Experimental liver necrosis in rats. I. Changes in liver, blood and spleen glutathione and ascorbic acid levels in dietetic liver necrosis.

Leaf & Neuberger (1947) reported that feeding rats with diets low in protein or sulphur-containing amino acids produced a marked and rapid fall in the reduced glutathione level of the liver to 20-30% of the normal value. The authors stated that the original purpose of their work was 'to find out whether the acute massive necrosis of the liver observed in rats reared on diets containing only traces of cystine and methionine is caused by a change in the composition of the liver with respect to sulphur'. As the diets failed to produce liver necrosis, the question could not be answered. Subsequent to this work it became evident that a deficiency, not only in sulphur-containing amino acids but also in tocopherol, was required to produce dietetic liver necrosis (Himsworth, 1950). In this laboratory, much work has been carried out on the conditions necessary for rapid and consistent production of dietetic liver necrosis in rats (Himsworth & Glynn, 1944a, b; Himsworth & Lindan, 1949; Lindan & Himsworth, 1950). In the standard diet (called hereinafter a 'necrogenic diet') all the protein (7 % of the diet) was provided by baker's yeast, shown chemically to be deficient in cystine and methionine (Lindan & Work, 1951a), and the tocopherol content was about 1 mg./ 100 g. diet. This diet produced liver necrosis in young rats in 12-55 (mean 28) days, provided that the rats had been subjected to preliminary tocopherol depletion prior to weaning. When supplemented with cystine or with tocopherol, the diet ceased to be necrogenic (Lindan & Himsworth, 1950). This paper reports the effect of this yeast diet on the glutathione levels of livers, examined both before and after the development of massive necrosis. Estimations were made of both reduced glutathione (GSH) and oxidized glutathione (GSSG), since the obvious connexion between liver necrosis and tocopherol (an anti-oxidant) suggested that changes in the proportions of GSH and GSSG might occur in tocopherol deficiency. Ascorbic acid, another oxidizable compound, was also estimated. * Present address: Human Nutrition Research Unit, Medical Research Council Laboratories, Hampstead, London, N.W. 3. Water, nitrogen (total and non-protein), fat and glycogen estimations were also carried out. The interchangeability of tocopherol and sulphurcontaining amino acids as preventive factors in liver necrosis led us to investigate liver glutathione levels in rats given the yeast diet supplemented with one or other of these factors. It was also of interest to find out whether the biochemical changes in necrotic livers were specific to that organ, or were a more general result of the illness and common to other tissues; accordingly spleen and blood were also examined. Preliminary figures have been reported already (Lindan & Work, 1951 b-d).