Comparison of response indices to toxic microcystin-LR in blood of mice

In order to investigate the response indices to toxic microcystin-LR (MC-LR) in blood of mice, concentrations of free and total MC-LR in blood and tissues, accompanied by serous parameters in series including some enzymatic activities, hematology and the function of leukocytes, were determined in mice exposed to the toxin ranging from 3.125 to 25.000 μg kg−1 day−1 by intraperitoneal injection for 7 days. On the 7th day, the ratios of mass of free MC-LR in serum to the mass of MC-LR in given dose were 3.843-4.555%, while the ratios of total MC-LR in liver were 34.465-38.567%. Comparing the overall experimental results, the three most sensitive indices are total MC-LR in the liver, the phagocytic index and reactive oxygen species (ROS) which have shown significant differences between the lowest dose group and the control group. Alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase had proportional correlations with the MC-LR exposure doses, and the hematology of the majority of blood cells and the volume of erythrocytes were also influenced by the toxin. The alterations of some cytokines and the ROS of leukocytes were observed. The results of the studies suggest that measurement of MC-LR in blood is powerful and clear evidence to indicate that subjects have been exposed to MC-LR and can be used to discriminate from other causes leading to hepatic lesions although it is not as sensitive as other indices that are usually as useful complements to reflect the liver function.