ABSTRACT
ObjectiveTo explore the effect of Anmeidan （AMD） on the learning and memory ability of sleep-deprived rats and the mechanism. MethodA total of 50 SD rats were randomized into control group， model group， low-dose AMD group （4.55 g·kg-1·d-1）， high-dose AMD group （18.18 g·kg-1·d-1）， and estazolam group （0.09 mg·kg-1·d-1）. Insomnia was induced in rats with the self-made sleep deprivation box （21 days）. The learning and memory ability of rats was measured by Morris water maze. Immunofluorescence method was employed to detect the number of cells expressing N-myc downstream-regulated gene 2 （NDRG2） and glial fibrillary acidic protein （GFAP） in hippocampus of rats， real-time fluorescent quantitative polymerase chain reaction （Real-time PCR） to determine the mRNA expression of hippocampal NDRG2， glial glutamate transporter-1 （GLT-1）， and GluNR2A and GluNR2B N-methyl-D-aspartate （NMDA） receptor subunits， and Western blot to examine the protein expression of NDRG2 and GLT-1 in hippocampus. ResultCompared with control group， the model group showed increase in the latency to reach the platform and total swimming distance， significant decrease in the total distance moved in the target quadrant， time in target quadrant， and times of crossing the platform （P<0.01）， rise in the number of cells expressing NDRG2 and GFAP in the hippocampal CA1 region （P<0.01） and the mRNA level of NDRG2 and GluNR2B， reduction in the mRNA level of GLT-1 and GluNR2A， elevation in NDRG2 protein expression （P<0.01）， and decrease in GLT-1 protein expression （P<0.01）. In contrast to the model group， low-dose and high-dose AMD improved the learning and memory levels of sleep-deprived rats （P<0.01）， reduced the number of cells expressing NDRG2 and GFAP （P<0.01）， significantly decreased the mRNA expression of NDRG2 and GluNR2B， increased the mRNA expression of GLT-1 and GluNR2A， reduced NDRG2 protein level （P<0.05， P<0.01）， and raised GLT-1 protein level （P<0.01）. ConclusionAMD can improve the learning and memory ability of sleep-deprived rats. The mechanism is the likelihood that it regulates astrocyte activity， thereby affecting the neurotransmitter level and synaptic plasticity in the brain.
ABSTRACT
Objective:To explore the action mechanism of suppressing expression of mitogen- activated protein kinase 14（MAPK14）to alleviate glutamate excitatory toxicity and its neuronal protection effect.Methods:Lentivirus-mediated MAPK14 interference vector was synthetized by Shanghai Jikai Gene Chemical Technology Co.，Ltd. Astrocytes were obtained from SD rats 48 hours after birth，which were cultured in vitro and transfected by lentivirus-mediated transfection. According to the random number table，the cells were divided into three groups：（1）un-transfected group（normal group）with normal astrocytes and the cells were cultured in regular medium composed of Dulbecco's?modified Eagle's?medium（DMEM）；（2）negative control group with astrocytes transfected by MAPK14 no-loaded interference vector；（3）lentivirus transfected group with astrocytes transfected by MAPK14 interference vector. Seventy-two hours after transfection，astrocytes were co-cultured with neurons for 48 hours，and then they were cultured in a medium containing glutamate for 2 hours. The detection indexes included the optimal multiplicity of infection（MOI）value for astrocytes transfected by lentivirus vector，mRNA levels of MAPK14 and glial glutamate transporter 1（GLT-1）detected by rPCR 72 hours after transfection，protein levels of MAPK14 and GLT-1 detected by Western blot 72 hours after transfection，level of lactate dehydrogenase（LDH）and mortality of neurons measured by spectrophotometry and flow cytometry 2 hours after culturing in the medium with glutamate. Results:（1）The optimal MOI value for lentivirus transfecting astrocytes was 30，and astrocytes grew well after transfection.（2）Seventy-two after transfection，the mRNA level of MAPK14 in lentivirus transfected group（0.005 7±0.000 6）was significantly decreased as compared with un-transfected group（0.013 1±0.001 1）and negative control group（0.013 9±0.001 0）（ P<0.01），the mRNA level of GLT-1 in lentivirus transfected group（0.009 1±0.001 2）was not significantly changed as compared with un-transfected group（0.008 7±0.000 3）and negative control group（0.008 9±0.001 1）（ P>0.05）.（3）Seventy-two hours after transfection，the protein level of MAPK14 in lentivirus transfected group（0.29±0.04）was significantly decreased as compared with non-transfected group（0.61±0.05）and negative control group（0.63±0.01）（ P<0.01），the protein level of GLT-1 in lentivirus transfected group（0.73±0.06）was significantly increased as compared with un-transfected group（0.20±0.03）and negative control group（0.23±0.09）（ P<0.01）.（4）After astrocytes were co-cultured with neurons and subsequently cultured in the medium containing glutamate for 2 hours，the level of LDH in lentivirus transfected group［（109.67±2.40）U/L］was significantly lower than that in un-transfected group［（141.52±3.88）U/L］and negative control group［（141.29±3.61）U/L］（ P<0.01）. The mortality of neurons in lentivirus transfected group［（38.72±0.26）%］was significantly lower than that in un-transfected group［（52.94±1.36）%］and negative control group［（54.30±1.23）%］（ P<0.01）. Conclusions:The transfection with lentivirus-mediated MAPK14 interference vector can increase expression of GLT-1 in astrocytes to increase glutamate re-uptake and relieve the glutamate excitatory toxicity in neurons，which may provide a new experimental basis for future use of astrocyte gene regulation to alleviate neuronal injury caused by glutamate excitatory toxicity after traumatic brain injury.