Neuroprotective Effects And Possible Mechanisms Of Zi-Bu-Pi-Yin Decoction On Spleen-Yin Deficiency Alzheimer's Disease Model Rats

Objective:Alzheimer's disease (AD) is a severe neurodegenerative disorder which has two apparente pathological characteristics: senile plaque and neurofibrillary tangles.It is accepted by most that overproduction and aggregation of beta-amyloid and the aggregation of hyperphosphorylated tau to tangles are causative to the degenerative processes. Aβis the primary component of the senile plaques found in brains of AD patients and is also the biochemistic foundation of neurofibrillary tangles and vessel amyloid degeneration. The toxicity of Aβwas first representation as synaptic toxicity and then neuron toxicity.People have noticed that spnaptic loss was a distinguished neuropathologic change in the cortex and hippocampus of AD patients and it appeared in the early time of the disease.In the brains of AD patients synaptic loss is more significant than neuron loss.So synaptic loss is the structural base of AD.The synapstic changes of AD patients not only include the morphological abnormalities ,but also include the changes of functional proteins.The postsynaptic density (PSD) is the area that messages to be processed,so the changes of postsynaptic density proteins maybe more significant for the changes of synaptic functions. Spine-associated Rap guanosine triphosphatase (GTPase) activating protein (SPAR), with its postsynaptic location in the N-methyl-D-aspartate (NMDA) receptor–PSD-95 complex, SPAR is an important candidate for mediating activity-dependent remodeling of synapses, and is critically involved in spine maturity, especially in the mature spine formation and the maintenance of spine maturity. Serum-inducible kinase (SNK), one of thepolo-like kinases, induced by synaptic activity and was targeted to dendritic spines, eliminates SPAR protein, depletes a core postsynaptic scaffolding molecule (PSD-95), and causes loss of mature dendritic spines and synapses. These findings implicate SNK as mediators of activity dependent change in molecular composition and morphology of synapses.NMDA receptors participate in the control of CNS developing and could regulate synaptic plasticity during synaptic communication and developing and also take part in the formation of learning and memory.ZBPY decoction can reinforce spleen and stomach and nourish spleen yin.It is established to aim directly at spleen-yin deficiency.The studies before showed that ZBPY decoction had anti-oxidative function and could regulate the metabolism of cell membrane phospholipid and improve the ability of learning and memory of the old.So our experiment is going to further investigate the neuroprotective effects and possible mechanisms of ZBPY decoction on spleen-deficiency Alzheimer's Disease model rats .Methods:1. Totally 35 healthy adult male SD rats were divided randomly into control group, AD group, spleen-yin deficiency group, spleen-yin deficiency AD group + ZBPY group,7 rats every group.2. We first used the classical method to construct the spleen-yin deficiency rats model, then the incubated Aβ1-40(5μg/μl)was injected into bilateral hippocampus of each rat to construct the AD models.And administrated ZBPY decoction to spleen-yin deficiency AD group and ZBPY treatment group intragastrically.Then observed the changes of physical signs of the rats.3. Morris water maze test and step-down test were used to evaluate the behavioral changes.4. Using the RT-PCR method to detect the mRNA expression of SPAR,SNK and NMDAR in postsynaptic density of different brain areas.Results:1. The spleen-yin deficiency group and the spleen-yin deficiency AD group displayed endogenous heat symptomes caused by yin-deficiency ,such as the increment of water drinking(P<0.01), objective elevation of the rectal temperature(P<0.01). The ability of learning and memory of the two AD groups was reduced significantly(P<0.05). The results of Morris water maze test and step-down test showed that thelearning and memory ability of AD control group and spleen-yin deficiency AD group decreased significantly(P<0.05),and the ZBPY decoction treatment group increased significantly(P<0.05).2. The mRNA expression of SPAR and NMDAR subunit NR1,NR2A,NR2B mRNA in PSD of AD group and spleen-yin deficiency AD group decreased significantly(P<0.05),the mRNA expression of SNK was up-regulated compared with the control group.3. The mRNA expression of SPAR and NMDAR subunit NR1,NR2A,NR2B mRNA in PSD of ZBPY decoction treatment group increased significantly(P<0.05),the mRNA expression of SNK was down-regulated compared with the control group.Conclusions:1. The spleen-yin deficiency AD model rats could be induced by bilateral hippocampal injection of Aβ1-40 in the spleen-yin deficiency rats and the models could simulate the behavior changes of AD patients,so could be taken as ideal AD animal models.2. ZBPY decoction could improve the learning and memory ability of spleen-yin deficiency AD group significantly.3. The effect of ZBPY decoction may be related to the inhibited of the SNK-SPAR signal pathway, and the maintenance of morphology and structure of dendritic spines.4. ZBPY decocion could up-regulate the NMDAR subunits NR1,NR2A,NR2B mRNA expression in order to regulate the plasticity of synapses and dendritic spines,then improve the ability of learning and memory of spleen-yin deficiency AD rats model.