Study On The Damagement By Lanthanum In Cortex Neurons Of Rats

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. Since Rare Earth has been widely used in agriculture, industry, animal husbandry, industry, national defense and high-tech industries, as well as biomedical research, RE has widely come into the environment, and through food chains into human beings. Therefore, RE as well as their influence on environment and human health has become a hygienic issue which can not be ignored.There were reports about rare earth elements showed their neurotoxicity. Epidemiological investigation of rare earth mining showed that long-term intake of rare earth can lead to lower IQ and reduced memory function in children, thus endangering the basis quality of those children, may cause far-reaching impact. Animal experiment also proved that the rare earth affected learning and memory possibly through reducing antioxidant capacity; interrupting metabolism of brain trace amount elements; affecting enzyme activity and the release of neurotransmitter and so on.Lanthanum with a lively chemical nature is the representative of light rare earth elements, and its neurotoxicity has been reported in vivo, however, the mechanism is not clear. In this study, we choose cerebral cortex neurons as the object to investigate the effect of neuron apoptosis by lanthanum and its possible mechanism, through observing changes in mitochondrial activity, intracellular ROS content, mitochondrial membrane potential, bcl-2,bax mRNA expression and apoptosis, to supply a new experimental prove about neurotoxicity of lanthanum.Experimental GroupingLaC13 was prepared with serum-free DMEM to a final concentration of 0.01,0.1, 1.0,2.0mmol/L, and control group use the serum-free DMEM. Research Methods1,The primary culture of neurons and immunocytochemistry staining were applied to identify neurons.2,MTT was used to assess the effect of LaC13 on the mitochondrial activity of neurons.3,Fluorescence Probe DCFH-DA was used to detect intracellular ROS content in neurons.4,Fluorescence Probe Rodanmin 123 was used to detect mitochondrial membrane potential of neurons.5,RT-PCR was used to detect bcl-2,bax mRNA expression in neurons.6,Flow cytometry was applied to measure the effect of LaCl3 on the apoptosis rate of neurons.7,Cell morphological observation.Results1,Results of immunocytochemical indentification in neurons The microsope showed that the vast majority of cells were stained brown, choosed 10 visions of each slide to count the percentage of positive cells, the positive rate was more than 90% by calculating, so this primary culture of neurons can be a model in vitro.2,Results of mitochondrial activity of neurons by MTTAfter exposure of lanthanum chloride the mitochondrial activity and the survival rate of neurons significantly reduced compared with the control (p＜0.01), and showed some dose-effect relationship.3,Changes in intracellular ROS contentIn La-exposed groups intracellular ROS content showed increasing trend, and there was a significant difference compared with the control (p＜0.05 or 0.01).4,Changes in mitochondrial membrane potentialMitochondrial membrane potential of neurons decreased after La exposure, and with the increase of lanthanum concentration, MMP decreased with a significant difference compared to control (p＜0.01). 5,Changes in bcl-2,bax mRNA expressionIn lanthanum exposed neurons, bax expression increased whereas expression of bcl-2 reduced at 0.1 and 1.0 mmol/L group, and differences were significant to the control (p＜0.01).6,Changes in apoptosis rateApoptosis rate appeared a increasing trend after lanthanum exposure, and differences were significant compared with control at 0.1 and 1.0 mM dose (p＜0.01).Conclusion1,Lanthanum chloride can escalate the intracellular ROS level, and damage mitochondrial function, so that mitochondrial membrane potential of neuron decreased, mitochondrial activity descended.2,Lanthanum chloride increased bax expression whereas decreased bcl-2 expression in neurons, and induced apoptosis of cortex neurons in vitro.