Biological Effects of Methionine Sulfoximine II. Comparative Sulfur Metabolism Studies in Rats and Rabbits

¹ From the Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts

To obtain information concerning methionine sulfoximine-induced convulsions, comparative sulfur metabolism studies of rats and rabbits have been made. Most rat tissues studied contained more sulfur than those of rabbits. Although rabbits excrete the same amount of sulfur as rats per unit body weight, they were found to excrete four times as much of administered methionine. When methionine sulfoximine was injected, extremely small quantities of methionine sulfoximine sulfur were deposited in the brains and spinal cords of rats and rabbits, even though the injections induced convulsions in the rabbits. Methionine sulfoximine inhibited the incorporation of methionine in the tissues of fed animals but not fasted ones. Fasting was also found to partially protect rabbits against methionine sulfoximine toxicity. The possible production of an unknown convulsant by animals in the presence of methionine sulfoximine has been suggested.