Fatty acid composition and arachidonic acid concentrations in alveolar bone of rats fed diets with different lipids

The purpose of the present study was to determine if the type of dietary fat can modify the fatty acid composition and arachidonic acid levels in the alveolar bone phospholipids. Three groups of rats were fed nutritionally adequate semipurified diets containing different lipids: 10% corn oil (control, group I, rich in n-6 fatty acids); 9% butter + 1% corn oil (experimental, group II, rich in saturated fatty acids); and 9% ethyl ester concentrate of n-3 fatty acids + 1% corn oil (experimental, group III, rich in n-3 fatty acids). After 10 weeks of feeding the various diets, rats were killed, maxillae and mandibles were dissected out, and the soft tissue was removed. Bone was frozen in liquid nitrogen and pulverized. Powdered bone was extracted for total lipids, and phospholipids were isolated by column chromatography. The fatty acid composition and arachidonic acid concentrations were determined in total phospholipids after the addition of an internal standard, octadecatetraenoic acid (18:4n-3), and subsequent gas chromatography. The type of dietary lipids had a profound influence on the fatty acid composition of bone lipids. Arachidonic acid concentrations were significantly lower in total phospholipids of mandibles and maxillae of rats fed the experimental diets than in those fed the control diet. Because arachidonic acid is a precursor of prostaglandin E2 and leukotriene C4, a significant reduction in its concentration may result in reduced levels of these eicosanoids in the alveolar bone.