Recently there has been considerable interest in the metabolism of cystine, homocystine, and methionine, and in the biological relationship of these amino acids to choline (1-6). This paper reports certain pathological changes produced by excess dietary cystine in albino rats. Blum (7), in 1904, found that in dogs the intravenous administration of 1 gm. of cystine per kilo of body weight was nephrotoxic. In 1925, Lignac (8) reported that subcutaneous injections of cystine suspensions caused severe injury to the renal tubules of mice. He was able to find cystine crystals in the kidneys, liver, and spleen. In the same year, during the course of studies on the toxic effect of amino acids, Newburgh and Marsh (9) found similar lesions in dogs after intravenous injections of large doses of cystine. Later, a number of workers (10-12) studied the effects of the oral administration of excess cystine. Here again, renal damage was found, consisting of severe injury and necrosis of the cortical tubules, associated with hemorrhage into the renal capsule and parenchyma. Recently, Gy6rgy and Goldblatt (13), have stressed the similarity of the renal lesions caused by excess cystine feeding and by choline deficiency in the diet.Changes in the liver of rats fed cystine have also been described by Curtis and Newburgh (14), Sullivan, Hess, and Sebrell (15), and Lillie (16). On 10 to 20 per cent cystine intralobular hemorrhagic necrosis of the liver occurred with death in 2 to 13 days. Rats fed smaller quantities of cystine showed fat accumulation in the liver and a much longer life span. The rats fed 10 to 20 per cent cystine also had more advanced renal lesions. Control rats on the 4 per cent casein diet showed only moderate fatty infiltrations in the liver.The hepatic lesion found in young albino rats fed a choline deficient diet, is characterized by a massive fatty infiltration (5, 13). No necrosis, hemorrhage, or cirrhosis has been reported, although du Vigneaud (17) found evidence of cellular damage other than the fatty infiltration.
Materials and MethodsMale albino rats of the Sherman stock, weighing between 60 and 70 gm., were housed in cages with raised wire mesh floors. Fresh water was supplied every day and the