A re-interpretation of lipoxygenase-dependent insulin release: which metabolites of arachidonic acid, or none?
There are considerable data implicating a pancreatic islet 12-lipoxy-genase in glucose-induced insulin secretion. This enzyme traditionally is conceived as converting unesterified arachidonic acid to "free" hydroperoxyeicosatetraenoic acid and metabolites thereof. However, studies employing the provision of exogenous metabolites of arachidonic acid to islet tissue fail to identify convincingly the mediator of insulin release. It is proposed that the islet lipoxygenase directly peroxidizes unsaturated fatty acids esterified within membrane phospholipids, leading to changes in ion flux and enzyme activity (particularly phospholipase A2) at the membrane level. The release of unesterified metabolites of arachidonate, although reflecting islet lipoxygenase activity, may be an epiphenomenon.
D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D015117:5,8,11,14-Eicosatetraynoic Acid / Q000494:pharmacology; D001091:Arachidonate Lipoxygenases; D001095:Arachidonic Acids / Q000378:metabolism*; D004789:Enzyme Activation; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D005947:Glucose / Q000494:pharmacology; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D007328:Insulin / Q000378:metabolism*; D007515:Islets of Langerhans / Q000201:enzymology; D015289:Leukotrienes; D008054:Lipid Peroxides / Q000378:metabolism; D008084:Lipoxygenase / Q000378:metabolism*; D008563:Membrane Lipids / Q000378:metabolism; D008954:Models, Biological; D010741:Phospholipases A / Q000378:metabolism; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism
D001095:Arachidonic Acids; D005231:Fatty Acids, Unsaturated; D006893:Hydroxyeicosatetraenoic Acids; D007328:Insulin; D015289:Leukotrienes; D008054:Lipid Peroxides; D008563:Membrane Lipids; D010743:Phospholipids; D015117:5,8,11,14-Eicosatetraynoic Acid; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; C021201:12-HPETE; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid; D001091:Arachidonate Lipoxygenases; D008084:Lipoxygenase; D010741:Phospholipases A; D054467:Phospholipases A2; D005947:Glucose