Differential Effect of Gluten and Casein Diets on Rat Liver HMP Shunt Dehydrogenases

Abstract

The effect of diets containing as their protein component wheat gluten or casein, fed ad libitum to adult male rats for 1 to 6 days, after 6 days of protein deprivation, on the liver levels of glucose-6-phosphate dehydrogenase (G8PD) and 6-phosphogluconate dehydrogenase (6PGD) were studied. In rats fed the gluten diet the values of body weight gain, liver size, liver protein, liver xanthine oxidase, G«PD and 6PGD activities were lower in comparison with rats fed the casein diet. Amino acid supplements to the gluten diet improved the nutritive value of this diet, as shown b> the enhancement of body weight gain, liver size, liver protein and xanthine oxidase activity to levels found in rats fed the casein diet, but failed to increase GePD and 6PGD activities. Essential fatty acids added to the casein diet, in order to bring their level up to that of the gluten diet, proved incapable of decreasing the levels of G«PD and 6PGD activities found in rats fed the casein diet..It was concluded that the differ ential effect of gluten and casein on liver GoPD and 6PGD is independent of differences in the nutritive value and in the essential fatty acid content of these proteins, and is dependent upon one or more factors different from those known to affect the liver HMP shunt dehydrogenases.

Concomitant Repression by Gluten of HMP Shunt Dehydrogenases, Citrate Cleavage Enzyme and Malic Enzyme in Rat Liver and Adipose Tissue

“…In table 3 the levels of plasma insulin are shown. As has previously been found (21)(22)(23)(24), rats fed the gluten diet for 6 days had lower body weight gain, smaller liver and less liver protein than rats fed the casein diet. These effects were overcome by adding a suffi cient amount of Lys and Thr to the gluten.…”

“…Adult male WAG rats (240 to 340 g) were caged from weaning at constant tem perature (23°) and had free access to a stock diet.2 At the beginning of the experi ment, the animals were housed individually and fed a protein-free diet for 6 days; sub sequently some were fed for 4 days and others for 6 days a balanced diet contain ing, as its exclusive nitrogen source, casein or wheat gluten with or without \% L-lysine-HCL and 0.40% L-threonine. In order to equalize the essential fatty acid content of the casein-and gluten diet, the former was supplemented at the expense of starch (w/w) with 1.2% corn oil and 0.019% methyl-linolenate.3 The composi tion of the diets has been described in a preceding paper (23). At the end of refeeding the rats were anaesthetized with sodium pentobarbital * and the abdomen was opened in order to extract the blood from the cava inferior and to remove the liver and the epididymal pads.…”

“…G6PD (EC 1.1.1.49), 6PGD (EC 1.1.1.44), ME (EC 1.1.1.40) and CCE (EC 4.1.3.8) assays were conducted at 25°on the super natant with the methods of Bottomley (Method II) (27), Ochoa (28) and Cottam (29) respectively. Liver glycogen and total liver protein were also assayed by methods previously described (23). Plasma insulin was determined 5 using rat insulin as standard.6 Body, liver and adipose tissue parameters were related to body weight at the end of protein deprivation.…”

“…In our previous studies of the effect of dietary protein on the response of HMPD we have shown that in rats fed a gluten diet, the HMPD activity did not reach the level found in the rats fed the casein diet. This effect was independent of both the amino acid composition of the gluten and of its essential fatty acids content (21)(22)(23)(24)(25).…”

On the Repression of Rat Liver HMP Shunt Dehydrogenases by Wheat Gluten

“…In our previous papers it has been shown that liver levels of both hexose monophosphate (HMP) shunt dehydrogenases are higher when casein replaces wheat gluten as the dietary protein component (1)(2)(3).…”