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Objective:To study the effect of modified Xiao Chaihutang on the expressions of excitatory amino acid transporters（EAATs） and vesicle glutamate transporters（VGLUTs）in hippocampus of rats with chronic depression， in order to explore the anti-depressant mechanism of modified Xiao Chaihutang based on glutamate transport. Method:A total of 120 SD rats were randomly divided into normal group， model group， and low， middle and high-dose modified Xiaochaihutang groups （6.5， 13， 26 g·kg-1） and riluzole group， with 20 rats in each group．Except normal group， the depression model of rats was prepared through Chronic restraint stress（CRS）. The normal group and the model group were intragastrically （ig） given normal saline. The modified Xiao Chaihutang groups were intragastrically given corresponding herbal drugs （6.5， 13， 26 g·kg-1）， and the Riluzole group was given Riluzole 20 mg·kg-1 through intraoeritoneal injection for 21 days， once a day. Then the depressive behaviors of rats were observed by forced swimming test （FST） and tail suspension test （TST）. The level of glutamic acid （Glu） in rats hippocampus was determined by high performance liquid chromatography （HPLC）. The mRNA expressions of EAAT1， EAAT2 and EAAT3 in hippocampus were detected by Real-time fluorescence quantitative polymerase chain reaction （Real-time PCR）method. Western blot was used to detect the protein expressions of EAAT1， EAAT2， EAAT3， VGLUT1 and VGLUT2 in rat hippocampus tissue. Nissl staining was used to observe the morphology of hippocampal neurons in rats. Immunohistochemical（IHC）S-P method were used to detect the location expressions of EAAT1， EAAT2 and NeuN proteins in rat hippocampal CA1 region tissue. Result:The immobility times in FST and TST were increased significantly（P<0.01）， the mRNA and protein expressions of EAAT1，EAAT2，EAAT3 were decreased significantly （P<0.01）， and as well as the expressions of VGLUT1 and NeuN were decreased significantly（P<0.01）， while the level of Glutamate and the expression of VGLUT2 were increased significantly（P<0.01） in model group， compared with normal group. Compared with model group，the immobility times in FST and TST were decreased significantly（P<0.05， P<0.01）， mRNA and protein expressions of EAAT1，EAAT2，EAAT3 were increased significantly（P<0.01）， and expressions of VGLUT1 and NeuN were increased significantly（P<0.01）. However， the level of Glutamate and the expression of VGLUT2 were decreased significantly（P<0.01）， and the damage of hippocampal neurons in rats was mild in middle and high-dose modified Xiao Chaihutang groups. Conclusion:Modified Xiao Chaihutang has an anti-depressive effect. Its mechanism may be related to its up-regulation of expressions of EAAT1， EAAT2， EAAT3 genes and VGLUT1 protein in the hippocampus of depression model rats.
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Objective:To study the effect of modified Suanzaoren Tang on the expression of excitatory amino acids receptor（EAARs） in hippocampus of rats with chronic depression， and to explore the anti-depressant mechanism of modified Suanzaoren Tang based on excitatory amino acids receptor. Method:Sixty SD rats were randomly divided into normal group，model group，and low，middle and high-dose modified Suanzaoren Tang groups，and ketamine group，with 10 rats in each group．Except normal group，the depression model of rats was prepared by using chronic restraint stress（CRS）.The normal group and model group were intragastrically（ig） given normal saline．the modified Suanzaoren Tang groups were intragastrically given corresponding herbal drugs 6，12，24 g·kg-1， ketamine group group were given ketamine 0.015 g·kg-1 through intraoeritoneal injection，for 21 days，once a day．Then the depressive behaviors of rats were observed by Morris water maze and novelty feeding experiment.Western blot was used to detect the levels of DAR1，NMDAR2A，NMDAR2B，GluR1，mGluR1，CaMKⅡα and CaMKⅡβ protein expression in rat hippocampus tissue. Result:Compared with normal group，the time of novel ingestion and escape latencywere prolonged significantly（P<0.01）， and the time of space exploration was shortened significantly（P<0.01）.The levels of NMDAR1，NMDAR2A，NMDAR2B，mGluR1 and CaMKⅡβ expression were increased significantly（P<0.01），while the levels of GluR1 and CaMKⅡα expression were decreased significantly（P<0.01）in model group. Compared with model group，the time of novel ingestion and escape latency were shortened significantly （P<0.01）， and the time of space exploration was prolonged significantly（P<0.01）.The levels of NMDAR1，NMDAR2A，NMDAR2B，mGluR1 and CaMKⅡβ protein expression were decreased significantly（P<0.01），but the levels of GluR1 and CaMKⅡα expression were increased decreased significantly（P<0.01）in middle and high-dose modified Suanzaoren Tang groups. Conclusion:Modified Suanzaoren Tang can improve the behavior of chronic depression rats effectly. Its mechanism may be related with reduction the expression of NMDAR1，NMDAR2A，NMDAR2B，mGluR1 and CaMKⅡβ protein ，increase the expression of GluR1and CaMKⅡα protein.
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Objective To investigate the effects of ginkgo biloba extracts ( EGb761) on learning and memory and the protective effect on hippocampal neurons in rats with vascular dementia (VD). Meth-ods Ninety rats were randomly divided into sham-operated group,model group and EGb761-treated group, with 30 rats in each group. Rats in each group were examined at 15 days,1 month and 2 months,with 10 rats in each time point. VD model was established by bilateral carotid artery occlusion combinding with injection of sodium nitroprusside. Morris water maze test was used to detect the learning and memory function of rats. The expression of glial fibrillary acidic protein (GFAP) was observed by immunofluorescence. Western-blot was used to detect the protein expression of P-glycoprotein ( P-GP ), excitatory amino acid transporters 2 ( EAAT2),caspase-3 and cleaved caspase-3. RT-PCR was used to detect the mRNA expression of P-GP and EAAT2 in the hippocampus of rats in each group. Results Compared with sham-operated group,the escape latency (EL) was significantly prolonged at each time point in model group ( sham-operated group:15 days (15. 52±3. 23) s,1 month ( 14. 21 ± 2. 62) s,2 months ( 15. 37 ± 1. 66) s;model group:15 days ( 30. 35 ± 2. 30)s,1 month(40. 78± 3. 55) s, 2 months( 33. 88± 1. 47) s; all P<0. 01). The EL of EGb761-treated group was significantly shorter than that of the model group(EGb761-treated group:15 days(25. 69±2. 44)s, 1 month(20. 78±1. 72)s,2 months(18. 23±1. 67)s,all P<0. 01). Immunofluorescence showed that the ex-pression of GFAP in EGb761-treated group was lower than that of the model group (P<0. 01). Western blot showed that cleaved caspase-3 protein expression in EGb761-treated group at each time point was significant-ly lower than that in the model group (P<0. 01). Western-blot and RT-PCR results showed that the protein and mRNA expression of P-GP and EAAT2 in EGb761-treated group at 15 day and 1 month time points were significant increased than those in the model group (P<0. 01). At 2 month time point,which were lower than those in the model group (P<0. 01). Conclusion EGb761 can improve the learning and memory ability of VD rats,and regulate the protein and mRNA expression of P-GP and EAAT2 in hippocampus of VD rats at different time points (up-regulated in 1 month and down-regulated in 2 month),and down-regulate the ex-pression of cleaved caspase-3 and GFAP at different time points,thereby delaying the brain damage of VD rats and protecting neurons.
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In the central nervous system, gap junctions exist between neurons and glial cells. Among them, connexin 43 (Cx43) is one of the most abundant connexin proteins in the central nervous system,involved in the metabolic coupling of intercellular substance exchange and electrical coupling of electrical signaling. It plays an important role in regulating cell metabolism, homeostasis, and cell differentiation. After cerebral ischemia, the uncoupling of gap junctions and abnormal hemichannel activity cause a steady-state imbalance of the internal and external environment of the cells, eventually leading to brain tissue damage.Therefore, maintaining the normal function of Cx43 is essential for protecting brain tissue from neuronal damage induced by cerebral ischemia-reperfusion.
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Objective To investigate the effect of rhynchophylline on mRNA expression of excitatory amino acid transporter 2 (EAAT2 ) and N-methyl-D-aspartic acid receptor 2B (NR2B) after astrocyte oxygen-glucose deprivation. Methods The subcultured third generation astrocytes from the hippocampus were inoculated into 6-well plates, and they were divided into blank control group, hypoxia-ischemia group,low-dose rhynchophylline group (0. 02 mg/ml) and high-dose rhynchophylline group (0. 2 mg/ml) after the cells were attached to the wall and grew out protrusion. The total RNAs in each group were extracted.Real-time fluorescence quantitative polymerase chain reaction was used to detect the expression levels of EAAT2 and NR2B mRNA in astrocytes of each group. Results Compared with the blank control group, the expression levels of NR2B and EAAT2 mRNA in astrocytes of the ischemia-hypoxia group were significantly higher (all P < 0. 05 ). The expression levels of NR2B and EAAT2 mRNA in the low-dose rhynchophylline group were lower than those in ischemia-hypoxia group, but there was no significant difference. The expression levels of NR2B and EAAT2 mRNA in the high-dose rhynchophylline group were significantly lower than the ischemia-hypoxia group and the low-dose rhynchophylline group (all P < 0. 05).Conclusion The expression of EAAT2 and NR2B mRNA in astrocytes of hippocampus cultured in vitro was significantly increased after ischemia and hypoxia, and rhynchophylline intervention could significantly reduce its expression in a concentration dependent manner.
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Objective To evaluate the role of μ-δ heterodimer in down-regulation of the expression of excitatory amino acid transporter 3 (EAAT3) in hippocampi caused by reinstatement of morphine-induced conditioned place preference (CPP) in rats.Methods Thirty-two healthy clean-grade male Sprague-Dawley rats,weighing 200-240 g,were assigned into 4 groups (n =8 each) using a random number table method:control group (group C),extinction group (group E),reinstatement group (group R) and reinstatement plus interference plasmid group (group RI).The model of morphine-induced CPP was established,and extinction of CPP was gradually induced by stopping administration.A small dose of morphine 5 mg/kg was intraperitoneally injected again to induce CPP reinstatement,and dwell time around the medicine box was recorded.μ-δ heterodimer interference plasmid 5 μl was injected into the lateral cerebral ventricle after successful establishment of CPP model in group RI.The content of glutamate (Glu) in hippocampi was measured using high-performance liquid chromatography.The EAAT3 expression in hippocampal CA1 and CA3 regions was detected using Western blot.Results Compared with group C,no significant change was found in the dwell time around the medicine box or content of Glu in hippocampi (P＞0.05),and the expression of EAAT3 in hippocampal CA1 and CA3 regions was significantly up-regulated in group E,and the dwell time around the medicine box was significantly prolonged,the content of Glu in hippocampi was increased (P＜0.05),and no significant change was found in the expression of EAAT3 in hippocampal CA1 and CA3 regions in group R (P＞0.05).Compared with group E,the dwell time around the medicine box was significantly prolonged,the content of Glu in hippocampi was increased,and the expression of EAAT3 in hippocampal CA1 and CA3 regions was down-regulated in group R (P＜0.05).Compared with group R,the dwell time around the medicine box was significantly shortened,the content of Glu in hippocampi was decreased,and the expression of EAAT3 in hippocampal CA 1 and CA3 regions was upregulated in group RI (P＜0.05).Conclusion μ-δ heterodimer is involved in down-regulation of EAAT3 expression in the hippocampus caused by reinstatement of morphine-induced CPP in rats.
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OBJECTIVE Based on the methods of microdialysis,HPLC-MS/MS and gene chip tech-nology,the mechanism of Baicalin and Geniposide(BC/GP)against excitatory amino acid toxicity in ce-rebral ischemia was studied. This will provide guidance for the clinical application of BC/GP and the study of excitatory amino acid toxicity in cerebral ischemia.METHODS (1)Microdialysis technique and HPLC-MS/MS was performed to study the pharmacodynamics of BC/GP against cerebral ischemia. ①18 SD rats with body weight of(280±20)g were randomly divided into control group,treatment groups with BC/CP at low dose,medium dose and high dose(equal to the dosage of crude drugs for 30 mg·kg-1, 45 mg·kg-1and 60 mg·kg-1respectively).Rats in each group were given intragastric administration for seven days to establish cerebral ischemia model. Then, microdialysis probe was applied to collect cerebrospinal fluid from hippocampus before and after cerebral ischemia. ② First, we established the HPLC-MS/MS method for measuring drugs and excitatory amino acids.Then we detected the microdi-alysis samples and observed their changes in animals.(2)The mechanism of BC/GP against excitatory toxicity of cerebral ischemia were observed at gene level by chip technique. ① 16 SD rats with body weight of 240±20 g were randomly divided into sham group, model group, treatment group of BC(60 mg·kg-1),treatment group of GP(60 mg·kg-1)and treatment group of BC/GP(7:3)(60 mg·kg-1).Rats in eachgroup were given intragastric administration for seven days to establish cerebral ischemia model. Then the rats were sacrificed,and the hippocampus were rapidly harvested and stored at-80℃for further detection. ②After the quality inspection of the hippocampal,the qualified samples were subjected to detect the levels of neurotransmitter receptor gene in the ischemic of rats by gene chip technology.Finally,the results were analyzed by the method of Δ ΔCt.RESULTS (1)Only three compounds includ-ed GP,glutamic acid and aspartic acid were detected in microdialysis samples by HPLC-MS/MS.The concentration of GP increased and lasted for 120 min with a significant dose-dependent after cerebral ischemia.Compared with low dose group,the AUC(0-t),MRT(0-∞),Cmaxand t1/2zin high-dose group showed significant difference(P<0.01).Compared with the model group,the levels of glutamic acid and aspartic acid in the treatment groups decreased significantly,especially in the middle and high dose groups.(2) 89 genes in the neurotransmitter receptor gene signaling pathway were detected by gene chip technol-ogy. There were 22 genes with |Fold Regulation|>1.5 in the model group, compared with the sham group.Five of the 22 genes showed statistically significant differences,including Grin2c(2.9026),Chrna7 (-1.5877), and Tacr2 (-1.7695). Htr3a (-1.8172) and Grm6 (-2.3527). There were 5 genes with |Fold Regulation|>1.5 in the BC group, compared with the model group, Two of them exhibited statistically significant differences,including Brs3(1.797)and Grin2c(-1.7979).There were 14 genes with|Fold Reg-ulation|>1.5 in the GP group, compared with the model group. Three of them displayed statistically significant differences,including Hcrtr2 (-1.6584), Sctr (-3.8524) and Grin2c (-4.8408). Compared with model group, the genes of |Fold Regulation|>1.5 in BC/GP (7:3) group are 5, and only one of them showed a significant differences. CONCLUSION (1)After administration of BC and GP,GP can cross the blood-brain barrier and reduce the release of excitatory amino acids in the hippocampus. (2) BC/GP can inhibit the interaction between excitatory amino acids and excitatory amino acid receptors and attenuate the toxicity of excitatory amino acids by down-regulating the expression of glutamic acid receptor Grin2c gene.(3)BC/GP may exert their brain protection effect by reducing the release of excit-atory amino acids and inhibiting the expression of excitatory amino acid receptors.
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Objective To evaluate the role of excitatory amino acid transporter 2 ( EAAT2) in can-nabinoid receptor 2 ( CB2 receptor) activation-induced attenuation of microglial injury caused by glutamate. Methods N9 microglial cells were divided into 4 groups ( n=26 each) using a random number table meth-od: control group ( group Con) , glutamate group ( group Glu) , CB2 receptor agonist AM1241 plus gluta-mate group (group AM1241+Glu) and AM1241 plus EAAT inhibitor TBOA plus glutamate group (group AM1241+TBOA+Glu) . The cells were routinely cultured for 30 h in group Con. In group Glu, the cells were routinely cultured for 6 h, and then were incubated for 24 h in the culture medium containing gluta-mate 10 mmol∕L. In group AM1241+Glu, the cells were incubated for 4 h in the culture medium containing AM12412 μmol∕L, and then were routinely cultured for 2 h, and then were incubated for 24 h in the cul-ture medium containing glutamate 10 mmol∕L. In group AM1241+TBOA+Glu, the cells were incubated for 4 h in the culture medium containing AM12412 μmol∕L and TBOA 100 μmol∕L, and then were routinely cultured for 2 h, and then were incubated for 24 h in the culture medium containing glutamate 10 mmol∕L. The cell viability was measured by MTT assay, the activity of lactic dehydrogenase ( LDH) in supernatant was determined using colorimetric method, and the expression of EAAT2 was determined by Western blot. Results Compared with group Con, the cell viability was significantly decreased and LDH activity was in-creased in Glu, AM1241+Glu and AM1241+TBOA+Glu groups, and the expression of EAAT2 was signifi-cantly up-regulated in Glu and AM1241+Glu groups ( P<0. 05) . Compared with group Glu, the cell viabil-ity was significantly increased, LDH activity was decreased, and the expression of EAAT2 was up-regulated in group AM1241+Glu ( P<0. 05) , and no significant change was found in the parameters mentioned above in group AM1241+TBOA+Glu ( P>0. 05) . Compared with group AM1241+Glu, the cell viability was sig-nificantly decreased, LDH activity was increased, and the expression of EAAT2 was down-regulated in group AM1241+TBOA+Glu ( P<0. 05) . Conclusion The mechanism by which the activation of CB2 re-ceptor attenuates microglial injury caused by glutamate is related to up-regulating the expression of EAAT2.
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Background Meningothelial cells (MECs) occupy the predominant cell component of barrier between optic nerve and the cerebral spinal fluid,and any change of cerebral fluid components probably affects the MECs function and further impairs the optic nerve.Objective This study was designed to investigate the influence of glutamate,a potentially excitotoxic amino acid,to the functional changes of MECs and provide a theoretical evidence for clarifying the mechanism of optic nerve disorders.Methods Human MECs strains were cultured in vitro and prepared into cell suspension.The cells were inoculated to 96-well plates with the densities of 1 × 104/we11.The glutamate of 100,200,400,600,800 and 1 000 μmol/L was added into medium for 12,24,36,48 and 72 hours,respectively,and the cultured cells without glutamate were used as normal control group.MTS assay was employed to measure the proliferative rate (absorbency) of the cells.The regularly cultured MECs were divided into 600 μmol/L glutamate-treated group and normal control group and the cells were treated for 12 and 24 hours respectively,and the expression of superoxide dismutase (SOD) mRNA and heat shock protein 90 (HSP90) mRNA in the cells was detected by real-time PCR;the level of total anti-oxidative capacity (T-AOC) of the cells was processed by enzyme linked immunosorbent assay (ELISA),and the reactive oxygen species (ROS) production was determined by DCFH-DA probe.Results Cultured MECs grew well and formed 80％ confluence after 72 hours culture.The proliferative rate of the cells were gradually decreased with the increase of glutamate dose and the lapse of affected time,with significant differences among different concentrations of glutamate and various time points (F tration =52.501,P＜0.001;Ftime =8.505,P＜0.001).The relative expression level of SOD mRNA was significantly reduced in the glutamate-treated group compared with the normal control group in both 24 hours and 48 hours after culture (t =20.278,t =16.724,both at P＜0.001),and the expression of HSP90 mRNA in the cells was significantly lower in the glutamate-treated group than that in the normal control group in 24 hours after culture (t =5.065,P =0.002).No significant difference was found in T-AOC activity between glutamate-treated group and normal control group in 24 hours after culture ([30.835±2.094] nmol/(min · L) vs.[32.873±2.317] nmol/(min · L)) (t=1.599,P =1.414).In 48 hours after culture,T-AOC activity was (29.561 ± 1.831) nmol/(min · L) in the glutamate-treated group,which was significantly lower in comparison with normal control group (33.680±2.039) nmol/(min · L)(t =3.682,P =0.004).Fluorescence staining showed that the intensity of green fluorescence of ROS in MECs in the normal control group was weaker than that in the glutamate-treated group under the immunofluorescense microscope.The ROS level was 48.110± 1.712 and 40.982± 1.853 at 24 hours and 48 hours in the glutamate-treated cells,and which was significantly elevated in comparison with 36.608± 1.009 and 37.153 ± 1.424 in the normal control group (t=14.178,P＜0.001;t=4.012,P=0.002).Conclusions Glutamate inhibits the proliferation of MECs in vitro,and excitatory toxicity of glutamate on MECs probably is associated with oxidative stress response.
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Objective To make clear glial acidic protein and excitatory amino acid levels in the early expression of neonatal brain injury and the mechanism of brain injury,and the value of early diagnosis and prediction of serum glial fiber acidic protein and excitatory amino acid in neonatal cerebral palsy.Methods This study chose high-risk infants with cerebral palsy as the research object,the concentration of excitatory amino acid and enzyme linked immunosorbent assay were detected by reverse phase high performance liquid chromatography,followed up for 12 months,the occurrence of cerebral palsy was analyzed statistically.Results Compared with the normal group of glial fibrillary acidic protein,glutamic acid and aspartic acid levels,three indexes of children with cerebral palsy were higher than normal group(glial fibrillary acidic protein:(119.46±43.68),(119.46±43.68),(62.57±35.31),(134.02±32.79) ng/L;glutamic acid:(7.52±3.94),(6.49±2.88),(8.15 ±2.03),(1.72±0.59) μmol/L;aspartic acid:(3.81±1.09),(4.23±1.91),(3.67±2.14),(1.35±0.71) μmol/L;F=4.117,4.117,4.117;P0.05).The levels of serum glial fiber acidic protein,glutamic acid and aspartate in children with cerebral palsy were higher than those in the normal group,comparison between spastic group,athetotic group and mixed group(F=5.032,6.004,3.792),there was no significant difference in the levels of glial acidic protein,glutamic acid and aspartate(P>0.05).Conclusion The concentration of excitatory amino acids and acidic protein in the serum of the patients with high risk of cerebral palsy has some value,the concentration of serum excitatory amino acid and the concentration of glial fiber acidic protein are correlated with the degree of brain injury and the time in children with cerebral palsy.
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OBJECTIVE: To investigate the effects of prolonged exposure to isoflurane on the expression of glial fibrillary acidic protein (GFAP) and excitatory amino acid transporter-2 (EAAT2) in cortex of frontal lobe and hippocampus of neonatal rats. METHODS: Forty Wistar rats at postnatal day 7 were randomly divided into isoflurane group and control group according to the random number table method (n=20). Isoflurane group were exposed to 1.1% isoflurane (equivalent to 0.5 MAC for neonatal rats) for 6 h, the others were exposed to the gas mixture of 30% of the oxygen and nitrogen for 6 h in the control group. Five neonatal rats were sacrificed 12, 24 h, 3 and 7 d after exposure in each group. The brain were frozen and sliced, brain sections were double-stained with GFAP and EAAT2 markers. The fluorescence intensity of GFAP and EAAT2 double-labeled immunofluorescence was quantified in cortex of frontal lobe and hippocampus at 12, 24 h, 3 and 7 d after exposure by the Image J programme. RESULTS: Compared with the control group, the immunofluorescence intensity of GFAP in cortex of frontal lobe after exposure 12, 24 h in isoflurane group was significantly decreased(P < 0.01), whereas there was no significant difference after exposure 3, 7 d. The immunofluorescence intensity of GFAP in hippocampus after exposure 12, 24 h and 3 d in isoflurane group decreased compared with control group(P < 0.01), except 7 d after exposure. Double-labeled immunofluorescence showed lowered expression of GFAP and EAAT2 co-stained region in cortex of frontal lobe and hippocampus at 12, 24 h, 3 and 7 d after exposure in isoflurane group when compared with control group(P < 0.01). CONCLUSION: The 1.1% isoflurane prolonged exposure transiently reduces the expression of GFAP in the cortex and hippocampus, and delays the development of cytoskeleton. Whereas inhibiting the expression EAAT2 of astrocytes is prolonged, that may be one of the mechanisms for isoflurane-induced neurotoxicity.
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Objective To evaluate the effects of GLYX-13 on cognitive function after long-time isoflurane anesthesia in mice. Methods A total of 192 healthy male C57∕B6J mice, aged 8 weeks, weig-hing 22-25 g, were divided into 4 groups(n=48 each)using a random number table: control group (group C), isoflurane anesthesia group(group I), GLYX-13 group(group G), and isoflurane anesthesia plus GLYX-13 group(group IG). The animals were exposed to 15% isoflurane for 6 h in I and IG groups. GLYX-13 1 mg∕kg was injected via the caudal vein at 2 h before anesthesia in G and IG groups. Novel ob-ject recognition test and contextual fear conditioning test were performed on 1st, 3rd and 7th days after an-esthesia. The expression of 2B subunits-containing NMDA receptor(NR2B)and cyclic adenosine mono-phosphate response element-binding protein(CREB)mRNA in the hippocampus was detected by quantita-tive real-time polymerase chain reaction after the end of behavioral tests on 1st, 3rd and 7th days after anes-thesia. Results Compared with group C, the percentage of time spent in exploring a novel object, dis-crimination index and percentage of freezing time were significantly decreased, and the expression of NR2B and CREB mRNA in the hippocampus was down-regulated in group I(P <005). Compared with group I, the percentage of time spent in exploring a novel object, discrimination index and percentage of freezing time were significantly increased, and the expression of NR2B and CREB mRNA in the hippocampus was up-regulated in group IG(P <005). Conclusion GLYX-13 can significantly improve the cognitive func-tion after long-time isoflurane anesthesia in mice.
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Objective To investigate the effect of phenolic alkaloids from Menispermum dauricum( PAMd)on the mRNA expression of the glutamate transporter EAAC1 in hippocampal neurons of rats subjected to focal cerebral ischemia and to elucidate its neuroprotective mechanisms. Methods A total of 42 Sprague Dawley(SD)rats were randomly divided into three groups:sham group,model control group,and PAMd(10 mg·kg-1 ,i.g)group(n = 14 each).The focal cerebral ischemia model of rat was induced by the middle cerebral artery occlusion( MCAO). The 2,3,5-triphenyltetrazolium chloride( TTC) staining was applied to measure the cerebral infarct size and the reverse transcriptase-polymerase chain reaction(RT-PCR)assay to detect EAAC1 mRNA expression in hippocampal neurons. Results After 24 h ischemia,the cerebral infarct volumes were (0.0±0.0)%,(35.3±2.9)% and(21.3±3.8)% in sham group,model control group and PAMd group,respectively(P<0.05). The relative expression levels of EAAC1 mRNA were 0.97±0.04,2.46±0.13,and 1.91±0.15 in the three groups,respectively (P<0. 05). Conclusion PAMd may protect against cerebral ischemia by up-regulating EAAC1 mRNA expression and alleviating the excitotoxicity of glutamic acid.
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Glutamate is an essential excitatory neurotransmitter which regulates brain functions.An increase in extracellular glutamate could excessively activate ionotropic glutamate receptors,initiate calcium overload,and lead to cell death after cerebral ischemia.Glutamate transporter-1 (GLT-1) is one of the major glutamate transporters expressed predominantly in astrocytes.Astrocytes also express the enzyme glutamine synthetase (GS) which converts the glutamate to glutamine; the latter is then 'recycled' into neurons.Pretreatment with ceftriaxone (CEF),ischemia and intermittent hypobaric hypoxia could lead to neuroprotection by increasing the expression of GLT-1 and regulating the activity of glutamate transporter in brain.
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Adolescentes humanos frequentemente associam o fumo do tabaco ao consumo de bebidas alcoólicas. A despeito desta associação, pouco se sabe sobre a neurobiologia básica da coexposição no cérebro adolescente. No presente estudo, avaliamos os efeitos da exposição, que ocorreu do 30º ao 45º dia de vida pós natal (PN30 a PN45), à nicotina e/ou ao etanol durante a adolescência (PN38-45) e da retirada (PN50-57) na memória visuoespacial através do Labirinto Aquático de Morris (LAM: 6 sessões + 1 prova, 3 tentativas/sessão, latência = 2 min), em 4 grupos de camundongos Suíços machos e fêmeas: (1) exposição concomitante à NIC [solução de nicotina free base (50 μg/ml) em sacarina a 2% para beber] e ETOH [solução de etanol (25%, 2 g/kg) injetada i.p. em dias alternados]; (2) exposição à NIC; (3) exposição ao ETOH; (4) veículo (VEH). Uma vez que os resultados comportamentais podem sofrer a interferência de alterações motoras, avaliamos (a) a atividade locomotora no Teste de Campo Aberto (sessão única, 5 min) e (b) a coordenação e o equilíbrio no Teste de Locomoção Forçada sobre Cilindro Giratório (5 tentativas, latência = 2 min). Para os efeitos da exposição à NIC e/ou ao ETOH na eficiência do transporte de aminoácidos excitatórios, avaliamos a captação de [3H] D-aspartato no hipocampo. A expressão do transportador glial GLAST/EAAT1 foi avaliada por Western-blot. Durante a exposição, animais ETOH e NIC+ETOH apresentaram déficits de memória nas sessões de teste e de prova no LAM enquanto, na retirada, os grupos NIC e NIC+ETOH apresentaram prejuízos na retenção. Não houve diferenças significativas entre os grupos de tratamento em nenhum dos parâmetros testados em ambos os testes motores, tanto na exposição quanto na abstinência. Os grupos NIC, ETOH e NIC+ETOH tiveram uma diminuição significativa na captação de [3H] D-aspartato ao final do período de exposição, com uma normalização da atividade dos EAATs na retirada das drogas...
Human adolescents frequently associate tobacco smoke and alcoholic drinks. Despite this association, little is known about the basic neurobiology of co-exposure in the adolescent brain. In the present study, we assessed the effects of nicotine and/or ethanol exposure (postnatal days 30 to 45: PN30-45) during adolescence (PN38-45) and withdrawal (PN50-57) on visuospacial memory through the Morris Water Maze (MWM: 6 sessions + 1 probe, 3 trials/session, latency = 2 min), in four groups of male and female Swiss mice: (1) Concomitant NIC [nicotine free base solution (50µg/ml) in 2% saccharin to drink] and ETOH [ethanol solution (25%, 2g/kg) i.p. injected every other day] exposure; (2) NIC exposure; (3) ETOH exposure; (4) Vehicle (VEH). Once behavioral results can be affected by motor disorders, we assessed (a) locomotor activity through the Open field Test (one session, 5 min) and (b) coordination and balance through the ROTAROD Test (5 trials, latency = 2 min). To investigate the effects of NIC and/or ETOH exposure on the efficiency on excitatory amino acid transport, we assessed the [3H] D-aspartate uptake in mice hippocampus. The GLAST/EAAT1, a glial transporter, was assessed by Western-blot technique. During exposure, ETOH and NIC+ETOH animals showed deficits on memory through the session and probe trial in WMW while, during withdrawal, NIC and NIC+ETOH groups showed impairments on retention. There were no significant differences between the experimental groups in any parameters assessed in both motor tests, either during exposure and withdrawal. There was a significant decrease in the [3H] D-aspartate for NIC, ETOH and NIC+ETOH groups in the end of exposure, turning to the normal levels of EAATs activity during withdrawal...
Subject(s)
Animals , Adolescent , Rats , Glutamic Acid/analysis , Ethanol/adverse effects , Memory , Nicotine/adverse effects , Alcohol Drinking , Alcohol-Related Disorders , Adolescent Behavior , Ethanol/pharmacology , Ethanol/toxicity , Memory/physiology , Nicotine/pharmacology , Nicotine/toxicity , Tobacco Use DisorderABSTRACT
BACKGROUND: Propofol (2, 6-diisopropylphenol) has been known to have neuroprotective effects. Excitatory amino acid transporter 4 (EAAT4) is a glutamate transporter predominantly expressed in the cerebellar Purkinje cells, which is vulnerable to ischemic injury. Thus, we hypothesized that propofol reverses reduced EAAT4 activity which was induced by oxidative stress and investigated the effects of propofol on EAAT4 under oxidative stress induced by tert-butyl hydroperoside (t-BHP). METHODS: EAAT4 was expressed in Xenopus oocytes by injection of its mRNA. By using two-electrode voltage clamping, membrane currents were recorded before, during, and after application of L-aspartate (3 microM) in the presence or absence of t-BHP and propofol. RESULTS: L-aspartate induced an inward current in EAAT4 expressing oocytes. Exposure of these oocytes to t-BHP (1-20 mM) for 10 min dose-dependently decreased EAAT4 activity (1 +/- 0.01 microC for control; 0.88 +/- 0.05 microC for 1 mM; 0.83 +/- 0.03 microC for 2mM; 0.65 +/- 0.04 microC for 3 mM; 0.51 +/- 0.07 microC for 5 mM; 0.45 +/- 0.03 f microC for 10 mM and 0.24 +/- 0.06 microC for 20 mM). IC50 for t-BTH was 6.05 mM and further study was performed with 10 mM t-BTH. Propofol (3-10 microM) dose-dependently reversed this t-BHP-attenuated EAAT4 activity. CONCLUSIONS: Oxidative stress by t-BHP decreased EAAT4 activity and 3-10 microM propofol restored oxidative stress-reduced EAAT4 activity.
Subject(s)
Amino Acid Transport System X-AG , Aspartic Acid , Constriction , Excitatory Amino Acid Transporter 4 , Glutamic Acid , Inhibitory Concentration 50 , Membranes , Neuroprotective Agents , Oocytes , Oxidative Stress , Propofol , Purkinje Cells , RNA, Messenger , XenopusABSTRACT
Objective To explore the role of excitatory amino acid carrier 1 (EAAC1)in dorsal root ganglion (DRG) in the mechanism of developing morphine tolerance. Methods Thirty male SD rats were implanted intrathecal catheters and randomized into 6 groups with 5 rats each. The rats of 4 groups were made into the model of adjuvant-induced arthritis in the left hind limb and were administered intrathecally, morphine 10 μg(group M_(10)), morphine 20μg(group M_(20)), morphine 20 μg plus naloxone 10 μg(group MN) ,or saline(group C) respectively. The other 2 groups without were administered intrathecally saline (group C_0) or morphine 20 μg (group M0). The drugs were administered twice daily for 7 days. Mechanical withdrawl threshold(MWT) of the left hind limb was examined to evaluate the behavior. Immunohistochemistry was used to detect the expression of EAAC1 in the left L_(3-4) and L_(4-5) DRG. Results Morphine tolerance was formmed stably in the arthritis rats of group M_(10) and group M_(20) after administering morphine for 7 days. The expression of EAAC1 in DRG was downregulated. Conclusion DRG EAAC1 may be involved in the mechanism of developing morphine tolerance in rats with inflammatory pain.
ABSTRACT
Objective To investigate the change in the expression of excitatory amino acid transporter 3 (EAAT3) in the spinal cord neurons in a rat model of chronic morphine tolerance. Methods Forty-five male SD rats were randomly divided into 5 groups ( n = 9 each) : group I sham operation (group S); group II normal saline (group NS); group Ⅰ morphine (group M); group Ⅳ ketamine (group K) and groupV M + K. In group II - V a catheter was placed in the subarachnoid space at L_(3-5) interspace. The animals were observed for 3 days. The animals with motor or sensory paralysis of the hindlimbs were excluded. NS 40 μl,morphine 20 μg, ketamine 30μg,morphine 20μg + ketamine 30μg were injected via intrathecal catheter twice a day for 7 consecutive days. 50% paw withdrawal threshold and latency (PWT, PWL) of the hindpaw to radiant heat were measured before (T_0, baseline) , on day 1, 3, 5, 7 of (T_(1-4)) and 1 day after (T_5 ) IT drug administration. The rats were sacrificed after last pain threshold measurement. The expression of EAAT3 protein in the spinal cord was determined by Western blotting and immuno-histochemistry. Results The sensitivity of the hindpaw to noxious heat stimulation was significantly decreased during (T_(1,2)) and increased after IT administration (T_(4,5)) in group M and was significantly decreased during and after FT administration (T_(1-5)) in group M + K as compared with the baseline values at T_0 and group S and was significant lower in group M + K than in group M. The expression of EAAT3 protein in the spinal cord was significantly decreased in group M and M + K as compared with group S and was significantly lower in group M than in group M + K. Conclusion The down-regulation of the expression of EAAT3 in the spinal dorsal horn neurons is involved in the development of chronic morphine tolerance and the expression of EAAT3 is down-regulated by morphine partly through the activation of NMDA receptor.
ABSTRACT
Cascade in cerebral ischemic injury may cause cholinergic dysfunction,inflammation and oxidative stress. It plays an important role in the pathological processes of vascular dementia. A large amount of basic research has confirmed that cholinesterase inhibitor and N-methyl-d-aspartate receptor inhibitor may improve cognitive function in patients with vascular dementia. However, the efficacy of these drugs has been confirmed in only a part of the patients, and their safety and efficiency have not achieved the expected results. Thus, it needs further study and exploration.
ABSTRACT
BACKGROUND: Remifentanil has gained wide clinical acceptance during anesthesia due to its short context-sensitive half time and organ-independent metabolism. However, its mechanism as an anesthetic remains unclear. Glutamate transporters may be important targets for anesthetic action in the central nervous system, and we tested whether remifentanil affected the activity of the primary neuronal glutamate transporter, EAAC1 (excitatory amino acid carrier 1). METHODS: EAAC1 was expressed in Xenopus oocytes by mRNA injection. By using two-electrode voltage clamping, membrane currents were recorded before, during, and after application of L-glutamate (30microM) in the presence or absence of remifentanil. Oocytes were exposed to a protein kinase C (PKC) activator and inhibitor to study the role of PKC on EAAC1 activity. RESULTS: L-Glutamate induced an inward current in EAAC1-expressing oocytes. This response increased in a bell-shaped manner in the presence of 0.1microM to 1 mM remifentanil. Remifentanil significantly increased Vmax (3.1 +/- 0.2microC for controls vs. 4.9 +/- 0.3 microC for remifentanil treatment; n = 12-15; P < 0.05). However, remifentanil did not significantly change Km. Treatment of the oocytes with phorbol-12-myristate-13-acetate (PMA), a PKC activator, caused a significant increase in transporter current (1.00 +/- 0.03 to 1.35 +/- 0.03microC; P < 0.05). Oocytes pretreated with the PKC inhibitor alone (staurosporine) abolished remifentanilenhanced EAAC1 activity. CONCLUSIONS: Our data suggests that remifentanil enhances EAAC1 activity and that PKC is involved in mediating this effect.