OXIDATION OF VERY-LONG-CHAIN FATTY-ACIDS IN RAT-BRAIN - CEROTIC ACID IS BETA-OXIDIZED EXCLUSIVELY IN RAT-BRAIN PEROXISOMES

We studied the effect of sodium 2-[5-(4-chlorophenyl)pentyl]oxirane-2-carboxylate (POCA), a potent inhibitor of mitochondrial carnitine palmitoyltransferase I, on fatty acid oxidation by rat brain cells. In cultured glial cells as well as in dissociated brain cells from adult rats palmitic acid (16:0) oxidation was inhibited by about 85% of control values when 25-mu-M POCA was added to the medium, whereas no inhibition of cerotic acid (26:0) oxidation was observed. Furthermore, omission of carnitine from the culture medium resulted in a 57.7% decrease in palmitic acid oxidation in cultured glial cells, whereas cerotic acid oxidation was not influenced. These results indicate that rat brain peroxisomes contribute only little (about 15%) to palmitic acid oxidation and provide conclusive evidence that cerotic acid is oxidized exclusively in rat brain peroxisomes.