Ginsenoside Rg1 protects against neurodegeneration by inducing neurite outgrowth in cultured hippocampal neurons

Ginsenoside Rg1（Rg1） has anti-aging and anti-neurodegenerative effects. However, the mechanisms underlying these actions remain unclear. The aim of the present study was to determine whether Rg1 affects hippocampal survival and neurite outgrowth in vitro after exposure to amyloid-beta peptide fragment 25–35（Aβ_（25–35））, and to explore whether the extracellular signal-regulated kinase（ERK） and Akt signaling pathways are involved in these biological processes. We cultured hippocampal neurons from newborn rats for 24 hours, then added Rg1 to the medium for another 24 hours, with or without pharmacological inhibitors of the mitogen-activated protein kinase（MAPK） family or Akt signaling pathways for a further 24 hours. We then immunostained the neurons for growth associated protein-43, and measured neurite length. In a separate experiment, we exposed cultured hippocampal neurons to Aβ_（25–35） for 30 minutes, before adding Rg1 for 48 hours, with or without Akt or MAPK inhibitors, and assessed neuronal survival using Hoechst 33258 staining, and phosphorylation of ERK1/2 and Akt by western blot analysis. Rg1 induced neurite outgrowth, and this effect was blocked by API-2（Akt inhibitor） and PD98059（MAPK/ERK kinase inhibitor）, but not by SP600125 or SB203580（inhibitors of c-Jun N-terminal kinase and p38 MAPK, respectively）. Consistent with this effect, Rg1 upregulated the phosphorylation of Akt and ERK1/2; these effects were reversed by API-2 and PD98059, respectively. In addition, Rg1 significantly reversed Aβ_（25–35）-induced apoptosis; this effect was blocked by API-2 and PD98059, but not by SP600125 or SB203580. Finally, Rg1 significantly reversed the Aβ_（25–35）-induced decrease in Akt and ERK1/2 phosphorylation, but API-2 prevented this reversal. Our results indicate that Rg1 enhances neurite outgrowth and protects against Aβ_（25–35）-induced damage, and that its mechanism may involve the activation of Akt and ERK1/2 signaling.

Protective mechanisms of micro RNA-27a against oxygen-glucose deprivation-induced injuries in hippocampal neurons

Hypoxic injuries during fetal distress have been shown to cause reduced expression of micro RNA-27a（mi R-27a）,which regulates sensitivity of cortical neurons to apoptosis.We hypothesized that miR-27 a overexpression attenuates hypoxia- and ischemia-induced neuronal apoptosis by regulating FOXO1,an important transcription factor for regulating the oxidative stress response.miR-27 a mimic was transfected into hippocampal neurons to overexpress miR-27 a.Results showed increased hippocampal neuronal viability and decreased caspase-3 expression.The luciferase reporter gene system demonstrated that mi R-27 a directly binded to FOXO1 3′UTR in hippocampal neurons and inhibited FOXO1 expression,suggesting that FOXO1 was the target gene for mi R-27 a.These findings confirm that mi R-27 a protects hippocampal neurons against oxygen-glucose deprivation-induced injuries.The mechanism might be mediated by modulation of FOXO1 and apoptosis-related gene caspase-3 expression.

Chrysophanol attenuates lead exposure-induced injury to hippocampal neurons in neonatal mice

Previous studies have shown that chrysophanol protects against learning and memory impairments in lead-exposed adult mice. In the present study, we investigated whether chrysophanol can alleviate learning and memory dysfunction and hippocampal neuronal injury in lead-exposed neonatal mice. At the end of lactation, chrysophanol（0.1, 1.0, 10.0 mg/kg） was administered to the neonatal mice by intraperitoneal injection for 15 days. Chrysophanol significantly alleviated injury to hippocampal neurons and improved learning and memory abilities in the lead-poisoned neonatal mice. Chrysophanol also significantly decreased lead content in blood, brain, heart, spleen, liver and kidney in the lead-exposed neonatal mice. The levels of malondialdehyde in the brain, liver and kidney were significantly reduced, and superoxide dismutase and glutathione peroxidase activities were significantly increased after chrysophanol treatment. Collectively, these findings indicate that chrysophanol can significantly reduce damage to hippocampal neurons in lead-exposed neonatal mice.

Real-time Microwave Exposure Induces Calcium Efflux in Primary Hippocampal Neurons and Primary Cardiomyocytes

Objective To detect the effects of microwave on calcium levels in primary hippocampal neurons and primary cardiomyocytes by the real-time microwave exposure combined with laser scanning confocal microscopy. Methods The primary hippocampal neurons and primary cardiomyocytes were cultured and labeled with probes, including Fluo-4 AM, Mag-Fluo-AM, and Rhod-2, to reflect the levels of whole calcium [Ca], endoplasmic reticulum calcium [Ca]ER, and mitochondrial calcium [Ca]MIT, respectively. Then, the cells were exposed to a pulsed microwave of 2.856 GHz with specific absorption rate(SAR) values of 0, 4, and 40 W/kg for 6 min to observe the changes in calcium levels. Results The results showed that the 4 and 40 W/kg microwave radiation caused a significant decrease in the levels of [Ca], [Ca]ER, and [Ca]MIT in primary hippocampal neurons. In the primary cardiomyocytes, only the 40 W/kg microwave radiation caused the decrease in the levels of [Ca], [Ca]ER, and [Ca]MIT. Primary hippocampal neurons were more sensitive to microwave exposure than primary cardiomyocytes. The mitochondria were more sensitive to microwave exposure than the endoplasmic reticulum. Conclusion The calcium efflux was occurred during microwave exposure in primary hippocampal neurons and primary cardiomyocytes. Additionally, neurons and mitochondria were sensitive cells and organelle respectively.

Inhibition of TYRO3/Akt signaling participates in hypoxic injury in hippocampal neurons

In this study, we investigated the role of the TYRO3/Akt signaling pathway in hypoxic injury to hippocampal neurons. 3-（4,5-Dimethylthiazol-2-yl）-2,5-diphenyltetrazolium bromide assay showed that hypoxia inhibited the proliferation and viability of hippocampal neurons. Terminal deoxynucleotidyl transferase-mediated d UTP nick end labeling assay demonstrated that hypoxia induced neuronal apoptosis in a time-dependent manner, with a greater number of apoptotic cells with longer hypoxic exposure. Immunofluorescence labeling revealed that hypoxia suppressed TYRO3 expression. Western blot assay showed that hypoxia decreased Akt phosphorylation levels in a time-dependent manner. Taken together, these findings suggest that hypoxia inhibits the proliferation of hippocampal neurons and promotes apoptosis, and that the inhibition of the TYRO3/Akt signaling pathway plays an important role in hypoxia-induced neuronal injury.

MicroRNA-219 alleviates glutamate-induced neurotoxicity in cultured hippocampal neurons by targeting calmodulin-dependent protein kinase Ⅱ gamma

Septic encephalopathy is a frequent complication of sepsis,but there are few studies examining the role of micro RNAs（mi Rs） in its pathogenesis.In this study,a mi R-219 mimic was transfected into rat hippocampal neurons to model mi R-219 overexpression.A protective effect of mi R-219 was observed for glutamate-induced neurotoxicity of rat hippocampal neurons,and an underlying mechanism involving calmodulin-dependent protein kinase II γ（Ca MKIIγ） was demonstrated.mi R-219 and Ca MKIIγ m RNA expression induced by glutamate in hippocampal neurons was determined by quantitative real-time reverse transcription-polymerase chain reaction（q RT-PCR）.After neurons were transfected with mi R-219 mimic,effects on cell viability and apoptosis were measured by 3-（4,5-dimethylthiazolyl-2）-2,5-diphenyltetrazolium bromide（MTT） assay and flow cytometry.In addition,a luciferase reporter gene system was used to confirm Ca MKIIγ as a target gene of mi R-219.Western blot assay and rescue experiments were also utilized to detect Ca MKIIγ expression and further verify that mi R-219 in hippocampal neurons exerted its effect through regulation of Ca MKIIγ.MTT assay and q RT-PCR results revealed obvious decreases in cell viability and mi R-219 expression after glutamate stimulation,while Ca MKIIγ m RNA expression was increased.MTT,flow cytometry,and caspase-3 activity assays showed that mi R-219 overexpression could elevate glutamate-induced cell viability,and reduce cell apoptosis and caspase-3 activity.Moreover,luciferase Ca MKIIγ-reporter activity was remarkably decreased by co-transfection with mi R-219 mimic,and the results of a rescue experiment showed that Ca MKIIγ overexpression could reverse the biological effects of mi R-219.Collectively,these findings verify that mi R-219 expression was decreased in glutamate-induced neurons,Ca MKIIγ was a target gene of mi R-219,and mi R-219 alleviated glutamate-induced neuronal excitotoxicity by negatively controlling Ca MKIIγ expression.

Dose-dependent effects of lead on cell-cycle arrest, DNA damage, and cyclin D1 expression in primary cultured rat hippocampal neurons

BACKGROUND： Previous studies have suggested that the hippocampus is one of the neurotoxic target sites for lead. However, the molecular mechanisms of action, including the effect of lead on cell-cycle arrest, remain poorly understood. OBJECTIVE： To investigate the effects of different lead concentrations on cell-cycle arrest, DNA damage, and cyclin D1 expression in primary cultured rat hippocampal neurons. DESIGN, TIME AND SETTING： A randomized, controlled, in vitro experiment was performed at the China Medical University between July 2008 and May 2009. MATERIALS： Antibodies specific to cyclin D1 and actin were synthesized and purified by Santa Cruz Biotechnology, USA. FACStar flow cytometer was purchased from Becton Dickinson, San Jose, California, USA. METHODS： Wistar rat hippocampal neurons were primary cultured for 7 days. Neurons in the control group were treated with 0.01 mol/L phosphate buffered saline. Neurons in the 0.2, 1.0, and 10 umol/L lead acetate groups were subjected to 0.2, 1.0, and 10 umol/L lead acetate. Subsequently hippocampal neurons in each group were cultured for 24 hours. MAIN OUTCOME MEASURES： The effects of lead on cell cycle were measured by flow cytometry, DNA damage was measured using the comet assay, and cyclin D1 expression was measured using Western blot analysis. RESULTS： Treatment of hippocampal neurons with 0.2 umol/L lead acetate did not significantly alter cell cycle phase distribution, i.e., sub-G1, S, G0/G1, G2/M, whereas treatment with 1.0 and 10 umol/L lead acetate significantly increased the percentage of S and sub-G1 phase cells （P 〈 0.05）. Olive tail moment in all lead-treated groups and the percentage of DNA in the tail in 1.0 umol/L and 10 umol/L lead acetate groups were significantly greater compared with the control group （P 〈 0.05）. In addition, the percentage of tail DNA was greater in the 0.2 umol/L lead acetate group compared with the control group （P 〉 0.05）. Following incubation with 0.2, 1.0, and 10 umol/L lead acetate for 24 hours, cyclin D1 expression gradually decreased with exposure to increasing lead acetate concentrations （1.0-10 umol/L）. CONCLUSION： Lead exposure to primary cultured rat hippocampal neurons resulted in dose-dependently disturbed cellular homeostasis, including DNA damage, reduced cyclin D1 expression, and stagnation of cell-cycle progression.

Gentianine protects hippocampal neurons in a rat model of recurrent febrile convulsion

Gentianine has been shown to have a protective effect on hippocampal CA1 neurons in rats subjected to recurrent febrile convulsion（FC）.The present study sought to explore the possible mechanism of gentianine by intraperitoneally injecting gentianine into rats with warm water-induced FC.The results revealed that neuronal organelle injury was slightly ameliorated in the hippocampal CA1 region.The level of glutamate was decreased,but the level of γ-aminobutyric acid was increased,as detected by ninhydrin staining.In addition,glutamate acid decarboxylase expression in hippocampal CA1 was increased,as determined by immunohistochemistry.The results demonstrated that gentianine can ameliorate FC-induced neuronal injury by enhancing glutamate acid decarboxylase activity,decreasing glutamate levels and increasing γ-aminobutyric acid levels.

A Comparative Study About the Neuroprotective Effects of EPA-Enriched Phosphoethanolamine Plasmalogen and Phosphatidylethanolamine Against Oxidative Damage in Primary Hippocampal Neurons

s Oxidative stress is involved in the progression of neurodegenerative diseases.Previous evidences showed that plasma-logens could improve neurodegenerative diseases.In this study,we investigated the function of phosphoethanolamine plasmalogens enriched with EPA(EPA-pPE)and phosphatidylethanolamine enriched with EPA(EPA-PE)on oxidative damage prevention after hy-drogen peroxide(H2O2)and tert-butylhydroperoxide(t-BHP)challenge in primary hippocampal neurons.Results showed that neurons pretreated with EPA-pPE and EPA-PE demonstrated the ability to alleviate oxidative damage,which was proved by the in-creased cell viability.Moreover,the shape and number of neurons were more similar to those of the control group.Antioxidant acti-vity,apoptosis,as well as TrkB/ERK/CREB signaling pathway were investigated to explore the mechanisms.The results suggested that EPA-PE was superior to EPA-pPE in regulating mitochondrial apoptosis.EPA-pPE was more prominent than EPA-PE in upre-gulating TrkB/ERK/CREB signaling pathway.Phospholipids with EPA exerted neuroprotective effects via inhibiting oxidative stress,suppressing apoptosis,and regulating TrkB/ERK/CREB signaling pathway.Therefore,the results provide a scientific basis for utili-zation of phospholipids enriched with EPA on the treatment of neurodegenerative disease.

Protective effects of Zuogui Jiangtang Jieyu Formula on hippocampal neurons in rats of diabetes complicated with depression via the TRP/KYN metabolic pathway

Objective To explore the protective effects and mechanism of Zuogui Jiangtang Jieyu Formula(左归降糖解郁方,ZGJTJYF)on hippocampal neurons in rats of diabetes complicated with depression(DD)via the TRP/KYN metabolic pathway.Methods(i)In vivo experiments:60 specified pathogen free(SPF)grade male Sprague-Dawley(SD)rats were randomly divided into six groups with 10 rats in each groups:control,DD model,positive(1.8 mg/kg fluoxetine+0.18 g/kg metformin),high-dose ZGJTJYF(ZGJTJYFH,40.500 g/kg ZGJTJYF),middle-dose ZGJTJYF(ZGJTJYF-M,20.250 g/kg ZGJTJYF),and lowdose ZGJTJYF(ZGJTJYF-L,10.125 g/kg ZGJTJYF)groups.Except for the control group,other groups were established DD model by high-fat emulsion intake with single tail vein streptozotocin(STZ)and four weeks of chronic unpredictable mild stress(CUMS).All drug administration groups were treated by gavage during CUMS modeling,and the control and model groups were given equal amount of distilled water.After four weeks,the serum levels of blood glucose and glycosylated hemoglobin were measured to determine the hypoglycemic effect of ZGJTJYF.Moreover,the open field test and Morris water maze test were performed to evaluate the antidepressant effect of ZGJTJYF.Changes in 5-hydroxytryptamine(5-HT)level were detected via high-performance liquid chromatography with electrochemical detection(HPLC-ECD);the levels of tryptophan(TRP),kynurenine(KYN),and indoleamine 2,3-dioxygenase(IDO)in the hippocampus were detected using enzyme-linked immunosorbent assay(ELISA);the protein expression levels of synaptophysin(SYN)and postsynaptic density material-95(PSD-95)were detected via immunohistochemistry(IHC);and the protein expression levels of N-methyl-D-aspartate receptor(NR)2 A and NR2 B were detected using Western blot.(ii)In vitro experiments:five SPF grade SD pregnant rats(E16–18)were used to obtain primary hippocampal neurons(Ne),six SD new-born rats were used to collected primary astrocytes(As)and microglia(MG),and to establish a Ne-As-MG co-culture system.All co-culture systems were divided into six groups:control(PBS),model[150 mmol/L glucose+200μmol/L corticosterone(G&P)+PBS],blank(G&P+blank serum),positive(G&P+positive drug-containing serum),ZGJTJYF(G&P+ZGJTJYF serum),and 1-methyl-D-tryptophan(1-MT,IDO inhibitor)(G&P+1-MT)groups.After 18 h of intervention by corresponding treatment,immunofluorescence was used to analyze the protein expression levels of SYN,PSD-95,NR2 A,and NR2 B;ELISA was performed to measure the levels of interleukin(IL)-1β,IL-6,tumor necrosis factor(TNF)-α,and TRP/KYN metabolic pathway-related factors[TRP,KYN,kynurenine acid(KYNA),quinolinic acid(QUIN)].Results(i)In vivo experimental results showed that ZGJTJYF-M and ZGJTJYF-L significantly improved the elevated blood glucose state of DD rats(P<0.01 and P<0.05,respectively);ZGJTJYF-H,ZGJTJYF-M,and ZGJTJYF-L increased their autonomous activity,learning,and memory ability(P<0.01,P<0.01,and P<0.05,respectively).Moreover,the levels of 5-HT and TRP were significantly increased(P<0.01),and the levels of KYN and IDO were significantly decreased in the hippocampus(P<0.01)of rats after ZGJTJYF-M treatment.The protein expression levels of SYN and PSD-95 were significantly upregulated in hippocampal neurons(P<0.01),while the abnormal activation of NR2A and NR2B was markedly inhibited in hippocampus(P<0.05)of rats after ZGJTJYF-M treatment.(ii)In vitro experimental results showed that ZGJTJYF-containing serum significantly increased the protein expression levels of SYN and PSD-95 in hippocampal neurons(P<0.01),decreased the levels of IL-1β(P<0.01),IL-6(P<0.05),TNF-α(P<0.01),IDO(P<0.05),KYN(P<0.05),and QUIN(P<0.01),and increased the levels of TRP and KYNA(P<0.01)in the simulated DD state.ZGJTJYF also had an significantly inhibitory effect on the abnormal activation of NR2A and NR2B in neurons(P<0.05)in a stimulated DD state.Conclusion ZGJTJYF can effectively improve 5-HT deficiency in the hippocampus of rats by inhibiting IDO expression and regulating the TRP/KYN metabolic pathway,and it has a favorable protective effect on hippocampal neuron injury caused by DD.Therefore,ZGJTJYF is an effective potential therapeutic drug for the prevention and treatment of DD.

Effect of Thrombin on the Apoptosis of Hippocampal Neurons in vitro

Hippocampal neurons were treated by thrombin and thrombin receptor activatingpeptides (TRAP). Cell survival rate was decreased in a dose-dependent manner by MTT assay. Thenumbers of apoptotic cell and apoptotic rate of hippocampal neurons treated bydifferentconcentrations of thrombin were increased in a dose-dependent manner by terminal deoxynucleotidyltransferase (TdT) mediated dUTP-biotin nick end-labeling (TUNED method and Flow Cytometry. When theconcentration of thrombin is 40 U/mL, TUNEL positive cells and apoptotic rate of hippocampal neuronsreached peak value, were 27. 3 +- 4. 0 and (29. 333 +- 4. 633 ) % , respectively.Immunocytochemistry assay show that Bcl-2 protein expression was down- regulated and Bax proteinexpression was up-regulated with the concentration of thrombin increased. TRAP can mimic the effectof thrombin to induce apoptosis on hippocampal neurons. These data demonstrated that thrombininduced hippocampal neuron apoptosis in a dose-dependent manner through activatingprotease-acti-vated protein-1 (PAR-1). The change in expression of Bcl-2 and Bax was related withthe effect of high concentration thrombin induced apoptosis on hippocampal neurons.

Polygalasaponin F protects hippocampal neurons against glutamate-induced cytotoxicity

Excess extracellular glutamate leads to excitotoxicity,which induces neuronal death through the overactivation of N-methyl-D-aspartate receptors(NMDARs).Excitotoxicity is thought to be closely related to various acute and chronic neurological disorders,such as stroke and Alzheimer’s disease.Polygalasaponin F(PGSF)is a triterpenoid saponin monomer that can be isolated from Polygala japonica,and has been reported to protect cells against apoptosis.To investigate the mechanisms underlying the neuroprotective effects of PGSF against glutamateinduced cytotoxicity,PGSF-pretreated hippocampal neurons were exposed to glutamate for 24 hours.The results demonstrated that PGSF inhibited glutamate-induced hippocampal neuron death in a concentration-dependent manner and reduced glutamate-induced Ca^(2+)overload in the cultured neurons.In addition,PGSF partially blocked the excess activity of NMDARs,inhibited both the downregulation of NMDAR subunit NR2A expression and the upregulation of NMDAR subunit NR2B expression,and upregulated the expression of phosphorylated cyclic adenosine monophosphate-responsive element-binding protein and brain-derived neurotrophic factor.These findings suggest that PGSF protects cultured hippocampal neurons against glutamate-induced cytotoxicity by regulating NMDARs.The study was approved by the Institutional Animal Care Committee of Nanchang University(approval No.2017-0006)on December 29,2017.

Proliferation changes in hippocampal neurons following pilocarpine-induced intractable epilepsy in adult rats

Epilepsy can lead to the changes in neurons residing in the dentate gyrus. The present study aimed to observe the cell dividing features following epilepsy in adult rat hippocampi, and to study difference in cell proliferation between adult rats with common epilepsy and intractable epilepsy.Adult, male, Sprague Dawley rats ware randomly divided into control （n = 8, treatment with normal saline） and three expenmental groups： common epilepsy （n = 33）, intractable epilepsy （n = 11）, and drug-responsive （n = 25）. Pilocarpine （15 mg/kg） was intrapentoneally administered to establish epilepsy in the three experimental groups. Rats that developed epilepsy were treated with chloral hydrate. Rats that did not exhibit spontaneous seizures were enrolled in the common epilepsy group, and rats with spontaneous seizure were included in the spontaneous seizure group. At 6 hours after epileptic attack termination, rats ware intraperitoneally injected with bromodeoxyuridine （BrdU; 50 mg/kg）, an optimal marker forlabeling cell proliferation in vivo, four times.Immunohistochemistry results at 48 hours after BrdU injection indicated that the number of BrdU-positive cells was the highest in the common epilepsy group, followed by the control group,and lastly the intractable group （P 〈 0.01）. In addition, the number of BrdU-positive cells in the common epilepsy group was similar to the drug-responsive group. The present findings demonstrated that intractable epilepsy led to decreased hippocampal neurons in adult rats when compared to common epilepsy.

Influence of morphine on levels of type Ⅱ inhibitory guanine nucleotide binding protein in primary hippocampal neurons

BACKGROUND： The pharmacological action of opioid drugs is related to signal transduction of inhibitory guanine nucleotide binding protein. OBJECTIVE： To quantitatively and qualitatively analyze the influence of morphine on levels of type Ⅱ inhibitory guanine nucleotide binding protein （Gi2 protein） in primary cultured hippocampal neurons at different time points. DESIGN, TIME AND SETTING： A randomized controlled study, which was performed at the Department of Neurobiology, Changzheng Hospital, Second Military Medical University of Chinese PLA between September 2002 and March 2004. MATERIALS： Cerebral hippocampal neurons were obtained from newborn SD rats at 1 2 days of age. Biotin-antibody Ⅱ-avidin fluorescein isothiocyanate （Avidin-FITC） was purchased from Sigma Company （USA） and the Gi2 protein polyclonal antibody from Santa Cruz Biochemistry Company （USA）. METHODS： Seven days after culture, mature hippocampal neurons were randomly divided into six groups： 4-, 8-, 16-, 24-, and 48-hour morphine groups, and a blank control group. Neurons in the morphine groups received morphine （10 μ mol/L）, which could cause alterations of G-protein mRNA and cAMP expression in the prefrontal cortex. Neurons in the blank control group were given the same volume of saline. MAIN OUTCOME MEASURES： Gi2 protein levels were detected by an immunofluorescence technique, and were analyzed by the image analytic system with the use of green fluorescence intensity. RESULTS： Gi2 protein levels in hippocampal neurons gradually decreased in the 4-, 8-, 16-, 24-, and 48-hour morphine groups. In particular, Gi2 protein levels in the 16-, 24-, and 48-hour morphine groups were significantly lower than that in the blank control group （P 〈 0.05 0.01）. CONCLUSION： Morphine may decrease Gi2 protein level in primary hippocampal neurons, and the decreasing trend is positively related to morphine-induced time.

Experimental Study of Effect of Corticosterone on Primary Cultured Hippocampal Neurons and Their Ca^(2+) /CaMKⅡ Expression

Summary: To explore the effect of different concentrations of corticosterone (CORT) on primary cultured hippocampal neurons and their Ca~2+ /CaMKⅡ 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 CaMKⅡ by using MTT assay, flow cytometry, fluorescent labeling of Fura-2/AM and Western blotting after 10~-7 , 10~-6 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+ ]_i increased in the neurons treated with 10~-6 and 10~-5 mol/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 apoptosis or necrosis in the cells treated with 10~-6 and 10~-5 mol/L of CORT respectively. The correlation analysis showed that a reverse correlation existed between [Ca~2+ ]_i and the expression of CaMKⅡ. Either apoptosis or necrosis occurs in the hippocampal neurons treated with CORT. The increased hippocampal [Ca~2+ ]_i is both the result of CORT impairing the hippocampal neurons and the cause of the apoptosis of hippocampal neurons and the decreased CaMKⅡ expression.

Rapid effect of stress concentration corticosterone on glutamate receptor and its subtype NMDA receptor activity in cultured hippocampal neurons

Objective: To study the rapid effect of glucocorticoids (GCs) on NMDA receptor activity in hippocampal neurons in stress and to elucidate its underlying probable membrane mechanisms. Methods: Whole-cell patch-clamp recording was used to assess the effect of stress concentration corticosterone (B) on the responses of cultured hippocampal neurons to glutamate and NMDA (N-methy-D-asparatic acid). To make clear the target of B, intracellular dialysis of B(10 μmol/L)through patch pipette and extracellular application of bovine serum albumin-conjugated corticosterone(B-BSA, 10 μmol/L)were carried out to observe their influence on peak amplitude of NMDA-evoked current. Results: B had a rapid, reversible and inhibitory effect on peak amplitude of GLU- or NMDA-evoked current in cultured hippocampal neurons. Furthermore, B-BSA had the inhibitory effect on INMDA as that of B, but intracellularly dialyzed B had no significant effect on I NMDA. Conclusion: These results suggest that under the condition of stress, GCs may rapidly, negatively regulate excitatory synaptic receptors-glutamate receptors (GluRs), especially NMDA receptor (NMDAR) in central nervous system, which is mediated by rapid membrane mechanisms, but not by classical, genomic mechanisms.

An improved primary culture method for hippocampal neurons in fetal rats and MAP2 identification

Objective： To establish a simple, effective and high-purity primary culture method for fetal rat hippocampalneurons. Methods： Wistar rats of gestational age 18 days were taken and the brain tissue was separated under themicroscope. Single neuronal cells were obtained by digestion with Brain Dissociation Kit, and then were seeded incell plates to observe the basic morphologic structure after 24h, 3d, and 5d. Immunofluorescence of microtubuleassociated protein 2 was applied to assess cell purity of the culture. Results： The hippocampal neurons obtained inthis culture method are in good condition and grow vigorously. On the 7th day after culture, the purity of neuronswas up to 99.62%. Conclusion： The method is simple and effective for obtaining the high-purity and stableneurons.

Changes in hippocampal neurons and memory function during the developmental stage of newborn rats with hypoxic-ischemic encephalopathy

BACKGROUND: Under the normal circumstance, there exist some synapses with inactive functions in central nervous system (CNS), but these functions are activated following nerve injury. At the early stage of brain injury, the abnormal functions of brain are varied, and they have very strong plasticity and are corrected easily. OBJECTIVE: To observe the changes of neuronal morphology in hippocampal CA1 region and memory function in newborn rats with hypoxic-ischemic encephalopathy(HIE) from ischemia 6 hours to adult. DESIGN: Completely randomized grouping, controlled experiment. SETTING: Taian Health Center for Women and Children; Taishan Medical College. MATERIALS: Altogether 120 seven-day-old Wistar rats, of clean grade, were provided by the Experimental Animal Center, Shandong University of Traditional Chinese Medicine. Synaptophysin (SYN) polyclonal antibody was provided by Maixin Biological Company, Fuzhou. METHODS: This experiment was carried out in the Laboratory of Morphology, Taishan Medical College between October 2000 and December 2003. ① The newborn rats were randomly divided into 2 groups: model group and control group, 60 rats in each group. Five rats were chosen from each group at postoperative 6 hours, 24 hours, 72 hours, 7 days, 2 weeks and 3 weeks separately for immunohistochemical staining. Fifteen newborn rats were chosen from each group at postoperative 4 weeks and 2 months separately for testing memory ability (After test, 5 rats from each group were sacrificed and used for immunohistochemical staining)② The right common carotid artery of newborn rats of model group was ligated under the anesthetized status. After two hours of incubation, the rats were placed for 2 hours in a container filled with nitrogen oxygen atmosphere containing 0.08 volume fraction of oxygen, thus, HIE models were created; As for the newborn rats in the control group, only blood vessels were isolated, and they were not ligated and hypoxia-treated. ③ Thalamencephal tissue sections of newborn rats of two groups were performed DAB developing and haematoxylin slight staining. Cells with normal nucleous in 250 μm-long granular layer which started from hippocampal CA1 region were counted with image analysis system under high-fold optical microscope (×600), and the thickness of granular layer was measured. The absorbance (A) of positive reactant of SYN in immunohistochemically-stained CA1 region was measured. Learning and memory ability were measured with step through test 3 times successively. ④ t test and paired t test were used for comparing intergroup and intragroup difference of measurement data respectively, and Chi-square for comparing the difference of enumeration data. MAIN OUTCOME MEASURES: Comparison of cytological changes in hippocampal CA1 region and memory ability at different postoperative time points between two groups. RESULTS: Totally 120 newborn rats were involved in the result analysis. ① Cell morphological changes in hippocampal CA1 region: In the control group, with aging, perikaryon, nucleus and nucleolus in cortex of parietal lobe were significantly increased, Nissl body was compacted, the amount of neurons was declined, but the A of SYN positive reactant was relatively increased. In the model group, at postoperative each time point, neurons were seriously shrunk and dark-stained, nucleus was contracted, chromatin was condensed, nucleolus was unclear, even cells disappeared, especially the cells in 6 hours and 24 hours groups. The amount of neurons with normal morphology in hippocampal CA1 region and granular layer thickness in the model group at postoperative each time point were significantly less or smaller than those in the control group at postoperative 6 hours respectively (t =3.002-1.254, P < 0.01). The A value of SYN positive reactant at postoperative 2, 3 and 4 weeks was significantly higher than that at previous time point (t =2.011-2.716,P < 0.05-0.01). ② Test results of learning and memory ability: In the first test, there was no significant difference in the ratio of rats which kept memory ability between two groups (P > 0.05); In the third test, the ratio of rats which kept memory ability in the model group was significantly lower than that in the control group at postoperative 4 weeks and 2 months[53%(8/15),100%(15/15);60%(9/15),93%(14/15),χ 2=2.863,2.901,P < 0.01]. CONCLUSION: The destroyed hippocampal structure induces the decrease of learning and memory ability of developmental rats. Early interference can increase the quality of neurons and also promote functional development of the nervous system.

Astragalus injection inhibits c-Jun N terminal kinase mRNA expression following oxygen-glucose deprivation and reintroduction in rat hippocampal neurons

BACKGROUND： In studies concerning cell injury induced by cerebral ischemia-reperfusion, current experiments have primarily focused on altered protein levels. In addition, the apoptotic proteins Bax and Bcl-2 have been thoroughly studied with regard to initiating neuronal apoptosis. OBJECTIVE： To establish an in vitro model of oxygen-glucose deprivation and reintroduction in the rat hippocampus to simulate cerebral ischemia-reperfusion injury; to observe c-Jun N-terminal kinase 3 （JNK3） mRNA expression in hippocampal neurons following Astragalus injection; and thus to determine changes in the signaling and downstream pathways of neuronal apoptosis at the cellular and molecular level. DESIGN, TIME AND SETTING： A randomized, controlled, cellular and molecular experiment was performed at the Department of Central Laboratory, Chengde Medical College from February to June 2008. MATERIALS： Astragalus injection, the main ingredient of astragaloside, was purchased from Chengdu Di＇ao Jiuhong Pharmaceutical Manufactory, China. JNK3 mRNA probe and in situ hybridization kit were purchased from Tianjin Haoyang Biological Technology, China, and JNK3 RT-PCR primers were designed by Shanghai Bio-engineering, China. METHODS： Primary cultures of hippocampal neurons derived from Sprague Dawley rats, aged 1 2 days, were established. After 8 days, the hippocampal neurons were assigned to the following interventions： model group, Astragalus group, and vehicle control group, cells were subjected to oxygen-glucose reintroduction after oxygen-glucose deprivation for 30 minutes in sugar-free Earle＇s solution and a hypoxia device, which contained high-purity nitrogen. The normal control group was subjected to primary culture techniques and was not treated using above-mentioned interventions. In addition, the Astragalus and vehicle control groups were treated with Astragalus injection （0.5 g/L raw drug） or sterile, deionized water at 2 hours prior to oxygen-glucose deprivation, respectively. MAIN OUTCOME MEASURES： JNK3 mRNA expression was measured by in situ hybridization and RT-PCR at 0, 0.5, 2, 6, 24, 72, and 120 hours after oxygen-glucose reintroduction. RESULTS： Hippocampal neuronal morphology was normal in the normal control group. Hippocampal neurons exhibited apparent apoptosis-like pathological changes in the model, as well as the vehicle control, groups. The apoptosis-like pathological changes in the hippocampal neurons were less in the Astragalus group. Results from in situ hybridization and RT-PCR showed that JNK3 mRNA expression significantly increased in hippocampal neurons from model group, as well as the vehicle control group, compared with the normal control group （P 〈 0.05）. In addition, JNK3 mRNA expression significantly decreased in hippocampal neurons of the Astragalus group, compared with the model group and vehicle control group （P 〈 0.05）. CONCLUSION： Astragalus injection inhibited apoptosis-related JNK3 mRNA expression following oxygen-glucose deprivation and reintroduction, and accordingly played a role in inhibiting hippocampal neuronal apoptosis.

Oxidative damage of primary cultured hippocampal neurons Does androgen have an antagonistic effect?

BACKGROUND： Evidence illustrates that androgen has a neuroprotective role. However, whether androgen also has the protective effect on hippocampal neurons during free radical mediated injury remains unclear. OBJECTIVE： To investigate the neuroprotective effect of androgen on hippocampal neurons during free radical damage. DESIGN, TIME AND SETTING： A controlled in vitro experiment was performed at the Department of Human Anatomy, Cell Culture Lab, and Neuroendocrinology Lab, Basic Medical School, Hebei Medical University from February to June 2009. MATERIALS： Testosterone was provided by Tianjin Jinyao Amino Acid Company, China. METHODS： Primary cultured neurons from 24 Sprague Dawley rats were randomly assigned into four groups： control, H202, testosterone, and testosterone （pre-added） plus H2O2 groups. MAIN OUTCOME MEASURES： The positive cell ratio of microtubule associated protein-Ⅱ and neuron specific enolase was determined by immunocytochemistry. Neuronal morphology was observed by hematoxylin-eosin staining and Nissl staining. Cell vitality and viability were determined using an inverted phase contrast microscope. The content of nitric oxide synthase, malondialdehyde, and superoxide dismutase were measured with a spectrophotometer. RESULTS： As compared with the control group, cell vitality and viability, and superoxide dismutase level were significantly decreased in the H202 group （P 〈 0.05）, while nitric oxide synthase and malondialdehyde levels were significantly increased （P 〈 0.05）. Neuronal vitality and viability as well as superoxide dismutase level in the testosterone plus H2O2 group were significantly greater than in the H2O2 group （P 〈 0.05）, and nitric oxide synthase and malondialdehyde levels were significantly less than in the H2O2 group （P〈 0.05）. CONCLUSION： Androgen partially reversed H2O2-induced neuronal damage and protected neurons.