Influence of long-term per oral taurine treatment on activity of liver enzymes in mature rats

Taurine is sulfur-containing derivative of methionin and cysteine that plays a key role in glucose and lipid metabolism. Taurine regulates antioxidant defense system, membrane potential of mitochondria, and glycolysis. Thus, it might have a serious impact on cell metabolism in mammals. The aim of this work was to study the influence of long-term per oral taurine treatment (5, 10 and 20 mg/kg) on the antioxidant defense system, cholesterol content, activity of transaminases and lactate dehydrogenase in rat liver. To achieve that goal, mature Wistar rats (weight 140–160 g, age – 4 months) were divided in four groups – control, rats which once a day during 28 days were injected drinking water in esophagus, and three experimental groups, that were injected taurine solution in concentrations: І – 5 mg/kg, ІІ – 10 mg/kg and ІІІ – 20 mg/kg of body mass. After 28 days, rats were decapitated under light chloroform narcosis and liver mass was determined. In liver, content of cholesterol, TBA-active products and activity of antioxidant defense enzymes, transaminases, and lactate dehydrogenase were measured. Our results show that after a long-term per oral taurine treatment liver mass decreased by 27.5 % comparing to control group. Lactate dehydrogenase activity increased two times, while the activity of alanine aminotranferase and aspartate aminotransferase in mitochondrial fraction increased by 40–90 % in liver of animals of all experimental groups. Total activity of these enzymes in rat liver increased by 20–37 % in all experimental groups. Cholesterol content increased dy 32.4 % in rats of experimental group II. This may indicate intensification of liver metabolism. The content of TBA-active products in submitochondrial and mitochondrial fractions increased more than two times in rats of experimental groups II and III. The activity of superoxide dismutase in the submitochondrial fraction increased by 49.8 and 36.5 % in liver of that rats. The activation of superoxi­de dismutase and a rise in content of TBA-active products may suggest a rise of free oxygen radicals production and inability of antioxidant defense system. These results may indicate a negative influence of taurine in doses higher than 5 mg/kg, since the balance between antioxidant protection and lipid peroxidation processes was violated.