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KMID : 0390119930330010139
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Journal of Pusan Medical College
1993 Volume.33 No. 1 p.139 ~ p.150
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Effect of Arachidonic Acid on Synaptosomal 14C-GABA Uptake in Rabbit Brain Cortex
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Abstract
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The effect of arachidonic acid, a major product of membrane phospholipid metabolism, on gamma-aminobutyric acid (GABA) uptake was studied in the synaptosome isolated from rabbit brain cortex.
1. Arachidonic acid inhibited synaptosomal GABA uptake in a dose-dependent manner with I50 (concentration for 50% inhibition) of 6.1x10-5 M. Arachidonic acid also inhibited synaptosomal L-glutamate uptake in similar manner with I50 of 3.2x10-5
M.
2. Arachidonic acid inhibited synaptosomal Na-K-ATPase activity in a dose-dependent manner with I50 of 1.1x10-5 M.
3. The kinetic analysis showed that arachidonic acid reduced Vmax value for GABA uptake without a change in apparent Km value.
4. The inhibitory effect of synaptosomal GABA uptake and Na-K-ATPase activity by arachidonic acid was partially reversed.
5. The effect of arachidonic acid on GABA uptake and N-K-ATPase activity was not affected by indomethacin as a cyclo-oxygenase inhibitor, but significantly reduced by α-tocopherol.
6. Arrhenius plot showed that arachidonic acid decreased apparent activation energy.
These results suggest that arachidonic acid inhibits synaptosonal GABA uptake and Na-K-ATPase activity by the alteration of lipid environment of the synaptosomal membrane, the effect being independent of the synthesis of prostaglandins.
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