Dietary alpha-linolenate suppresses endotoxin-induced platelet-activating factor production in rat kidney

In comparison with dietary high-linoleate safflower oil, high alpha-linolenate perilla oil decreased alkylacyl- and alkenylacyl-glycerophosphocholine (GPC) content in rat kidney by roughly 30 and 25%, respectively. The fatty acid composition was also modified by high alpha-linolenate oil; arachidonic acid (AA) level in alkylacyl-GPC, a platelet-activating factor (PAF) precursor, decreased by 30% along with concomitant increases in the n-3 fatty acid levels. PAF contents under resting conditions were similarly low in the two dietary groups. Fifteen minutes after endotoxin administration, PAF and lyso-PAF contents increased significantly, and the PAF content in the high alpha-linolenate group was 60% lower than in the high linoleate group; the lyso-PAF contents also tended to be lower. Lyso-PAF acetyltransferase and CoA-independent transacylase activities in kidney microsomes increased significantly after endotoxin administration, while PAF acetylhydrolase activity in the cytosol was relatively unchanged. The lyso-PAF acetyltransferase and PAF acetylhydrolase activities did not differ between the two dietary groups, but the CoA-independent transacylase activity was roughly 30% lower in the high alpha-linolenate group. In agreement with in vitro study, our present study demonstrates that dietary high alpha-linolenate suppresses PAF production in rat kidney during systemic endotoxemia, and which is mainly due to the decrease in alkylacyl-GPC content, altered fatty acid compositions of the precursor lipids and lower CoA-independent transacylase activity.