OBJECTIVES: To observe the effect of 4-(arylethynyl)-pyrrolo[2,3-d] pyrimidine (10b) on post-traumatic stress disorder (PTSD)-like behaviors and ERK1/2-SGK1 signaling pathway in mice. METHODS: C57BL/6 mouse models exposed to single prolonged stress (SPS) were treated with daily gavage of saline, 10b at low, moderate and high doses, or paroxetine for 14 days. The changes in PTSD-like behaviors of SPS mice with different treatments were observed using behavioral tests. Western blotting and immunofluorescence assay were used to detect the protein expression levels of mGluR5, p-ERK, and SGK1 in the hippocampus of the mice. Pathological changes in the liver and kidney tissues of the mice were examined using HE staining. Molecular docking and molecular dynamics analyses were employed to evaluate the binding stability between the compound 10b and mGluR5. RESULTS: Compared to the normal control mice, the SPS mice exhibited obvious PTSD-like behaviors with increased hippocampal expressions of mGluR5 and p-ERK proteins and decreased SGK1 protein expression. Compound 10b significantly ameliorated behavioral abnormalities in SPS mice, inhibited mGluR5 expression, and reversed the dysregulation of p-ERK and SGK1. No obvious liver or kidney toxicity was observed after 10b treatment. Molecular docking and dynamics studies demonstrated a stable interaction between 10b and mGluR5. CONCLUSIONS The compound 10b ameliorates PTSD-like behaviors induced by SPS in mice possibly by inhibiting mGluR5 expression to modulate the ERK1/2-SGK1 signaling pathway.
Animals ; Stress Disorders, Post-Traumatic/drug therapy* ; Receptor, Metabotropic Glutamate 5/metabolism* ; Mice, Inbred C57BL ; Mice ; Protein Serine-Threonine Kinases/metabolism* ; Pyrimidines/pharmacology* ; Immediate-Early Proteins/metabolism* ; Signal Transduction/drug effects* ; MAP Kinase Signaling System/drug effects* ; Male ; Molecular Docking Simulation ; Hippocampus/metabolism*

To investigate the role of metabotropic glutamate receptor 5 (mGluR5) in laterocapcular division of the central nucleus of amygdala (CeLC) in fentanyl-induced hyperalgesia in rats. 
 Methods: A total of 12 Sprague-Dawley male rats (60-100 g) were randomly divided into a normal group 1 (n=6) and an opioid-induced hyperalgesia (OIH) group 1 (n=6). The OIH group 1 was injected with fentanyl through the lower neck skin to build OIH model, and the normal group 1 was given the same volume of saline. After 6.5 h, paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were tested to verify the success of the induction of OIH. Then rats were sacrificed and the right CeLC tissue were taken for detection of the mGluR5 by Western blotting. Forty SD male rats were randomly divided into 4 groups (n=10 each): an OIH+DMSO, an OIH+MTEP (3.0 μg), an OIH+MTEP (7.5 μg) and an OIH+MTEP (15.0 μg) group. MTEP was a selective antagonist of mGluR5. Catheterization in the right CeLC was first performed. After one-week recovery, OIH was induced. Then 0.5 μL DMSO, MTEP 3.0 μg, MTEP 7.5 μg and MTEP 15.0 μg were administrated through the CeLC catheter accordingly. PWMT and PWTL were tested at pre-OIH, 6 h after OIH and post-drug. Then the expression levels of mGluR5 of CeLC tissue were analyzed by Western blotting. Another 8 SD male rats were randomly divided into a normal group 2 and an OIH group 2 (n=4 each). The rats were induced OIH by injecting of fentanyl while rats in the normal group 2 were injected with same volume of saline. The miniature excitatory postsynaptic currents (mEPSCs) of the 2 groups' neurons in the right CeLC region were recorded by whole cell voltage-clamp before and after the administration of MTEP in brain slice.
 Results: Compared with the normal group 1, the PWTL and PWMT were significantly decreased and the expression of mGluR5 was apparently increased in the OIH group 1 (P<0.05). The PWMT and PWTL were significantly decreased in each group and indicated success of OIH model (P<0.05). The expression of mGluR5 in the CeLC was increased. MTEP reversed these changes in a dose-dependent way (P<0.05). Compared with the normal group 2, the amplitude and frequency of mEPSCs in the OIH group 2 were significantly increased (P<0.05) and they were reversed by MTEP (P<0.05). 
 Conclusion: mGluR5 in the CeLC may be involved in the maintenance of OIH. Inhibition of the activity of mGluR5 in the CeLC may alleviate the symptoms of fentanyl-induced hyperalgesia.
Animals ; Central Amygdaloid Nucleus ; Fentanyl ; Hyperalgesia ; Male ; Rats ; Rats, Sprague-Dawley ; Receptor, Metabotropic Glutamate 5

Animals ; Fragile X Mental Retardation Protein ; metabolism ; Fragile X Syndrome ; metabolism ; Humans ; Neurons ; metabolism ; RNA-Binding Proteins ; metabolism ; Receptor, Metabotropic Glutamate 5 ; metabolism ; Sumoylation ; physiology

Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) is the most abundant kinase within excitatory synapses in the mammalian brain. It interacts with and phosphorylates a large number of synaptic proteins, including major ionotropic glutamate receptors (iGluRs) and group I metabotropic glutamate receptors (mGluRs), to constitutively and/or activity-dependently regulate trafficking, subsynaptic localization, and function of the receptors. Among iGluRs, the N-methyl-D-aspartate receptor (NMDAR) is a direct target of CaMKII. By directly binding to an intracellular C-terminal (CT) region of NMDAR GluN2B subunits, CaMKII phosphorylates a serine residue (S1303) in the GluN2B CT. CaMKII also phosphorylates a serine site (S831) in the CT of α-amino-3-hydroxy-5- methylisoxazole-4-propionic acid receptors. This phosphorylation enhances channel conductance and is critical for synaptic plasticity. In addition to iGluRs, CaMKII binds to the proximal CT region of mGluR1a, which enables the kinase to phosphorylate threonine 871. Agonist stimulation of mGluR1a triggers a CaMKII-mediated negative feedback to facilitate endocytosis and desensitization of the receptor. CaMKII also binds to the mGluR5 CT. This binding seems to anchor and accumulate inactive CaMKII at synaptic sites. Active CaMKII dissociates from mGluR5 and may then bind to adjacent GluN2B to mediate the mGluR5-NMDAR coupling. Together, glutamate receptors serve as direct substrates of CaMKII. By phosphorylating these receptors, CaMKII plays a central role in controlling the number and activity of the modified receptors and determining the strength of excitatory synaptic transmission.
Calcium-Calmodulin-Dependent Protein Kinase Type 2 ; metabolism ; Neuronal Plasticity ; Phosphorylation ; Receptor, Metabotropic Glutamate 5 ; metabolism ; Receptors, Metabotropic Glutamate ; metabolism ; Receptors, N-Methyl-D-Aspartate ; metabolism ; Serine ; metabolism ; Synapses ; Synaptic Transmission

OBJECTIVETo investigate the expression of metabotropic glutamate receptor 5 (mGluR5) and its cellular distribution in the frontal cortex, ventricular zone (VZ) and subventricular zone (SVZ) in human fetuses.

METHODSAccording to the gestational age, the collected fetuses were divided into 4 groups, namely 9-11 weeks, 14-16 weeks, 22-24 weeks and 32-36 weeks. Brain tissue blocks including the frontal lobe or VZ/SVZ were prepared into slices, and the expression pattern and cellular distribution of mGluR5 in the frontal cortex and VZ/SVZ were observed by immunohistochemistry or immunofluorescence.

RESULTSmGluR5 immunoreactivity was present in the cell membrane in the frontal cortex, VZ and SVZ from the 9th to 36th weeks and the immunoreactivity in the marginal zone (MZ) and cortical plate (CP) was markedly stronger than that in VZ and SVZ. The cells expressing mGluR5 included neural stem/progenitor cells in the VZ and SVZ, immature neurons in the VZ and MZ, and numerous mature neurons in the CP.

CONCLUSIONmGluR5 is expressed by a variety of cells such as neural stem cells in the frontal cortex, VZ and SVZ in human fetus, suggesting a role of mGluR5 in the development of human cerebral cortex.

Cerebral Cortex ; cytology ; Cerebral Ventricles ; cytology ; metabolism ; Fetus ; cytology ; metabolism ; Frontal Lobe ; cytology ; metabolism ; Humans ; Neural Stem Cells ; cytology ; metabolism ; Receptor, Metabotropic Glutamate 5 ; Receptors, Metabotropic Glutamate ; metabolism

L-glutamate (Glu) is an excitatory neurotransmitter in the mammalian central nervous system. Relatively much attention has been paid to functional expression of Glu signaling molecules in peripheral tissues very recently. The present study tested the hypothesis that the activation of group I metabotropic glutamate receptor (mGluRI) in neutrophils stimulated neutrophils adherence to endothelial cells by increasing the surface expression of certain adhesion molecules. Peripheral blood was obtained by venipuncture from healthy donors, and the neutrophils were isolated by Ficoll-Hypaque gradient centrifugation. Neutrophils floating into DMEM/F12 culture medium containing 10% fetal bovine serum were then used immediately. Immunocytochemistry and real-time quantitative RT-PCR were used to detect the expression of mGluRI (mGluR1 and mGluR5) in neutrophils. The adherence of neutrophils to cultured human normal umbilical vein endothelial cells (HUVE-12) was measured by the colorimetric method. Cell surface expression of adhesion molecule CD11a in the neutrophils was determined by flow cytometry. Immunocytochemistry and real-time quantitative RT-PCR showed that mGluR1 and mGluR5 were constitutively expressed in neutrophils. Application of mGluRI agonist S-3,5-dihydroxyphenylglycine (S-DHPG) (1x10(-8)-1x10(-6) mol/L) showed a dose-dependent stimulatory effect on the adherence of neutrophils to HUVE-12 (P<0.05 or P<0.01), with a maximum effect at 1x10(-6) mol/L (P<0.01). Incubations as short as 30 min were sufficient to induce increased adherence after the beginning of S-DHPG treatment. Following time extension (0.5-5 h), S-DHPG (1x10(-6) mol/L) increased the rate of neutrophils adhesion to HUVE-12 with a maximum effect at 0.5 h (P<0.01). However, a time-dependent effect of S-DHPG on the rate of neutrophils adhesion to HUVE-12 was not observed during the experimental period. 1x10(-6) mol/L of S-DHPG also induced an increased surface expression of adhesion molecule CD11a (P<0.01) when neutrophils were preincubated with 1x10(-6) mol/L of S-DHPG for 1 h. Furthermore, the specific mGluRI antagonist (RS)-alpha-methyl-4-carboxyphenylglycine ((+/-)-MCPG, 0.5 mmol/L) significantly abolished the stimulatory effect of S-DHPG (1x10(-6) mol/L) on the adherence of neutrophils to HUVE-12 (P<0.01). These results suggest that the activation of mGluRI in neutrophils results in increased adhesion molecule CD11a expression and thereby promotes the adherence of neutrophils to endothelial cells.
Benzoates ; pharmacology ; CD11a Antigen ; metabolism ; Cell Adhesion ; Endothelial Cells ; cytology ; Glycine ; analogs & derivatives ; pharmacology ; Human Umbilical Vein Endothelial Cells ; Humans ; Neutrophils ; cytology ; Receptor, Metabotropic Glutamate 5 ; metabolism ; Receptors, Metabotropic Glutamate ; metabolism ; Resorcinols ; pharmacology

OBJECTIVE: To observe the expression of mGluR5 in the medial vestibular nucleus (MVN) following unilateral labyrinthectomy (UL). METHOD: Thirty Wistar rats were randomly divided into two groups. Twenty four animals received unilateral labyrinthectomy while the others maintained labyrinthine well. After setting left labyrinthine, the change of mGluR5 was induced by immunohistochemistry, in situ hybridization. RESULT: mGluR5 was increased in lesioned side MVN after unilateral labyrinthectomy. The 12 h post-UL was highest. Then it was decrease in 36 h post-UL, while 7 d post-UL was same as control group. The change of contralateral was same as that in ipsilateral. CONCLUSION UL can induce increase of mGluR5 in the MVN. The reduced resting discharge in the primary vestibular afferents or in the central vestibular neurons may be responsible for the change of mGluR5. However the significance of the change of mGluR1 in the vestibular compensation is still unknown.
Animals ; Male ; Postoperative Period ; Rats ; Rats, Wistar ; Receptor, Metabotropic Glutamate 5 ; Receptors, Metabotropic Glutamate ; metabolism ; Vestibular Nuclei ; metabolism ; Vestibule, Labyrinth ; metabolism ; surgery

OBJECTIVE: Studies revealed that cerebellar flocculus-paraflocculus complex plays an important in vestibular compensation. To observe the expression change of Group I mGluRs in flocculus following left unilateral labyrinthectomy (UL). METHOD: After setting left labyrinthectomy, the change of Group I mGluRs was detected by RT-PCR. RESULT: Group I mGluR5 was induced increase in both side flocculus after unilateral labyrinthectomy. By contrast, mGluR1 was induced decrease. However, that of the lesioned side was stronger than that of the unlesioned side. CONCLUSION UL can induce change of Group I mGluRs in the flocculus. The fall in the resting discharge of the primary vestibular afferents and/or in the deafferented central vestibular neurons may cause the change of mGluRs. But the significance of the change of mGluRs in the vestibular compensation is still unknown.
Animals ; Cerebellar Nuclei ; metabolism ; Male ; Rats ; Rats, Wistar ; Receptor, Metabotropic Glutamate 5 ; Receptors, Metabotropic Glutamate ; metabolism ; Vestibular Nuclei ; metabolism ; Vestibule, Labyrinth ; metabolism

OBJECTIVETo investigate the expression changes of metabotropic glutamate receptor 5 (mGluR5) in neuropathic pain.

METHODSEighty-four adult male Sprague Dawley rats weighing 180-220 g were randomly divided into 7 groups (n = 12) : control group; S3, S7, and S14 groups: rats received the sham operation, the mechanical pain threshold was measured, and then the rats were decapitated and the ipsilateral lumbar spinal cord dorsal horn and dorsal root ganglion (DRG) samples were obtained on the 3rd, 7th, 14th postoperative day, respectively; C3, C7, and C14 groups: the chronic sciatic nerve constriction (CCI) model was established, the mechanical pain threshold was measured and the samples were obtained on the 3rd, 7th, 14th postoperative day, respectively. The expression level of mGluR5 mRNA and protein in the spinal cord and DRG were measured using the reverse transcriptase polymerase chain reaction and Western blot.

RESULTSIn the CCI group, the mechanical pain threshold in each observation day was significantly lower than in the sham operation group (P < 0.05). In the spinal cord, the expressions of mGluR5 mRNA and protein were significantly elevated in the C3 group than in the S3 and the control group (P < 0.05). On the 7th and the 14th postoperative day, no significant difference was found in the expression of mGluR5 mRNA and protein between CCI groups and the sham operation groups or the control group. No change was detected in DRG mRNA or protein.

CONCLUSIONmGluR5 is differentially expressed in spinal cord in response to neuropathic pain, which suggests that mGluR5 may be involved in the mechanism of neuropathic pain.

Animals ; Disease Models, Animal ; Ganglia, Spinal ; metabolism ; Male ; Neuralgia ; metabolism ; Pain Threshold ; RNA, Messenger ; genetics ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptor, Metabotropic Glutamate 5 ; Receptors, Metabotropic Glutamate ; genetics ; metabolism ; Sciatic Neuropathy ; metabolism ; Spinal Cord ; metabolism

OBJECTIVETo study the effects on the expression of mGluR5 mRNA and protein levels in primarily cultured hippocampal neurons after lead exposure.

METHODSPrimary embryonic rat hippocampal neuronal culture was prepared. On the 3(rd) day of incubation, lead chloride solution was added into medium to produce four different lead exposure levels: 0, 1 x 10(-8) mol/L, 1 x 10(-6) mol/L, 1 x 10(-4) mol/L Pb(2+). After 10 days of incubation, the neurons were collected to measure the alteration of mGluR5 mRNA expression by real-time fluorescent quantity PCR and the expression of mGluR5 in protein level by Western blot.

RESULTSThe studies revealed that mGluR5 mRNA expression was down-regulated after lead exposure in a dose-dependent manner. The mGluR5 mRNA expression of the lower lead-exposed neurons (Pb(2+) 10(-8) mol/L), the medium lead-exposed neurons(Pb(2+) 10(-6) mol/L), the higher lead-exposed neurons(Pb(2+) 10(-4) mol/L) were 0.724, 0.421, 0.321 times less than that of the controls, respectively. The Western blot demonstrated that mGluR5 expression in protein level should be decreased after lead exposure.

CONCLUSIONThe expression of mGluR5 in mRNA and protein levels should be down-regulated after lead exposure at different lead levels in a dose-dependent manner.

Animals ; Animals, Newborn ; Cells, Cultured ; Female ; Hippocampus ; drug effects ; metabolism ; Lead ; toxicity ; Lead Poisoning, Nervous System ; metabolism ; Neurons ; drug effects ; metabolism ; Pregnancy ; RNA, Messenger ; genetics ; Rats ; Rats, Sprague-Dawley ; Receptor, Metabotropic Glutamate 5 ; Receptors, Metabotropic Glutamate ; biosynthesis ; genetics