| Abstrakt: |
Studies were conducted to investigate whether the blood ammonia level regulates a mechanism controlling appetite for a low protein diet containing imbalanced (histidine or tryptophan) amino acid mixtures. In ad libitum-feeding experiments, an increase in the amount of amino acid mixtures causing imbalances in the basal diet resulted in a slight increase in the blood ammonia level, but the correlation between ammonia level and food intake was not close enough to substantiate a relationship. The blood ammonia levels of rats meal-fed (8 hours feed, 16 hours fast) imbalanced diets were significantly elevated 4 hours after the beginning of the feeding period. Food intake and blood ammonia levels decreased between 4 and 8 hours. Addition of 2% ammonium acetate to imbalanced diets depressed food intake, and oral administration of antibiotics to groups fed imbalanced diets tended to increase food intake, whereas food intake of rats fed the basal diet was not altered by either treatment. Addition of arginine or ornithine to a histidine-imbalanced diet did not increase food intake. Of the urea cycle intermediates, citrulline concentration in the livers of rats fed the imbalanced diet was considerably increased in spite of an increase in argininosuccinate synthetase activity in the liver. Ammonia metabolism in perfused livers from rats fed the imbalanced diet was similar to that in livers from animals fed the basal diet. |
