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

In comparison with dietary high-linoleate safflower oil, high alpha-linolen ate 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; arachidoni c acid (AA) level in alkylacyl-GPC, a platelet-activating factor (PAF) prec ursor, decreased by 30% along with concomitant increases in the n-3 fatty a cid levels. PAF contents under resting conditions were similarly low in the two dietary groups. Fifteen minutes after endotoxin administration, PAF an d lyso-PAF contents increased significantly, and the PAF content in the hig h linolenate group was 60% lower than in the high linoleate group; the lyso -eAF contents also tended to be lower. Lyso-PAF acetyltransferase and CoA-i ndependent transacylase activities in kidney microsomes increased significa ntly after endotoxin administration, while PAF acetylhydrolase activity in the cytosol was relatively unchanged. The lyso-PAF acetyltransferase and PA F 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 agree ment with in vitro study, our presen t study demonstrates that dietary high alpha-linolenate suppresses PAF prod uction in rat kidney during systemic endotoxemia, and which is mainly due t o the decrease in alkylacyl-GPC content, altered fatty acid compositions of the precursor lipids and lower CoA-independent transacylase activity.