EFFECTS OF GLUTAMATE ON SODIUM CHANNEL IN ACUTELY DISSOCIATED HIPPOCAMPAL CA1 PYRAMIDAL NEURONS OF RATS

Objective To observe the effects of glutamate on sodium channel in acutely dissociated hippocampal CA1 pyramidal neurons of rats.Methods Voltage-dependent sodium currents (INa) in acutely dissociated hippocampal CA1 pyramidal neurons of neonate rats were recorded by whole-cell patchclamp of the brain slice technique when a series of doses of glutamate (100-1000μmol/L) were applied.Results Different concentrations of glutamate could inhibit INa,and higher concentration of glutamate affected greater inhibitio...     

Curcumin improves learning and memory ability and its neuroprotective mechanism in mice

Background Increasing evidence suggests that many neurons may die through apoptosis in Alzheimer＇s disease （AD）. Mitochonddal dysfunction has been implicated in this process of neuronal cell death. One promising approach for preventing AD is based upon anti-apoptosis to decrease death of nerve cells. In this study, we observed the memory improving properties of curcumin in mice and investigated the neuroprotective effect of curcumin in vitro and in vivo. Methods The mice were given AlCl3 orally and injections of D-galactose intraperitoneally for 90 days to establish the AD animal model. From day 45, the curcumin group was treated with curcumin for 45 days. Subsequently, the step-through test, neuropathological changes in the hippocampus and the expression of Bax and Bcl-2 were carried out to evaluate the effect of curcumin on the AD model mice. In cultured PC12 cells, AlCl3 exposure induced apoptosis. The MTT assay was used to measure cell viabilities; flow cytometric analysis to survey the rate of cell apoptosis; DNA-binding fluorochrome Hoechst 33258 to observe nuclei changes in apoptotic cells and Western blot analysis of Bax, Bcl-2 to investigate the mechanisms by which curcumin protects cells from toxicity. Results Curcumin significantly improved the memory ability of AD mice in the step-through test, as indicated by the reduced number of step-through errors （P 〈0.05） and prolonged step-through latency （P 〈0.05）. Curcumin also attenuated the neuropathological changes in the hippocampus and inhibited apoptosis accompanied by an increase in Bcl-2 level （P 〈0.05）, but the activity of Bax did not change （P 〉0.05）. AICI3 significantly reduced the viability of PC12 cells （P 〈0.01）. Curcumin increased cell viability in the presence of AICI3 （P 〈0.01）. The rate of apoptosis decreased significantly in the curcumin group （P 〈0.05） when measured by flow cytometric analysis. Curcumin protected cells by increasing Bcl-2 level （P 〈0.05）, but the level of Bax did not ch     

Screening for glutamate-induced and dexamethasone-downregulated epilepsy-related genes in rats by mRNA differential display

Background It is known that excessive release of glutamate can induce excitotoxicity in neurons and lead to seizure. Dexamethasone has anti-seizure function. The aim of this study was to investigate glutamatedexamethasone interaction in the pathogenesis of epilepsy, identify differentially expressed genes in the hippocampus of glutamate-induced epileptic rats by mRNA differential display, and observe the effects of dexamethasone on these genes expression. Methods Seizure models were established by injecting 5μl （250 μg/μl） monosodium glutamate （MSG） into the lateral cerebral ventricle in rats. Dexamethasone （5 mg/kg） was injected intraperitoneally at 30 minutes after MSG inducing convulsion. The rats＇ behavior and electroencephalogram （EEG） were then recorded for 1 hour. The effects of dexamethasone on gene expression were observed in MSG-induced epileptic rats at 1 hour and 6 hours after the onset of seizure by mRNA differential display. The differentially expressed genes were confirmed by Dot blot. Results EEG and behaviors showed that MSG did induce seizure, and dexamethasone could clearly alleviate the symptom, mRNA differential display showed that MSG increased the expression of some genes in epileptic rats and dexamethasone could downregulate their expression. From more than 10 differentially expressed eDNA fragments, we identified a 226 bp eDNA fragment that was expressed higher in the hippocampus of epileptic rats than that in the control group. Its expression was reduced after the administration of dexamethasone. Sequence analysis and protein alignment showed that the predicted amino acid sequence of this cDNA fragment kept 43% identity to agmatinase, a member of the ureohydrolase superfamily. Conclusions The results of the current study suggest that the product of the 226 bp eDNA has a function similar to agmatinase. Dexamethasone might relax alleviate seizure by inhibiting expression of the gene.     

The Expression of Cyclins in Neurons of Rats after Focal Cerebral Ischemia

The change of the expression of Cyclins in neurons of rats after focal cerebral ischemia was investigated. Ischemia was induced by temporary middle cerebral artery occlusion （MCAO）. The experimental rats induced by MCAO were sacrificed on 7th and 14th day after reperfusion. The brain was taken out at 7th and 14th day after injury, and the expression of Cyclin D1, E, A and B1 in neurons of cerebral cortex or hippocampal CA1 region was detected by immunofluorescence and confocal microscope. The results showed that after MCAO, in the ipsilateral CA1 subfield of hippocampus the expression of Cyclin D1, E, A and B1 in neurons was significantly gradually up-regulated at 7th and 14th day after reperfusion （P〈0.05） as compared with that in control group. In the ipsilateral cerebral cortex the expression of Cyclin D1 and B1 in neurons was notably gradually down-regulated at 7th and 14th day, and that of Cyclin E and A was significantly up-regulated at 14th day after reperfusion as compared with that in control group （all P〈0.05）. It was concluded that there was a differential sensitivity among neurons from different brain regions to ischemic injury. But all of them re-enter into cell cycle after MCAO.     

Protective effects of Ginkgo biloba extract 761 against glutamate-induced neurotoxicity in cultured retinal neuron

Alarge part of neuronal death is the result of episodes of anoxia and ischaemia in the retina and other eye diseases, such as anterior ischemic optic neuropathy, glaucoma. The neuronal death is due to the accumulation of glutamate in the extracellular space. Glutamate is the primary excitatory neurotransmitter in the retina. However,excessive overactivation of glutamate receptors leads to excitotoxic neuronal cell death. Glutamate induces cell death by increasing the levels ofintracellular Ca^2 in neurons, thereby leading to generation of free radicals and activation proteases,     

PROTECTIVE EFFECT OF RADIX SALVIAE MILTIORRHIZAE ON APOPTOSIS OF NEURONSDUREVG FOCAL CEREBRAL ISCHEMIA AND REPERFUSION INJURY

We have found that Radix Salviae Miltiorrhizae (RSM) plays a protective role in ischemic brain injury,which attracted us to investigate the effect of RSM on apoptosis of neurons during cerebral ischemia and reperfusion. The apoptotic cells in ischemic brains at different reperfusion intervals were tested with the method of TdT-mediated dUTP-DIG nick end labeling (TUNEL), and the effect of RSM on the apoptosis of neurons was studied in left middle cerebral artery (LMCA) occlusion in rat models (n=18). The results showed that few scattered apoptotic cells were observed in right cerebral hemisphere after LMCA occlusion and reperfusion, and that a lot of apoptotic cells were found in left ischemic cerebral cortex and caudoputamen at 12 h reperfusion, and they reached peak at 24-48h reperfusion. However, in rats pretreated with RSM, the number of apoptotic cells in left cortex and caudoputamen reduced significantly and the neuronal damage was much milder at 24h reperfusion as compared with those of saline-treated rats. From this study, we conclude that administration of RSM can reduce the apoptosis of neurons induced by cerebral ischemia and reperfusion and afford significant cerebroprotection in the model of focal cerebral ischemia and reperfusion.     

Protective effects of Ginkgo biloba extract on rats during cerebral ischemia/rep erfusion

Objective To study the effect of Ginkgo biloba extract on rats during ischemia/reperfusion and its influence on intracellular calcium in hippocampal neurons.Methods Model of intraluminal occlusion of the middle cerebral artery (MCAO) was used to prepare the ischemia/reperfusion cortex tissue.Concentration of MDA was determined by measuring thiobarbituric acid-reactive substance.GSH-PX was quantified using the thiobarbituric acid (TBA) technique.SOD was assayed througha xanthine method.Endogenous amino acids were quantified by high performance liquid chromatographic (HPLC) analysis.Primary culturs of hippocampal neurons were prepared for a free intracellular calcium (［Ca(2+)］I ) assay by Fura-2 based single cell microfluoremetric technique.Results Comparing control and treatment groups, the concentration of SOD and GSH-PX were higher, whereas that of MDA was much lower; the concentration of glutamate and aspartate decreased and that of GABA increased markedly at all time point (P<0.01), Gly also decreased at some time points (P<0.05). The differences were significant between the groups of 10 mg/kg, 15 mg/kg and the groups of 5 mg/kg.When 1×10(-5) mol/L glutamate was applied with 25 μg/ml ginkgo biloba extract to cultured neurons, the increase in ［Ca(2+)］I was lower than that caused by applying glutamate alone.Its peak value was much lower and increased phase was longer, its declining phase was shorter.After returning to baseline, the application of 1×10(-5) mol/L glutamate could induce the reaction to recover.Conclusions Ginkgo biloba extract could protect damaged neurons by keeping the balance of inhibitory/excitatory aminoacids, enhancing the free radical scavengers system, and inhibiting the effect of glutamate on ［Ca(2+)］I.     

Neuroprotective Effects of Electroacupuncture Preventive Treatment in Senescence-Accelerated Mouse Prone 8 Mice

Objective: To investigate the preventive treatment effects of electroacupuncture(EA) on cognitive changes and brain damage in senescence-accelerated mouse prone 8(SAMP8) mice. Methods: The 5-month-old male SAMP8 and age-matched homologous normal aging mice(SAMR1) were adopted in this study. EA stimulation at Baihui(GV 20) and Yintang(EX-HN 3) was performed every other day for 12 weeks, 4 weeks as a course. Morris water maze test and Nissl-stained with cresyl violet were used for cognitive impairments evaluation and brain morphometric analysis. Amyloid-β(Aβ) expression in hippocampus and parietal cortex was detected by immunohistochemistry, and apoptosis was observed by TUNEL staining. Results: After 3 courses of EA preventive treatment, the escape latencies of 8-month-old SAMP8 mice in EA group were significantly shortened than those of un-pretreated SAMP8 mice. Compared with SAMR1 mice, extensive neuronal changes were visualized in the CA1 area of hippocampus in SAMP8 mice, while these pathological changes and attenuate cell loss in hippocampal CA1 area of SAMP8 mice markedly reduced after EA preventive treatment. Furthermore, Aβ expression in hippocampus and parietal cortex of SAMP8 mice decreased significantly after EA treatment, and neuronal apoptosis decreased as well. Conclusion: EA preventive treatment at GV 20 and EX-HN 3 might improve cognitive deficits and neuropathological changes in SAMP8 mice, which might be, at least in part, due to the effects of reducing brain neuronal damage, decreasing neuronal apoptosis and inhibiting Aβ-containing aggregates.     

Influences of NR2B-containing NMDA receptors knockdown on neural activity in hippocampal newborn neurons

Adult-born neurons undergo a transient period of plasticity during their integration into the neural circuit.This transient plasticity may involve NMDA receptors containing NR2B,the major subunit expressed at early developmental stages.The main objective of the present study was to investigate the effects of NR2B gene knockdown on the functional integration of the adult-born granule cells generated from the subgranule zone (SGZ) in the hippocampus.The small interfering RNA (siRNA) was used to knock down the NR2B gene in the adult-born hippocampal neurons.In the functional integration test,the mice were exposed to a novel environment (open field arena),and the expression of c-fos was immunohistochemically detected in the hippocampus.After exposure to the novel environment,siRNA-NR2B mice were significantly different from control mice in either the number of squares or the number of rears they crossed,showing decreased horizontal and vertical activity (P<0.05).Moreover,the c-fos expression was increased in both control and siRNA-NR2B mice after open field test.But,it was significantly lower in siRNA-NR2B neurons than in control neurons.It was concluded that the neural activity of newborn neurons is regulated by their own NR2B-containing NMDA glutamate receptors during a short,critical period after neuronal birth.     

Effect of GAPT Extract on Expression of Tau Protein and Its Phosphorylation Related Enzymes in Hippocampal Neurons of APPV717I Transgenic Mice

Objective:To investigate the effect of GAPT,an extract mixture from Radix Ginseng,Rhizoma Acor tatarinowii,Radix Polygalae and Radix Curcuma(containing ingredient of turmeric),etc.on expression of tau protein and its phosphorylation related enzyme in hippocampal neurons of APPV717I transgenic mice.Methods:Sixty three-month-old APPV717I transgenic mice were randomly divided into model group,donepezil group[0.92 mg/(kg·d)],the low,medium and high dosage of GAPT groups[0.075,0.15,0.30 g/(kg·d),12 in each group],and 12 three-month-old C57BL/6J mice were set as a normal control group,treatments were administered orally once a day respectively,and both the normal group and model group were given 0.5%sodium carboxymethyl cellulose solution.Immunohistochemistry(IHC)and Western blot analysis were used to detect the expression of total tau protein(Tau-5),cyclin-dependent kinase 5(CDK5)and protein phosphatase 2A(PP2A)in hippocampal neurons of experimental mice after 8-month drug administration(11 months old).Results:In the model group,the expression of Tau-5 and CDK5 were increased,whereas the expression of PP2A was decreased in hippocampal neurons,which were significantly different compared with that in the normal group(all P0.01).IHC test indicated the number and area of either Tau-5 or CDK5 positive cells were decreased with a dose-depended way in GAPT groups,and an increase of PP2A.Compared with the model group,the changes were significant in GAPT groups(P0.05 or P0.01).Similar results were shown by Western blot.Conclusion:GAPT could attenuate abnormal hyperphosphorylation of tau protein in hippocampal neurons of APPV717I transgenic mice via inhibiting the expression of CDK5 and activating the expression of PP2A.     

Long-term impact of intrauterine MCMV infection on development of offspring nervous system

This study examined the impacts of intrauterine murine cytomegalovirus(MCMV) infection on the long-term learning and memory of offspring.Sexually matured male and female BALB/C mice without MCMV infection were identified by ELISA and then mated.Seventy pregnant mice were randomly divided into the virus group(n=40) and the control group(n=30),in which the pregnant mice were subjected to placenta inoculation of MCMV suspension(1 μL,1×106 PFU) or the same amount of cell culture medium,respectively,at gestational age of 12.5 days.Some pregnant mice [virus group(n=20),control group(n=15)] were sacrificed by cervical dislocation at gestational age of 18.5 days,and the head circumference and brain weight of the mouse fetuses were measured,and the MCMV infection in their brain tissues was detected by PCR.The other pregnant mice [virus group(n=20),control group(n=15)] delivered naturally,and the learning and memory capability of the offspring at 70-day-old was analyzed by Morris water maze test.The results showed that 28.57% mouse fetuses in the virus group developed viral infection in the brain.Their head circumference and brain weight were significantly reduced as compared with those in the control group(P<0.01).The Morris water maze test revealed that the mouse offspring in the control group found the platform with straight-line trajectories after training.In contrast,the counterparts in the virus group intended to enter the central area,but looked for the platform with a circular trajectory.And the infected mice exhibited prolonged swimming distance and swimming latency(P<0.01).It was concluded that:(1) placenta inoculation of MCMV can cause fetal brain infection and intrauterine development retardation;(2) the offspring of MCMV placenta inoculation mice showed a long-term decline in learning and memory capability.     

Experimental Study of Effect of Corticosterone on Primary Cultured Hippocampal Neurons and Their Ca^2＋／CaMK Ⅱ Expression

Summary: To explore the effect of different concentrations of corticosterone (CORT) on primary cultured hippocampal neurons and their Ca^2 /CaMK Ⅱ expression and possible mechanism, the changes of hippocampal neurons were observed in terms of morphology, activity of cells, cell death.concentrations of cytosolic free calcium, and the expression of CaMK Ⅱ by using MTT assay, flow cytometry, fluorescent labeling of Fura-2/AM and Western hlotting after 10^-7. 10^-8 and 10^-5 mol/L of CORT was added to culture medium. The evident effect of 10^-6 and 10^-5 mol/L of CORT on the morphology of hippocampal neuron was found. Compared with control neurons, the activity of the cells was markedly decreased and [Ca^2 ], increased in the neurons treated with 10^-6 and 10^-7mol/L of CORT. but no change was observed in the neuron treated with 10^-7 mol/L of CORT.The death was either by way of apoptosisor necrosis in the cells treated with 10^-4 and 10^-5mol/L of CORT respectively. The correlation analysis showed that a reverse correlation existed between [Ca^2 ];and the expression of CaMKⅡ. Either apoptosis or necrosis occurs in the hippocampal neurons treated with CORT. The increased hippocampal [Ca^2 ], is both the result of CORT impairing the hippocampal neurons and the cause of the apoptosis of hippocampal neurons and the decreased CaMKⅡ expression.     

Selective loss of basal forebrain cholinergic neurons in APP770 transgenic mice

Objective To determine whether cholinergic neurons in the basal nucleus magnocellularis (N BM) and the medial septum are affected in transgenic mice overexpressing human a myloid precursor protein 770 (APP₇₇₀).
Methods Eight age groups, from 3 months old to 10 months old, of either heterozygous tra nsgenic or non-transgenic mice were used for choline acetyltransferase (ChAT) s taining using immunohistochemistry. The number of ChAT-positive neurons was co unted on the MCID Image Analysis System. Neurons in the cerebral cortex and are a CA1 of hippocampus were also stained with cresyl violet and counted using opti cal dissector technique.
Results There is no change in the number of forebrain cholinergic neurons in the transge nic mice up to 9 months of age. A loss of these cholinergic neurons starts in 9 months old transgenic mice, with a further decrease in the number of NBM and me dial septum neurons in 10-month-old transgenic mice. On the other hand, the n umber of neurons in the cerebral cortex and hippocampal area CA1 remained unchanged.
Conclusion These results demonstrate a selective loss of basal forebrain cholinergic neuron s in APP₇₇₀ transgenic mice.     

Effects of Electroacupuncture on Hippocampal and Cortical Apoptosis in A Mouse Model of Cerebral Ischemia-reperfusion Injury

Objective: To observe the effects of electroacupuncture on hippocampal and cortical apoptosis in a mouse model of cerebral ischemia-reperfusion injury. Methods: Mouse models established by repeated cerebral ischemia-reperfusion, followed by electroacupuncture at Shenshu, Geshu, and Baihui points. The control group mice were intragastrically administered Hydergine. On day 1 and 7 post-treatment, hippocampal and cortical apoptosis was detected by terminal-deoxynucleotidyl transferase mediated dUTP nick-end labeling (TUNEL), and apoptosis images in the hippocampal CA1 zone and cortical area were analyzed. Results: In the model group, apoptotic cells were detected one day after treatment and some cellular fibers were disarrayed. By day 7 post-treatment, there was an increase in the number of apoptotic cells in the hippocampal CA1 region. In addition, there were apoptotic cells in the cortical area, the cortical layers were thinner with localized neuronal loss and sieve-like lymphocyte infiltration, as well as glial cell proliferation and visible infarct lesions. However, in the Hydergine and electroacupuncture groups, there was a small number of apoptotic cells. At 7 days post-treatment in the model group, field number, numerical density on area, and surface density were increased. However, in the Hydergine and electroacupuncture groups these parameters were decreased (P<0.01), with a significant difference between the two treatment groups (P<0.01). Conclusion: Electroacupuncture treatment inhibited apoptosis and provided neuroprotection.     

Harmful Effects of MSG on Function of Hypothalamus—Pituitary—Target Gland System

It has been demonstrated that neonatal administration of monosodium glutamate(MSG)results in a clearly defined lesion of the arcuate nucleus(AN)of the hypothalamus.The present study shows that fat was accumulated in the abdomen of male rats treated with MSG;weights of the body,pituitary and testis were lower;β-EP content in hypothalamus decreased while L-EnK content increased;serum LH,FSH,TSH,GH and TS levels all decreased in varying degrees while serum PRL level significantly increased.The cAMP content lowered in pituitary,but nor in testes;clear histological changes occurred in testicular tissue;Se-GSH-Px activity in both testis and adrenal gland lowered while LPO level significantly increased.Both Se-GSH-Px activity and LPO level in liver increased.These results indicate that MSG is harmful to the function of the hypothalamus-pituitarytarget system of neonatal rats.     

Microvascular protective role of pericytes in melatonin-treated spinal cord injury in the C57BL/6 mice

Background Pericytes,located on microvessels,help to maintain vascular stability and blood-brain barrier integrity.The influence of pericytes on microvessels after spinal cord injury （SCI） is less clear.Therefore,the aim of this study was to investigate whether pericytes took a protective effect on microvessels in melatonin-treated SCI.Methods C57BL/6 mice were randomly divided into three groups：sham group,SCI group,and melatonin group （n=27per group）.Functional recovery was evaluated using the Basso Mouse Scale.Motor neurons were observed using hematoxylin and eosin staining.Pericyte coverage was analyzed using immunofluorescence.Permeability of blood-spinal cord barrier （BSCB） was assessed by administration of Evan＇s Blue.Protein levels of occludin,aquaporin-4 （AQP4）,angiopoietin-1 （Ang1）,intercellular cell adhesion molecule-1 （ICAM-1）,Bcl-2,and Bax were determined using Western blotting.Mimicking the pathological conditions of SCI,melatonin-treated primary pericytes were subjected to oxygenglucose deprivation/reperfusion （OGD/R）.Secretion of Ang1 was analyzed using an enzyme-linked immunosorbent assay,and the expression of ICAM-1 was detected by immunofluorescence.Results Melatonin treatment improved locomotor functional outcome and rescued motor neurons.Pericyte coverage was significantly reduced after SCI; melatonin treatment alleviated the loss of pericyte coverage and rescued perfused microvessels 7 days after injury.The permeability of BSCB and loss of occludin were attenuated,and edema formation and upregulation of AQP4 were inhibited,after melatonin treatment.The expression of Ang1 and Bcl-2 was improved,while the expression of ICAM-1 and Bax was inhibited,in melatonin-treated SCl mice.Furthermore,the secretion of Ang1 was increased and the expression of ICAM-1 was inhibited in melatonin-treated pericytes after OGD/R.Conclusions Melatonin ameliorated the loss of blood vessels and disruption of BSCB to exert a protective effect on SCI,which might be mediated by increased p     

Effects of shenmai injection on expression of TNF- α mRNA in peritoneal macrophages of scald mice

Objective To explore the effect of shenmai injection (SI) on expression of TNF- α mRNA in peritoneal macrophages (pMΦs) of scald mice. Methods BALB/c mice were inflicted with 11% of body surface area Ⅲ degree scald and injected intraperitoneally (ip) with SI daily for 5 days, and expression of TNF- α mRNA in pMΦs was determined by semi- quantitative RT- PCR.Results In scald mice, the expression of TNF- α mRNA in pMΦs increased significantly, but it was reduced obviously (P&lt;0.01) after SI administration, while the livability was increased markedly (P&lt;0.05). Conclusions For scald mice, the cause of death at early stage might be related to the high expression of TNF- α mRNA in pMΦs and the use of SI can decrease the death rate.     

Minocycline Attenuates Microglial Response and Reduces Neuronal Death after Cardiac Arrest and Cardiopulmonary Resuscitation in Mice

The possible role of minocycline in microglial activation and neuronal death after cardiac arrest(CA) and cardiopulmonary resuscitation(CPR) in mice was investigated in this study. The mice were given potassium chloride to stop the heart beating for 8 min to achieve CA, and they were subsequently resuscitated with epinephrine and chest compressions. Forty adult C57BL/6 male mice were divided into 4 groups(n=10 each): sham-operated group, CA/CPR group, CA/CPR+minocycline group, and CA/CPR+vehicle group. Animals in the latter two groups were intraperitoneally injected with minocycline(50 mg/kg) or vehicle(normal saline) 30 min after recovery of spontaneous circulation(ROSC). Twenty-four h after CA/CPR, the brains were removed for histological evaluation of the hippocampus. Microglial activation was evaluated by detecting the expression of ionized calcium-binding adapter molecule-1(Iba1) by immunohistochemistry. Neuronal death was analyzed by hematoxylin and eosin(H&E) staining and the levels of tumor necrosis factor-alpha(TNF-α) in the hippocampus were measured by enzyme-linked immunosorbent assay(ELISA). The results showed that the neuronal death was aggravated, most microglia were activated and TNF-α levels were enhanced in the hippocampus CA1 region of mice subjected to CA/CPR as compared with those in the sham-operated group(P<0.05). Administration with minocycline 30 min after ROSC could significantly decrease the microglial response, TNF-α levels and neuronal death(P<0.05). It was concluded that early administration with minocycline has a strong therapeutic potential for CA/CPR-induced brain injury.     

Dendrobium Alkaloids Attenuates Learning and Memory Impairment in APP/PS1 Mice

Objective：To observe the effect of the total alkaloids of Dendrobium nobile Lindl on the learning and memory impairment of APP/PS1 transgenic mice. Methods：Seven months male APP/PS1 transgenic mice （n=24） were randomly divided into two groups：APP/PS1+vehicle and APP/ PS1+DNLA（the total alkaloids of Dendrobium nobile Lindl） groups. Age-matched male wild-type（ WT）littermates （n=24） were randomly divided into two groups：WT+vehicle and WT+DNLA groups. The normal group and APP / PS1 group were garaged with normal volume of saline（ NS） for 6 consecutive months. The mice in the normal administration group and APP/PS1-administered group were given the daily total alkaloid of Dendrobiumnobile 40 mg·kg-1. Morris water maze was used to detect learning and memory ability in mice. At the end of the behavioral test,the cortical area of senile plaques were detected in the mice by anesthesia,and the survival of the hippocampal neurons was detected by Nissl’s staining.Transmission electron microscope was performed to observe neuron structure and synaptic structure in hippocampus. The levels of IL-1β were measured by ELISA .The levels of Aβ1-40,Aβ1-42 and the expression of GFAP,IL-6,COX-2,p-NF-ΚB,p-p38,PSD95 and SYP in hippocampus were detected by Western blot. Results：Compared with WT+vehicle group,the mean escape latency was markedly increased and the time percentage in target quadrant showed notable decrease in APP/PS1+vehicle group. The number of neurons were significantly reduced in hippocampal CA1 region. The results of transmission electron microscope showed that the structure of neuron and synaptic structure were damaged and the number of synaptic density was decreased. The amyloid plaques,Aβ1-40,Aβ1-42 contents the protein expression of GFAP,IL-6,COX-2,p-NF-κB and p-p38 were increased,meanwhile,the protein expression of PSD95 and SYP were dramatically decreased in the hippocampus in APP/PS1+vehicle group. These effects in WT+DNLA group showed no notable differences compared to the WT+vehicle group. However,compared with APP/PS1+vehicle group,the mean escape latency was decreased and the time percentage in target quadrant was notably increased in APP/PS1+DNLA. Moreover,the number of neurons were significantly increased in hippocampal CA1 region. The
structure of neuron and synaptic structure was improvement Furthermore,the amyloid plaques,Aβ1-40,Aβ1-42 contents,GFAP,IL-6,COX-2,p- NF-κB and p-p38 expression were decreased in thehippocampus,the protein expression of PSD95 and SYP were significantly increased in APP/PS1+DNLA group. Conclusions：Under the experimental conditions,DNLA attenuates the learning and memory loss of Alzheimer’s disease mice and reduces the number of senile plaques and increases the number of surviving neurons. The mechanism may be related to level of Aβ,activation of astrocytes,activation of astrocytes,inhibition of NF-κB and p38 and improvement of synaptic dysfunction.