| Rare earth elements (REEs) consist of 17 elements, they are lanthanum, scandium and yttrium which their chemical properties are similar. Lanthanum series include 15 kinds of elements. REEs are divided into light REEs and heavy REEs. There are the first storage and widespread application of REE in China. Changle consist of four compound light REEs. It is much applicated in agriculture than in other fields. With wide appliance of REEs in agriculture and industry, REEs had entered ecosystem gradually and human bodies through food chains. Liver is an important organ of metabolism, it has powerful bioconversion, metabolism and detoxification function. REEs can enter body through digestive tract after taking it orally. When REEs are absorbed, most of them may go into liver firstly through blood circulation, and then enter other organs, therefore liver is the main organ for accumulating REEs. Light REEs are major distributed in liver, and certain dose of light REEs can make hepatocyte damage, therefore our research is to emphasized on studying the influences on rat liver after given with different doses of Changle and its mechanisms.In this study, 120 young Wistar rats were divided into four groups,which were given Changle at 2.0,5.0,20.0mg·kg-1 and the control group with physiological saline respectively for three months. Pathological changes of liver were observed by light microscope and transmission electron microscope; The changes of SDHase, G-6-Pase and Ca2+-ATPase in rat liver were oberserved by enzyme histochemistry technique; AST(aspartate aminotransferase), ALT(alanine aminotransferase), GGT(gamma glutamyltransferase), ALP(alkline phosphatase) and calcium contents in the serum were measured. The contents of SOD (superoxiden dismutase) and MDA (malondialdehyde) in rat liver were studied by means of biochemistry. Comparing with the control group, in the 2.0, 5.0mg·kg-1 group of Changle, there are no obvious changes in hepatocytes, blood serum enzyme, SDHase,G-6-Pase and Ca2+-ATPase . All of 2.0,5.0,20.0mg·kg-1 group display a rise change in blood serum calcium contents. In the 20.0mg·kg-1 group shows injurious effects on the rat hepatocytes, there are decrease of glycogen in the rat hepatocytes, denser matrix of the mitochondria, deformation of the nuclei of some hepatocytes with different degrees and infiltration of inflammatory cells at portal area. The levels of SDHase,G-6-Pase and Ca2+-ATPase in rat hepatocytes in the group of 20.0mg·kg-1 group were reduced obviously. The more the rats are given doses, the more the number of bodies contain high electronic dense gravel-like granules and the secondary lysosomes with dense bodies around the bile canaliculus. The activities of SOD decreased markedly in the group of 20.0mg·kg-1group, but the concentration of MDA increased obviously compared with the control group. There are increased changes of GGT, ALP in blood serum of 20.0mg·kg-1 group .There were some experiments verified that REEs could enter into hepatocytes, organelles and accumulate in the liver after giving rats different dose of REEs for a long time. We found that the more given doses, the more the number of bodies contain high electronic dense gravel-like granules and the secondary lysosomes with dense bodies around the bile canaliculus in each of 2.0,5.0,20.0mg·kg-1group. REEs have high affinity to mitochondrion, membrane of mitochondrion may be damaged with high concentration of lanthanum in it. We found that in the 20.0 mg·kg-1 group, mitochondrial crista is swollen and the activity of SDHase is lower than the control group, so certain REEs can affect the structure and function of mitochondrion .Human bodies have antioxidation system such as SOD, GSH-Px, which can eliminate surplus of free radical. Lipid peroxide is peroxide such as MDA, which is the product of phospholipid in the biomembrane being injured by the free radical. Compared with control group, activity of SOD decreases , but increases of MDA in 20.0 mg·kg-1 group, it indicates that degree of lipid peroxida...
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