ABSTRACT
Objective:To investigate the effect of Huangjingwan （HW） on the activities of glycogen synthase kinase-3β （GSK-3β）， protein phosphatase 2A （PP2A） and the mechanism in inhibiting tau protein hyperphosphorylation in the hippocampal neurons of mice with Alzheimer's disease. Method:After subcutaneous injection with 1.0% D-galactose （0.14 g·kg-1·d-1） into the back and neck of mice for 4 weeks， the right ventricle of mice was injected with 2 μL （75 ng） of okadaic acid for one time to make AD model， and the successfully modeled AD mice were selected by Morris water maze. Then， the selected AD mice were randomly divided into AD model group， memantine group （1.3×10-3 g·kg-1·d-1） and HW group （2.5 g·kg-1·d-1）. In addition， the sham model control group and the normal control group were set up. At the same time， 2 μL normal saline was injected into the right ventricle of mouse in the sham model control group for modeling control. Two weeks after modeling， the mice in the two experimental drug groups were given the corresponding dose of the experimental drug by gavage for 4 weeks. In addition， after 2 weeks of AD modeling， mice in control group and AD model group were intragastrically administrated with the same amount of normal saline daily for 4 weeks. The mice in normal control group were only given daily feed. At the end of gavage， all the mice were tested by the open field experiment and jumping platform experiment to evaluate the differences in exploratory activity ability， anxiety level and learning and memory ability. The number of neurons in CA1 and CA3 areas of hippocampus in all the mice was detected by Nissl staining. Quantitative real-time polymerase chain reaction （Real-time PCR） was used to detect mRNA expressions of GSK-3β and PP2A in hippocampus of mice in each group. Protein expressions of GSK-3β， PP2A， phosphorylated tau （p-tau） and total tau protein （t-tau） in hippocampus of mice in each group were detected by Western blot. Result:Compared with the normal control group， mice in AD model group showed an obvious dementia state， which was characterized by a lower spontaneous activity， lower exploration behavior ability， higher anxiety level， less movement and easier to stay and hide， longer learning response time， significantly increased number of learning and memory errors， and decreased numbers of hippocampal neuron in CA1 and CA3 areas， and reduced mRNA and protein expressions of PP2A， mRNA and protein expressions of GSK-3β， p-tau protein and the ratio of p-tau/t-tau were all increased significantly （P<0.01）， while expression of t-tau protein was decreased， with no significant difference. Compared with the AD model group， mice in the HW group showed a higher spontaneous activity， higher exploration ability， lower anxiety level， higher learning and memory performance， and the numbers of hippocampal neuron in CA1 and CA3 areas increased， while mRNA and protein expressions of PP2A increased， and the mRNA and protein expressions of GSK-3β， the expression of p-tau protein and the ratio of p-tau/t-tau were all decreased significantly （P<0.01）， but with no significant difference in the protein expression of t-tau. Conclusion:HW can inhibit tau hyperphosphorylation in hippocampal neurons of AD mice， restore tau protein function， protect hippocampal neurons， and exert an anti-AD effect， which may be related to the regulatory mechanism in the activity balance between GSK-3β and PP2A in hippocampal neurons.
ABSTRACT
Objective:To explore the effect of Huangjingwan （HW） on the expressions of Wnt/β-catenin signal pathway-associated proteins in the hippocampus of mice with Alzheimer's disease （AD） induced by D-galactose and okadaic acid with learning and memory disorders， as well as its mechanism. Method:After subcutaneous injection with 1.0% D-galactose （0.14 g·kg-1·d-1） into the back and neck of mice for 4 weeks， the right ventricle of mice was injected with 2 μL（75 ng） of okadaic acid for one time to make AD model， and the successfully modeled AD mice were selected by Morris water maze. Then， the selected AD mice were randomly divided into AD model group， memantine group （1.3×10-3 g·kg-1·d-1） and HW group （2.5 g·kg-1·d-1）. In addition， the sham model control group and the normal control group were set up. At the same time， 2 μL normal saline was injected into the right ventricle of mouse in the sham model control group as the modeling control. Two weeks after molding， the mice in the two experimental drug groups were given the corresponding dose of the experimental drug by gavage for 4 weeks. In addition， after 2 weeks of AD modeling， mice in sham model control group and AD model group were intragastrically administrated with the same amount of normal saline daily for 4 weeks. There was no special treatment in the normal control group. At the end of gavage， the shuttle experiment was performed to detect the differences in learning and memory levels of mice in each group. The changes of β-catenin and GSK-3β positive neurons in CA1 area of hippocampus in each group were tested by immunohistochemistry. Quantitative real-time polymerase chain reaction （Real-time PCR） was used to measure the mRNA expressions of GSK-3β， β-catenin and CyclinD1 in hippocampus of mice in each group. The Western blot was used to detect the expressions of total GSK-3β （t-GSK-3β）， phosphorylation of GSK-3β at Ser9 （p-Ser9-GSK-3β）， phosphorylation of GSK-3β at Tyr216 （p-Tyr216-GSK-3β）， total β-catenin （t-β-catenin）， phosphorylation of β-catenin （p-β-catenin） and CyclinD1 proteins in hippocampus of mice in each group. Result:Compared with the normal control group， mice in AD model group showed an obvious dementia state， which was characterized by significant declines in learning and memory ability， the number of β-catenin immunoreactive neurons in hippocampal CA1 area， the mRNA and protein expressions of t-β-catenin and CyclinD1， the protein expressions of p-Ser9-GSK-3β， and the ratio of p-Ser9-GSK-3β/t-GSK-3β and p-Tyr216-GSK-3β/t-GSK-3β in hippocampal region （P<0.01）， and significant increases in the number of GSK-3β immunoreactive neurons in hippocampal CA1 area， the mRNA and protein expressions of t-GSK-3β， the protein expressions of p-Tyr216-GSK-3β and p-β-catenin， the ratio of p-β-catenin/t-β-catenin in hippocampal region （P<0.01 respectively）. Compared with the AD model group， the dementia symptoms of mice in HW group were significantly alleviated， and the number of β-catenin immunoreactive neurons in hippocampal CA1 area， the mRNA and protein expressions of t-β-catenin and CyclinD1， the protein level of p-Ser9-GSK-3β， the ratio of p-Ser9-GSK-3β/t-GSK-3β in hippocampal region were all significantly increased （P<0.01 respectively）， whereas the number of GSK-3β immunoreactive neurons in hippocampal CA1 area， the mRNA and protein expressions of t-GSK-3β， the proteins expressions of p-Tyr216-GSK-3β and p-β-catenin， the ratio of p-β-catenin/t-β-catenin in hippocampal region were all significantly decreased （P<0.01 respectively）， but the ratio of p-Tyr216-GSK-3β/t-GSK-3β has no significant statistical difference. Conclusion:HW shows the role of AD treatment， which can down-regulate the expression of GSK-3β in the hippocampus of AD mice and reduce its protein activity， and up-regulate the expression of β-catenin as well as increase its protein activity， so as to enhance the expression of downstream CyclinD1 and promote the transcription of the target genes. Its mechanism may be related to the activation of Wnt/β-catenin signal pathway.
ABSTRACT
Objective::To observe the effect of Huangjingwan (HW) on antioxidant functions and β-amyloid 1-42 (Aβ1-42) and amyloid precursor protein (APP) expressions in the brain of Alzheimer' s disease (AD) rats. Method::SD rats were randomly divided into normal control group, sham model control group, AD model group, and low, medium, high-dose (equivalent raw drug dose 1, 3, 9 g·kg-1·d-1) HW groups.The AD models were established through intraperitoneal injection with 1.25% D-galactose (120 mg·kg-1·d-1, 6 consecutive weeks) and then one-time right ventricular injection with Aβ1-42 (10 μg). Two weeks after modeling, the rats in each HW group received corresponding drugs through intragastric administration, once a day, while the rats in sham model control group, AD model group were given normal saline 1 mL through intragastric administration, once a day.Gastric perfusion lasted for 8 weeks.At the end of the experiment, learning and memory abilities of the rats were assessed by Platform Jumping Test.The changes of physical endurance in rats were tested by 10% weight swimming under load.The activities of superoxide dismutase (SOD), glutathione reductase (GR), glutathione peroxidase (GSH-Px) antioxidant enzymes and the contents of glutathione (GSH) and malondialdehyde (MDA) in rat brain tissue were detected by colorimetry.The changes of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), Aβ1-42 and APP protein in rat brain tissues were determined by enzyme linked immunosorbent assay (ELISA). Western blot analysis was used to measure the expression of APP protein in rat brain. Result::Compared with the normal control group, rats in AD model group showed an obvious dementia state, that is more lying and less movement, longer learning response time, significant increase in the number of learning and memory errors, significant attenuation in physical fitness, significant decrease in the activities of antioxidant enzymes (SOD, GR, GSH-Px) and anti-inflammatory factors GSH in brain, significant rise in the levels of inflammatory factors MDA, IL-1β and TNF-α and the content of Aβ1-42 protein, and significant reduction in the content of APP protein in brain (P<0.01). Low, medium and high-dose HW could ameliorate dementia symptoms in AD rats, improve the achievement of learning and memory, antagonize body weakness and increase physical fitness, promote SOD, GR, GSH-Px activities and anti-inflammatory factor GSH level in the brain, reduce the levels of MDA, IL-1β and TNF-α in the brain, decrease the level of Aβ1-42 and increase the level of APP protein in the brains of AD rats compared with the AD model group (P<0.05, P<0.01), besides, within the dose range of 1-9 g·kg-1·d-1, HW has a more obvious effect with the increase of dose. Conclusion::HW has the effects in preventing and treating AD, which is related to the HW' s mechanisms in enhancing the function of antioxidant system in brain, reducing neuroinflammatory reaction and deposition of Aβ1-42 induced by oxidative stress, and maintaining the expression level of APP protein.