhans when the culture is prolonge d over a week. Animals were killed by decapitation and pancreatic isle ts of Langerhans isolated. The islets were incubated in enriched RPMI and oleic or linoleic acid was added at concentrations of 0.04, 0.1, 0 .375, and I mmol/l. The medium without FFAs was used as a control. The culture time was 7 days. For insulin secretion studies, islets were s elected after preincubation in batches of six islets in 1 ml of KRB (K rebs-Ringer buffer) containing one of the following: 5.5, 11.1, 16 or 26.7 mmol/l glucose, 10 mu mol/l forskolin or 20 mmol/l arginine. The results showed a significant increase in insulin secretion observed af ter culture with 1 mmol/l oleic and linoleic acid compared to the othe r concentrations and the control culture for all the secretagogues use d. However, at this same concentrations no increase was observed in in sulin secretion as the glucose concentration rose, and this was notice able with linoleic acid at concentrations of 0.375 mmol/l. In conclusi on, culture of islets of Langerhans for a week with high concentration s of unsaturated fatty acids produces a hypersecretion of insulin whic h is not influenced by secretagogues such as glucose, arginine, or for skolin. The loss of gluco-sensitivity may become greater as the degree of unsaturation of the fatty acid used increases. (C) 1997 Published by Elsevier Science Ireland Ltd.