The Protective Effect against X-Irradiation of Methyl Lineolate in the Rat

Abstract

In radiation-survival experiments rats with no more than 2% cottonseed oil in their diet lived much longer when subjected to repeated weekly sublethal doses of X-ray, than rats on the same basic diet but without the oil. Since the essential fatty acid, linoleate, makes up about half of cottonseed oil, it was thought the fatty acid might be the protective agent. Young rats (5-6 mos. old) were kept on fat-free diets until fat-deficiency symptoms appeared; after 8 further weeks on this diet they were divided into 2 groups of 71 and 72 (sexes approx. equal), and continued on identical diets, except that the 2d group received 10 mg of methyl linoleate daily by mouth. All rats were subjected to 300 r of X-radiation weekly for 4 wks., and then to the same dose on alternate or 3d weeks until 2400 r had been received. Throughout the expt., after the 2d wk. of radiation, more linoleate-free rats died than did those receiving the fatty acid, and, at the end of the expt. (98 days), 30 rats with supplement were still alive, whereas only 8 of the others survived. It is postulated that methyl linoleate in skin metabolism may have a role in the lack of protection of linoleate-deprived animals exposed to X-ray.