To Study The Molecular Mechanism And The Preventive Measures Of Learning And Memory Impairment Of Neonatal Rats After Fetal Intrauterine Distress From Tau Protein Hyperphosphorylation

Protein Tau is a very unequal phosphoric microtubule associated protein, which affect the transport of substances in the axons of the neurons, whose phosphorylation is one of the key methods to regulate neuronal function. The hyperphosphorylation of protein Tau can damage the learning and memory of rats. The impairment of learning-memory induced by fetal intrauterine distress in neonatal rats is relevant to the function failure of glutamic acid signal system. The rise of glutamate which induced by fetal intrauterine distress in neonatal rats can lead to the impairment of learning-memory through up-regulate the hyperphosphorylation of protein Tau? Is this process related to the excitotoxicty of glutamate? Can the excitatory amino acids receptor antagonists and astragalosidewhich play a role as GluR antagonist inhibit this process? What are the similarities and differences about the effects and the neuropsychology mechanisms of astragaloside, ginsenoside Rg-1, protein phosphatae-2A and lithium protects against the impairment of learning-memory induced by fetal intrauterine distress in neonatal rats? The series of problems above attracted strong interest of researchers. Therefore, we engaged in this research in order to explore the mechanism of this process.PART I The effect of the fetal intrauterine distress of different degree and duration of blocking uterine blood supply on the content of glutamate in the hippocampus of the fetal ratsObjetive This study explore the effect of fetal intrauterine distress of different degree and duration of blocking uterine blood supply up-regulated the content of glutamate in the hippocampus of neonatal rats. Methods The fetal intrauterine distress fetal rats were established. As the analysis of variance of factorial design set up two intervention factors which are the degree of blocking uterine blood supply (three levels:block 1/3, block 2/3, completely blocked) and the duration of blocking uterine blood supply (three level:5 min、10 min、15 min). Seventy-two pregnant rats were removed were randomly divided into six experimental groups (n=6, in each group). In the after the fetal intrauterine distress molds were had been maded, cut open the the uterus to remove the fetal rats. The hippocampuses of fetal rats were removed. Results Fetal intrauterine distress can significantly up-regulated the content of glutamate. The changes were correlated with the degree and duration of blocking uterine blood supply of the fetal intrauterine distress. And both influences present additive effect. Conclusions Our results indicate that fetal intrauterine distress up-regulated the content of glutamate in the hippocampus of fetal rats.PART II The effect of MK-801 and astragaloside on the impairment of learning-memory and hyperphosphorylation of Tau in neonatal rats after the fetal intrauterine distressObjetive This study explore the reversion of the excitatory amino acid receptor antagonists against the impairment of learning-memory and the hyperphosphorylation of protein Tau induced by fetal intrauterine distress in neonatal rats. Methods As the analysis of variance of factorial design set up two intervention factors which are fetal intrauterine distress (two levels:no fetal intrauterine distress; A course of fetal intrauterine distress) and the excitatory amino acid receptor antagonists (three levels:iv Saline; iv NMDA receptor antagonist MK-801; iv astragalosides). Fourty-eight pregnant rats were randomly divided into six experimental groups (n=8, in each group). After the end of the fetal intrauterine distress, the pregnant rats continued until the birth of newborn rats. When the neonatal rats grow to 12W, the Morris water maze test started in order to evaluate learning-memory. The hippocampus was removed from newborn rats within 1 day after the morris water maze test finished. Detect of the content of glutamate in the hippocampus of rats by High Performance Liquid Chromatography. Detect of the content of protein Tau which includes Tau5 (total protein Tau), p-PHF1Ser396/404, p-AT8Ser199/202, p-12E8Ser262 in the hippocampus of rats with the method of immunohistochemistry staining (SP). Results Fetal intrauterine distress and the glutamate ionic receptor blockers can induce the impairment of learning-memory in neonatal rats, extending the evasive latency time and shorten the space exploration time. And both influences present subtract effect. Fetal intrauterine distress can significantly up-regulated the content of glutamate in the hippocampus of neonatal rats which was not affected by the glutamate ionic receptor blockers. Fetal intrauterine distress and the glutamate ionic receptor blockers do not affect the total protein Tau in the hippocampus of rats. Fetal intrauterine distress can up-regulated the hyperphosphorylation of protein Tau in the hippocampus of neonatal rats which is can be reduced by the glutamate ionic receptor blockers. And both influences present subtract effect. Conclusions Our results indicate that Fetal intrauterine distress up-regulated the content of glutamate in the hippocampus of neonatal rats, which up-regulated the hyperphosphorylation of protein Tau which can induce the impairment of learning-memory in neonatal rats.PART III The preventive measures of learning and memory impairment of neonatal rats fetal intrauterine distressExperiment 1:The effect of astragaloside on the content of glutamate in the hippocampus of the fetal rats after the fetal intrauterine distress in neonatal ratsObjetive This study explore the reversion of the astragaloside reducing the overtop content of glutamate in the hippocampus induced by fetal intrauterine distress in neonatal rats. Methods As the analysis of variance of factorial design set up two intervention factors which are fetal intrauterine distress (two levels:no disposition; a course of fetal intrauterine distress) and the astragaloside (two levels:5ml Saline iv; 5ml astragaloside iv by dosage of 40mg/kg). Thirty-two the pregnant rats were randomly divided into four experimental groups (n=8, in each group). After the end of the fetal intrauterine distress, the pregnant rats continued until the birth of newborn rats. When the neonatal rats grow to 12W, the hippocampus was removed from rats. Detect of the content of glutamate in the hippocampus of rats by High Performance Liquid Chromatography. Results Fetal intrauterine distress can significantly up-regulated the content of glutamate in the hippocampus of neonatal rats which was reduces by the astragaloside. And both influences present subtract effect. Conclusions Our results indicate that fetal intrauterine distress up-regulated the content of glutamate in the hippocampus of neonatal rats; and the astragaloside can reduce the content of glutamate in the hippocampus.Experiment 2:Comparison of the effects of astragaloside and NMD A receptor antagonist on the impairment of learning-memory after the fetal intrauterine distress in neonatal ratsObjetive This study explore the reversion of astragaloside and NMDA receptor antagonist against the hyperphosphorylation of protein Tau induced by fetal intrauterine distress in neonatal rats. Methods As the analysis of variance of factorial design set up two intervention factors which are fetal intrauterine distress (two levels: no disposition; a course of fetal intrauterine distress) and the drugs (three levels:iv Saline; iv astragaloside; iv MK-801). Forty-eight pregnant rats were randomly divided into six experimental groups (n=8, in each group). After the end of the fetal intrauterine distress, the pregnant rats continued until the birth of newborn rats. When the neonatal rats grow to 12W, the hippocampus of was removed from the neonatal rats. Detect of the content of glutamate in the hippocampus of rats by High Performance Liquid Chromatography. Detect of the expression of protein Tau which includes p-AT8Ser202 and GSK-3p1H8 in the hippocampus of rats with the methods of immunohistochemistry staining (SP). Results Fetal intrauterine distress can significantly up-regulated the content of glutamate, which was not affected by MK-801, in the hippocampus of neonatal rats which was reduces by the astragaloside. And both influences present subtract effects. Fetal intrauterine distress and the drugs do not affect the total protein Tau in the hippocampus of rats. Fetal intrauterine distress can up-regulated the hyperphosphorylation of protein Tau in the hippocampus of neonatal rats which is can be reduced by astragaloside and MK-801. And the influences between fetal intrauterine distress and the drugs present subtract effects. Our results indicate that fetal intrauterine distress up-regulated the content of glutamate in the hippocampus of neonatal rats, which up-regulated the hyperphosphorylation of protein Tau; and astragaloside reduce the hyperphosphorylation of protein Tau induced by fetal intrauterine distress in neonatal rats. GSK-3β is the key protein in this signaling pathway. Conclusions Our results indicate that fetal intrauterine distress reduce the hyperphosphorylation of protein Tau in neonatal rats though up-regulated the content of glutamate.Experiment 3:Comparison of the effects of astragaloside, ginsenoside Rg-1, protein phosphatae-2A and lithium on the impairment of learning-memory after the fetal intrauterine distress in neonatal ratsObjetive This study explore the reversion of astragaloside, ginsenoside Rg-1, protein phosphatae-2A and lithium reduce the overtop concentration of glutamic acid in the hippocampus in neonatal rats induced by fetal intrauterine distress. Methods As the analysis of variance of factorial design set up two intervention factors which are fetal intrauterine distress groups (two levels:no disposition; A course of fetal intrauterine distress) and the drug intervention groups (five levels:Through the uterine artery microinject astragaloside, ginsenoside Rg-1, protein phosphatae-2A and lithium,20μg·ul-1). Eighty pregnant rats divided into ten experimental groups (n=8, in each group). After the end of the fetal intrauterine distress, the pregnant rats continued until the birth of newborn rats. When the neonatal rats grow to 12W, the hippocampus of was removed from the neonatal rats. Detect of the content of glutamate in the hippocampus of rats by High Performance Liquid Chromatography. Results Fetal intrauterine distress can significantly up-regulated the content of glutamate, which was reduces by astragaloside and ginsenoside Rg-1. Conclusions Our results indicate that astragaloside and ginsenoside Rg-1 can reduce the overtop content of glutamate in the hippocampus which induced by fetal intrauterine distress.CONCLUSIONS OF THE TATOL PAPEROur results indicate that fetal intrauterine distress up-regulated the content of glutamate in the hippocampus of neonatal rats, which up-regulated the hyperphosphorylation of protein Tau through up-regulating the expression of GSK-3β1H8, which can induce the impairment of learning-memory in neonatal rats. Astragaloside protects against the impairment of learning-memory and reduce the hyperphosphorylation of protein Tau induced by fetal intrauterine distress in neonatal rats through reducing the expression of GSK-3β1H8 and the content of glutamate in the hippocampus. GluR antagonists, ginsenoside Rg-1 and lithium protects against the impairment of learning-memory induced by fetal intrauterine distress in neonatal rats though reducing the hyperphosphorylation of protein Tau, too.