Polyunsaturated fatty acids and protection of newborn rats from oxygen toxicity

To test whether polyunsaturated fatty acids (PUFA) might be associated with protection against oxygen toxicity in newborn experimental animals, we performed two series of experiments. In the first series, adult female rats were fed one of three diets--regular Rat Chow, a high-PUFA (safflower oil-based) diet, or a low-PUFA (palm oil-based) diet--for several weeks before and throughout pregnancy and lactation. Newborn offspring of the three diet groups had similar antioxidant enzyme activities and surfactant development. Offspring of dams fed the high-PUFA diet had total lung lipid fatty acids characterized by increased linoleic acid (18:2 omega 6) and arachidonic acid (20:4 omega 6) and a significantly increased PUFA/saturated fatty acid ratio, compared with offspring of dams fed the regular diet or low-PUFA diet; associated with this increased PUFA pattern was markedly superior survival (80 of 84 (95%) vs 56 of 84 (67%) for regular-diet offspring, P less than 0.01) after 7 days in greater than 95% oxygen. Conversely, offspring born to dams fed the low-PUFA diet had decreased lung PUFA content and inferior tolerance to prolonged high O2 exposure (survival 38 of 84 (45%)). In the second experimental series, the postnatal provision of high PUFA rat milk to offspring born to dams fed the low-PUFA diet (via "cross-nurturing" by high-PUFA diet dams) rapidly increased their lung lipid PUFA and improved their hyperoxic survival (44 of 50 vs 25 of 50 for low-PUFA diet newborn animals kept with their low-PUFA mother rats, P less than 0.01). These studies suggest that increasing lung lipid PUFA can confer a protective effect against the toxic effects of hyperoxia on the newborn animal lung.