INHIBITION BY N-3 FATTY-ACIDS OF ARACHIDONIC-ACID METABOLISM IN A PRIMARY CULTURE OF ASTROGLIAL CELLS

Docosahexaenoic acid (22:6 n-3) was present in low concentrations in a primary culture of rat brain astroglial cells, when compared to brain cortex. We have thus supplemented these cells with this fatty acid an d investigated the effects of its incorporation in cell phospholipids on the conversion of arachidonic acid, 20:4 n-6, through the cycle and lipoxygenase pathways, after cell stimulation. Docosahexaenoic acid-e nriched cells produced less thromboxane B-2 and 6-keto-Prostaglandin F -1 alpha and markedly less 12-hydroxyeicosatetraenoic acid than unsupp lemented cells, after stimulation with the Ca2+-ionophore A23187. The production of 15-hydroxyeicosatetraenoic acid from arachidonic acid wa s slightly increased in docosahexaenoic acid-supplemented cells. We ha ve also supplemented these cells with eicosapentaenoic acid (20:5 n-3) and, in addition to accumulation of this fatty acid in cell phospholi pids, we found elevation of 22:5 n-3 and some increment of 22:6, confi rming that glial cells are able to convert eicosapentaenoic acid to th e long chain, more unsaturated derivatives. In conclusion, n-3 fatty a cids, when supplemented to glial cells, appear to modulate the arachid onic acid cascade and to be converted through the elongation and desat uration pathways.