mGluR5 mRNA Research Articles

LncRNA-AC130710/miR-129-5p/mGluR1 axis promote migration and invasion by activating PKCα-MAPK signal pathway in melanoma.

Invasion and metastasis of melanoma are a series of complicated biological events regulated by multiple factors. The coregulation of many molecules involved in the development and progression of melanoma contributes to invasion and migration. mGluR1 is a metabotropic glutamate receptor that is overexpressed in melanocytes and is sufficient to induce melanoma. In our study, we found that mGluR1 was obviously increased in melanoma. Furthermore, we found that miR-129-5p could directly target and regulate mGluR1 mRNA, which was significantly reduced in A375 cells. Overexpression of miR-129-5p inhibited cell migration, invasion and clonal formation. lncRNA-AC130710 directly targeted and suppressed miR-129-5p in A375 cells. Downregulation of lncRNA-AC130710 suppressed the levels of mGluR1 mRNA by promoting miR-129-5p expression and further inhibiting migration, invasion and colony formation in A375 cells, which was associated with the activation of the PKCα-MAPK signaling pathway. Taken together, our study showed that the lncRNA-AC130710/miR-129-5p/mGluR1 axis plays an important role in the invasion and metastasis of melanoma.

The Anti-Inflammatory Effect of Preventive Intervention with Ketogenic Diet Mediated by the Histone Acetylation of mGluR5 Promotor Region in Rat Parkinson’s Disease Model: A Dual-Tracer PET Study

Materials and Methods The neuroprotective effect of ketosis state prior to the onset of PD (preventive KD, KDp) was compared with that receiving KD after the onset (therapeutic KD, KDt) in the lipopolysaccharide- (LPS-) induced rat PD model. A total of 100 rats were randomly assigned to the following 4 groups: sham, LPS, LPS + KDp, and LPS + KDt groups. Results Significant dopamine deficient behaviors (rotational behavior and contralateral forelimb akinesia), upregulation of proinflammatory mediators (TNF-α, IL-1β, and IL-6), loss of dopaminergic neurons, reduction of mGluR5+ microglia cells, increase of TSPO+ microglia cells, reduction of H3K9 acetylation in the mGluR5 promoter region and mGluR5 mRNA expression, and decline in the phosphorylation levels of Akt/GSK-3β/CREB pathway were observed after the intervention of LPS (P < 0.01). TSPO and DAT PET imaging revealed the increased uptake of 18F-DPA-714 in substantia nigra and decreased uptake of 18F-FP-CIT in substantia nigra and striatum in LPS-treated rats (P < 0.001). These impairments were alleviated by the dietary intervention of KD, especially with the strategy of KDp (P < 0.05). Conclusions The anti-inflammatory effect of KD on PD was supposed to be related to the modulation of Akt/GSK-3β/CREB signaling pathway mediated by the histone acetylation of mGluR5 promotor region. The KD intervention should be initiated prior to the PD onset in high-risk population to achieve a more favorable outcome.

Changes in Metabotropic Glutamate Receptor Gene Expression in Rat Brain in a Lithium-Pilocarpine Model of Temporal Lobe Epilepsy.

Preventing epileptogenesis in people at risk is an unmet medical need. Metabotropic glutamate receptors (mGluRs) are promising targets for such therapy. However, drugs acting on mGluRs are not used in the clinic due to limited knowledge of the involvement of mGluRs in epileptogenesis. This study aimed to analyze the changes in gene expression of mGluR subtypes (1–5, 7, 8) in various rat brain regions in the latent and chronic phases of a lithium–pilocarpine model of epilepsy. For this study, multiplex test systems were selected and optimized to analyze mGluR gene expression using RT-qPCR. Region- and phase-specific changes in expression were revealed. During the latent phase, mGluR5 mRNA levels were increased in the dorsal and ventral hippocampus, and expression of group III genes was decreased in the hippocampus and temporal cortex, which could contribute to epileptogenesis. Most of the changes in expression detected in the latent stage were absent in the chronic stage, but mGluR8 mRNA production remained reduced in the hippocampus. Moreover, we found that gene expression of group II mGluRs was altered only in the chronic phase. The study deepened our understanding of the mechanisms of epileptogenesis and suggested that agonists of group III mGluRs are the most promising targets for preventing epilepsy.

Alterations in the transcriptional profile of genes related to glutamatergic signalling in animal models of Alzheimer's disease. The effect of fingolimod.

Alzheimer's disease (AD) is a multi-factorial illness that leads to progressive cognitive impairment. A glutamatergic system dysfunction has been reported to be implicated in the pathomechanism of AD. Therefore, in the current study we characterized the transcriptional profile of glutamate-related genes in transgenic AbPP V717I (TgAD) and sporadic (SAD, streptozotocin-induced) models of AD. Genes encoding glutamate membrane-bound (GLAST, GLT1, EAAC1) and vesicular (VGLUT1-3) transporters as well as ionotropic (AMPA, NMDA) and metabotropic (mGluR3, mGluR5) receptors were analysed. Based on qPCR analysis, we observed a discrepancy between TgAD and SAD mice in the profile of targeted genes. We noticed age-dependent upregulation of genes encoding VGLUT1, NMDAR1 and mGluR3 in 12-month-old TgAD mice. In the SAD model upregulation of genes encoding AMPAR1 and NMDAR1 as well as downregulation of GLAST, VGLUT3 and mGluR5 were found. Next, the effect of fingolimod (FTY720) was indicated. In the TgAD model, the drug reversed altered transcription of the mGluR3 glutamate receptor to the control level, whereas in the SAD model it downregulated the genes encoding VGLUT1, AMPAR2 and mGluR3. Interestingly, FTY720 influenced mGluR3 mRNA in both examined models. Observed alterations of gene transcription and the effects of FTY720 may potentially constitute an interesting target for further pharmacological studies.

Neonatal maternal separation affects metabotropic glutamate receptor 5 expression and anxiety-related behavior of adult rats.

Exposure to early life stress leads to long-term neurochemical and behavioral alterations. Stress-induced psychiatric disorders, such as depression, have recently been linked to dysregulation of glutamate signaling, mainly via its postsynaptic receptors. The role of metabotropic glutamate receptor 5 (mGluR5) in stress-induced psychopathology has been the target of several studies in humans. In rodents, blockade of mGluR5 produces antidepressant-like actions, whereas mice lacking mGluR5 exhibit altered anxiety-like behaviors and learning. In this study, we used well-known rodent models of early life stress based on mother-infant separation during the first 3 weeks of life in order to examine the effects of neonatal maternal separation on mGluR5 expression and on anxiety-related behavior in adulthood. We observed that brief (15 min) neonatal maternal separation, but not prolonged (3h), induced increases in mGluR5 mRNA and protein expression levels in medial prefrontal cortex and mGluR5 protein levels in dorsal, but not ventral, hippocampus of adult rat brain. Behavioral testing using the open-field and the elevated-plus maze tasks showed that brief maternal separations resulted in increased exploratory and decreased anxiety-related behavior, whereas prolonged maternal separations resulted in increased anxiety-related behavior in adulthood. The data indicate that the long-lasting effects of neonatal mother-offspring separation on anxiety-like behavior and mGluR5 expression depend on the duration of maternal separation and suggest that the increased mGluR5 receptors in medial prefrontal cortex and hippocampus of adult rats exposed to brief neonatal maternal separations may underlie their heightened ability to cope with stress.

Amyloid-β (1-42) peptide induces rapid NMDA receptor-dependent alterations at glutamatergic synapses in the entorhinal cortex

The hippocampus and entorhinal cortex (EC) accumulate amyloid beta peptides (Aβ) that promote neuropathology in Alzheimer's disease, but the early effects of Aβ on excitatory synaptic transmission in the EC have not been well characterized. To assess the acute effects of Aβ1-42 on glutamatergic synapses, acute brain slices from wildtype rats were exposed to Aβ1-42 or control solution for 3 hours, and tissue was analyzed using protein immunoblotting and quantitative PCR. Presynaptically, Aβ1-42 induced marked reductions in synaptophysin, synapsin-2a mRNA, and mGluR3 mRNA, and increased both VGluT2 protein and Ca2+-activated channel KCa2.2 mRNA levels. Postsynaptically, Aβ1-42 reduced PSD95 and GluN2B protein, and also downregulated GluN2B and GluN2A mRNA, without affecting scaffolding elements SAP97 and PICK1. mGluR5 mRNA was strongly increased, while mGluR1 mRNA was unaffected. Blocking either GluN2A- or GluN2B-containing NMDA receptors did not significantly prevent synaptic changes induced by Aβ1-42, but combined blockade did prevent synaptic alterations. These findings demonstrate that Aβ1-42 rapidly disrupts glutamatergic transmission in the EC through mechanisms involving concurrent activation of GluN2A- and GluN2B-containing NMDA receptors.

Metabotropic glutamate receptor 5 regulates synaptic plasticity in a chronic migraine rat model through the PKC/NR2B signal

BackgroundThe mechanism of chronic migraine (CM) is complex, central sensitization is considered as one of the pathological mechanism. Synaptic plasticity is the basis of central sensitization. Metabotropic glutamate receptor 5 (mGluR5) plays a vital role in the synaptic plasticity of the central nervous system. However, whether mGluR5 can promote the central sensitization by regulating synaptic plasticity in CM is unknown.MethodsMale Wistar rats were used to establish a CM rat model, and the expression of mGluR5 mRNA and protein were detected by qRT-PCR and western blot. The allodynia was assessed by mechanical and thermal thresholds, and central sensitization was assessed by expression of the phosphorylation of cyclic adenosine monophosphate (cAMP) response element-binding protein (CREB) at Serine 133(pCREB-S133) and c-Fos. The synaptic-associated protein postsynaptic density protein 95 (PSD), synaptophysin (Syp), and synaptophysin-1(Syt-1), synaptic ultrastructure, and dendritic spines were detected to explore synaptic plasticity. The expression of PKC, total NR2B(tNR2B), and phosphorylation of NR2B at Tyr1472(pNR2B-Y1472) were detected by western blot.ResultsWe found that the expression of mGluR5 was upregulated in CM rats. Downregulated the mGluR5 with MPEP alleviated the allodynia and reduced the expression of CGRP, pCREB-S133, c-Fos, PSD, Syp and Syt-1 and synaptic transmission. Moreover, the administration of MPEP inhibited the upregulation of PKC and pNR2B-Y1472.ConclusionsThese results indicate that mGluR5 contributes to central sensitization by regulating synaptic plasticity in CM through the PKC/NR2B signal, which suggests that mGluR5 may be a potential therapeutic candidate for CM.

Methamphetamine pre-exposure induces steeper escalation of methamphetamine self-administration with consequent alterations in hippocampal glutamate AMPA receptor mRNAs

Methamphetamine use disorder (MUD) is often modeled using rodent self-administration (SA) experiments. Noncontingent injections of a drug given to rodents before self-administration training can increase drug SA. In the present study, we injected methamphetamine before putting rats through methamphetamine SA to investigate SA escalation. We also measured consequent changes in the expression of glutamate receptors in the hippocampus. Experimental groups included rats that received the methamphetamine injection prior to self-administration (MM) and those that received a prior saline injection before they underwent methamphetamine SA (SM). After SA training, rats also underwent tests of relapse potentials at one day and one month after withdrawal from methamphetamine SA. We used qPCR to identify potential changes in mRNA expression of AMPA, NMDA, and mGluR glutamate receptors. MM rats showed greater escalated methamphetamine intake in comparison to SM animals. There were no differences in incubation of methamphetamine craving between the two groups. In the hippocampus, MM rats showed decreased levels of GluA2 and GluA3 mRNAs in comparison to controls and of GluN2c mRNA in comparison to SM rats. In addition, SM rats had increased mGluR3 mRNA levels in comparison to control and MM rats. These data implicate hippocampal glutamate receptors in the longterm effects of methamphetamine. Further studies are necessary to identify the specific role that changes in the expression of these receptors might play in escalated intake of methamphetamine by human users.

Establishment of a rat model with ageing insomnia induced by D-galactosef and para-chlorophenylalanine.

The current study aimed to establish a rat model of ageing insomnia induced by D-galactose and/or para-chlorophenylalanine. Following establishment of the model, body weights were measured, and Morris water maze and pentobarbital-induced sleep tests were performed. The serum levels of inflammatory mediators and the neural levels of neurotransmitters were detected. The results demonstrated that the body weights of PCPA+D-gal-induced ageing insomnia rats decreased significantly. Ageing insomnia rats exhibited longer latencies to the platform in the Morris water maze tests and fewer target crossings. The sleep latency of the model rats was longer and sleep time was shorter by contrast. The relative expression of hippocampal IL-6, TNF-α, NF-κB and mGluR2 mRNA of the PCPA+D-gal-induced ageing insomnia group was higher, while the relative expression of 5-HT1AR and GABAARa1 mRNA were lower. The serum levels of IL-1β, IL-6, TNF-α and brain level of glutamate increased in the PCPA+D-gal-induced ageing insomnia group, while the levels of 5-HT and GABA decreased. In conclusion, memory function, sleep time, expression of inflammatory factors and neurotransmitters are altered in ageing insomnia rats induced by D-galactose and para-chlorophenylalanine, indicating the successful establishment of a murine model of ageing insomnia.

Excitatory amino acid transporter (EAAT)1 and EAAT2 mRNA levels are altered in the prefrontal cortex of subjects with schizophrenia

Excitatory amino acid transporter (EAAT)1 and EAAT2 mediate glutamatergic neurotransmission and prevent excitotoxicity through binding and transportation of glutamate into glia. These EAATs may be regulated by metabotropic glutamate receptor 5 (mGluR5), which is also expressed by glia. Whilst we have data from an Affymetrix™ Human Exon 1.0 ST Array showing higher levels of EAAT1 mRNA (+36%) in Brodmann's are (BA)9 of subjects with schizophrenia, there is evidence that EAAT1 and EAAT2, as well as mGluR5 levels, are altered in the cortex of subjects with the disorder. Hence, we measured mRNA levels of these genes in other cortical regions in subjects with that disorder. EAAT1, EAAT2 and mGluR5 mRNA were measured, in triplicate, using Quantitative PCR in BA10 and BA46 from subjects with schizophrenia (n = 20) and age and sex matched controls (n = 18). Levels of mRNA were normalised to the geometric mean of two reference genes, transcription factor B1, mitochondrial (TFB1M) and S-phase kinase-associated protein 1A (SKP1A), for which mRNA did not vary between diagnostic groups in either region. Normalised levels of EAAT1 and EAAT2 mRNA were significantly higher in BA10 (EAAT1: U = 58, p = 0.0002; EAAT2 U = 70, p = 0.0009), but not BA46 (EAAT1: U = 122, p = 0.09; EAAT2: U = 136, p = 0.21), from subjects with schizophrenia compared to controls. mGluR5 levels in BA10 (U = 173, p=0.85) and BA46 (U = 178, p = 0.96) did not vary by cohort. Our data suggests that region-specific increases in cortical EAAT1 and EAAT2 mRNA are involved in schizophrenia pathophysiology and that disrupted glutamate uptake in schizophrenia may be of particular significance in BA10.

Transgenerational deep sequencing revealed hypermethylation of hippocampal mGluR1 gene with altered mRNA expression of mGluR5 and mGluR3 associated with behavioral changes in Sprague Dawley rats with history of prolonged febrile seizure.

The impact of febrile seizure has been shown to transcend immediate generation with the alteration of glutamatergic pathway being implicated. However, transgenerational effects of this neurological disorder particularly prolonged febrile seizure (PFS) on neurobehavioral study and methylation profile is unknown. We therefore hypothesized that transgenerational impact of prolonged febrile seizure is dependent on methylation of hippocampal mGluR1 gene. Prolonged febrile seizure was induced on post-natal day (PND) 14, by injecting lipopolysaccharide (LPS; 217μg/kg ip) and kainic acid (KA; 1.83 mg/kg ip). Sucrose preference test (SPT) and Forced swim test (FST) were carried out in the first generation (F0) of animals at PND37 and PND60. The F0 rats were decapitated at PND 14, 37 and 60 which corresponded to childhood, adolescent and adulthood respectively and their hippocampal tissue collected. The second generation (F1) rats were obtained by mating F0 generation at PND 60 across different groups, F1 rats were subjected to SPT and FST test on PND 37 only. Decapitation of F1rats and collection of hippocampal tissues were done on PND 14 and 37. Assessment of mGluR5 and mGluR3 mRNA was done with PCR while mGluR1 methylation profile was assessed with the Quantitative MassARRAY analysis. Results showed that PFS significantly leads to decreased sucrose consumption in the SPT and increased immobility time in the FST in both generations of rats. It also leads to significant decrease in mGluR5 mRNA expression with a resultant increased expression of mGluR3 mRNA expression and hypermethylation of mGluR1 gene across both generations of rats. This study suggested that PFS led to behavioral changes which could be transmitted on to the next generation in rats.

Study on Effect of Striatal mGluR2/3 in Alleviating Motor Dysfunction in Rat PD Model Treated by Exercise Therapy.

Background: Exercise therapy has been widely applied in clinical rehabilitation as an important practical and side effect—free adjuvant therapy, with a significant effect in alleviating motor dysfunction of patients with Parkinson’s disease (PD) or animal PD models. This study focuses on the effect of exercise therapy in reducing the concentration of extracellular glutamate (Glu) in the striatum in a rat PD model by upregulating the expression of group II metabotropic Glu receptor (mGluR2/3), so as to alleviate motor dysfunction in the rat PD model.Methods: Neurotoxin 6-hydroxydopamine (6-OHDA) was injected into the right medial forebrain bundle (MFB) of the rats to establish the semi-lateral cerebral damage PD model. The sham-operated group was given an equal amount of normal saline at the same site and taken as the control group. The apomorphine (APO)-induced rotational behavior test combined with immunohistochemical staining with tyrosine hydroxylase (TH) in the substantia nigra (SNc) and striatum was performed to assess the reliability of the model. The exercise group was given treadmill exercise intervention for 4 weeks (11 m/min, 30 min/day, 5 days/week) 1 week after the operation. The open field test (OFT) was performed to assess the locomotor activity of the rats; the Western blot technique was used to detect SNc TH and striatal mGluR2/3 protein expressions; real-time polymerase chain reaction (RT-PCR) was applied to detect striatal mGluR2 and mGluR3 mRNA expressions; the microdialysis—high-performance liquid chromatography (HPLC) method was adopted to detect the concentration of extracellular Glu in striatal neurons.Results: Compared with the control group, the number of rotations of each model group at the first week was significantly increased (P < 0.01); compared with the PD group, the number of rotations of the PD + exercise group at the third week and the fifth week was significantly decreased (P < 0.05, P < 0.01). Compared with the control group, the total movement distance, the total movement time, and the mean velocity of each model group at the first week were significantly reduced (P < 0.05); compared with the PD group, the total movement distance, the total movement time, and the mean velocity of the PD + exercise group at the third week and the fifth week were significantly increased (P < 0.01). Compared with the control group, the count of immunopositive cells and protein expression of SNc TH, and the content of immunopositive fiber terminals in the striatal TH of each model group significantly declined (P < 0.01). Compared with the PD group, the striatal mGluR2/3 protein expression of the PD + exercise group significantly rose (P < 0.01). Compared with the control group, the concentration of extracellular Glu in striatal neurons of each model group at the first week significantly grew (P < 0.05); compared with the PD group, the concentration of extracellular Glu in striatal neurons of the PD + exercise group at the third week and the fifth week was significantly decreased (P < 0.01); compared with the PD + exercise group, the concentration of extracellular Glu in striatal neurons of the group injected with mGluR2/3 antagonist (RS)-1-amino-5-phosphonoindan-1-carboxylic acid (APICA) into the striatum at the third week and the fifth week was significantly increased (P < 0.05, P < 0.01). Compared with the control group, the striatal mGluR2/3 protein expression of the PD group was significantly downregulated (P < 0.01); compared with the PD group, the striatal mGluR2/3 protein expression of the PD + exercise group was significantly upregulated (P < 0.05); compared with the control group, the striatal mGluR3 mRNA expression of the PD group was significantly downregulated (P < 0.01); compared with the PD group, the striatal mGluR3 mRNA expression of the PD + exercise group was significantly upregulated (P < 0.01); 6-OHDA damage and exercise intervention had no significant effect on the striatal mGluR2 mRNA expression (P > 0.05). Compared with the PD + exercise group, the total movement distance, the total movement time, and the mean velocity of the PD + exercise + APICA group were significantly decreased (P < 0.05); compared with the PD group, the PD + exercise + APICA group had no significant change in the total movement distance, the total movement time, and the mean velocity (P > 0.05).Conclusion: These data collectively demonstrate that the mGluR2/3-mediated glutamatergic transmission in the striatum is sensitive to dopamine (DA) depletion and may serve as a target of exercise intervention for mediating the therapeutic effect of exercise intervention in a rat model of PD.

Acute spatial spread of NO-mediated potentiation during hindpaw ischaemia in mice.

Key points Neuropathic pain spreads spatially beyond the injured sites, and the mechanism underlying the spread has been attributed to inflammation occurring in the spinal cord.However, the spatial spread of spinal/cortical potentiation induced by conduction block of the peripheral nerves can be observed prior to inflammation.In the present study, we found that spreading potentiation and hypersensitivity acutely induced by unilateral hindpaw ischaemia are nitric oxide (NO)‐dependent and that NO is produced by ischaemia and quickly diffuses within the spinal cord.We also found that NO production induced by ischaemia is not observed in the presence of an antagonist for group II metabotropic glutamate receptors (mGluRs) and that neuronal NO synthase‐positive dorsal horn neurons express group II mGluRs.These results suggest strongly that NO‐mediated spreading potentiation in the spinal cord is one of the trigger mechanisms for neuropathic pain. Cortical/spinal responses to hindpaw stimulation are bilaterally potentiated by unilateral hindpaw ischaemia in mice. We tested the hypothesis that hindpaw ischaemia produces nitric oxide (NO), which diffuses in the spinal cord to induce spatially spreading potentiation. Using flavoprotein fluorescence imaging, we confirmed that the spreading potentiation in hindpaw responses was induced during ischaemia in the non‐stimulated hindpaw. This spreading potentiation was blocked by spinal application of l‐NAME, an inhibitor of NO synthase (NOS). Furthermore, no spreading potentiation was observed in neural NOS (nNOS) knockout mice. Spinal application of an NO donor was enough to induce cortical potentiation and mechanical hypersensitivity. The spatial distribution of NO during unilateral hindpaw ischaemia was visualized using 4‐amino‐5‐methylamino‐2′,7′‐difluorofluorescein (DAF‐FM). An increase in fluorescence derived from the complex of DAF‐FM with NO was observed on the ischaemic side of the spinal cord. A similar but smaller increase was also observed on the contralateral side. Somatosensory potentiation after hindpaw ischaemia is known to be inhibited by spinal application of LY354740, an agonist of group II metabotropic glutamate receptors (mGluRs). We confirmed that the spinal DAF‐FM fluorescence increases during hindpaw ischaemia were not observed in the presence of LY354740. We also confirmed that approximately half of the nNOS‐positive neurons in the superficial laminae of the dorsal horn expressed mGluR2 mRNA. These results suggest that disinhibition of mGluR2 produces NO which in turn induces a spreading potentiation in a wide area of the spinal cord. Such spreading, along with the consequent non‐specific potentiation in the spinal cord, may trigger neuropathic pain.

Metabotropic glutamate receptor subtype 5 is altered in LPS-induced murine neuroinflammation model and in the brains of AD and ALS patients.

The aim of the present study was to determine the expression levels of mGluR5 in different mouse strains after induction of neuroinflammation by lipopolysaccharide (LPS) challenge and in the brains of patients with Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS) post mortem to investigate mGluR5 expression in human neurodegenerative diseases. C57BL/6 and CD1 mice were injected intraperitoneally with either 10mg/kg LPS or saline. mGluR5 and TSPO mRNA levels were measured after 1 and 5days by qPCR, and mGluR5 protein levels were determined by PET imaging with the mGluR5-specific radiotracer [18F]PSS232. mGluR5 expression was evaluated in the post-mortem brain slices from AD and ALS patients using in vitro autoradiography. mGluR5 and TSPO mRNA levels were increased in brains of C57BL/6 and CD1 mice 1day after LPS treatment and remained significantly increased after 5days in C57BL/6 mice but not in CD1 mice. Brain PET imaging with [18F]PSS232 confirmed increased mGluR5 levels in the brains of both mouse strains 1day after LPS treatment. After 5days, mGluR5 levels in CD1 mice declined to the levels in vehicle-treated mice but remained high in C57BL/6 mice. Autoradiograms revealed a severalfold higher binding of [18F]PSS232 in post-mortem brain slices from AD and ALS patients compared with the binding in control brains. LPS-induced neuroinflammation increased mGluR5 levels in mouse brain and is dependent on the mouse strain and time after LPS treatment. mGluR5 levels were also increased in human AD and ALS brains in vitro. PET imaging of mGluR5 levels could potentially be used to diagnose and monitor therapy outcomes in patients with AD and ALS.

PO-187 Exercise reduced the extracellular Glu concentration of striatum neurons in PD model rats by up-regulating mGluR2/3 expression

Objective To investigate the effects of motor intervention on the extracellular Glu concentration and mGluR2/3 mRNA and mGluR2/3 protein expression levels of striatum neurons in PD model rats.&#x0D; Methods Rat model of unilateral injury was established by injecting neurotoxin 6-hydroxydopamine (6-OHDA) into the right brain medial forebrain bundle (MFB)，the sham operation group was given the same dose of normal saline at the same site.Apomorphine (APO) induced rotation behavior test with substantia nigra and striatum TH immunohistochemical staining used to evaluate the reliability of the model. The exercise group began to exercise the treadmill training intervention (11m/min，30min/day，5day/week) at 1 weeks after the operation. Open field experiment and climbing pole experiment used to evaluate the ability of autonomous activity and movement coordination in rats.Western blotting used to detect tyrosine hydroxylase and mGluR2/3 expression level. RT-PCR was used to detect the expression level of mGluR2 and mGluR3 mRNA in the striatum；In vivo microdialysis combined with high performance liquid chromatography (HPLC) used to detect extracellular Glu concentration in striatal neurons. &#x0D; Results The results of the microdialysis combined with high performance liquid chromatography (HPLC) showed that，compared with control group，in PD group，Glu concentration of the extracellular of striatal neurons was significantly increased at third and fifth weeks，and the difference was very significant (P&lt;0.01)；Compared with PD group，in PD+Ex group，Glu concentration of the extracellular of striatal neurons was significantly decreased at third and fifth weeks，and the difference was very significant (P&lt;0.05，P&lt;0.01)；Compared with the PD+Ex group，in PD+Ex+ APICA group，Glu concentration of the extracellular of striatal neurons was significantly increased at third and fifth weeks，and the difference was very significant (P&lt;0.05, P&lt;0.01). RT-PCR test results indicated that,the expression level of striatal mGluR3 mRNA of PD group decreased compared with the control group，and the difference was significant (P&lt;0.01)；Compared with the PD group，in the PD+Ex group，the expression level of striatal mGluR3 mRNA increased，a the difference was very significant (P&lt;0.01)；6-OHDA damage and exercise intervention had no effect on the expression of striatum mGluR2 mRNA，and the difference was was not significant (P&gt;0.05). Western blotting results indicated that，the expression level of striatum mGluR2/3 protein of PD group was decreased compared with the control group，and the difference was vey significant (P&lt;0.01)，compared with the PD group，in PD+Ex group，the expression level of striatum mGluR2/3 protein was increased，and the difference significant (P&lt;0.05) . The correlation between the extracellular Glu concentration of the striatum neurons and the total moving distance in PD rats showed that，at third weeks，the extracellular Glu concentration of striatal neurons was negatively correlated with the total movement distance (r=-0.82，P&lt;0.05)，at fifth weeks，the extracellular Glu concentration of striatal neurons was negatively correlated with the total movement distance (r=-0.91，P&lt;0.01).&#x0D; Conclusions The expression level of mGluR2/3 decreased in rats with PD model with increased Gu concentration. The decrease of Gulu concentration and the increase of expression level of mGluR2/3 in the striatum striatum of PD model rats could be induced by the training intervention of running platform, which promoted the improvement of motor dysfunction in PD model rats.

The Role of Metabotropic Glutamate Receptor 1 Dependent Signaling in Glioma Viability

Glioma refers to malignant central nervous system tumors that have histologic characteristics in common with glial cells. The most prevalent type, glioblastoma multiforme, is associated with a poor prognosis and few treatment options. On the basis of reports of aberrant expression of mGluR1 mRNA in glioma, evidence that melanoma growth is directly influenced by glutamate metabotropic receptor 1 (mGluR1), and characterization of β-arrestin-dependent prosurvival signaling by this receptor, this study investigated the hypothesis that glioma cell lines aberrantly express mGluR1 and depend on mGluR1-mediated signaling to maintain viability and proliferation. Three glioma cell lines (Hs683, A172, and U87) were tested to confirm mGluR1 mRNA expression and the dependence of glioma cell viability on glutamate. Pharmacologic and genetic evidence is presented that suggests mGluR1 signaling specifically supports glioma proliferation and viability. For example, selective noncompetitive antagonists of mGluR1, CPCCOEt and JNJ16259685, decreased the viability of these cells in a dose-dependent manner, and glutamate metabotropic receptor 1 gene silencing significantly reduced glioma cell proliferation. Also, results of an anchorage-independent growth assay suggested that noncompetitive antagonism of mGluR1 may decrease the tumorigenic potential of Hs683 glioma cells. Finally, data are provided that support the hypothesis that a β-arrestin-dependent signaling cascade may be involved in glutamate-stimulated viability in glioma cells and that ligand bias may exist at mGluR1 expressed in these cells. Taken together, the results strongly suggest that mGluR1 may act as a proto-oncogene in glioma and be a viable drug target in glioma treatment.

Differential mGluR5 expression in response to the same stress causes individually adapted hippocampal network activity

Individual differences in stress vulnerability and resilience have been observed even within a single cohort of inbred rats or mice. Stress phenotypes are typically quantified as changes in the behavior of experimental animals, which is the outcome of altered electrical activity of the brain network. Although mGluR5 is associated with individual vulnerability to stress and can act as a sensitive biomarker of stress adaptation, our understanding of mGluR5-dependent modifications to neural network activities in vivo remains limited. Here, we examined individual rats for changes in hippocampal mGluR5 expression induced by restraint stress and found that these changes cause accompanying changes in hippocampal electroencephalography (EEG) activity. We found six days of restraint stress caused variable changes in hippocampal mGluR5 expression, ranging from 20.9% to 210.7% of the control group. The low mGluR5 protein group (LE) showed increased methylation of the mGluR5 CpG island, reduced mGluR5 mRNA levels, and unaltered basal EEG theta spectral power between stress day 1 and 6. In contrast, the high mGluR5 protein group (HE) showed reduced methylation of CpG sites, increased mGluR5 mRNA expression, and reduced basal theta spectral power on stress day 6. We also found that injection of lentiviruses expressing mGluR5-specific shRNAs into the hippocampus rescued this reduction in baseline theta power in HE rats. These data suggest a causal relationship between individual differences in the changes in hippocampal mGluR5 expression induced by repetitive restraint stress and the accompanying changes in ensemble neural activity in the hippocampus.

Interrelation between expression of HOXA transcript at the distal tip and metabotropic glutamate receptor 1 and their influence on prognosis in pancreatic cancer patients

Objective To investigate the clinical significance and interrelation of long-chain non-coding RNA (lcnRNA) HOXA transcript at the distal tip (HOTTIP) and metabotropic glutamate receptor 1 (mGluR1) in pancreatic cancer patients. Methods Pancreatic cancer samples, which were treated in our hospital were collected. The expression levels of HOTTIP and mGlUR1 mRNA were detected by reverse transcriptase-polymerase chain reaction (RT-PCR) in fresh pancreatic cancer tissue, and those of HOTTIP and mGluR1 protein by Western blotting and immunohistochemistry. Moreover, the relationship between the expression of HOTTIP, mGlUR1 and clinicopathological features was analyzed. Results The levels of HOTTIP and mGlUR1 mRNA and protein were significantly up-regulated in pancreatic cancer tissues as compared with normal pancreatic tissue (P=0.000). The expression of HOTTIP protein was positive in 32 samples (68.09%) and mGlUR1 protein was positive in 30 samples (63.83%). The positive rate of HOTTIP and mGlUR1 in adjacent tissues was 31.91% and 36.17%, respectively, and the difference was also statistically significant (P=0.000). The expression of HOTTIP and mGluR1 was correlated with lymph node metastasis, differentiation degree and TNM stage (P=0.000, 0.004, 0.000). The survival time of HOTTIP and mGlUR1 positive patients was significantly shorter than that of negative patients (P=0.029, 0.047). Cox regression multivariate analysis showed that lymph node metastasis, differentiation degree, TNM stage, HOTTIP and mGlUR1 expression were independent prognostic factors for pancreatic cancer (P=0.022, 0.048, 0.026, 0.000, 0.002). In addition, HOTTIP and mGlUR1 expression showed a significant positive correlation in cervical cancer patients (r=0.689, P=0.002). Conclusion The positive expression of HOTTIP and mGlUR1 is associated with the occurrence, progression and prognosis of pancreatic cancer. Key words: Pancreatic cancer; HOXA transcript at the distal tip; Metabotropic glutamate receptor 1; Pathological features; Prognosis

Abstract 1328: Mechanism of transcriptional regulation of metabotropic glutamate recepter-5 induced by the CXCR4 signaling pathway

Abstract We have previously demonstrated that stromal cell-derived factor (SDF)-1/CXCR4 system enhances the metastases of oral cancer cells via induction of mGluR5. In this study, we examined the transcriptional regulation of mGluR5 induced by the SDF-1/CXCR4 system, using oral cancer cells, B88, which express functional CXCR4 and have highly metastatic potentials. mGluR5 was markedly induced both by the exogenous SDF-1 addition and overexpression of SDF-1 in B88 cells. These induction was completely inhibited by a MEK inhibitor, U0126, and partially inhibited by a PI3K inhibitor, wortmannin. Furthermore, these inhibitors significantly inhibited the SDF-1/CXCR4 dependent cell-migration in the presence or absence of mGluR5 agonist, DHPG. Recently, several investigators demonstrated that activation of the ERK1/2 pathway is responsible for the transcription of several cancer-associated microRNAs (miRNAs). Thus, we performed miRNA microarray in SDF-1 stimulated B88 cells. we isolated miR-30 family which has predictive binding sites in 3'-UTR of mGluR5 mRNA in silico analysis. We now analyze the regulation of these miRNA by MEK/ERK1/2 and PI3K/Akt pathway. Citation Format: Nobuyuki Kuribayashi, Daisuke Uchida, Makoto Kinouchi, Sayaka Izumi, Kyoko Kuribayashi, Hitoshi Kawamata. Mechanism of transcriptional regulation of metabotropic glutamate recepter-5 induced by the CXCR4 signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1328. doi:10.1158/1538-7445.AM2017-1328

Hippocampal GR- and CB1-mediated mGluR5 differentially produces susceptibility and resilience to acute and chronic mild stress in rats

The molecular mechanism of individual response of susceptibility and resilience under psychological stress remains controversial and unclear. The present study aimed to explore the relationship of metabotropic glutamate receptor 5 (mGluR5) with glucocorticoid receptor (GR) or cannabinoid receptor (CB1) and further indicate the molecular mechanism of susceptibility and resilience to acute stress (AS) and chronic mild stress (CMS). Sucrose preference test and open field test were used to evaluate the response of susceptibility and resilience under stress in rats. The mRNA levels and protein expressions of mGluR5, GR, and CB1 were detected. AS induced a 35% reduction in the sucrose intake of rats, and these rats were considered as susceptible to stress; 21% of the rats showed resilience to the stress. Thirty-three percent of rats in the CMS group showed reduced sucrose water intake and were considered susceptible, while 20% of rats were considered resilient. Hippocampal mGluR5 mRNA and protein levels were increased in the susceptible rats. Pharmacological testing showed that GR was positively associated with mGluR5 in susceptible rats in the CMS group, while CB1 was negatively related to mGluR5 in susceptible rats in the AS group. The results suggested that GR and CB1 in the hippocampus might regulate mGluR5 protein and mRNA levels, which might be related to individual responses of susceptibility and resilience under AS and CMS.