Menhaden Fish Oil, n-3 Polyunsaturated Fatty Acids, and Protection of Newborn Rats from Oxygen Toxicity

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Abstract
We have previously reported that newborn rats born to mothers fed a high n-6 polyunsaturated fatty acid (PUFA) (safflower oil) diet demonstrated increased n-6 PUFA in lung lipids and superior tolerance to high oxygen exposure. In the present study, we explored whether high n-3 PUFA might also protect against hyperoxic damage and by what mechanism. Adult female rats were fed either regular rat chow, a high n-3 (menhaden fish oil-based) diet, or a high n-6 (safflower oil-based) diet for 6 wk before and then throughout pregnancy and lactation. Newborn offspring of the high n-3 (fish oil) dams demonstrated increased n-3 PUFA {i.e. eicosapentaenoic and docosahexaenoic acid) and decreased n-6 PUFA {i.e. linoleic and arachidonic acid) in their lung lipids compared to the other two diet groups. The high n-6 (safflower oil) offspring had the opposite PUFA lung lipid pattern (with increases in total n-6 fatty acids and decreases in total n-3 fatty acids). The high n-3 offspring demonstrated markedly decreased lung levels of prostaglandin E2, vja and thromboxane B2, whereas the high n-6 offspring had higher eicosanoid levels than the regular diet offspring. Offspring of both high n-6 and high n-3 diet dams demonstrated essentially the same superior hypperoxic tolerance compared to regular diet offspring [7-d (>95% O2) survival rates of 110/115 and 99/109, respectively, versus 70/91, p<0.01]. These studies lend further support to the speculation that increasing lung PUFA content may provide the newborn lung with increased ability to scavenge oxygenfree radicals and thus may serve to protect against oxygen toxicity.