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Specificity of polyunsaturated fatty acid release from rat brain synaptosomes
Author(s) -
Kim HeeYong,
Edsall Lisa,
Ma YeeChung
Publication year - 1996
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02637081
Subject(s) - synaptosome , biochemistry , phospholipid , polyunsaturated fatty acid , fatty acid , arachidonic acid , phospholipase , phospholipase a2 , phosphatidylethanolamine , phospholipase a , phosphatidylcholine , lipase , docosahexaenoic acid , chemistry , biology , enzyme , membrane
Release of specific polyunsaturated fatty acids from cell membranes may have a significant implication in biological function, considering the involvement of various fatty acids in cell signal transduction. In the present study, release of polyunsaturated fatty acids from rat brain synaptosomes by endogeneous synaptosomal lipase activity was examined in comparison to that by cobra venom phospholipase A 2 (Naja naja naja). Cobra venom phospholipase A 2 (Naja naja naja) preferentially hydrolyzed docosahexaenoic acid (22∶6n−3) from both synaptosomes and lipid muxtures containing similar classes of lipids commonly found in the brain. Arachidonic acid (20∶4n−6) and oleic acid (18∶1n−9) were also hydrolyzed; however, monoene species was hydrolyzed slower than were polyenoic species in synaptosomes. Phosphatidylethanolamine was the most preferred phospholipid class for release of 22∶6n−3 fatty acid from both lipid mixtures and synaptosomes. In contrast to hydrolysis by cobra venom phospholipase A 2 , endogenous synaptosomal lipase activity preferentially hydrolyzed 20∶4−6 from rat brain synaptosomes, despite the high abundance of 22∶6n−3 in synaptosomal membranes. Preferential release of 20∶4n−6 was observed over a wide range of pH values and calcium concentrations. Synaptosomal 22∶6 species appeared to be resistant to hydrolysis even after stimulation with various agents such as phorbolmyristate, suggesting that physiological importance of 22∶6−3 in neuronal membranes may not be as the release fatty acid.