Molecular Mechanisms of Acidic Amino Acid Release from Mossy Fiber Terminals of Rat Cerebellum
The stimulus-induced release of neurotransmitters from nerve terminals requires rapid and reversible changes in the permeability properties of presynaptic membranes. Phospholipids, which provide the basis for the bilayer structure of biological membranes, have been implicated in chemical transmission. In particular, it has been suggested that an obligatory step in neurotransmitter release is the accumulation of unesterified, polyunsaturated fatty acids following the depolarization-induced degradation of phospholipids. Depolarization of cerebral synaptosomes results in the Ca2+-dependent release of free arachidonic acid (Lazarewicz et al., 1983) from phosphatidylcholine and phosphatidylinositol (Majewska and Sun, 1982). The Ca2+dependent release of gamma-aminobutyric acid (GABA) from cerebral synaptosomes has also been shown to require the accumulation of free arachidonic acid and this release can be mimicked with exogenous arachidonic acid, but not other free fatty acids (Asakura and Matsuda, 1984). The release of neurotransmitters induced by exogenous fatty acids does not require Ca2+ (Rhoads et al., 1983), suggesting that the Ca2+ is required for phospholipid degradation and fatty acid accumulation.
KeywordsArachidonic Acid Mossy Fiber Acidic Amino Acid Cyclooxygenase Inhibitor Exogenous Fatty Acid
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