OBJECTIVES: To investigate the effect of orexin-A-mediated regulation of ionotropic glutamate receptors for promoting motor function recovery in rats with spinal cord injury (SCI). METHODS: Thirty-six newborn SD rats (aged 7-14 days) were randomized into 6 groups (n=6), including a normal control group, a sham-operated group, and 4 SCI groups with daily intrathecal injection of saline, DNQX, orexin-A, or orexin-A+DNQX for 3 consecutive days after PCI. Motor function of the rats were evaluated using blood-brain barrier (BBB) score and inclined plane test 1 day before and at 1, 3, and 7 days after SCI. For patch-clamp experiment, spinal cord slices from newborn rats in the control, sham-operated, SCI, and SCI+orexin groups were prepared, and ventral horn neurons were acutely isolated to determine the reversal potential and dynamic indicators of glutamate receptor-mediated currents under glutamate perfusion. RESULTS: At 3 and 7 days after SCI, the orexin-A-treated rats showed significantly higher BBB scores and grip tilt angles than those with other interventions. Compared with those treated with DNQX alone, the rats receiving the combined treatment with orexin and DNQX had significantly higher BBB scores and grip tilt angles on day 7 after PCI. In the patch-clamp experiment, the ventral horn neurons from SCI rat models exhibited obviously higher reversal potential and greater rise slope of glutamate current with shorter decay time than those from sham-operated and orexin-treated rats. CONCLUSIONS Orexin-A promotes motor function recovery in rats after SCI possibly by improving the function of the ionotropic glutamate receptors.
Animals ; Spinal Cord Injuries/drug therapy* ; Rats ; Rats, Sprague-Dawley ; Receptors, Ionotropic Glutamate/metabolism* ; Recovery of Function/drug effects* ; Orexins/pharmacology* ; Male ; Female ; Animals, Newborn ; Neuropeptides/pharmacology* ; Intracellular Signaling Peptides and Proteins/pharmacology*

The aim of the present study was to explore the role of group II and III metabotropic glutamate receptors (mGluRs) in carotid body plasticity induced by chronic intermittent hypoxia (CIH) in rats. Sprague Dawley (SD) rats were treated with CIH in Oxycycler A84 hypoxic chamber for 4 weeks, and the tail artery blood pressure was measured at the end of model preparation. RT-qPCR was performed to examine the mRNA expression levels of mGluR2/3/8 in rat carotid body. Carotid sinus nerve activity was detected by ex vivo carotid sinus nerve discharge recording technique, and acute intermittent hypoxia (AIH) was administered to induce carotid body sensory long-term facilitation (sLTF), in order to observe the role of group II and group III mGluRs in carotid body plasticity induced by CIH. The results showed that: 1) After 4 weeks of CIH exposure, the blood pressure of rats increased significantly; 2) CIH down-regulated the mRNA levels of mGluR2/3, and up-regulated the mRNA level of mGluR8 in the carotid body; 3) AIH induced sLTF in carotid body of CIH group. In the CIH group, activation of group II mGluRs had no effect on sLTF of carotid body, while activation of group III mGluRs completely inhibited sLTF. These results suggest that CIH increases blood pressure in rats, and group III mGluRs play an inhibitory role in CIH-induced carotid body plasticity in rats.
Rats ; Animals ; Carotid Body/metabolism* ; Rats, Sprague-Dawley ; Hypoxia ; Receptors, Metabotropic Glutamate/metabolism* ; RNA, Messenger/metabolism*

Post-traumatic stress disorder (PTSD) has been reported to be associated with a higher risk of cardiovascular disease. The amygdala may have an important role in regulating cardiovascular function. This study aims to explore the effect of amygdala glutamate receptors (GluRs) on cardiovascular activity in a rat model of PTSD. A compound stress method combining electrical stimulation and single prolonged stress was used to prepare the PTSD model, and the difference of weight gain before and after modeling and the elevated plus maze were used to assess the PTSD model. In addition, the distribution of retrogradely labeled neurons was observed using the FluoroGold (FG) retrograde tracking technique. Western blot was used to analyze the changes of amygdala GluRs content. To further investigate the effects, artificial cerebrospinal fluid (ACSF), non-selective GluR blocker kynurenic acid (KYN) and AMPA receptor blocker CNQX were microinjected into the central nucleus of the amygdala (CeA) in the PTSD rats, respectively. The changes in various indices following the injection were observed using in vivo multi-channel synchronous recording technology. The results indicated that, compared with the control group, the PTSD group exhibited significantly lower weight gain (P < 0.01) and significantly decreased ratio of open arm time (OT%) (P < 0.05). Retrograde labeling of neurons was observed in the CeA after microinjection of 0.5 µL FG in the rostral ventrolateral medulla (RVLM). The content of AMPA receptor in the PTSD group was lower than that in the control group (P < 0.05), while there was no significant differences in RVLM neuron firing frequency and heart rate (P > 0.05) following ACSF injection. However, increases in RVLM neuron firing frequency and heart rate were observed after the injection of KYN or CNQX into the CeA (P < 0.05) in the PTSD group. These findings suggest that AMPA receptors in the amygdala are engaged in the regulation of cardiovascular activity in PTSD rats, possibly by acting on inhibitory pathways.
Rats ; Animals ; Rats, Sprague-Dawley ; Stress Disorders, Post-Traumatic ; Receptors, AMPA ; 6-Cyano-7-nitroquinoxaline-2,3-dione/pharmacology* ; Receptors, Glutamate/metabolism* ; Amygdala ; Weight Gain ; Medulla Oblongata/physiology* ; Blood Pressure

The purpose of the present study was to explore the role of carotid body metabotropic glutamate receptor 1 (mGluR1) in chronic intermittent hypoxia (CIH)-induced carotid body plasticity. Sprague Dawley (SD) rats were exposed to CIH (6%-21% O₂, 4 min/cycle, 8 h/day) for 4 weeks. The blood pressure of rats was monitored non-invasively by tail-cuff method under consciousness. RT-qPCR was used to examine the mRNA expression level of mGluR1 in rat carotid body. Western blot was used to detect the protein expression level of mGluR1 in rat carotid body. The role of mGluR1 in CIH-induced carotid body sensory long-term facilitation (sLTF) was investigated by ex vivo carotid sinus nerve discharge recording, and the carotid body sLTF was evoked by a 10-episode of repetitive acute intermittent hypoxia (AIH: 1 min of 5% O₂ interspersed with 5 min of 95% O₂). The results showed that: 1) CIH increased the systolic blood pressure (P < 0.001), diastolic blood pressure (P < 0.005) and mean arterial blood pressure (P < 0.001) of rats; 2) CIH decreased the mRNA and protein levels of mGluR1 in the rat carotid body (P < 0.01); 3) 4 weeks of CIH induced carotid body sLTF significantly, exhibiting as an increasing baseline sensory activity during post-AIH, which was inhibited by application of an agonist of group I metabotropic glutamate receptors, (S)-3,5-dihydroxyphenylglycine (DHPG), during sLTF induction (P < 0.005). In summary, these results suggest that activation of mGluR1 inhibits CIH-induced carotid body plasticity in rats.
Rats ; Animals ; Carotid Body/metabolism* ; Rats, Sprague-Dawley ; Hypoxia ; Receptors, Metabotropic Glutamate/metabolism* ; RNA, Messenger/metabolism*

This study investigated the effect of Suanzaoren Decoction on the expression of N-methyl-D-aspartate receptors(NMDAR) and α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors(AMPAR) in the hippocampus and synaptic plasticity in rats with conditioned fear-induced anxiety. The effect of Suanzaoren Decoction on rat behaviors were evaluated through open field experiment, elevated plus maze experiment, and light/dark box experiment. Enzyme-linked immunosorbent assay(ELISA) was used to measure the levels of glutamate(Glu) and γ-aminobutyric acid(GABA) in the rat hippocampus. Real-time fluorescence quantitative PCR(qRT-PCR) and Western blot were employed to assess the gene and protein expression of ionotropic glutamate receptors in the hippocampal region. Transmission electron microscopy was utilized to observe the changes in the ultrastructure of synaptic neurons in the hippocampal region. Long-term potentiation(LTP) detection technique was employed to record the changes in population spike(PS) amplitude in the hippocampal region of mice in each group. The behavioral results showed that compared with the model group, the Suanzaoren Decoction group effectively increased the number of entries into open arms, time spent in open arms, percentage of time spent in open arms out of total movement time, number of entries into open arms out of total entries into both arms(P<0.01), and significantly increased the time spent in the light box and the number of shuttle crossings(P<0.01). There was an increasing trend in the number of grid crossings, entries into the center grid, and time spent in the center grid, indicating a significant anxiolytic effect. ELISA results showed that compared with the model group, the Suanzaoren Decoction group exhibited significantly reduced levels of Glu, Glu/GABA ratio(P<0.01), and significantly increased levels of GABA(P<0.01) in the rat hippocampus. Furthermore, Suanzaoren Decoction significantly decreased the gene and protein expression of NMDAR(GluN2B and GluN2A) and AMPAR(GluA1 and GluA2) compared with the model group. Transmission electron microscopy results demonstrated improvements in synapses, neuronal cells, and organelles in the hippocampal region of the Suanzaoren Decoction group compared with the model group. LTP detection results showed a significant increase in the PS amplitude changes in the hippocampal region of Suanzaoren Decoction group from 5 to 35 min compared with the model group(P<0.05, P<0.01). In conclusion, Suanzaoren Decoction exhibits significant anxiolytic effects, which may be attributed to the reduction in NMDAR and AMPAR expression levels and the improvement of synaptic plasticity.
Rats ; Mice ; Animals ; Receptors, Ionotropic Glutamate/metabolism* ; Hippocampus ; Neuronal Plasticity ; Receptors, N-Methyl-D-Aspartate/genetics* ; Anxiety/genetics* ; gamma-Aminobutyric Acid

Based on the CX3C chemokine ligand 1(CX3CL1)-CX3C chemokine receptor 1(CX3CR1) axis, this study explored the potential mechanism by which Zuogui Jiangtang Jieyu Formula(ZGJTJY) improved neuroinflammation and enhanced neuroprotective effect in a rat model of diabetes mellitus complicated with depression(DD). The DD rat model was established by feeding a high-fat diet combined with streptozotocin(STZ) intraperitoneal injection for four weeks and chronic unpredictable mild stress(CUMS) combined with isolated cage rearing for five weeks. The rats were divided into a control group, a model group, a positive control group, an inhibitor group, and a ZGJTJY group. The open field test and forced swimming test were used to assess the depression-like behaviors of the rats. Enzyme-linked immunosorbent assay(ELISA) was performed to measure the expression levels of the pro-inflammatory cytokines interleukin-1β(IL-1β) and tumor necrosis factor-α(TNF-α) in plasma. Immunofluorescence staining was used to detect the expression of ionized calcium-binding adapter molecule 1(Iba1), postsynaptic density protein-95(PSD95), and synapsin-1(SYN1) in the hippocampus. Hematoxylin-eosin(HE) staining, Nissl staining, and TdT-mediated dUTP nick end labeling(TUNEL) fluorescence staining were performed to assess hippocampal neuronal damage. Western blot was used to measure the expression levels of CX3CL1, CX3CR1, A2A adenosine receptor(A2AR), glutamate receptor 2A(NR2A), glutamate receptor 2B(NR2B), and brain-derived neurotrophic factor(BDNF) in the hippocampus. Compared with the model group, the ZGJTJY group showed improved depression-like behaviors in DD rats, enhanced neuroprotective effect, increased expression of PSD95, SYN1, and BDNF(P<0.01), and decreased expression of Iba1, IL-1β, and TNF-α(P<0.01), as well as the expression of CX3CL1, CX3CR1, A2AR, NR2A, and NR2B(P<0.01). These results suggest that ZGJTJY may exert its neuroprotective effect by inhibiting the CX3CL1-CX3CR1 axis and activation of hippocampal microglia, thereby improving neuroinflammation and abnormal activation of N-methyl-D-aspartate receptor(NMDAR) subunits, and ultimately enhancing the expression of synaptic-related proteins PSD95, SYN1, and BDNF in the hippocampus.
Rats ; Animals ; Depression/drug therapy* ; Brain-Derived Neurotrophic Factor ; Neuroprotective Agents ; Tumor Necrosis Factor-alpha/metabolism* ; Neuroinflammatory Diseases ; Diabetes Mellitus ; Receptors, Glutamate ; CX3C Chemokine Receptor 1/genetics*

OBJECTIVETo investigate the effect of extracellular regulating kinase (ERK) signaling pathway on the secretion of gamma-aminobutyric acid (GABA) in cultured rat hippocampal neurons induced by stromal cell derived factor-1 (SDF-1).

METHODSThe hippocampal neurons of newborn SD rats were cultured and identified in vitro; the phosphorylation level of ERK1/2 was examined by Western blot; ELISA was used to detect the effect of PD98059, a ERK1/2 specific blocker on GABA secretion of cultured hippocampal neurons and Western blot were adopted to measure the protein expression levels of glutamate decarboxylase (GAD65/67) and gamma aminobutyric acid transporter (GAT); after blocking ERK1/2 signaling pathway with PD98059; RT-PCR was used to detect the mRNA expression levels of GAT-1 and GAD65 after treated with PD98059.

RESULTSThe levels of ERKl/2 phosphorylation were increased significantly by SDF1 acting on hippocampal neurons, and CX-CR4 receptor blocker AMD3100, could inhibit SDF-1 induced ERK1/2 activation; SDF-1 could inhibit the secretion of GABA in cultured hippocampal neurons, and ERK1/2 specific inhibitor PD98059, could partly reverse the inhibition of GABA secretion by SDF-1. The effects of SDF-1 on cultured hippocampal neurons was to decrease the mRNA genesis of glutamic acid decarboxylase GAD65 and GABA transporter GAT-1, besides, ERK inhibitor PD98059 could effectively flip the effect of SDF-1. The results of Western blot showed that SDF-1 could inhibit the protein expression of GAT-1 and GAD65/67 in hippocampal neurons and the inhibition of GAT-1 and GAD65/67 protein expression could be partially restored by ERK1/2 blocker.

CONCLUSIONSDF-1 acts on the CXCR4 of hippocampal neurons in vitro, and inhibits the expression of GAD by activating the ERK1/2 signaling pathway, and this may represent one possible pathway of GABA secretion inhibition.

Animals ; Blotting, Western ; Cells, Cultured ; Chemokine CXCL12 ; pharmacology ; Flavonoids ; pharmacology ; Glutamate Decarboxylase ; metabolism ; Hippocampus ; cytology ; MAP Kinase Signaling System ; Neurons ; metabolism ; Phosphorylation ; RNA, Messenger ; Rats ; Rats, Sprague-Dawley ; Receptors, CXCR4 ; metabolism ; gamma-Aminobutyric Acid ; secretion

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

Disease Progression ; Humans ; Neoplasms ; diagnosis ; metabolism ; Receptors, Metabotropic Glutamate ; metabolism

This study was aimed to investigate the protective effect of bone mesenchymal stem cell-derived microvesicles (BMMSC-MV) on glutamate injured PC12 cells so as to elucidate the mechanism of the neural damage repair. BMMSC were isolated and purified with density-gradient centrifugation method, BMMSC-MV were harvested from the supernatants of BMMSC by hypothermal ultracentrifugation method. The surface markers of BMMSC reacted against different antibodies were detected by flow cytometry. The morphology features of MV were observed under an electron microscope. Experiment was divided into three groups, one was a control group, and the other two were glutamate-injured group and co-culture group of BMMSC-MV and glutamate-damaged cells respectively. MTT test was used to evaluate the proliferative status of PC12 cells and the AnnexinV-FITC detecting kit and Hoechst33342 were used to detect the apoptosis of PC12 cells in different groups. The results showed that BMMSC isolated from rat bone marrow were highly positive for CD29, CD44 and negative for CD31, CD34 and CD45. The morphology of MV was round and the vesicles were homogenous in size. BMMSC-MV exhibited a protective effect on the excitotoxicity-injured PC12 cells, displaying increase of cell viability, decrease of Annexin-V/PI staining positive and nuclear condensed cells. It is concluded that BMMSC-MV can protect PC12 cells from glutamate-induced apoptosis, suggesting that BMMSC-MV may be a potential candidate for treatment of neurological diseases.This study provides the preliminary experimental and theoretical evidence for use of BMMSC-MV in treatment of neural excited damage.
Animals ; Apoptosis ; Bone Marrow Cells ; cytology ; Cell Survival ; Coculture Techniques ; Cytoplasmic Vesicles ; Flow Cytometry ; Glutamic Acid ; adverse effects ; Mesenchymal Stromal Cells ; cytology ; PC12 Cells ; Rats ; Receptors, Glutamate ; metabolism