Study Of The Mechanism On The Imbalance Of Brain Function In The Decline Of Learning And Memory Function In Aging Based On The Theory Of Correlation Of Shen Zang And Brain

Objective: The purpose of this study is to investigate the expression and mechanism of brain Yin and Yang imbalance at various levels in the state of senility.Elucidate the action mechanism of rehmannia rehmannia yinzi on hippocampal synaptic plasticity of senility mouse model and provide the modern biological basis for the method of tonifying shen and strengthening brain.Methods:This research adopts the method of combining theoretical research with experimental research.1.Theoretical discussion: This paper systematically reviews the cognition of aging and learning in traditional Chinese medicine and modern medicine.2.Experimental research:(1)Group of Experiments: There were 6 groups in the experiment,including normal control group,aging model group,decoction of Dihuang Yinzi(low,medium and high dose)group and memantine hydrochloride group.Among them,6-month-old male SAMP8 mice were used as the animal model of aging,and SAMR1 mice of the same age were used as the normal control.Other groups were treated with SAMP8 mice of the same age and given drug intervention.(2)Drug intervention: Each group feeding to 5 months under the same condition of normal diet,and treating start from the 6th month with different concentrations.Decoction of Dihuang Yinzi(low,middle and high dose)treated groups of mice respectively to intragastric administrating every day different concentrations of decoction of Dihuang Yinzi(7.51g/kg·d,15.02g/kg·d,30.04g/kg·d).Memantine hydrochloride suspension(3.03mg/kg·d)was given to mice in the memantine hydrochloride group by gavage.And mice in the normal control group and the aging model group were given gavage with the same amount of solvent.Animals in each group were given the drug by intragastric administration once a day for one month,then the following indicators were tested.(3)Detection of learning and memory ability.Each group mice's spatial learning ability,reference memory ability,and object recognition ability were tested by morris water maze and novel object recognition test.(4)Detection of synaptic functional plasticity.Each groups mice's Synaptic transmission efficiency was tested by long-term potentiation(LTP)and long-term depression(LTD)in vivo field potentials recording.The recording synaptic circuit is from schaffer collaterals to CA1 dendrite field.(5)Detection of synaptic structural plasticity.After cardiac perfusion,the changes of neurons and synaptic structure in hippocampus of mice were observed by transmission electron microscopy.(6)Detection of neurotransmitter secretion.Enzyme linked immunosorbent assay(ELISA)was used to detect the difference of glutamate and gamma-aminobutyric acid contents in the hippocampus of mice in each group.(7)Detection of glutamate receptor and calmodulin-dependent protein kinase II.Western blot(WB)was used to detect the differences in the protein content and phosphorylation degree of glutamate receptor and calmodulin-dependent protein kinase II in the hippocampus of mice in each group.The tested proteins include AMPAR2,NMDAR1,pNMDAR1,NMDA2 A,pNMDA2A,NMDA2 B,pNMDA2B,CaMKII and pCaMKII.Results:1.Results of theoretical discussion: This paper discusses the possibility of treating the declination of learning and memory function from the aspects of meridian connection,essence relationship,yuanshen relationship,shenzhi relationship with brain spirit,and the change of Yin and Yang,based on the theory of "kidney brain correlation".And we considered that the research results of modern brain science are the representation of Yin and Yang,which is the enrichment and expansion of the theory of Yin and Yang in traditional Chinese medicine,based on the theory of Yin and Yang.2.Results of experimental research:(1)Results of behavioral test.The results of morris water maze test showed that the spatial learning and memory ability of mice in the model group decreased(P<0.05).After the treatment of Dihuang Yinzi decoction,it can effectively improve the spatial identification and memory extraction ability of mice and reduce the time of spatial search(P<0.05).The results of novel object recognition test showed that the memory of model mice was impaired,short-term memory was not extracted or formed as the long-term memory in the brain(P<0.05).After the treatment of Dihuang Yinzi decoction,mice were able to accurately distinguish between the novel object and the old one(P<0.05).It also showed the mice of decoction of Dihuang Yinzi(medium and high dose)group had spent much more time on identifying novel object(P<0.01).(2)Results of in vivo field potentials recording.After the high frequency stimulation(200Hz),the gains of filed excitatory postsynaptic potential(fEPSP)of SAMP8 mice was not significant,LTP was significantly lower than that of SAMR1 mice(P<0.001).Treat with Dihuang Yinzi decoction can enhance LTP of model mice(P<0.05).After the low frequency stimulation(2Hz),LTD and the inhibition of EPSP degree were significantly different in each group.Compared with 6-month-old SAMP8 mice,the LTD effect of SAMR1 mice was strengthened only for a short period of time after the low-frequency stimulating(P<0.001),and the fEPSPs could gradually returned to normal.After the treatment of Dihuang Yinzi decoction,the LTD effect of mice was also recovered to a certain extent(P<0.05).(3)Transmission electron microscope observations.We found that the SAMP8 mice's neurons in the hippocampal CA1 region were injured,the synaptic cleft turned to increase or disappear,presynaptic and postsynaptic membranes were not clear,synaptic vesicles were reduced,and postsynaptic dense materials became thinner,by using transmission electron microscope.The damage of neuron organelle was reduced and the synaptic structure was repaired after using Dihuang Yinzi decoction for 4 months.(4)Results of ELISA.The contents of Glu and GABA in of the model group were significantly increased(P<0.001).After the drug administration,the contents of Glu and GABA in the hippocampus of mice in each group were decreased,especially in the high-dose group of Dihuang Yinzi decoction(P<0.01).(5)Results of Western Blot.For SAMP8 mice,the protein content of AMPAR2,NMDAR1 and NMDAR2B in the hippocampus increased(P<0.05),while the content of CaMKII reduced(P<0.05).The phosphorylation level of pNMDAR1,pNMDAR2 A and pNMDAR2 B were increased(P<0.05),and the contents of pCaMKII were decreased(P<0.05).The midium-dose of Dihuang Yinzi decoction was reduce the protein content of NMDAR1.Decoction of Dihuang Yinzi(high dose)can effectively increase the protein content of CaMKII and its phosphorylation level,reduce the abnormal expression of AMPAR2,NMDAR2 B and pNMDAR2 B.Conclusion:1.Increased levels of Glu and GABA in the hippocampus and metabolic imbalance were associated with learning and memory function losing in aging mice.2.The imbalance of effects of LTP and LTD in hippocampal "schaffer collateral-CA1" synaptic circuit were the manifestations of the imbalance between brain Yin and Yang of electrophysiology in the senility.3.Calcium ion overload in hippocampal neurons is the key mechanism of the imbalance of brain Yin and Yang in the the senility.3.The study has been proved that the decoction of Dihuang Yinzi can improve the learning and memory function of the aging mice by regulating the concentration of calcium in nerve cells,inhibiting calcium influx and facilitating synaptic plasticity.