Enzyme Activities of the Livers of Mice Infected with Salmonella typhimurium

Irvin S. Snyder
1971 Infection and Immunity  
The activities of the mouse liver enzymes tryptophan oxygenase, tyrosine aminotransferase, and pyruvate kinase were measured after infection with three dose levels of Salmonella typhimurium strain SR-11. Infection occurred in all groups as evidenced by an increase in bacterial numbers and by death of the animals. The activities of the enzymes increased in all groups during the course of the infection. The results obtained during infection are compared with those obtained after endotoxin
more » ... r endotoxin injection. Considerable progress has been made in recent years in describing the metabolic events that follow injection of gram-negative endotoxin into animals (13). Berry and Smythe (3) reported a decrease in liver tryptophan oxygenase (TO) activity in animals given endotoxin; this decrease was maximal at the time the animals succumbed. The decrease in the activity of this enzyme and death of the animals could be prevented by administration of cortisone at time of endotoxin injection (4); but the activities of some other enzymes were increased. Rapoport et al. (15) have shown that induction of TO occurs early in the course of pneumococcal infection but returns to normal levels 1 day after infection. Berry et al. (5) demonstrated that the activity of tyrosine aminotransferase (TAT) increases and suggested that the associated loss of glycogen in endotoxininjected animals might be related to inability of these animals to utilize glyconeogenic intermediates. Snyder et al. (17) associated the increased activity of pyruvate kinase (PK) in endotoxininjected animals with the depletion of liver glycogen. LaNoue et al. (12) measured three gluconeogenic liver enzymes in rats infected with Pseudomonas aeruginosa and in animals injected with endotoxin. These investigators did not distinguish differences in the activity of either phosphoenol pyruvate carboxykinase or fructose-1,6-diphosphatase after infection or endotoxin injection. However, the activity of glucose-6-phosphatase in endotoxin-treated rats was about 80% of control animals, whereas the activity in infected animals dropped to less than one-half that of control animals. The effect of infection with Salmonella typhi-muriwn on the activities of host enzymes has not been measured and the significance of these biochemical events during infection with a gramnegative organism is unknown at this time. The purpose of this report is to relate the changes observed in the activity of the enzymes TO, TAT, and PK in mice infected with S. typhimurium to the results of prior studies with endotoxin. MATERIALS AND METHODS Preparation of organisms. S. typlhimurium strain SR-11 was maintained by weekly transfer on Brain Heart Infusion-agar slants. Brain Heart Infusion broth (Difco) was inoculated with organisms from an overnight culture. After incubation for 12 hr at 37 C, the organisms were centrifuged and washed 3 times with 0.15 M NaCl. The bacterial suspension was adjusted to an optical density of 0.3 at 600 nm with a Bausch & Lomb Spectronic 20 colorimeter. Duplicate plate counts of this suspension showed 1.5 X 108 organisms/ml. Inoculation of animals. Female Swiss-Webster mice (18 to 20 g; Rockland Farms, Boyertown, Pa.) were used. The mice were allowed to rest 1 week after arrival before experimental use. Infection was established by intraperitoneal injection of 0.5 ml of the appropriate dilution of the standardized culture. Preparation of mouse liver. The animal was sacrificed by cervical dislocation, and the entire animal was immersed in 70% ethanol for about 1 min. The liver was removed aseptically and placed in a homogenizing tube containing sterile 0.15 M KCl. The organ was homogenized for 2 min and samples were taken for bacterial counts, enzyme determinations, and determination of dry weight or protein content. Bacterial counts. The numbers of organisms were determined by serial 10-fold dilution of the liver homogenates in sterile 0.15 M NaCl. A 0.1 -ml amount of each dilution was spread on the surface of SS agar 411 on May 7, 2020 by guest http://iai.asm.org/ Downloaded from
doi:10.1128/iai.4.4.411-415.1971 fatcat:jman7bql25dt7d6kcyv3qp74me