TMT對原代海馬神經(jīng)元損傷與BDNF保護作用研究
[Abstract]:Research background and purpose:
Three chloromethyl tin (Trimethyltin, TMT) is an important occupational hazard and an important environmental pollutant. Acute TMT exposure can cause the damage of multiple systems mainly including the nervous system damage to the central nervous system. The main mechanism of injury is to cause the apoptosis of the nerve cells, the inflammatory reaction of the nervous system, and the nervous system. .TMT can selectively induce the brain marginal system, especially the hippocampal neuron death, and cause the damage effect of the nervous system. The main role of BDNF in the central nervous system is to regulate the down regulation of BDNF expression in the rat brain of the hippocampal synaptic plasticity.TMT exposure, and the neurons that overexpress BDNF It has an antagonistic effect on the neurotoxicity of TMT. However, the damage mechanism of TMT on brain neurons, especially the damage of neuron dendrites, is not clear, and the mechanism of BDNF antagonism to the neuroprotective effect of TMT damage remains to be further studied. Therefore, this topic selects TMT and BDNF as the research content to try to understand the damage of TMT to neurons. The mechanisms and mechanisms of BDNF protection are also used to provide ideas for the treatment and prevention of neuronal damage caused by occupational exposure to TMT.
Synaptic plasticity refers to the functional enhancement or reduction of synaptic efficiency, and the changes in the intensity of neural signal transduction are accompanied by structural changes in synapses. And BDNF participates in the development and plasticity of dendritic spines that regulate activity dependent dendrites. Recent studies have shown that BDNF can be used as a regulatory factor in the adult brain to regulate neuronodes. The structure and function change.BDNF is secreted from the dendrite and immediately combines with the neurotrophic factor receptor TrkB, thereby promoting the release of the presynaptic neurotransmitter and increasing the transcriptional translation level of the postsynaptic protein, which is mainly expressed in the neuron dendrite axis, independent or in coordination with other microtubule related proteins to regulate the function of the dendritic axis microtubule. In neural cells, tau protein is associated with cell membrane or interaction with microtubule, the expression of.Tau protein or changes in structure may affect the function of its stable microtubule. Under physiological conditions, tau protein may be phosphorylated at different sites, and then affect the function of its microtubule. Mature neurons can use microtubule. The dynamic nature of the tube maintains the flexibility of the cell system to accommodate the changes occurring in the neural network.
Method:
The observation of the toxicity of TMT in the first part
18 days of primary cultured hippocampal neurons were used as a model. After treatment with TMT, the protective effect of BDNF on TMT was observed by CCK-8. The effects of TMT on the morphology of dendritic spines and the protective effect of BDNF were observed, and the characteristics of the toxicity of TMT to the dendritic spines were also identified.
The second part is the observation of the effect of BDNF on the growth of neuron synapses and dendritic spines.
The effects of the primary cultured hippocampal neurons 18 days on the synapse growth and dendritic spines in the primary cultured hippocampal neurons were observed by BDNF. The plasmids were used to transfect GFP or RFP to mark the dendritic spines of the primary hippocampal neurons. The co localization of tau egg white and microtubules was observed by cell immunofluorescence chemistry. The synapses were measured by synapses. The changes of synapse growth after BDNF treatment were measured, and Westernblot was used to detect the changes of tau protein and its phosphorylation. The changes in morphological synaptic plasticity of neurons and the role of tau protein were determined after BDNF treatment of hippocampal neurons.
The third part is the observation of Tau protein phosphorylation and cell distribution by BDNF.
RA differentiated human neuroblastoma SH-SY5Y and 18 days of primary cultured hippocampal neurons were used as models. After BDNF treatment, the subcellular distribution of tau protein was observed by cell immunofluorescence chemistry. Leica software was used to measure the synaptic growth of SH-SY5Y cells. Westernblot was used to detect the changes in the expression of tau protein, and tau eggs were determined by Westernblot. The relationship between the distribution of white subcellular cells and the synaptic growth of BDNF treated cells.
Result:
Part 1 abnormal morphological changes of dendritic spines caused by TMT
TMT treated the primary cultured hippocampal neurons 24h for 14 days in vitro, and the viability of the cells was significantly decreased by CCK-8. After the addition of BDNF and TMT, the viability of the cells was not significantly increased by CCK-8. The primary cultured hippocampal neurons were transfected to the GFP plasmid at 7 days in vitro and cultured to 20 days, TMT and / or BDNF treated the fixed cells after 24h, and the confocal microscope found TMT. After the treatment, the abnormal circle of the dendritic spines increased after BDNF treatment. The abnormal circular increase of the dendritic spines was reduced and the co stimulation of.BDNF and LiCl could also make the dendritic spines similar to the TMT treatment. The.Westerbnlot experimental results showed that BDNF treatment could be used at the same time in the primary culture. The hippocampal neurons phosphorylate Akt and ERK., but lithium alone does not seem to affect the phosphorylation of Akt and ERK. When lithium and BDNF simultaneously act, the phosphorylation of ERK induced by BDNF does not affect the phosphorylation of ERK, but lithium inhibits the abnormal increase of the dendrite dendrites induced by BDNF induced Akt phosphorylation.TMT and BDNF and LiCl. The cross-talk balance between T is damaged.
The second part of BDNF regulates synapses and dendritic spines through tau protein.
BDNF treated hippocampal neurons 24h and Tau protein expression in 14 days in vitro, and the expression of Tau protein increased significantly. The phosphorylation status of Ser262 loci was decreased after BDNF stimulation. Cell immunofluorescence chemical experiments also demonstrated that the co localization of tau protein and microtubule protein after BDNF treatment enhanced the expression of tau protein and the tree after.BDNF treatment. The density of spinous spines increased consistently. The density of dendritic spines in hippocampal neurons of the hippocampal neurons decreased significantly after 7 days in vitro culture, and the density of dendritic spines was not increased by 24h BDNF in the hippocampal neurons which were downregulated by shRNA for the 21 day after 7 days in vitro culture.
The third part of BDNF regulates the phosphorylation and subcellular distribution of tau protein.
By immunocytochemical methods, we found that tau protein forms a sphere in undifferentiated SH-SY5Y cells with a lack of neurite protuberance. On the contrary, tau protein is distributed in the neurite protuberance and the cell in the SH-SY5Y cells of 5 days of differentiation induced by retinoic acid. Through Western blot detection, we found that the treatment of retinoic acid is also Increase the level of total tau protein and decrease the expression of tau protein Ser262 phosphorylation level.Tau protein expression and the downregulation of tau protein ser262 phosphorylation level and neural cell protuberance length (related factors are r=0.94 and r=-0.98). When the original E18 hippocampal neurons were treated with microtubule depolymerization agent nocodazole, new neuron protuberance was lost. Loss of tau protein transfer to the cell body. This process of distant protrusion can be reversed to some extent by BDNF.
research conclusion
Based on the above findings, we draw the following conclusions: the abnormal increase of dendritic spines in neurons after TMT treatment in cultured hippocampal neurons may be the neurotoxic expression of TMT, the potential.TMT treatment for the protection of TMT dendritic spines and the neuron dendrite spines produced by the combination of BDNF and LiCl. Abnormal enlargement may be associated with the disruption of the cross-talk balance between ERK and Akt..BDNF can regulate the expression of tau protein in the primary hippocampal neurons. This regulation has a dose dependence and aging dependence. Transfection of the primary cultured hippocampal neurons by plasmid and down regulation of the expression of tau protein by plasmid and BDNF stimulation of the growth of dendritic spines in the neuron. Inhibition, suggesting that tau protein may be involved in BDNF signaling pathways in the growth of synapses and dendritic spines. Further experiments suggest that the role of BDNF in regulating the plasticity of dendritic spines may be achieved by regulating the expression of tau protein and thus affecting the stability of the tau protein, the phosphorylation level of the tau protein Ser262 site, the total TA. The expression of u protein and the changes in the subcellular distribution of tau protein are significantly related to the growth of synapses in the nerve cells. The increase of the expression of tau protein and the dephosphorylation of the Ser262 site may be beneficial to the growth of neural synapses. This experiment provides a new evidence for the neurotoxicity of TMT, especially on the damage of the hippocampal deity dendritic spines. It is revealed that BDNF can play a neuroprotective role by regulating the synapses and dendritic spines through tau protein.
【學位授予單位】:第三軍醫(yī)大學
【學位級別】:博士
【學位授予年份】:2014
【分類號】:R114
【共引文獻】
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