| N- the methyl - D- aspartic acid (NMDA) the acceptor is an subset of ion tunnels,what is already confirmed in the earlier period research, the NMDA acceptor play an important physiological function in the biological process. It can adjust neuron's activeness, dendrite and axon structure growth and synapse plasticity. The growth of normal nervous system needs the activeness of excitability amino acid acceptor. If NMDA acceptor activeness is excessively low, it is possible that the growth of normal nervous system will be retard. In the other hand if the NMDA acceptor activeness is excessively high, it also cause neuron's damage or the brain damage. The NMDA receptor has a close relationship with learning, memory and some diseases.The lead is one of oldest poisons the humanity known, which is widespread existence in human living environment. In some countries, it is a quite serious problem that there is a low level exposure in human living areas. The lead has a mainly effect on central nervous system, and it can not only interfere the child's neural development, but also interfere the human learning and memory functions. Long-time living in the environment of exposing to lead, the human will present barrier on behavior, learning and memory. The lead is the NMDA acceptor's non-competitive antagonist compound, and it has an inhibitory action to the NMDA protein.Objective:This experiment was to investigate the change of NMDAR1 (NR1) and NMDAR2A (NR2A) expression in the different brain region of lean exposure rat. In the level of mRNA and protein, we discuss effect of Pb2+ on human memory barrier and some possible diseases.Methods:One age of the month Sprague-Dawley(SD) big mouse 45, female and male does not arrest, weight (120±15)g, Divides into nine groups stochastically, the lead exposition group rats were feed 1.0Mmol/L,2.4Mmol/L,3.6Mmol/L,4.8Mmol/L,7.2Mmol/L,9.6Mmol/L,14.4Mmol/L,19.6Mmol/L lead acetate solution with the distilled water compounds, the control group was given the distilled water. Three weeks later, the brain of rat was acquired to study. We use immunohistochemistry, western blot and RT-PCR methods to detective the expression of NMDA receptor subunitNR1, NR2A in different brain areas of lean exposure Rats.Results:Immunohistochemical results: For the 4.8mmol / L solution of lead acetate-fed rats,after three weeks fed, taking hippocampus, we used immunohistochemical methods to clear whether the solution of lead acetate fed rats'hippocampus expressed NMDA receptors. For 4.8mmol / L lead acetate solution of brain tissue in rats fed immunohistochemical staining showed in Figure 2.1-2.4. 4.8mmol / L of lead acetate fed rats have NR1, NR2A receptors expression in the hippocampus.Western Blot results: within the hippocampus of rats in each group have different levels of NR1 protein expression: 19.6mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 1.37±0.04,14.4 mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 1.53±0.02,9.6 mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 1.65±0.02,7.2 mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 1.69±0.02,4.8 mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 3.17±0.03,3.6 mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 3.11±0.06,2.4 mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 3.17±0.06,1.0 mmol / L of lead acetate group of NR1 protein expression in rat hippocampus is 2.92±0.05. NR1 protein expression in hippocampal volume of lead acetate concentration increased with little change, when the lead acetate concentration reaches a certain threshold, we did the experiment when the concentration of lead acetate to 7.2mmol / L, at that time, NR1 protein expression shown a significant reduction in experiment repeated three times with 4.8mmol / L lead acetate solution, a clear statistically significant feeding group (P <0.01). Subsequently, with the increased concentration of lead acetate, NR1 protein expression could be a reduction trend. The hippocampus of rats in each group showed a different levels of NR2A protein expression: 1.0mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 4902.38±22.97,2.4 mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 3918.80±78.47,3.6 mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 5126.22±89.73,4.8 mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 3553.81±116.25,7.2 mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 2529.60±89.11,9.6 mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 1314.22±54.79,14.4 mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 2192.02±76.23,19.6 mmol / L of lead acetate group in NR2A protein expression in rat hippocampus is 2475.76±76.89, control group, NR2A protein expression in rat hippocampus is 5362.35±77.29 . And the NR2A protein with the concentration of lead acetate showed the expression of the overall downward trend. When the lead acetate concentration of 9.6mmol / L, when, NR2A protein expression in the lowest, reaching peak and valley, then there is an increasing trend. NR2 receptors play a major regulator function of NR1 receptor protein and its expression in general with the NR1 receptor expression on the consistency, that is from 4.8mmol / L of lead acetate fed rats began to increase the concentration of lead acetate, and protein expression were significantly reduced. But the NR1 protein and between the concentration of lead acetate is a clear positive correlation trend that increased with the concentration of lead acetate and its protein expression decreasing. The NR2A protein in 9.6mmol / L of lead acetate concentration in the hippocampus in rats fed expression levels to meet the minimum expression, the concentration of lead acetate to increase its protein expression without reducing the contrary, there is a little higher. To sum up, NR1, NR2A receptor proteins with increasing concentration of lead acetate feeding in the rat hippocampus has displayed all assume a downward trend, the downward trends are consistent.RT-PCR results: in different parts of rat brain tissue, NR1 and NR2A mRNA levels, both expressed, NR1 mRNA in normal brain tissue, the new cerebellum have the highest expression levels, and showed no different in other regions of the brain; NR2A mRNA in normal rat brain tissue showed the highest volume in new cerebellum, and these are consistent with the distribution of NR1 mRNA expression. After the feeding of lead acetate solution, as shown in Figure 2.8, rat NR1 mRNA expression in a variety of different parts of the brain (temporal lobe, hippocampus, New cerebellum, striatum), the expression of a downward trend, and the NR1 mRNA decreased in the hippocampus is most. Rat NR2 mRNA expression in a variety of different parts of the brain (temporal lobe, hippocampus, New cerebellum, striatum), the expression of different degrees downward trend, and in the rat hippocampus in NR2A mRNA expression levels of decline most. To sum up, NR1 mRNA, NR2A mRNA were expressed in normal rat brain, and have the most abundant expression in new cerebellum, NR1 and NR2A mRNA expression levels of distribution were consistent. After the feeding of lead acetate, NR1 mRNA and NR2A mRNA in different parts of rat brain (temporal lobe, hippocampus, New cerebellum, striatum) have the expression of a downward trend, and in the hippocampus decreased the most obviously, NR1 with the NR2A mRNA were significantly consistency.Conclusion:This experimental study result success indicated that in the level of protein and mRNA, the expression of NR1 and NR2A was descent in different brain areas of lean exposure rats. It indicated that in the different areas of the lean exposure rat, the change of the expression of NMDA receptor has been occurred in the level of mRNA. This is a fundament for study the relationship between the NMDA receptor and learning and memory function further.
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