Study On The Toxic Mechanism Of Lanthanum In Astrocytes

PrefaceRare Earth(RE)is composed of 17 kinds of elements,including lanthanum to Eu for the light rare earth elements,while Gd to Lu for the heavy rare earth elements. Recent years Rare Earth has been widely used in agriculture,animal husbandry, industry,national defense and high-tech industries,as well as biomedical research,the scientific community by the Government and the general importance.However,with a wide range of rare earth development and use,will make it more and more into the environment,food chain and the food chain to human beings in their daily lives which inevitably come into contact with,or low or high levels of rare earth.Therefore, rare-earth elements,as well as the ecological environment for human health has become a health concern issues.There are reports of rare earth elements show that the neurotoxic,and its role is similar to Al³⁺,some functions of nerve blockers.Human central nervous system is one of the most important,and exogenous compounds more sensitive toxic effect,the rare earth elements on the role of the central nervous system damage in particular deserves our attention.Epidemiological investigation of rare earth mining and experiments show that rare earth can be through long-term low-dose intake and brain volume in children and lead to toxic effects,as demonstrated by inhibition of nerve function,lower IQ, thus endangering the child's basic quality of the mining area may far-reaching impact. Animal experiments also proved that the rare-earth toxic to the animals the role of the nervous system,through a concrete manifestation of injury to the brain structure of the hippocampus region of apoptosis affecting learning and memory;the metabolic effects of nerve cell activity;affect neurotransmitter release and re-uptake.Central nervous system in the number of glial cells accounted for more than 90%, of which astrocytes(AST)is the most important component.Recent study found that astrocytes in some new features,suggesting that its senior center may be involved in the activities of the function of the system changed in the past only serve to support the role of auxiliary role.Lanthanum is the representative of light rare earth elements,the chemical nature of lively,at present its role in nervous system toxicity have been reported.In this study,therefore,choose to study astrocytes toxic effects of lanthanum chloride,the object,through the observation of different doses of lanthanum treated astrocytes vitality,intracellular Ca²⁺concentration,mitochondrial and cytosolic cytochrome C changes in content as well as the cell cycle,apoptosis and changes in rare-earth to explore the role of the central nervous system mechanisms for the safety evaluation of rare earth elements and provide a theoretical basis.Experimental GroupingLaCl₃ was prepared with serum-free DMEM to a final concentration of 0.25,0.5, 1.0,2.0 mmol / L,and control group use the serum-free DMEM.Research Methods1,The primary culture of astrocytes and immunocytochemistry staining were applied to identify astrocytes.2,MTT was used to assess the effect of LaCl₃ on the cell proliferation capacity of astrocytes.3,Fluorescence Probe was used to detect Intracellular free calcium concentration in astrocytes.4,Flow cytometry was applied to measure the effect of LaCl₃ on the mitochondrial membrane potential of astrocytes.5,Chemical colorimetry was applied to measure the impact of LaCl₃ on the content of cytochrome C in mitochondria and cytoplasm of astrocytes.6,Flow cytometry was applied to measure the effect of LaCl₃ on the apoptosis rate of astrocytes.7,Flow cytometry was applied to measure the effect of LaCl₃ on the cell cycle of astrocytes. 8,Cell morphological changesResults1,Results of immunocytochemical identification in astrocytesAfter GFAP immunohistochemistry complete,the microscope shows that the vast majority of cells were stained brown,in the inverted microscope slides for each choice of field of vision 10,counting the percentage of positive cells,the positive rate of more than 90%.So it can be to the cells in primary culture of astrocytes as a model.2,Results of cell proliferation capacity of astrocytes by MTTLanthanum chloride on astrocytes have some cytotoxicity,with the increased dose and exposure time,the survival rate of astrocytes gradually reduced,and show some dose-effect relationship(P＜0.05).3,Changes on the concentration of intracellular calcium[Ca²⁺]i in extracellular free calcium in astrocyte rise,and with the increase in the concentration of lanthanum exposure,intracellular[Ca²⁺]i was significantly increased, compared with the control group(P＜0.05);group of extracellular calcium within the astrocytes[Ca²⁺]i also increased compared with the control group(P＜0.05);however, comparison between the two was no significant difference.4,Changes in mitochondrial membrane potentialIn La-exposed groups mitochondrial membrane potential of astrocytes decreased, and with the increase in the concentration of lanthanum exposure,mitochondrial membrane potential significantly decreased compared with the control group significant difference(P＜0.05).5,Changes in cytochrome C content of Mitochondria and cytoplasmLanthanum exposure in each group in astrocyte mitochondrial cytochrome C was reduced,cytosolic cytochrome C content increased,compared with the control group significant difference(P＜0.05),and with the increase of dose in a dose-response relationship.6,Changes in apoptosis rateLanthanum astrocytes exposed to each group the rate of apoptosis compared with the control group significantly increased(P＜0.05),and also between each dose group was significant difference(P＜0.05).7,Changes in cell cycleWith an increase dose in Lanthanum chloride,G₁ phase cells as compared with the control group index increased significantly(P＜0.05);in contrast,S phase and G₂ phase cells compared with the control group index was reduced to varying degrees,the difference is also significant(P＜0.05).8,Morphological changesIn the control group,cell morphological was polygonal with a larger cell body and growth-intensive;0.25 mmol/L group and 0.5 mmol/L cells to change shape,cell body elongation,dendritic thickening,and observed that a small number of from parietal cells;1.0 mmol/L group of cells can be observed that the apparent reduction in the amount,and some round cell shrinkage;2.0 mmol/L cells from the wall is a serious problem,too many dead cells.Conclusion1,Lanthanum chloride can reduce cell survival rate in astrocytes and increase the intracellular free calcium ion concentration.2,Lanthanum chloride can damage mitochondrial function,so that mitochondrial membrane potential(ψm)of astrocyte decreased;cytosolic Cyt c content increased and Cyt c in mitochondria decreased.3,Lanthanum chloride could increase apoptosis rate of astrocytes in vitro and change the cell morphology.