RESUMO
Plant glutamate receptors (GLRs) are integral membrane proteins that function as non-selective cation channels, involved in the regulation of developmental events crucial in plants. Knowledge of these proteins is restricted to a few species and their true agonists are still unknown in plants. Using tomato SlGLRs, a search was performed in the pepper database to identify GLR sequences in habanero pepper (Capsicum chinense Jacq.). Structural, phylogenetic, and orthology analysis of the CcGLRs, as well as molecular docking and protein interaction networks, were conducted. Seventeen CcGLRs were identified, which contained the characteristic domains of GLR. The variation of conserved residues in the M2 transmembrane domain between members suggests a difference in ion selectivity and/or conduction. Also, new conserved motifs in the ligand-binding regions are reported. Duplication events seem to drive the expansion of the species, and these were located in the evolution by using orthologs. Molecular docking analysis allowed us to identify differences in the agonist binding pocket between CcGLRs, which suggest the existence of different affinities for amino acids. The possible interaction of some CcGLRs with proteins leads to suggesting specific functions for them within the plant. These results offer important functional clues for CcGLR, probably extrapolated to other Solanaceae.
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Glutamate is one of the most abundant amino acids in the blood. Besides its role as a neurotransmitter in the brain, it is a key substrate in several metabolic pathways and a primary messenger that acts through its receptors outside the central nervous system (CNS). The two main types of glutamate receptors, ionotropic and metabotropic, are well characterized in CNS and have been recently analyzed for their roles in non-neural organs. Glutamate receptor expression may be particularly important for tumor growth in organs with high concentrations of glutamate and might also influence the propensity of such tumors to set metastases in glutamate-rich organs, such as the liver. The study of glutamate transporters has also acquired relevance in the physiology and pathologies outside the CNS, especially in the field of cancer research. In this review, we address the recent findings about the expression of glutamatergic system components, such as receptors and transporters, their role in the physiology and pathology of cancer in non-neural organs, and their possible use as biomarkers and therapeutic targets.
Assuntos
Neoplasias , Humanos , Biomarcadores , Glutamatos , Sistema Nervoso Central , AminoácidosRESUMO
Aim: We investigated: Grin1, Grin2a, Grin2b DNA methylation; NR1 and NR2 mRNA/protein in the prefrontal cortex (PFC); and hippocampus of male Wistar rats exposed to isolation rearing. Materials & methods: Animals were kept isolated or grouped (n = 10/group) from weaning for 10 weeks. Tissues were dissected for RNA/DNA extraction and N-methyl-D-aspartate receptor subunits were analyzed using quantitative reverse transcription (RT)-PCR, ELISA and pyrosequencing. Results: Isolated-reared animals had: decreased mRNA in PFC for all markers, increased NR1 protein in hippocampus and hypermethylation of Grin1 in PFC and Grin2b in hippocampus, compared with grouped rats. Associations between mRNA/protein and DNA methylation were found for both brain areas. Conclusion: This study indicates that epigenetic DNA methylation may underlie N-methyl-D-aspartate receptor mRNA/protein expression alterations caused by isolation rearing.
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Metilação de DNA , Epigênese Genética , Hipocampo/metabolismo , Córtex Pré-Frontal/metabolismo , Receptores de N-Metil-D-Aspartato/genética , Isolamento Social , Animais , Locomoção , Masculino , RNA Mensageiro/metabolismo , Ratos Wistar , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
The NMDA receptor is crucial to several functions in CNS physiology and some of its effects are mediated by promoting nitric oxide production from L-arginine and activation of signaling pathways and the transcription factor CREB. Our previous work demonstrated in retinal cells that increasing intracellular free L-arginine levels directly correlates to nitric oxide (NO) generation and can be promoted by protein synthesis inhibition and increase of free L-arginine concentration. Eukaryotic elongation factor 2 kinase (eEF2K), a calcium/calmodulin-dependent kinase, is also known to be activated by NMDA receptors leading to protein synthesis inhibition. Here we explored how does eEF2K participate in NMDA-induced NO signaling. We found that when this enzyme is inhibited, NMDA loses its ability to promote NO synthesis. On the other hand, when NO synthesis is increased by protein synthesis inhibition with cycloheximide or addition of exogenous L-arginine, eEF2K has no participation, showcasing a specific link between this enzyme and NMDA-induced NO signaling. We have previously shown that inhibition of the canonical NO signaling pathway (guanylyl cyclase/cGMP/cGK) blocks CREB activation by glutamate in retinal cells. Interestingly, pharmacological inhibition of eEF2K fully prevents CREB activation by NMDA, once again demonstrating the importance of eEF2K in NMDA receptor signaling. In summary, we demonstrated here a new role for eEF2K, directly controlling NMDA-dependent nitrergic signaling and modulating L-arginine availability in neurons, which can potentially be a new target for the study of physiological and pathological processes involving NMDA receptors in the central nervous system.
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Sistema Nervoso Central/metabolismo , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismo , Quinase do Fator 2 de Elongação/metabolismo , N-Metilaspartato/farmacologia , Óxido Nítrico/biossíntese , Animais , Arginina/farmacologia , Galinhas , Cicloeximida/farmacologia , Quinase do Fator 2 de Elongação/antagonistas & inibidores , Indazóis/farmacologia , Masculino , Fosforilação/efeitos dos fármacos , Piridinas/farmacologia , Pirimidinas/farmacologia , RatosRESUMO
We examined effects of Group I metabotropic glutamate receptors on the excitability of mouse medial nucleus of the trapezoid body (MNTB) neurons. The selective agonist, S-3,5-dihydroxyphenylglycine (DHPG), evoked a dose-dependent depolarization of the resting potential, increased membrane resistance, increased sag depolarization, and promoted rebound action potential firing. Under voltage-clamp, DHPG evoked an inward current, referred to as IDHPG , which was developmentally stable through postnatal day P56. IDHPG had low temperature dependence in the range 25-34°C, consistent with a channel mechanism. However, the I-V relationship took the form of an inverted U that did not reverse at the calculated Nernst potential for K+ or Cl- . Thus, it is likely that more than one ion type contributes to IDHPG and the mix may be voltage dependent. IDHPG was resistant to the Na+ channel blockers tetrodotoxin and amiloride, and to inhibitors of iGluR (CNQX and MK801). IDHPG was inhibited 21% by Ba2+ (500 µM), 60% by ZD7288 (100 µM) and 73% when the two antagonists were applied together, suggesting that KIR channels and HCN channels contribute to the current. Voltage clamp measurements of IH indicated a small (6%) increase in Gmax by DHPG with no change in the voltage dependence. DHPG reduced action potential rheobase and reduced the number of post-synaptic AP failures during high frequency stimulation of the calyx of Held. Thus, activation of post-synaptic Group I mGlu receptors modifies the excitability of MNTB neurons and contributes to the reliability of high frequency firing in this auditory relay nucleus.
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Potenciais de Ação , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , Receptores de Glutamato Metabotrópico/metabolismo , Potenciais Sinápticos , Corpo Trapezoide/metabolismo , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Amilorida/farmacologia , Animais , Maleato de Dizocilpina/farmacologia , Feminino , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/antagonistas & inibidores , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Masculino , Metoxi-Hidroxifenilglicol/análogos & derivados , Metoxi-Hidroxifenilglicol/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Neurônios/fisiologia , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio Corretores do Fluxo de Internalização/antagonistas & inibidores , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Pirimidinas/farmacologia , Receptores de Glutamato Metabotrópico/agonistas , Receptores de Glutamato Metabotrópico/antagonistas & inibidores , Bloqueadores dos Canais de Sódio/farmacologia , Tetrodotoxina/farmacologia , Corpo Trapezoide/citologia , Corpo Trapezoide/efeitos dos fármacos , Corpo Trapezoide/fisiologiaRESUMO
Vitiligo is an acquired pigmentary disorder resulting from selective destruction of melanocytes. Emerging studies have suggested that T helper cell 17 (Th17) is potentially implicated in vitiligo development and progression. It was recently discovered that metabotropic glutamate receptor 4 (mGluR4) can modulate Th17-mediated adaptive immunity. However, the influence of mGluR4 on melanogenesis of melanocytes has yet to be elucidated. In the present study, we primarily cultured mouse bone marrow-derived dendritic cells (BMDC) and then knocked down and over-expressed mGluR4 using transfection. Transduced BMDC were co-cultured with CD4+ T cells and the expression of Th17-related cytokines were measured. The morphology and melanogenesis of B16 cells were observed after being treated with co-culture medium of CD4+ T cells and transduced BMDC. We found that mGluR4 knockdown did not affect the co-stimulatory CD80 and CD86 upregulation after lipopolysaccharide stimulation but did increase the expression of Th17-related cytokines, and further down-regulated the expression of microphthalmia-associated transcription factor (MITF) and the downstream genes, decreased melanin production, and destroyed the morphology of B16 cells. Conversely, over-expression of mGluR4 reduced the expression of CD80 and CD86, suppressed the production of Th17-related cytokines, increased the expression of MITF, and did not destroy the morphology of B16 cells. Our study confirmed that mGluR4 modulated the Th17 cell polarization and resulted in the alteration of melanogenesis and morphology of B16 cells. Collectively, these findings suggest mGluR4 might be a potent target involved in the immune pathogenesis of vitiligo.
Assuntos
Animais , Masculino , Vitiligo/imunologia , Células Dendríticas/citologia , Células da Medula Óssea/citologia , Diferenciação Celular/fisiologia , Receptores de Glutamato Metabotrópico/fisiologia , Células Th17/imunologia , Vitiligo/genética , RNA Interferente Pequeno/imunologia , Células Th17/citologia , Citometria de Fluxo , Melaninas/biossíntese , Melanócitos/citologia , Camundongos Endogâmicos C57BLRESUMO
A 68-years-old Hispanic man, complained of night sweats, low grade fewer, unexplained weight loss, and memory problems over 3 months. Abdominal tomography showed multiple intra-abdominal adenopathy and biopsy confirmed classic Hodgkin's lymphoma. He commenced treatment with chemotherapy. Three months later, he had acute onset of inattention, auditory hallucinations and alterations of anterograde memory. The patient developed psychomotor agitation, unresponsive to a combination of neuroleptics and benzodiazepines. Brain MRI showed a small established cerebellar infarction. Electroencephalogram was normal. Tests for toxic metabolic encephalopathy were negative. One oligoclonal IgG bands was found in the Cerebrospinal fluid (CSF), which was not observed in corresponding serum, but cell count and protein were normal. Extensive testing for infectious encephalitis was unremarkable. CSF testing for commercially available neural and non-neural autoantibodies was negative. The patient fulfilled the Gultekin diagnostic criteria for paraneoplastic limbic encephalitis and methylprednisolone IV 1g/d for 5 days was given. He recovered rapidly, with progressive improvement in memory and psychomotor agitation. After treatment commenced, results for antibodies to mGluR5 in CSF taken prior to treatment were returned as positive. mGluR5 is found on post-synaptic terminals of neurons and microglia and is expressed primarily in the hippocampus and amygdala. This case highlights the difficulties in diagnosing this type of encephalitis: the CSF did not show pleocytosis, the MRI showed only chronic change and the electroencephalogram was normal. The dramatic recovery after methylprednisolone help to better characterized the clinical spectrum of auto-immune encephalitis. Diagnosing anti mGlutR5 encephalitis may lead to potentially highly effective treatment option and may anticipate the diagnostic of a cancer. A high index of suspicion is needed to avoid missed diagnosis. In patients with unexplained encephalitis, testing for antibodies to mGluR5 in CSF and serum should be considered. When there is a reasonable index of suspicion of auto-immune encephalitis, treatment should not be delayed for the antibody results.
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Autoanticorpos/líquido cefalorraquidiano , Encefalite/líquido cefalorraquidiano , Encefalite/diagnóstico , Doença de Hashimoto/líquido cefalorraquidiano , Doença de Hashimoto/diagnóstico , Imunoglobulina G/líquido cefalorraquidiano , Encefalite Límbica/diagnóstico , Receptor de Glutamato Metabotrópico 5/imunologia , Idoso , Encefalite/tratamento farmacológico , Doença de Hashimoto/tratamento farmacológico , Doença de Hodgkin/diagnóstico , Doença de Hodgkin/tratamento farmacológico , Humanos , Encefalite Límbica/líquido cefalorraquidiano , Encefalite Límbica/tratamento farmacológico , Masculino , Metilprednisolona/uso terapêuticoRESUMO
The disorders of the central nervous system associated with cancer by remote immune-mediated mechanisms are a heterogeneous group. These disorders encompass the classic paraneoplastic disorders and the recently recognized autoimmune encephalitis associated with antibodies against neuronal cell surface or synaptic proteins that occur with or without cancer association. In the last decade, the new surge of interest in neuronal diseases associated with anti-neuronal antibodies led to the rapid discovery of new forms of disease that have different manifestations and were not previously suspected to be immune mediated. The recognition of these syndromes is important because it may lead to early detection of an underlying malignancy and prompt initiation of treatment, improving chances for a better outcome.
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Doenças do Sistema Nervoso Central/sangue , Encefalite/sangue , Doença de Hashimoto/sangue , Síndromes Paraneoplásicas do Sistema Nervoso/sangue , Anticorpos/sangue , Doenças do Sistema Nervoso Central/complicações , Doenças do Sistema Nervoso Central/patologia , Doenças do Sistema Nervoso Central/terapia , Detecção Precoce de Câncer , Encefalite/complicações , Encefalite/patologia , Encefalite/terapia , Doença de Hashimoto/complicações , Doença de Hashimoto/patologia , Doença de Hashimoto/terapia , Humanos , Neurônios/metabolismo , Neurônios/patologia , Síndromes Paraneoplásicas do Sistema Nervoso/complicações , Síndromes Paraneoplásicas do Sistema Nervoso/patologia , Síndromes Paraneoplásicas do Sistema Nervoso/terapia , Sinapses/metabolismo , Sinapses/patologiaRESUMO
Huntington's Disease (HD) is an autosomal-dominant neurodegenerative disorder, characterized by involuntary body movements, cognitive impairment, and psychiatric disorder. The metabotropic glutamate receptor 5 (mGluR5) plays an important role in HD and we have recently demonstrated that mGluR5-positive allosteric modulators (PAMs) can ameliorate pathology and the phenotypic signs of a mouse model of HD. In this study, we investigated the molecular mechanisms involved in mGluR5 PAMs effect on memory. Our results demonstrate that subchronic treatment with the mGluR5 PAM VU0409551 was effective in reversing the memory deficits exhibited by BACHD mice, a mouse model for HD. Moreover, VU0409551 treatment stabilized mGluR5 at the cellular plasma membrane of BACHD mice, increasing the expression of several genes important for synaptic plasticity, including c-Fos, brain-derived neurotrophic factor, Arc/Arg3.1, syntaxin 1A, and post-synaptic density-95. In addition, VU0409551 treatment also increased dendritic spine density and maturation and augmented the number of pre-synaptic sites. In conclusion, our results demonstrate that VU0409551 triggered the activation of cell signaling pathways important for synaptic plasticity, enhancing the level of dendritic spine maturation and rescuing BACHD memory impairment. OPEN PRACTICES: Open Science: This manuscript was awarded with the Open Materials Badge. For more information see: https://cos.io/our-services/open-science-badges/.
Assuntos
Doença de Huntington/tratamento farmacológico , Doença de Huntington/psicologia , Transtornos da Memória/tratamento farmacológico , Transtornos da Memória/psicologia , Plasticidade Neuronal/efeitos dos fármacos , Oxazóis/farmacologia , Piridinas/farmacologia , Receptor de Glutamato Metabotrópico 5/efeitos dos fármacos , Sinapses/efeitos dos fármacos , Animais , Condicionamento Clássico/efeitos dos fármacos , Espinhas Dendríticas/efeitos dos fármacos , Regulação da Expressão Gênica/efeitos dos fármacos , Doença de Huntington/complicações , Transtornos da Memória/etiologia , Camundongos , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Plasticidade Neuronal/genética , Receptor de Glutamato Metabotrópico 5/metabolismo , Reconhecimento Psicológico/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacosRESUMO
OBJECTIVE: Data from our laboratory suggest that recovery from a traumatic brain injury depends on the time of day at which it occurred. In this study, we examined whether traumatic brain injury -induced damage is related to circadian variation in N-methyl-D-aspartate receptor expression in rat cortex. RESULTS: We confirmed that traumatic brain injury recovery depended on the time of day at which the damage occurred. We also found that motor cortex N-methyl-D-aspartate receptor subunit NR1 expression exhibited diurnal variation in both control and traumatic brain injury-subjected rats. However, this rhythm is more pronounced in traumatic brain injury-subjected rats, with minimum expression in those injured during nighttime hours. These findings suggest that traumatic brain injury occurrence times should be considered in future clinical studies and when designing neuroprotective strategies for patients.
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Lesões Encefálicas Traumáticas/metabolismo , Lesões Encefálicas Traumáticas/fisiopatologia , Ritmo Circadiano/fisiologia , Córtex Motor/lesões , Córtex Motor/metabolismo , Córtex Motor/fisiopatologia , Receptores de N-Metil-D-Aspartato/metabolismo , Animais , Modelos Animais de Doenças , Masculino , Ratos , Ratos Wistar , Fatores de TempoRESUMO
Sea anemones produce proteinaceous toxins for predation and defense, including peptide toxins that act on a large variety of ion channels of pharmacological and biomedical interest. Phymanthus crucifer is commonly found in the Caribbean Sea; however, the chemical structure and biological activity of its toxins remain unknown, with the exception of PhcrTx1, an acid-sensing ion channel (ASIC) inhibitor. Therefore, in the present work, we focused on the isolation and characterization of new P. crucifer toxins by chromatographic fractionation, followed by a toxicity screening on crabs, an evaluation of ion channels, and sequence analysis. Five groups of toxic chromatographic fractions were found, and a new paralyzing toxin was purified and named PhcrTx2. The toxin inhibited glutamate-gated currents in snail neurons (maximum inhibition of 35%, IC50 4.7 mu M), and displayed little or no influence on voltage-sensitive sodium/potassium channels in snail and rat dorsal root ganglion (DRG) neurons, nor on a variety of cloned voltage-gated ion channels. The toxin sequence was fully elucidated by Edman degradation. PhcrTx2 is a new -defensin-fold peptide that shares a sequence similarity to type 3 potassium channels toxins. However, its low activity on the evaluated ion channels suggests that its molecular target remains unknown. PhcrTx2 is the first known paralyzing toxin in the family Phymanthidae.
RESUMO
We have previously demonstrated that maternal exposure to glyphosate-based herbicide (GBH) leads to glutamate excitotoxicity in 15-day-old rat hippocampus. The present study was conducted in order to investigate the effects of subchronic exposure to GBH on some neurochemical and behavioral parameters in immature and adult offspring. Rats were exposed to 1% GBH in drinking water (corresponding to 0.36% of glyphosate) from gestational day 5 until postnatal day (PND)-15 or PND60. Results showed that GBH exposure during both prenatal and postnatal periods causes oxidative stress, affects cholinergic and glutamatergic neurotransmission in offspring hippocampus from immature and adult rats. The subchronic exposure to the pesticide decreased L-[14C]-glutamate uptake and increased 45Ca2+ influx in 60-day-old rat hippocampus, suggesting a persistent glutamate excitotoxicity from developmental period (PND15) to adulthood (PND60). Moreover, GBH exposure alters the serum levels of the astrocytic protein S100B. The effects of GBH exposure were associated with oxidative stress and depressive-like behavior in offspring on PND60, as demonstrated by the prolonged immobility time and decreased time of climbing observed in forced swimming test. The mechanisms underlying the GBH-induced neurotoxicity involve the NMDA receptor activation, impairment of cholinergic transmission, astrocyte dysfunction, ERK1/2 overactivation, decreased p65 NF-κB phosphorylation, which are associated with oxidative stress and glutamate excitotoxicity. These neurochemical events may contribute, at least in part, to the depressive-like behavior observed in adult offspring.
Assuntos
Comportamento Animal/efeitos dos fármacos , Depressão/induzido quimicamente , Ácido Glutâmico/metabolismo , Glicina/análogos & derivados , Herbicidas/toxicidade , Hipocampo/efeitos dos fármacos , Síndromes Neurotóxicas/etiologia , Estresse Oxidativo/efeitos dos fármacos , Efeitos Tardios da Exposição Pré-Natal , Acetilcolinesterase/metabolismo , Fatores Etários , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/metabolismo , Sítios de Ligação , Fibras Colinérgicas/efeitos dos fármacos , Fibras Colinérgicas/metabolismo , Depressão/metabolismo , Depressão/fisiopatologia , Depressão/psicologia , Feminino , Proteínas Ligadas por GPI/metabolismo , Idade Gestacional , Ácido Glutâmico/química , Glicina/química , Glicina/metabolismo , Glicina/toxicidade , Herbicidas/química , Herbicidas/metabolismo , Hipocampo/metabolismo , Hipocampo/fisiopatologia , Masculino , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Simulação de Acoplamento Molecular , Estrutura Molecular , Atividade Motora/efeitos dos fármacos , NF-kappa B/metabolismo , Síndromes Neurotóxicas/metabolismo , Síndromes Neurotóxicas/fisiopatologia , Síndromes Neurotóxicas/psicologia , Gravidez , Ligação Proteica , Ratos Wistar , Receptores de N-Metil-D-Aspartato/agonistas , Receptores de N-Metil-D-Aspartato/metabolismo , Subunidade beta da Proteína Ligante de Cálcio S100/metabolismo , Relação Estrutura-Atividade , Transmissão Sináptica/efeitos dos fármacos , GlifosatoRESUMO
2-Arachidonoylglycerol and anandamide are the main endocannabinoids, which act through cannabinoid type-1 and type-2 receptors. Among its many functions, anandamide modulates anxiety-like behaviors in the ventromedial prefrontal cortex. The role of 2-arachidonoylglycerol in this region, however, has remained unclear. Here, we verified whether intra- ventromedial prefrontal cortex injection of 2-arachidonoylglycerol or URB602, a monoacylglycerol lipase inhibitor (responsible for 2-arachidonoylglycerol hydrolysis), induce anxiolytic-like effects in Wistar rats. Since activation of metabotropic glutamate receptor type 5 promotes diacylglycerol lipase-α-mediated 2-arachidonoylglycerol synthesis, we also verified if the blockade of this receptor impairs the anxiolytic-like effect induced by URB 602. 2-Arachidonoylglycerol reduced anxiety-like response in rats exposed to the Elevated Plus Maze test, an effect mimicked by URB602. Cannabinoid type-1 and type-2 receptor antagonists prevented these effects. The pre-treatment with an ineffective dose of MPEP, a metabotropic glutamate receptor type 5 antagonist, also attenuated the anxiolytic-like effect of URB602. Moreover, immunofluorescence microscopy revealed co-expression of metabotropic glutamate receptor type 5 and diacylglycerol lipase-α in several neurons in slices from the ventromedial prefrontal cortex. Altogether, our results implicate 2-arachidonoylglycerol and both cannabinoid receptors on anxiety-related behaviors mediated by ventromedial prefrontal cortex. Further, these data support a role for the coupling between metabotropic glutamate receptor type 5 activation and 2-arachidonoylglycerol signalling as a mechanism modulating aversive responses.
Assuntos
Ansiedade/tratamento farmacológico , Ácidos Araquidônicos/farmacologia , Endocanabinoides/farmacologia , Glicerídeos/farmacologia , Córtex Pré-Frontal/efeitos dos fármacos , Receptor de Glutamato Metabotrópico 5/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Ansiedade/metabolismo , Compostos de Bifenilo/farmacologia , Antagonistas de Receptores de Canabinoides/farmacologia , Masculino , Alcamidas Poli-Insaturadas/farmacologia , Córtex Pré-Frontal/metabolismo , Ratos , Ratos Wistar , Receptor CB1 de Canabinoide/antagonistas & inibidores , Receptor CB2 de Canabinoide/antagonistas & inibidoresRESUMO
Fragile X Mental Retardation Protein (FMRP) is a RNA-binding protein that modulates protein synthesis at the synapse and its function is regulated by glutamate. The retina is the first structure that participates in vision, and uses glutamate to transduce electromagnetic signals from light to electrochemical signals to neurons. FMRP has been previously detected in the retina, but its localization has not been studied yet. In this work, our objectives were to describe the localization of FMRP in the retina, to determine whether different exposure to dark or light stimulus alters FMRP expression in the retina, and to compare the pattern in two different species, the mouse and chick. We found that both FMRP mRNA and protein are expressed in the retina. By immunohistochemistry analysis we found that both mouse and chick present similar FMRP expression localized mainly in both plexiform layers and the inner retina. It was also observed that FMRP is down-regulated by 24 h dark adaptation compared to its expression in the retina of animals that were exposed to light for 1 h after 24 h in the dark. We conclude that FMRP is likely to participate in retinal physiology, since its expression changes with light exposure. In addition, the expression pattern and regulation by light of FMRP seems well conserved since it was similar in both mouse and chick.
Assuntos
Adaptação à Escuridão/fisiologia , Proteína do X Frágil da Deficiência Intelectual/genética , Regulação da Expressão Gênica , Luz , RNA/genética , Retina/metabolismo , Animais , Galinhas , Feminino , Proteína do X Frágil da Deficiência Intelectual/biossíntese , Proteína do X Frágil da Deficiência Intelectual/efeitos da radiação , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
INTRODUCTION: Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by a polyglutamine expansion in the amino-terminal region of the huntingtin (htt) protein, which underlies the loss of striatal and cortical neurons. Glutamate has been implicated in a number of neurodegenerative diseases, and several studies suggest that the metabotropic glutamate receptor 5 (mGluR5) may represent a target for the treatment of HD. AREAS COVERED: The main goal of this review is to discuss the current data in the literature regarding the role of mGluR5 in HD and evaluate the potential of mGluR5 as a therapeutic target for the treatment of HD. mGluR5 is highly expressed in the brain regions affected in HD and is involved in movement control. Moreover, mGluR5 interacts with htt and mutated htt profoundly affects mGluR5 signaling. However, mGluR5 stimulation can activate both neuroprotective and neurotoxic signaling pathways, depending on the context of activation. EXPERT OPINION: Although the data published so far strongly indicate that mGluR5 plays a major role in HD-associated neurodegeneration, htt aggregation and motor symptoms, it is not clear whether mGluR5 stimulation can diminish or intensify neuronal cell loss and HD progression. Thus, future experiments will be necessary to further investigate the outcome of drugs acting on mGluR5 for the treatment of neurodegenerative diseases.
Assuntos
Doença de Huntington/tratamento farmacológico , Terapia de Alvo Molecular , Receptor de Glutamato Metabotrópico 5/efeitos dos fármacos , Animais , Encéfalo/fisiopatologia , Desenho de Fármacos , Ácido Glutâmico/metabolismo , Humanos , Proteína Huntingtina , Doença de Huntington/fisiopatologia , Proteínas do Tecido Nervoso/metabolismo , Receptor de Glutamato Metabotrópico 5/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
Amyloid precursor protein (APP) shedding yields the Alzheimer's disease (AD)-related peptide amyloid ß (Aß) through ß- and γ-secretase cleavage. Alternatively, α-secretase cleavage generates a soluble and neuroprotective fragment (sAPPα) while precludes the production of Aß. Although metabotropic glutamate (mGlu) receptors were associated with induction of sAPPα production in astrocytes, there was no further evidence regarding the specific subtype receptor or the mechanisms involved in this action. In the present study, we used the dual mGlu2/3 receptor agonist LY379268, which in pure astrocyte cultures selectively activates mGlu3 receptor subtype since mGlu2 receptor subtype is not expressed by these cells. We showed that LY379268 incremented sAPPα release from cultured astrocytes by inducing α-secretases expression, whereas it decreased ß-secretase levels. LY379268-induced increase of PPAR-γ levels could be involved in the effect of the agonist on sAPPα release. Using the PDAPP-J20 murine model of AD we described a strong reduction in mGlu2/3 receptor expression in the hippocampus of 5- and 14-month-old transgenic mice compared to control littermates. Moreover, mGlu3 receptor expression is also decreased specifically in hippocampal astrocytes of these transgenic animals as a function of age. Therefore, diminished levels of hippocampal mGlu3 receptors might have implications in the development of the disease in these transgenic mice considering the anti-amyloidogenic action of mGlu3 receptors in astrocytes.
Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Astrócitos/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Envelhecimento , Aminoácidos/farmacologia , Precursor de Proteína beta-Amiloide/genética , Animais , Astrócitos/efeitos dos fármacos , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Células Cultivadas , Agonistas de Aminoácidos Excitatórios/metabolismo , Feminino , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Mutação , Ratos , Ratos Wistar , Receptores de Glutamato Metabotrópico/agonistasRESUMO
The metabotropic glutamate receptors 5 (mGluRs5) within the Nucleus Accumbens (NAc) have been implicated in the modulation of psychostimulant reward. We hypothesized that blockade of mGluR5 within the NAc shell would impair cocaine conditioning in rats. For this study, animals were implanted with cannulae within the NAc shell, and separate groups were exposed to a multimodal environment within activity chambers that signaled cocaine (cocaine-paired) or saline (controls, cocaine-unpaired) injections. Prior to placing the animals in the chambers, rats received systemic intraperitoneal injections of saline or cocaine for 10 consecutive sessions. In the test session (D12), animals were exposed to the multimodal environment without any cocaine or saline pre-treatment. Before placing the rats in the chambers, separate groups of animals were infused within the NAc shell with 2.5, 12 or 25 nmol/0.5 µl/side of 2-methyl-6-(phenylethynyl) pyridine (MPEP), an antagonist of mGluR5 or with vehicle. Blockade of the mGluR5 subtype at a 2.5 nmol dose showed no significant difference in either the ambulatory distance (AD) or the vertical plane move time (VPT). In contrast, mGluR5 blockade at 12 nmol and 25 nmol decreased conditioned locomotion in the cocaine-paired groups. An association of the environmental cues with the effects of cocaine implies the involvement of memory process during the conditioning response. Our results suggest that mGluR5 within the NAc shell could be modulating the expression of memory related to the association of environmental cues with the effects of cocaine. We suggest that mGluR5 could be taking into account to further studies related with cocaine exposure and cocaine addiction treatments.
Assuntos
Cocaína/farmacologia , Condicionamento Operante , Núcleo Accumbens/efeitos dos fármacos , Receptor de Glutamato Metabotrópico 5/metabolismo , Animais , Relação Dose-Resposta a Droga , Masculino , Núcleo Accumbens/metabolismo , Ratos , Ratos Sprague-Dawley , Receptor de Glutamato Metabotrópico 5/antagonistas & inibidoresRESUMO
El receptor ionotrópico de glutamato activado por N-metil-D-aspartato (iGluR-NMDA) está conformado por tres tipos diferentes de subunidades NR1, NR2A a D y NR3A y B codificadas por los genes GRIN1, GRIN2 y GRIN3. Dado que la variabilidad genómica de los GRIN está estrechamente asociada con la historia genética de la población analizada, era necesario realizar un estudio detallado del gen GRIN1 en la población colombiana. Por ello, en este trabajo se identificaron polimorfismos presentes en la región 5-UTR y en el exón 6 del gen GRIN1, en 101 muestras de sangre de cordón umbilical de recién nacidos sanos del Hospital Universitario San Ignacio de Bogotá, y se encontró que el polimorfismo A1970G con una frecuencia del alelo menor de 28,21%, no difiere de las poblaciones de caucásicos y nativos americanos. El polimorfismo G1140A, con una frecuencia del alelo menor de 1,49%, no mostró diferencias estadísticamente significativas con la población de Taiwán. El polimorfismo A1160G sólo mostró una forma alélica...
The ionotropic glutamate receptor activated by Nmethyl-D-aspartate is composed by three different kinds of subunits NR1, NR2A to D and NR3A and B, which are codified by GRIN1, GRIN2 and GRIN3 genes. Since the GRIN genomic variability is closely related to the genetic history of the studied population, it was necessary to develop a detailed study of the frequency of the polymorphisms of the gene GRIN-1 in Colombian population. The main goal of this research was to identify polymorphisms present in 5-UTR region and exon 6 of gene GRIN1, among 101 samples of umbilical cord taken on filter paper of healthy newborns at the University Hospital San Ignacio in Bogota. It was found that polymorphism A1970G with minor allele frequencies of 28.21%, doesn't differ significantly from the frequencies in Caucasian and native American populations. Polymorphism G1140A with minor allele frequencies of 1.49% did not show any significant statistic difference with the Taiwan population. Polymorphism A1160G just showed one allelic form, the A allele...