Protection against acute paraquat toxicity by dietary selenium in the chick

Experiments were conducted to determine whether both dietary vitamin E and selenium (Se) affect the acute toxicity of paraquat in the chick. Paraquat significantly stimulated the rate of NADPH-supported consumption of oxygen by the microsomal fractions of chick liver and lung, and this stimulation was decreased by addition of superoxide dismutase and/or catalase. The acute oral LD50 of paraquat in the 8-day-old vitamin E- and Se-deficient chick (131 mg/kg body weight) was increased more than threefold by supplementing the diet with 0.10 ppm Se as Na2SeO3, (419 mg/kg body weight) but was not significantly affected by supplementing the diet with vitamin E (148 mg/kg body weight). A high fat (20%) diet did not alter the protective effect of Se against the acute toxicity of paraquat; however exposure to an oxygen-enriched atmosphere did reduce the protection by dietary Se. Dietary Se at 0.01 ppm protected against acute paraquat toxicity, whereas 0.08 ppm Se produced detectable increases in the Se-dependent glutathione peroxidase. These results indicate that the acute toxicity of paraquat in the chick is highly responsive to nutritional Se status and not vitamin E status.