The purpose of this study was to investigate the effect of glutamate and its ionotropic receptor agonists on the response to acute hypoxia in rat carotid body in vitro. Briefly, after SD rats were anesthetized and decapitated, the bilateral carotid bifurcations were rapidly isolated. Then bifurcation was placed into a recording chamber perfused with 95% O₂-5% CO₂ saturated Kreb's solution. The carotid body-sinus nerve complex was dissected, and the carotid sinus nerve discharge was recorded using a suction electrode. To detect the response of carotid body to acute hypoxia, the chamber was perfused with 5% O₂-5% CO₂-90% N₂ saturated Kreb's solution for a period of 100 s at an interval of 15 min. To observe the effect of glutamate, ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor agonist AMPA or N-methyl-D-aspartate (NMDA) receptor agonist NMDA on the response to acute hypoxia in rat carotid body, the chamber was perfused with 5% O₂-5% CO₂-90% N₂ saturated Kreb's solution containing the corresponding reagent. The results showed that glutamate (20 μmol/L), AMPA (5 μmol/L) or NMDA (10 μmol/L) inhibited the acute hypoxia-induced enhancement of carotid sinus nerve activity, and these inhibitory effects were dose-dependent. In summary, the activation of glutamate ionotropic receptors appears to exert an inhibitory effect on the response to acute hypoxia in carotid body of rats.
Rats ; Animals ; Glutamic Acid/pharmacology* ; alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid/pharmacology* ; N-Methylaspartate/pharmacology* ; Carotid Body ; Rats, Sprague-Dawley ; Carbon Dioxide ; Receptors, N-Methyl-D-Aspartate ; Receptors, AMPA ; Hypoxia

This study investigated the potential mechanism of Cordyceps militaris(CM) against non-small cell lung cancer(NSCLC) based on serum untargeted metabolomics. Specifically, Balb/c nude mice were used to generate the human lung cancer A549 xenograft mouse model. The tumor volume, tumor weight, and tumor inhibition rate in mice in the model, cisplatin, Cordyceps(low-, medium-, and high-dose), and CM(low-, medium-, and high-dose) groups were compared to evaluate the influence of CM on lung cancer. Gas chromatography-mass spectrometry(GC-MS) was used for the analysis of mouse serum, SIMCA 13.0 for the compa-rison of metabolic profiles, and MetaboAnalyst 5.0 for the analysis of metabolic pathways. According to the pharmacodynamic data, the tumor volume and tumor weight of mice in high-dose CM group and cisplatin group decreased as compared with those in the model group(P<0.05 or P<0.01). The results of serum metabolomics showed that the metabolic profiles of the model group were significantly different from those of the high-dose CM group, and the content of endogenous metabolites was adjusted to different degrees. A total of 42 differential metabolites and 7 differential metabolic pathways were identified. In conclusion, CM could significantly inhibit the tumor growth of lung cancer xenograft mice. The mechanism is the likelihood that it influences the aminoacyl-tRNA biosynthesis, the metabolism of D-glutamine and D-glutamate, metabolism of alanine, aspartate, and glutamate, metabolism of glyoxylate and dicarboxylic acid, biosynthesis of phenylalanine, tyrosine, and tryptophan, arginine biosynthesis as well as nitrogen metabolism. This study elucidated the underlying mechanism of CM against NSCLC from the point of metabolites. The results would lay a foundation for the anticancer research and clinical application of CM.
Alanine/metabolism* ; Animals ; Arginine/metabolism* ; Aspartic Acid ; Carcinoma, Non-Small-Cell Lung/drug therapy* ; Cisplatin/pharmacology* ; Cordyceps ; Glutamic Acid ; Glutamine ; Glyoxylates/metabolism* ; Humans ; Lung Neoplasms/drug therapy* ; Metabolomics/methods* ; Mice ; Mice, Nude ; Nitrogen/metabolism* ; Phenylalanine/metabolism* ; RNA, Transfer/metabolism* ; Tryptophan/metabolism* ; Tyrosine/metabolism*

OBJECTIVETo investigate the protective effects of dexmedetomidine (Dex) against glutamate-induced cytotoxicity in PC12 cells and its mechanism.

METHODSPC12 cells were treated with varying concentrations of dexmedetomidine 1 h before exposure to a high concentration of glutamate. The cell viability was measured by MTT assay, and LDH release, MDA content and SOD activity were measured. The level of ROS was tested by DCFH-DA staining and flow cytometry. The level of intracellular Cawas detected by Fluo-8 staining and flow cytometry, and the mitochondrial membrane potential (MMP) was determined with JC-1 staining and flow cytometry.

RESULTSWithin the concentration range of 0.01 to 100 µmol/L, Dex dose-dependently protected PC12 cells against glutamate-induced cytotoxicity. Treatment with 100 µmol/L Dex significantly increased the cell viability to (86.6∓2.2)% of that of the control cells (P<0.01) and decreased LDH release to 1.4∓0.1 folds of the control level (P<0.01). In PC12 cells exposed to glutamate, Dex pretreatment significantly reduced MDA content (P<0.01), enhanced SOD activity (P<0.01), inhibited ROS overproduction (P<0.01), reduced intracellular Calevel (P<0.01) and maintained a stable MMP (P<0.01).

CONCLUSIONDexmedetomidine can protect PC12 cells against glutamate-induced injury possibly in relation with its anti-oxidative activity, inhibitory effect on intracellular calcium overload and protective effect of the mitochondria.

Animals ; Apoptosis ; Calcium ; metabolism ; Cell Survival ; drug effects ; Dexmedetomidine ; pharmacology ; Glutamic Acid ; adverse effects ; Membrane Potential, Mitochondrial ; Mitochondria ; drug effects ; metabolism ; PC12 Cells ; Rats ; Reactive Oxygen Species ; metabolism

To investigate the neuroprotective of ligustilide (LIG) against glutamate-induced apoptosis of PC12 cells, cell viability were examined by MTT assay. Flow cytometry was applied to assay cell apoptosis rate. Intracellular calcium concentration was measured by using fluorescent dye Fluo-3/AM. Cytochrome C (Cyt C), Caspase-3, Bax and Bcl-2 protein expression were assayed by western blot. The results showed that glutamate is cytotoxic with an inhibitory concentration 50 (ID50) of 15 mmol · L(-1). Pretreatment with LIG (1, 5, 15 μmol · L(-1)) significantly improved cell viability. The apoptosis rate in glutamate-induced PC12 cells was 13.39%, and decreased in the presence of LIG (1, 5, 15 μmol · L(-1)) by 9.06%, 6.48%, 3.82%, separately. Extracellular accumulation of Ca2+ induced by glutamate were significantly reduced by LIG. The results of western blot manifested that pretreatment LIG could decrease the release of Cyt C from mitochondria, down-regulate Caspase-3 protein expression and up-regulate Bcl-2/Bax ratio, thereby protects PC12 cells from apoptosis. In summary, LIG had protective effect on glutamate-induced apoptosis in PC12 cells through attenuating the increase in intracellular Ca2+ concentration, and inhibiting the release of Cyt C from mitochondria to cytoplasm.
4-Butyrolactone ; analogs & derivatives ; pharmacology ; Aniline Compounds ; Animals ; Apoptosis ; drug effects ; Apoptosis Regulatory Proteins ; Calcium ; metabolism ; Caspase 3 ; metabolism ; Cell Survival ; Cytochromes c ; metabolism ; Glutamic Acid ; adverse effects ; Mitochondria ; metabolism ; PC12 Cells ; drug effects ; Proto-Oncogene Proteins c-bcl-2 ; metabolism ; Rats ; Xanthenes ; bcl-2-Associated X Protein ; metabolism

OBJECTIVETo explore the possible neurophysiologic mechanisms of propofol and N-methyl-D- aspartate (NMDA) receptor antagonist against learning-memory impairment of depressed rats without olfactory bulbs.

METHODSModels of depressed rats without olfactory bulbs were established. For the factorial design in analysis of variance, two intervention factors were included: electroconvulsive shock groups (with and without a course of electroconvulsive shock) and drug intervention groups [intraperotoneal (ip) injection of saline, NMDA receptor antagonist MK-801 and propofol. A total of 60 adult depressed rats without olfactory bulbs were randomly divided into 6 experimental groups (n=10 per group): ip injection of 5 ml saline; ip injection of 5 ml of 10 mg/kg MK-801; ip injection of 5 ml of 10 mg/kg MK-801 and a course of electroconvulsive shock; ip injection of 5 ml of 200 mg/kg propofol; ip injection of 5 ml of 200 mg/kg propofol and a course of electroconvulsive shock; and ip injection of 5 ml saline and a course of electroconvulsive shock. The learning-memory abilities of the rats was evaluated by the Morris water maze test. The content of glutamic acid in the hippocampus was detected by high-performance liquid chromatography. The expressions of p-AT8Ser202 in the hippocampus were determined by Western blot analysis.

RESULTSPropofol, MK-801 or electroconvulsive shock alone induced learning-memory impairment in depressed rats, as proven by extended evasive latency time and shortened space probe time. Glutamic acid content in the hippocampus of depressed rats was significantly up-regulated by electroconvulsive shock and down-regulated by propofol, but MK-801 had no significant effect on glutamic acid content. Levels of phosphorylated Tau protein p-AT8Ser202 in the hippocampus was up-regulated by electroconvulsive shock but was reduced by propofol and MK-801 alone. Propofol prevented learning-memory impairment and reduced glutamic acid content and p-AT8Ser202 levels induced by electroconvulsive shock.

CONCLUSIONElectroconvulsive shock might reduce learning-memory impairment caused by protein Tau hyperphosphorylation in depressed rats by down-regulating glutamate content.

Animals ; Depression ; psychology ; Dizocilpine Maleate ; pharmacology ; Electroshock ; Glutamic Acid ; analysis ; Learning Disorders ; prevention & control ; Male ; Memory Disorders ; prevention & control ; Phosphorylation ; Propofol ; pharmacology ; Rats ; Rats, Sprague-Dawley ; tau Proteins ; metabolism

The present study was designed to investigate the inhibitory effects of intravenous general anesthetic propofol (0.1-3.0 mmol/L) on excitatory synaptic transmission in supraoptic nucleus (SON) neurons of rats, and to explore the underlying mechanisms by using intracellular recording technique and hypothalamic slice preparation. It was observed that stimulation of the dorsolateral region of SON could elicit the postsynaptic potentials (PSPs) in SON neurons. Of the 8 tested SON neurons, the PSPs of 7 (88%, 7/8) neurons were decreased by propofol in a concentration-dependent manner, in terms of the PSPs' amplitude (P < 0.01), area under curve, duration, half-width and 10%-90% decay time (P < 0.05). The PSPs were completely and reversibly abolished by 1.0 mmol/L propofol at 2 out of 7 tested cells. The depolarization responses induced by pressure ejection of exogenous glutamate were reversibly and concentration-dependently decreased by bath application of propofol. The PSPs and glutamate-induced responses recorded simultaneously were reversibly and concentration-dependently decreased by propofol, but 0.3 mmol/L propofol only abolished PSPs. The excitatory postsynaptic potentials (EPSPs) of 7 cells increased in the condition of picrotoxin (30 µmol/L, a GABA(A) receptor antagonist) pretreatment. On this basis, the inhibitory effects of propofol on EPSPs were decreased. These data indicate that the presynaptic and postsynaptic mechanisms may be both involved in the inhibitory effects of propofol on excitatory synaptic transmission in SON neurons. The inhibitory effects of propofol on excitatory synaptic transmission of SON neurons may be related to the activation of GABA(A) receptors, but at a high concentration, propofol may also act directly on glutamate receptors.
Anesthetics, Intravenous ; pharmacology ; Animals ; Excitatory Postsynaptic Potentials ; drug effects ; GABA-A Receptor Antagonists ; pharmacology ; Glutamic Acid ; pharmacology ; In Vitro Techniques ; Neurons ; drug effects ; Propofol ; pharmacology ; Rats ; Receptors, Glutamate ; metabolism ; Supraoptic Nucleus ; cytology

OBJECTIVE: To investigate the neuroprotective effects of osthole (OST) on glutamate-induced toxicity in hippocampal HT22 cells and to explore the correlation between the protection and phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt) signaling pathway.
 METHODS: The cell injury model of HT22 was induced by glutamate and the cell viability was detected by MTS assay. The lactate dehydrogenase (LDH) release and the caspase-3 activity were determined by commercial kits. Western blot analysis was utilized to detect the protein levels of PI3K, Akt, p-PI3K and p-Akt. 
 RESULTS: OST markedly improved the cell survival and decreased the LDH release in glutamate-treated HT22 cells in a dose-dependent manner. Furthermore, the levels of p-PI3K and p-Akt proteins were significantly increased in glutamate and OST-co-treated HT22 cells. The effect of OST on p-Akt phosphorylation in HT22 cells was attenuated in the presence of PI3K specific inhibitor (LY294002).
 CONCLUSION OST protects HT22 cells from glutamate excitotoxicity through a mechanism involving the activation of PI3K/Akt signaling pathway.
Animals ; Caspase 3 ; metabolism ; Cell Line ; Cell Survival ; Chromones ; pharmacology ; Coumarins ; pharmacology ; Glutamic Acid ; adverse effects ; Hippocampus ; cytology ; Mice ; Morpholines ; pharmacology ; Neuroprotective Agents ; pharmacology ; Phosphatidylinositol 3-Kinases ; metabolism ; Phosphorylation ; Proto-Oncogene Proteins c-akt ; metabolism ; Signal Transduction

The purpose of this study is to explore depression metabolic markers in rat hippocampus and to investigate the anti-depressant effect of genipin and its mechanisms using nuclear magnetic resonance (NMR) metabonomics. Chronic unpredictable mild stress (CUMS) procedure was conducted to establish the depressive rat model. At the beginning of the third week, genipin low dose (25 mg x kg(-1)), middle dose (50 mg x kg(-1)), high dose (100 mg x kg(-1)), and venlafaxine (50 mg x kg(-1)) were given to the CUMS rats separately once daily for two weeks except control and model groups. Rat hippocampus was analyzed by 1H NMR based metabonomics after drug administration for 2 weeks. Significant differences in the metabolic profile of rat hippocampus of the CUMS treated group and the control group were observed with metabolic effects of CUMS including decreasing in glycine and N-acetylaspartate, increasing in inositol, glutamate, lactate, glutamine, taurine and alanine. Genipin showed ideal antidepressive effects at a dose of 50 mg x kg(-1) in rats, decrease of inositol, glutamate, lactate, alanine were observed, while glycine and N-acetylaspartate were increased. Important influence has been found on normal nervous system function of these significant changed metabolites, which suggests that the antidepressant effect of genipin may be played by enhancing the activity of neurons in hippocampus, repairing and improving the function of the neuron. The metabonomics approach is an effective tool for the investigation of the anti-depressant effect and pharmacologic mechanisms of genipin.
Alanine ; metabolism ; Animals ; Antidepressive Agents ; isolation & purification ; pharmacology ; Aspartic Acid ; analogs & derivatives ; metabolism ; Behavior, Animal ; drug effects ; Chronic Disease ; Depression ; drug therapy ; metabolism ; physiopathology ; Gardenia ; chemistry ; Glutamic Acid ; metabolism ; Glycine ; metabolism ; Hippocampus ; drug effects ; metabolism ; Inositol ; metabolism ; Iridoids ; isolation & purification ; pharmacology ; Lactic Acid ; metabolism ; Magnetic Resonance Spectroscopy ; Male ; Metabolomics ; Plants, Medicinal ; chemistry ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo explore and compare the effects of propofol, ginsenoside Rg-1, protein phosphatae-2A, and lithium on the learning and memory and the concentration of glutamic acid in hippocampus after the electroconvulsive therapy (ECT) in the model of depressed rats induced after the removal of olfactory bulb.

METHODSThe depressed rats were randomized into ECT intervention (two levels:no disposition and a course of electroconvulsive shock) and drug intervention (five levels:microinjection of saline injection, propofol, ginsenoside Rg-1, protein phosphatae-2A, and lithium, 20 g/L). Learning and memory were evaluated using the Morris water maze test within 24 h after the course of ECT. Glutamate contents in the hippocampus of rats were examined using high-performance liquid chromatography.

RESULTSBoth propofol alone and ECT alone induced the impairment of learning and memory in depressed rats, but their combination alleviated the such impairment caused by ECT. Ginsenoside Rg-1, protein phosphatae-2A ,and lithium had no obvious effect on the leaning and improved the learning and memory when in combination with ECT. There was a synergic effect between ECT intervention and drug intervention. ECT remarkably increased the glutamate content in the hippocampus of depressed rats, which could be reduced by both propofol and ginsenoside Rg-1. Protein phosphatae-2A and lithium did not affect glutamate content in the hippocampus of depressed rats before and after ECT.

CONCLUSIONSECT can increase the content of glutamate in hippocampus and thus cause the impairment of learning and memory in depressed rats. Propofol and ginsenoside Rg-1 can ameliorate the impairment by reducing the content of glutamate in hippocampus. Protein phosphatae-2A and lithium may also improve the learning and memory in depressed rats.

Animals ; Electroshock ; Ginsenosides ; pharmacology ; Glutamic Acid ; metabolism ; Hippocampus ; metabolism ; Lithium ; pharmacology ; Male ; Maze Learning ; drug effects ; Memory ; drug effects ; Propofol ; pharmacology ; Protein Phosphatase 2 ; pharmacology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the effects of acetamide at different doses on the expression of inhibitory amino acids (gamma-aminobutyric acid, GABA) and excitatory amino acid (glutamate, Glu) in the cerebral cortex of rats with acute tetramine (TET) poisoning.

METHODSEighty Sprague-Dawley rats (SPF) were randomly divided into five groups, with 16 rats in each group: saline control group, dimethyl sulfoxide (DMSO) control group, TET exposure group, high-dose (2.8 g/kg/d) acetamide treatment group, and super-high-dose (5.6 g/kg/d) acetamide treatment group. Rats in the exposure group and treatment groups were exposed to TET by intragastric administration after fasting, and were then intramuscularly injected with saline or different doses of acetamide in the following 5 days. The cortex of the temporal lobe was collected at 3 h, 12 h, 48 h, or 7 d after treatment. The expression levels of GABA and Glu in the cortex of the temporal lobe were determined by average optical density (OD) values in immunohistochemistry.

RESULTS1) Expression of GABA: The OD value of GABA in TET exposure group started to increase at 12 h after treatment, reached the peak at 48 h, and decreased to the normal level at 7 d. In the high-dose acetamide treatment group, the increase in OD at 12 h was not so significant as that in the TET exposure group, OD value decreased to the normal level at 48 h and was lower than that in the exposure group, and the changes were more like those in the control groups. In the super-high-dose acetamide treatment group, OD value began to increase significantly at 3 h and was significantly higher than that in the TET exposure group (P < 0.01), it reached the peak at 12 h, and was restored to the normal value at 48 h. 2) Expression of Glu: The OD value of Glu in TET exposure group at 3 h after treatment was significantly lower than those in the two control groups, it increased gradually from 12 h to 48 h, and recovered to the normal level at the 7th d. The changes in the high-dose acetamide treatment group were similar to those in the TET exposure group, but became more like those in the control groups after 48 h; the OD value in super-high-dose acetamide treatment group was significantly higher than that in the TET exposure group at 3 h after treatment (P < 0.01), while no significant difference was found at 12 h; it was significantly lower than those of all other groups at 48 h and 7 d (P < 0.01).

CONCLUSIONSTreatment with high dose of acetamide has some curative effect on TET poisoning-induced central nervous lesion, while the effect of super-high-dose acetamide on expression of neurotransmitters is too complex to evaluate.

Acetamides ; pharmacology ; Animals ; Bridged-Ring Compounds ; poisoning ; Cerebral Cortex ; drug effects ; metabolism ; Female ; Glutamic Acid ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley ; gamma-Aminobutyric Acid ; metabolism