Research progress of 5-HT / 中国药理学通报

The serotonin 2A receptor(5-HT

Anti-mGluR5 encephalitis with mental disorders as the initial symptom： a case report / 四川精神卫生

This article reported the clinical features of a rare patient with anti-metabotropic glutamate receptor 5 （mGluR5） encephalitis with mental disorders as the initial symptom， so as to provide references for clinical diagnosis and treatment. The patient was a 38-year-old male， developed pharyngeal pain as prodromal symptoms， and the main clinical manifestations included rapidly progressive memory loss， anxiety and depression， and psychomotor excitement symptoms including irritability and impulsive behaviors. The disease had a progressive deterioration. In the most severe state， the patient became unconscious in a shallow coma， with further cognitive decline， hallucinations and delusions， and lack of self-awareness. Both cerebrospinal fluid and serum anti-mGluR5 antibody were strongly positive （1∶100）. After two sessions of hormone shock therapy， the patient showed significantly improvement in consciousness， cognitive， emotional and psychiatric dimensions.

The Interaction Between CAL and mGluR1 Alleviates Cytotoxicity Induced by mGluR1 Overactivation / 中国生物化学与分子生物学报

Glutamate excitotoxicity mediated by metabotropic glutamate receptor 1 (mGluR1) overexpression or overactivation plays an important role in the development of Parkinson's disease (PD). Although clinical trials support the therapeutic potential of certain mGluR negative allosteric modulators (NAMs), there are still some limitations of precise modulation of mGluR using NAMs. Thus, the identification of small molecules or endogenous genes that facilitate mGluR1 modulation might be potentially beneficial for PD treatment. We determined the role of interacting partner cystic fibrosis transmembrane conductance regulator-associated ligand (CAL) in overactivated mGluR1-mediated cell apoptosis and signaling pathway in vitro and in vivo. HEK293 cells were used as an experimental tool to directly examine the interaction between CAL and mGluR1. We found that agonist of mGluR1 significantly enhanced the interaction between CAL and mGluR1 (P< 0. 05). Furthermore, CAL suppressed overactivated mGluR1-induced cell apoptosis and the activation of mGluR1 downstream signaling pathways. CAL overexpression relieved rotenone-induced neuron death (P< 0. 001) by inhibiting the activation of mGluR1-mediated signaling pathways in rotenone-induced rat model of PD. This study may reveal a new mechanism of mGluR1 activity regulation, and hopefully provide a novel molecular mechanism for the nervous system related diseases.

Mechanisms of bupivacaine inhibition of glutamate-induced intracellular calcium elevation in primary cultured rat hippocampal astrocytes / 药学学报

This research investigated the mechanism by which bupivacaine inhibits glutamate-induced intracellular free Ca2+ increases in primary cultured hippocampal astrocytes. Immunofluorescence was used to demonstrate the expression of metabotropic glutamate receptor (mGluR5 receptor) on neurons and astrocytes. Calcium imaging was used to measure the alteration of intracellular free Ca2+ ([Ca2+]i) in primary cultured rat hippocampal neurons and astrocytes. The animal experiments were approved by the Animal Experiments Ethical Committee of Hebei Medical University. The results showed that mGluR5 receptor was abundantly expressed in the primary cultured rat neurons and astrocytes. Bupivacaine (300 μmol·L-1) significantly inhibited 1 mmol·L-1 glutamate-induced [Ca2+]i increase in astrocytes (P < 0.01). 2-Methyl-6-(2-phenylethynyl)-pyridine (MPEP) (10 μmol·L-1) completely abolished the increase of [Ca2+]i induced by 1 mmol·L-1 glutamate in the astrocytes (P < 0.01), while the inhibitory effect on neurons was only 10%-20%. Bupivacaine (300 μmol·L-1) completely inhibited the [Ca2+]i increase induced by mGluR5 receptor agonists (RS)-3,5-dihydroxyphenylglycine (DHPG) (50 μmol·L-1) and (RS)-2-chloro-5-hydroxyphenylglycine sodium salt (CHPG) (1 mmol·L-1) in astrocytes (P < 0.01). In addition, bupivacaine inhibited the CHPG-induced [Ca2+]i increase in a dose-dependent manner in astrocytes with an IC50 of 100 μmol·L-1. The results from this study indicate that bupivacaine inhibits glutamate-induced [Ca2+]i elevation by acting on the mGluR5 receptor in primary cultured hippocampal astrocytes.

Effect of rgs4 overexpression on related protein expression of mglur5-mediated signaling pathway in methamphetamine-dependent rat striatum / 中国药理学通报

Aim To investigate the effect of the regulator of G-protein signaling 4(RGS4) overexpression in rat striatum on the related protein expression of metabolic glutamate receptor 5(mGluR5) signaling pathway and the conditioned place preference(CPP) behavior in rats, by establishing the METH-dependent CPP model. Methods Rats were divided into five groups: Normal, normal saline(NS), METH, Ad5-RGS4-EGFP and Ad5-EGFP group. Normal group was without any administration, while the striatum of the other groups were respectively stereotactic injected with phosphate buffer methamphetamine (METH)-depardent soline (PBS), PBS, overexpressed adenovirus vector Ad5-RGS4-EGFP and negative control adenovirus vector Ad5-EGFP. The CPP behavior of rats in each group was analyzed. The expression of RGS4, mGluR5, Gαq, PLC1 was measured in rat striatum tissue by Western blot. Results The difference of CPP in Ad5-RGS4-EGFP group decreased compared with that in METH group and Ad5-EGFP group(P 0.05). PLCβ1 expression changed with no significant difference. Conclusions RGS4 overexpression in striatum is able to alleviate the CPP behavior in METH-dependent rats, and its mechanism may be associated with the overexpression of RGS4 in METH-dependent rat striatum, which could down-regulate the mGluR5-mediated Gαq and PLCβ1 signaling pathway.

Role of protein tyrosine phosphatase SHP-2 in group I metabotropic glutamate receptors-induced allodynia / 中国药理学通报

Aim To investigate whether the pain modi-fication by group I metabotropic glutamate receptors (mGluRs)required the involvement of Src homology-2 domain-containing phosphatase-2 (SHP-2 ).Methods Co-immunoprecipitation was performed to examine the possible interaction between SHP-2 and group I mGluRs in spinal cord dorsal horn of mice.By measur-ing the paw withdrawal thresholds,the effects of SHP-2 inhibitor NSC-87877 or its catalytically inactive SHP-2 (C459S ) mutant on allodynia induced by group I mGluRs agonist DHPG (50 nmol)were observed.Re-sults Anti-mGluR5 antibody was able to co-immuno-precipitate SHP-2 from spinal dorsal horn of mice, while no SHP-2 was precipitated by anti-mGluR1 anti-body.Inactivation of SHP-2 by NSC-87877 (6 nmol) or SHP-2 (C459S ) effectively attenuated allodynia caused by DHPG.Conclusion SHP-2 can physically interact with mGluR5.The activation of SHP-2 may be necessary for group I mGluRs to process the nocicep-tive information.

Association between Metabotropic Glutamate Receptor 1 Polymorphism and Cardiovascular Disease in Korean Adults

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.

Metabotropic glutamate receptor dependent long-term depression in the cortex

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.

Regulation of DREAM Expression by Group I mGluR

DREAM (downstream regulatory element antagonistic modulator) is a calcium-binding protein that regulates dynorphin expression, promotes potassium channel surface expression, and enhances presenilin processing in an expression level-dependent manner. However, no molecular mechanism has yet explained how protein levels of DREAM are regulated. Here we identified group I mGluR (mGluR1/5) as a positive regulator of DREAM protein expression. Overexpression of mGluR1/5 increased the cellular level of DREAM. Up-regulation of DREAM resulted in increased DREAM protein in both the nucleus and cytoplasm, where the protein acts as a transcriptional repressor and a modulator of its interacting proteins, respectively. DHPG (3,5-dihydroxyphenylglycine), a group I mGluR agonist, also up-regulated DREAM expression in cortical neurons. These results suggest that group I mGluR is the first identified receptor that may regulate DREAM activity in neurons.

mGluR5 is a central regulator of synaptic function and plasticity in the developing mouse barrel cortex.

Glutamate, the main excitatory neurotransmitter in the vertebrate brain, acts both on ligand-gated ion channels as well as on metabotropic receptors (mGluRs), which engage an array of biochemical regulatory pathways via activation of G-proteins. mGluRs have been shown to exert central roles in the regulation of neuronal excitability by both pre- and post-synaptic mechanisms, and consequently have been implicated in a variety of central nervous system functions that include, but are not limited to, learning, pain perception and anxiety. There exists three groups of mGluRs (types I, II and III), accounting for a total of eight different mGluR types (mGluR1-8) (Hollmann and Heinemann 1994). Group I mGluRs, which encompass mGluR1 and mGluR5, engage Gq-dependent second messenger systems which, in turn, regulate post-synaptic activity and local protein synthesis. Abnormal signalling through group I mGluRs have been associated with a series of neurological disorders including Fragile X syndrome and schizophrenia (Dolen and Bear 2008; Krivoy et al. 2008). Importantly, group I mGluRs have been shown to regulate synaptic plasticity both in developing and adult organisms. Noteworthy, genetic or pharmacological manipulations directed at mGluR5-containing receptors signifi cantly impair learning and memory formation (Lu et al. 1997; Chiamulera et al. 2001). These roles for mGluR5 correlate with marked experience-dependent changes in synaptic strength, including long-term potentiation and depression (Eckert and Racine 2004). The impact of mGluR5 activity on synaptic function and plasticity suggested that activation of this receptor may constitute a central molecular component underlying the developmental establishment and/or experience-dependent refi nement of sensory maps found in primary sensory cortex of mammals. Such a role for mGluR5 was recently confi rmed in an elegant study by She and colleagues (2009) recently published in the European Journal of Neuroscience. These authors report that mice devoid of the mGluR5 receptor expression (mGluR5–/–) lack the normal arrangement of thalamocortical afferents and layer IV cell bodies associated with the rostral smaller whiskers of the facial vibrissal system, commonly referred to as the barrel cortex. Interestingly, the anatomical organisation of the thalamocortical afferents carrying information from the caudal and larger vibrissae was preserved in mGluR5–/– mice. These animals, however, lack the aggregation of the cortical layer IV cell bodies into clusters that would, in wild-type or heterozygous mice (mGluR5+/–), exclusively represent each vibrissa. In addition, it was found that mGluR5-null mice exhibit a striking mis-alignment of the dendritic fi elds of spiny stellate neurons, which contribute to the formation of the classic columnar neuronal arrangements typical of the barrel cortex. In particular, in intact mice, dendritic fi elds of layer IV neurons are normally oriented towards the barrel center, an organisation that putatively oversamples inputs from the dominant vibrissae to sharpen the perceptual experience of sensory drive from each whisker (Harris and Woolsey 1981). In mGluR5-defi cient mice, dendritic fi elds are more dispersed suggesting that pruning or mobility may be mal-adaptive in these animals, and may ultimately compromise the resolution at which sensory input can be processed. It was found that at post-natal weeks 2–3, mGluR5–/– mice failed to show the expected polarisation of dendritic fi elds towards the barrel center and that this abnormal pattern persists into adulthood. Interestingly, the anatomical patterning of axonal terminations from thalamocortical afferents was appropriate for barrel formation, and functional synaptic transmission for sensory-driven responses was spared. Malformation of the barrel cortex in mGluR5–/– therefore appears to result from abnormalities in intra-cortical properties and localised to post-synaptic neurons targeted by the thalamocortical afferents. Consistent with abnormalities in the formation of the barrel cortex in mGluR5–/– mice, these mutant animals show reduced latency to the surround whisker responses. This feature is shared with barrelless.

The protective effect of LY367385 on impairment of cultured mouse cerebral cortical neurons induced by sodium glutamate or oxygen-glucose deprivation / 中国康复理论与实践

@#ObjectiveTo investigate the protective effect of LY367385 on impairment of cultured mouse cerebral cortical neurons induced by sodium glutamate (Glu) or oxygen-glucose deprivation (OGD).MethodsNeuron damage induced by Glu or OGD, as well as the action of (S)-(+)-a-amino-4-carboxy-2-methylbenzeneacetic acid (LY367385) were measured by determining the leakage of lactate dehydrogenase (LDH) from neurons. Immunocytochemistry and immunofluorescent methods were used to detect the expression of anti-mGluR1α. Morphological observation of primary cortical neurons was performed by phase contrast microscope.ResultsFollowing the exposure to 0.1 mmol/L Glu for 1 h or OGD for 1 h, LDH leakage from neurons obviously increased (P< 0.01 ). 50 mmol/L LY367385, when co-incubated with Glu or OGD, markedly reduced the LDH leakage (P<0.01). The 24-h leakage of LDH was increased from cells exposed to 0.1 mmol/L Glu for 15 min. Pre-and post-treatment with LY367385 (50 mmol/L ) decreased the leakage of LDH. The cultured neurons expressed mGluR1α.ConclusionLY367385 has protective effect on neurons damaged by Glu or OGD. It may be related to antagonizing mGluR1α.

Presynaptic Mechanism Underlying Regulation of Transmitter Release by G Protein Coupled Receptors

A variety of G protein coupled receptors (GPCRs) are expressed in the presynaptic terminals of central and peripheral synapses and play regulatory roles in transmitter release. The patch-clamp whole-cell recording technique, applied to the calyx of Held presynaptic terminal in brainstem slices of rodents, has made it possible to directly examine intracellular mechanisms underlying the GPCR-mediated presynaptic inhibition. At the calyx of Held, bath-application of agonists for GPCRs such as GABAB receptors, group III metabotropic glutamate receptors (mGluRs), adenosine A1 receptors, or adrenaline alpha2 receptors, attenuate evoked transmitter release via inhibiting voltage-activated Ca2+ currents without affecting voltage-activated K+ currents or inwardly rectifying K+ currents. Furthermore, inhibition of voltage-activated Ca2+ currents fully explains the magnitude of GPCR-mediated presynaptic inhibition, indicating no essential involvement of exocytotic mechanisms in the downstream of Ca2+ influx. Direct loadings of G protein beta gamma subunit (G beta gamma) into the calyceal terminal mimic and occlude the inhibitory effect of a GPCR agonist on presynaptic Ca2+ currents (IpCa), suggesting that G beta gammamediates presynaptic inhibition by GPCRs. Among presynaptic GPCRs glutamate and adenosine autoreceptors play regulatory roles in transmitter release during early postnatal period when the release probability (p) is high, but these functions are lost concomitantly with a decrease in p during postnatal development.

Expression of mGluR1 in hippocampus of spontaneously epileptic rats / 中国药理学通报

Aim To investigate the expression of mGluR1 in hippocampus of spontaneously epileptic rats(SER) by control study.Methods Total RNA was extracted from hippocampus of SER and Wistar rats,and mGluR1 mRNA expression was detected by RT-PCR;the expression of mGluR1 protein was detected by immunohistochemistry and Western blot.Results mGluR1 mRNA of SER was lower than that of Wistar rats in hippocampus(P0.05) were found.In positive cells,mGluR1 proteins were enhanced.By Western blot,total mGluR1 protein was down-regulated in SER hippocampus(P

The effects of a rotating magnetic field on Li pilocarpine-induced seizures in rats / 中华物理医学与康复杂志

Objective To study the effects of a rotating magnetic field(RMF)on Li pilocarpine-in- duced seizure activity and the expression of mGluR1 and mGluR5 in the hippocampus.Methods Thirty rats were divided into 5 groups.Each rat in the model(M),short treatment(ST)and long treatment(LT)groups was treated with intra-peritoneal injections of lithium chloride(60 mg/kg),followed by an intra-peritoneal injec- tion of pilocarpine(35 mg/kg)24 h later.The rats in the ST group were exposed to 20 mT RMF for 20 min ev- ery day for 3 d before seizure induction,while the rats in LT group were exposed to the same RMF for 8 d.The latency,severity and duration of seizure,as well as accompanying symptoms and electroencephalogram data, were recorded,and the expression of mGluR1 and mGluR5 was calculated using an electrophoretic imaging anal- ysis system.Results The duration,times and accompanying symptoms of seizure were significantly decreased in the LT group.The mGluR1 mRNA level and mGluR1/mGluR5 ratio in the M group were markedly increased, but the mGluR5 mRNA level was obviously decreased,while the expression of mGluR1 in the ST and LT groups was decreased,and mGluR5 was increased.Conclusions Seizure activity in rats can be inhibited by 20 mT RMF,and the expression of mGluRl and mGluR5 in the hippocampus of rats suffering seizures can be markedly influenced by longer-term RMF.

Molecular Biologic Study on the Changes of Glutamate Receptor (mGluR5) in Rat Hippocampus after Brain Ischemia / 대한구급학회지

BACKGROUND: Metabotropic glutamate receptors (mGluRs) participate in the induction of synaptic plasticity phenomena, such as long-term potentiation and long-term depression that are thought to be at the origin of learning and memory. They are also likely to play a role in modulating glutamate-induced neurotoxicity. It will become apparent that mGluRs are excellent targets for the development of drugs that modulate excitatory synaptic transmission. But there were several controversies about the exact role of group 1 mGluRs subtype 5 (mGluR5). This study was designed for evaluation of the neuroprotective role of mGluR5. METHODS: Fifty male Sprague-Dawley rats were divided into three groups, control, MK-801 and lamotrigine. The hippocampus and basal ganglia were removed at 6 hours and 3 days after the one hour transient middle cerebral artery occlusion. The gene expression of mRNA of the brain samples were evaluated by using reverse transcriptase polymerase chain reaction technique. RESULTS: The gene expression of mGluR5 mRNA in hippocampus was increased by 101.96 +/- 18.45% at 6 hours after ischemia and decreased by 50.70 +/- 15.73% at 3 days after ischemia (p<0.01). MK-801 and lamotrigine attenuated the ischemia-induced increases of gene expression of mGluR5 mRNA. In MK-801 group, the expression in basal ganglia was increased by only 0.23 +/- 5.41% at 6 hours after ischemia and decreased by 9.82 +/- 4.35% at 3 days after ischemia. In MK-801 group, the expression in hippocampus was decreased by 3.45 +/- 8.24% and 9.35 5.69% at 6 hours and 3 days after ischemia. In lamotrigine group, the expressions in hippocampus and basal ganglia were decreased by 26.66 +/- 9.85% and 9.45 +/- 5.22% at 6 hours after ischemia. CONCLUSIONS: From these results, the role of mGluR5 was defined as a mediator for neuronal damage after transient focal cerebral ischemia in hippocampus and basal ganglia.

THE CHANGE IN mGluR1? IN CA_1 AFTER INFRASONIC DAMAGE AND THE EFFECT OF ITS ANTAGONIST MCPG / 解放军医学杂志

To study the change in mGluR1? in CA 1 after infrasonic damage and the effect of its antagonist MCPG,120 SD rats were randomizied into infrasonic damage group and MCPG therapy group.The two groups were subdivided into control group and 1 challenge, 7 chellenges, 14 challenge groups respectively,each group consisted of 15 rats. Rats were exposed to 8Hz 130dB infrasound as designed,2h for each challenge.The mGluR1? was stained by immunohistochemistry method.The changes in mGluR1? and cell pattern were observed under light and electronic microscopes.The results showed the number of mGluR1? positive neurons increased after 1 challenge infrasonic damage( P 0 05).MCPG had an effect to protect neuron from infrasonic damage as identified by morphology.It is concluded that the change of mGluR1? activity could mediate excitotoxicity and was one of the major factors related with neuron injury after infrasound.