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*

OBJECTIVE: To investigate the expression and localization of metabotropic glutamate receptors 7 and 8 (mGluR7/8) in rat superior cervical ganglion (SCG) and their changes in response to chronic intermittent hypoxia (CIH). METHODS: We detected the expressions of mGluR7 and mGluR8 in the SCG of 8-week-old male SD rats using immunohistochemistry and characterized their distribution with immunofluorescence staining. The expression of mGluR7 and mGluR8 in the cytoplasm and nucleus was detected using Western blotting. A 6-week CIH rat model was established by exposure to intermittent hypoxia (6% oxygen for 30 s followed by normoxia for 4 min) for 8 h daily, and the changes in systolic blood pressure, diastolic blood pressure and mean arterial pressure were measured. The effect of CIH on expression levels of mGluR7 and mGluR8 in the SCG was analyzed using Western blotting. RESULTS: Positive expressions of mGluR7 and mGluR8 were detected in rat SCG. mGluR7 was distributed in the neurons and small fluorescent (SIF) cells with positive staining in both the cytoplasm and nuclei, but not expressed in satellite glial cells (SGCs), nerve fibers or blood vessels; mGluR8 was localized in the cytoplasm of neurons and SIF cells, but not expressed in SGCs, nerve fibers, or blood vessels. Western blotting of the nuclear and cytoplasmic fractions of rat SCG further confirmed that mGluR7 was expressed in both the cytoplasm and the nucleus, while mGluR8 exists only in the cytoplasm. Exposure to CIH significantly increased systolic blood pressure, diastolic blood pressure and mean arterial pressure of the rats (all P < 0.001) and augmented the protein expressions of mGluR7 and mGluR8 in the SCG (P < 0.05). CONCLUSION mGluR7 and mGluR8 are present in rat SCG but with different localization patterns. CIH increases blood pressure of rats and enhanced protein expressions of mGluR7 and mGluR8 in rat SCG.
Male ; Animals ; Rats ; Rats, Sprague-Dawley ; Superior Cervical Ganglion ; Receptors, Metabotropic Glutamate ; Hypoxia

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*

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*

Long-Term Potentiation ; Neuronal Plasticity ; Receptors, Metabotropic Glutamate ; Synaptic Transmission

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

OBJECTIVE: The mGluR1 (metabotropic glutamate receptor 1) gene, a G protein–coupled receptor, is known to mediate perceptions of umami tastes. Genetic variation in taste receptors may influence dietary intake, and in turn have an impact on nutritional status and risk of chronic disease. We investigated the association of mGluR1 rs2814863 polymorphism with lipid profiles and cardiovascular disease (CVD) risk, together with their modulation by macronutrient intake in Korean adults. METHODS: The subjects consisted of 8,380 Koreans aged 40-69 years participating in the Anseong and Ansan Cohort Study, which was a part of the Korean Genome Epidemiology Study (KoGES). Data was collected using self-administered questionnaires, anthropometric measurements, and blood chemical analysis. RESULTS: Carriers of C allele at mGluR1 rs2814863 was associated with decreased high density lipoprotein cholesterol (HDL-C) and increased triglyceride as compared to carriers of TT. Also, carriers of the C allele showed higher fat intake and lower carbohydrate intake than those with carriers of TT. After adjustment for multiple testing using false-discovery rate method, the significant difference of HDL-C, triglyceride, dietary fat, and carbohydrate across genotypes disappeared. Gene-diet interaction effects between rs2814863 and macronutrients intake were not significantly associated with HDL-C and triglyceride levels. However, carriers of C allele demonstrated significantly higher odds of CVD {odds ratio=1.13, 95% CI=1.02-1.25} compared with carriers of TT. CONCLUSIONS: Our findings support significant associations between the mGluR1 rs2814863 genotype and CVD-related variables in Korean adults. However, these associations are not modified by macronutrient intake.
Adult* ; Alleles ; Blood Chemical Analysis ; Cardiovascular Diseases* ; Cholesterol, HDL ; Chronic Disease ; Cohort Studies ; Dietary Fats ; Epidemiology ; Genes, vif ; Genetic Variation ; Genome ; Genotype ; Gyeonggi-do ; Humans ; Methods ; Nutritional Status ; Polymorphism, Single Nucleotide ; Receptors, Glutamate ; Receptors, Metabotropic Glutamate* ; Triglycerides

Recent studies indicate that mitochondria are an important source of reactive oxygen species (ROS) in the spinal dorsal horn. In our previous study, application of malate, a mitochondrial electron transport complex I substrate, induced a membrane depolarization, which was inhibited by pretreatment with ROS scavengers. In the present study, we used patch clamp recording in the substantia geletinosa (SG) neurons of spinal slices, to investigate the cellular mechanism of mitochondrial ROS on neuronal excitability. DNQX (an AMPA receptor antagonist) and AP5 (an NMDA receptor antagonist) decreased the malate-induced depolarization. In an external calcium free solution and addition of tetrodotoxin (TTX) for blockade of synaptic transmission, the malateinduced depolarization remained unchanged. In the presence of DNQX, AP5 and AP3 (a group I metabotropic glutamate receptor (mGluR) antagonist), glutamate depolarized the membrane potential, which was suppressed by PBN. However, oligomycin (a mitochondrial ATP synthase inhibitor) or PPADS (a P2 receptor inhibitor) did not affect the substrates-induced depolarization. These results suggest that mitochondrial substrate-induced ROS in SG neuron directly acts on the postsynaptic neuron, therefore increasing the ion influx via glutamate receptors.
Animals ; Calcium ; Electron Transport Complex I ; Glutamic Acid ; Membrane Potentials ; Membranes ; Mitochondria ; Mitochondrial Proton-Translocating ATPases ; N-Methylaspartate ; Neurons* ; Oligomycins ; Rats* ; Reactive Oxygen Species ; Receptors, AMPA ; Receptors, Glutamate ; Receptors, Metabotropic Glutamate ; Spinal Cord Dorsal Horn ; Substantia Gelatinosa* ; Synaptic Transmission ; Tetrodotoxin

Metabotropic glutamate receptor (mGluR)-dependent long-term depression (LTD), a type of synaptic plasticity, is characterized by a reduction in the synaptic response, mainly at the excitatory synapses of the neurons. The hippocampus and the cerebellum have been the most extensively studied regions in mGluR-dependent LTD, and Group 1 mGluR has been reported to be mainly involved in this synaptic LTD at excitatory synapses. However, mGluR-dependent LTD in other brain regions may be involved in the specific behaviors or diseases. In this paper, we focus on five cortical regions and review the literature that implicates their contribution to the pathogenesis of several behaviors and specific conditions associated with mGluR-dependent LTD.
Brain ; Cerebellum ; Depression* ; Hippocampus ; Neuronal Plasticity ; Neurons ; Receptors, Metabotropic Glutamate* ; Synapses