Starvation-induced changes of palmitate metabolism and insulin secretion in isolated rat islets stimulated by glucose.
The influence of 48 h starvation on glucose-induced changes of palmitate metabolism and insulin release in isolated rat islets was investigated. (1) Islet insulin response to 20 mM-glucose was abolished after 48 h starvation, and it was restored by 0.25 mM-2-bromostearate, an inhibitor of fatty acid oxidation. (2) The increase in glucose concentration from 3 to 20 mM was accompanied by a 50% decrease in the oxidation rate of 0.5 mM-[U-14C]palmitate in control (fed) islets, and a concomitant increase (100%) in its incorporation into triacylglycerol and phospholipid fractions. (3) Starvation induced a higher basal (3 mM-glucose) rate of palmitate oxidation, which was resistant to inhibition by 20 mM-glucose. The latter also failed to increase palmitate incorporation into islet triacylglycerols and phospholipids. (4) 2-Bromostearate (0.25 mM) strongly inhibited the high oxidation rate of palmitate in islets of starved rats, and allowed a normal stimulation of its incorporation rate into islet lipids by 20mM-glucose. (5) The results suggest that starvation restricts islet esterification of fatty acids by inducing a higher rate of their oxidative degradation that is insensitive to regulation by glucose.
D000818:Animals; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D010084:Oxidation-Reduction; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism*; D010477:Perfusion; D010743:Phospholipids / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation / Q000378:metabolism*; D013229:Stearic Acids / Q000494:pharmacology; D014280:Triglycerides / Q000378:metabolism
D007328:Insulin; D010169:Palmitic Acids; D010743:Phospholipids; D013229:Stearic Acids; D014280:Triglycerides; C000320:2-bromostearic acid; D019308:Palmitic Acid; D005947:Glucose