RESUMO
Malignant pleural mesothelioma (MPM) is a kind of invasive malignant tumor originated from pleural tissue. The incidence of MPM is not high in the population, but the prognosis is very poor. The median survival time is only about 12 months. Pemetrexed combined with platinum is the first-line chemotherapy regimen recommended by the current guidelines. The use of bevacizumab will further prolong the survival of chemotherapy. Once resistance happened, no anti-tumor treatment has been confirmed to achieve survival benefits. Therefore, there is no recommended standard second-line MPM regimen in international and domestic guidelines, including National Comprehensive Cancer Network (NCCN) guidelines. Vinorelbine, gemcitabine and other monotherapy regimens are commonly used in clinical practice, but the median progression free survival (PFS) is only about 3 months. Immune checkpoint inhibitors (ICIS) have been proved to have a significant inhibitory effect on tumor growth in a variety of malignant tumors, and their efficacy is related to the expression of programmed death-ligand 1(PD-L1). In unresectable MPM, programmed death 1 (PD-1)/PD-L1 inhibitors have been used in a series of clinical studies in the first-line, second-line and above treatment. Some of the results have been cited and recommended by international guidelines, but the overall efficacy improvement is still limited. This review summarizes the latest clinical studies and researches in the field of MPM treatment and predicts the directions and prospect of improving the therapeutic effect in the future.
Assuntos
Neoplasias Pulmonares , Mesotelioma Maligno , Mesotelioma , Neoplasias Pleurais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Humanos , Neoplasias Pulmonares/tratamento farmacológico , Mesotelioma/tratamento farmacológico , Pemetrexede/uso terapêutico , Pleura , Neoplasias Pleurais/tratamento farmacológico , PrognósticoRESUMO
Objective: Recently, increasing number of lung cancer patients benefit from immune-checkpoint inhibitors (ICIs). However, the data of Chinese small cell lung cancer (SCLC) patients is limited. This study aims to analyze the response and survival data of ICIs treatment in SCLC and to explore the predictive biomarkers. Methods: Forty-seven SCLC patients who received ICIs treatment from Peking University Cancer Hospital from May 2017 to September 2019 was recruited. Clinical characteristics including sex, age, smoking status, ICIs strategy, PD-L1 expression and therapeutic efficacy were collected to explore the clinical predictive biomarkers for SCLC ICIs treatment. Results: Among the 47 patients, 18 (38.3%) cases were partial repose (PR), 11 (23.4%) were stable disease (SD), 18 (38.3%) were progressive disease (PD), and the objective response rate (ORR) was 38.3%, disease control rate (DCR) was 61.7%, the median progression-free survival (PFS) was 5.3 months. ICIs monotherapy accounts for 27.7%, the ORR was 15.4%, DCR was 53.8%, median PFS was 2.7 months. Combined therapy accounts for 72.3%, the ORR was 47.1%, DCR was 64.7%, median PFS was 5.4 months. Fourteen (29.8%) patients received ICIs as the first line treatment, their ORR was 85.7%, DCR was 100%, median PFS was 9.1 month. The ORR was not related to the age, sex, body mass index (BMI), smoking status and programmed death-ligand 1 (PD-L1) expression (P>0.05). The ORRs were higher in patients underwent PD-L1 monotherapy (P=0.001), combined therapy (P=0.002) and received ICIs as the first line treatment (P<0.001). Log-rank analysis indicated that the PFS of female patients were 12.0 months, significantly longer than 4.4 months of male patients in ICIs treatment (P=0.038). Patients who received PD-L1 monotherapy, combined treatment, or ICIs as the first line treatment had longer PFS than their counterparts, though no statistical significant was observed (P>0.05). Cox multivariate analysis showed that, the gender was not an independent predictor for PFS in ICIs treatment (HR=3.777, 95%CI=0.974~30.891, P=0.054). Conclusions: Immunotherapy is an effective treatment strategy for SCLC. Patients who receive combined ICIs treatment, first line ICIs treatment and PD-L1 treatment may get greater benefits. PD-L1 expression cannot predict the response and PFS in SCLC ICIs treatment.
Assuntos
Antineoplásicos Imunológicos , Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Carcinoma de Pequenas Células do Pulmão , Antineoplásicos Imunológicos/uso terapêutico , Biomarcadores Tumorais , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Feminino , Humanos , Imunoterapia , Neoplasias Pulmonares/tratamento farmacológico , Masculino , Carcinoma de Pequenas Células do Pulmão/tratamento farmacológicoRESUMO
Objective: To investigate and analyze the current situation, screening, clinical characteristics, prevention and treatment of bleeding esophageal varices in cirrhotic patients with portal hypertension in Tibet region. Methods: Clinical data of cirrhotic patients with portal hypertension through March 2017 to February 2020 from Tibet region were collected and analyzed retrospectively. Results: 511 cases with liver cirrhosis were included in the study, of which 185 cases (36.20%) had compensated cirrhosis and 326 cases (63.80%) had decompensated cirrhosis. Further analysis of the etiological data of liver cirrhosis showed that 306 cases (59.88%) were of chronic hepatitis B, 113 cases (22.11%) of alcoholic liver disease, and 68 cases (13.31%) of chronic hepatitis B combined with alcoholic liver disease. Among patients with compensated liver cirrhosis, 48 cases (25.95%) underwent endoscopic examination of which 33 diagnosed as high-risk variceal bleeding. However, none of these 33 cases had received non-selective ß-blocker therapy, and only four patients had received endoscopic variceal banding therapy. Among patients with decompensated liver cirrhosis, 83 cases (25.46%) had a history of upper gastrointestinal bleeding, 297 cases (91.10%) had ascites, 23 cases (7.05%) had hepatic encephalopathy, and 3 cases (0.92%) had hepatorenal syndrome. Among the patients with a history of upper gastrointestinal bleeding, 42 cases (50.60%) had received secondary preventive treatment for bleeding esophageal varices, including 39 cases of endoscopic treatment, 1 case of endoscopic combined drug treatment, 3 cases of interventional treatment, and 2 cases of surgical treatment. Conclusion: Chronic hepatitis B and alcoholic liver diseases are the main causes of liver cirrhosis in Tibet region. Moreover, this region lacks screening, prevention and treatment for bleeding esophageal varices in cirrhotic patients with portal hypertension. Therefore, it is necessary to increase the screening of high-risk groups to prevent and improve the first-time bleeding, and promote multidisciplinary team to prevent and treat re-bleeding.
Assuntos
Varizes Esofágicas e Gástricas , Hipertensão Portal , Varizes Esofágicas e Gástricas/epidemiologia , Varizes Esofágicas e Gástricas/etiologia , Varizes Esofágicas e Gástricas/prevenção & controle , Hemorragia Gastrointestinal/etiologia , Hemorragia Gastrointestinal/prevenção & controle , Humanos , Hipertensão Portal/complicações , Cirrose Hepática/complicações , Estudos Retrospectivos , TibetRESUMO
PURPOSE: Long non-coding RNAs (lncRNAs) have been proved to play important roles in the tumorigenesis and development of human epithelial ovarian cancer (EOC). The aim of the present study was to investigate the expression and clinical value of BRAF-activated non-coding RINA (BANCR) in EOC patients. MATERIALS AND METHODS: BANCR expression was detected in 84 EOC and 36 normal ovarian epithelial tissue samples. Association between BANCR levels and clinicopathological factors and patient prognosis was also analyzed. RESULTS: BANCR expression was increased in EOC compared with normal ovarian epithelial tissues. Moreover, high expression of BANCR was closely correlated with advanced FIGO stage, higher serum, CAI125 expression level, and lymph node metastasis. Multivariate regression analysis identified BANCR overexpression as an independent unfavorable prognostic factor in EOC patients. CONCLUSIONS: These findings suggested that BANCR may act as a tumor promoter in EOC and would be a novel diagnostic and prognostic marker for this disease.
Assuntos
Neoplasias Epiteliais e Glandulares/genética , Neoplasias Ovarianas/genética , RNA Longo não Codificante/análise , Adulto , Idoso , Carcinoma Epitelial do Ovário , Feminino , Humanos , Pessoa de Meia-Idade , Neoplasias Epiteliais e Glandulares/mortalidade , Neoplasias Epiteliais e Glandulares/patologia , Neoplasias Ovarianas/mortalidade , Neoplasias Ovarianas/patologia , PrognósticoRESUMO
Cynomolgus macaques (Macaca fascicularis, Mafa) have emerged as an important animal model for infectious disease and transplantation research. Extensive characterization of their major histocompatibility complex (MHC) polymorphism regions therefore becomes urgently required. In this study, we identified 41 MHC class I A nucleotide sequences in 34 unrelated cynomolgus macaques of Vietnamese origin farmed in Southern China, including eight novel Mafa-A sequences. We found two sequences with perfect identity and six sequences with close similarity to previously defined MHC class I alleles from other populations, especially from Indonesian-origin macaques. We also found three Vietnamese-origin cynomolgus macaque MHC class I sequences for which the predicted protein sequences identical throughout their B and F binding pockets to Mamu-A1*001:01 and Mamu-A3*13:03, respectively. This is important because Mamu-A1*001:01 and Mamu-A3*13:03 are associated with longer survival and lower set-point viral load in simian immunodeficiency virus (SIV)-infected rhesus monkeys. These findings have implications for the evolutionary history of Vietnamese-origin cynomolgus macaque as well as for the use of this model in SIV/SHIV (a virus combining parts of the HIV and SIV genomes) research.
Assuntos
Genes MHC Classe I , Macaca fascicularis/genética , Macaca fascicularis/imunologia , Alelos , Sequência de Aminoácidos , Animais , Sequência de Bases , Primers do DNA/genética , Evolução Molecular , Genética Populacional , Antígenos de Histocompatibilidade Classe I/genética , Macaca/genética , Macaca/imunologia , Modelos Animais , Dados de Sequência Molecular , Filogenia , Homologia de Sequência de Aminoácidos , Vírus da Imunodeficiência Símia/imunologia , Vírus da Imunodeficiência Símia/patogenicidade , Especificidade da Espécie , VietnãRESUMO
We report herein the identification of 23 novel Mafa-B alleles in cynomolgus macaques of Vietnamese origin.
Assuntos
Alelos , Antígenos de Histocompatibilidade Classe I/genética , Macaca fascicularis/genética , Sequência de Aminoácidos , Animais , Dados de Sequência Molecular , VietnãRESUMO
We report herein the identification of 18 novel Mafa-A alleles in cynomolgus macaques of Vietnamese origin.
Assuntos
Genes MHC Classe I , Antígenos de Histocompatibilidade Classe I/genética , Reação em Cadeia da Polimerase/métodos , Alelos , Animais , China , DNA Complementar/metabolismo , Modelos Animais de Doenças , Frequência do Gene , Macaca fascicularis , Modelos Genéticos , Polimorfismo Genético , Análise de Sequência de DNA/métodos , VietnãRESUMO
Hippocampal neurons fire spikes when an animal is at a particular location or performs certain behaviors in a particular place, providing a cellular basis for hippocampal involvement in spatial learning and memory. In a natural environment, spatial memory is often associated with potentially dangerous sensory experiences such as noxious or painful stimuli. The central sites for such pain-associated memory or plasticity have not been identified. Here we present evidence that excitatory glutamatergic synapses within the CA1 region of the hippocampus may play a role in storing pain-related information. Peripheral noxious stimulation induced excitatory postsynaptic potentials (EPSPs) in CA1 pyramidal cells in anesthetized animals. Tissue/nerve injury caused a rapid increase in the level of the immediate-early gene product Egr1 (also called NGFI-A, Krox24, or zif/268) in hippocampal CA1 neurons. In parallel, synaptic potentiation induced by a single tetanic stimulation (100 Hz for 1 s) was enhanced after the injury. This enhancement of synaptic potentiation was absent in mice lacking Egr1. Our data suggest that Egr1 may act as an important regulator of pain-related synaptic plasticity within the hippocampus.
Assuntos
Amputação Cirúrgica , Proteínas de Ligação a DNA/metabolismo , Hipocampo/metabolismo , Hipocampo/fisiopatologia , Proteínas Imediatamente Precoces , Dor/fisiopatologia , Sinapses/metabolismo , Transmissão Sináptica/fisiologia , Fatores de Transcrição/metabolismo , Animais , Proteína 1 de Resposta de Crescimento Precoce , Estimulação Elétrica , Potenciais Pós-Sinápticos Excitadores/fisiologia , Ácido Glutâmico/metabolismo , Imuno-Histoquímica , Potenciação de Longa Duração/fisiologia , Masculino , Memória/fisiologia , Camundongos , Camundongos Knockout , Plasticidade Neuronal/fisiologia , Nociceptores/metabolismo , Células Piramidais/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de N-Metil-D-Aspartato/metabolismo , Fatores de TempoRESUMO
Nitric oxide (NO) and carbon monoxide (CO) may act as retrograde messages for long-term potentiation (LTP) in the hippocampus. Zinc protoporphyrin IX, an inhibitor of the enzyme that produces CO, blocked induction of LTP in the CA1 region of hippocampal slices. Application of either NO or CO to slices produced a rapid and long-lasting increase in the size of evoked synaptic potentials if, and only if, the application occurred at the same time as weak tetanic stimulation. This long-term enhancement was spatially restricted to synapses from active presynaptic fibers and appeared to involve mechanisms utilized by LTP, occluding the subsequent induction of LTP by strong tetanic stimulation. The enhancement by NO and CO was not blocked by an N-methyl-D-aspartate (NMDA) receptor blocker, suggesting that NO and CO act downstream from the NMDA receptor. Also, CO produced long-term enhancement when paired with low-frequency stimulation. These results are consistent with the hypothesis that NO and CO, either alone or in combination, serve as retrograde messages that produce activity-dependent presynaptic enhancement during LTP.
Assuntos
Monóxido de Carbono/farmacologia , Hipocampo/fisiologia , Óxido Nítrico/farmacologia , Sinapses/fisiologia , 6-Ciano-7-nitroquinoxalina-2,3-diona , Animais , Estimulação Elétrica , Cobaias , Hipocampo/efeitos dos fármacos , Técnicas In Vitro , Masculino , Potenciais da Membrana/efeitos dos fármacos , Protoporfirinas/farmacologia , Quinoxalinas/farmacologia , Transdução de Sinais/efeitos dos fármacos , Sinapses/efeitos dos fármacosRESUMO
OBJECTIVE: To investigate the status of human intestinal parasitic diseases in Nanping City from 2014 to 2018, so as to provide reference for the development of the effective control measures. METHODS: Administrative villages were selected using the two-stage cluster sampling in Nanping City from 2014 to 2018, and surveillance of human intestinal parasitic diseases was performed in 5 administrative villages in each county (district) of Nanping City. Intestinal parasitic infections were detected using a modified Kato-Katz thick smear method (two smears for a single stool sample) in villagers, and the hookworm species was differentiated. In addition, the eggs of Enterobius vermicularis were detected using the adhesive tape method in children aged 3 to 6 years. RESULTS: A total of 6 317 villagers were detected in Nanping City from 2014 to 2018, and the overall prevalence of human intestinal parasitic infections was 2.15%. There was year- (χ2 = 10.53, P < 0.05) and gender-specific prevalence of human intestinal parasitic infections in Nanping City during the study period (χ2 = 17.00, P < 0.01). The prevalence of human intestinal parasitic infections increased with age, and there was age-specific prevalence of human intestinal parasitic infections in Nanping City (χ2 = 102.62, P < 0.01). A total of 945 children at ages of 3 to 6 years were detected, and the prevalence of E. vermicularis infection was 3.28%. CONCLUSIONS: The prevalence of human intestinal parasitic infections is at a low level in Nanping City from 2014 to 2018, and the infection mainly occurs in villagers of advanced age and low education levels. Further comprehensive measures are required to control intestinal parasitic infections in key populations.
Assuntos
Enteropatias Parasitárias , Animais , Criança , Pré-Escolar , China/epidemiologia , Fezes/parasitologia , Humanos , Enteropatias Parasitárias/epidemiologia , PrevalênciaRESUMO
Dendritic arbors are critical for the information processing capability of central neurons, but quantitative analysis of their membrane properties has been hampered by their geometrical complexity. Here, we have focused on an important source of Ca2+ entry in dendrites, the voltage-gated Ca2+ channels, by applying the whole-cell voltage-clamp technique to isolated dendritic segments ("dendrosomes") from rat hippocampal neurons. We found that low voltage-activated T-type Ca2+ channels provide a significantly larger fraction of the Ca2+ influx in dendrites than their counterparts in cell bodies. Surprisingly, 60%-70% of the high voltage-activated Ca2+ current in dendrosomes was N and P/Q type, and these channels were susceptible to neurotransmitter inhibition, suggesting a novel physiological role for G protein-regulated Ca2+ channel modulation in controlling dendritic excitability and Ca2+ signaling.
Assuntos
Canais de Cálcio/metabolismo , Dendritos/metabolismo , Hipocampo/fisiologia , Animais , Cálcio/metabolismo , Condutividade Elétrica , Neurotransmissores/fisiologia , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-DawleyRESUMO
In the spinal cord dorsal horn, excitatory sensory fibers terminate adjacent to interneuron terminals. Here, we show that kainate (KA) receptor activation triggered action potential-independent release of GABA and glycine from dorsal horn interneurons. This release was transient, because KA receptors desensitized, and it required Na+ entry and Ca2+ channel activation. KA modulated evoked inhibitory transmission in a dose-dependent, biphasic manner, with suppression being more prominent. In recordings from isolated neuron pairs, this suppression required GABA(B) receptor activation, suggesting that KA-triggered GABA release activated presynaptic GABA(B) autoreceptors. Finally, glutamate released from sensory fibers caused a KA and GABA(B) receptor-dependent suppression of inhibitory transmission in spinal slices. Thus, we show how presynaptic KA receptors are linked to changes in GABA/glycine release and highlight a novel role for these receptors in regulating sensory transmission.
Assuntos
Glicina/metabolismo , Células do Corno Posterior/metabolismo , Terminações Pré-Sinápticas/metabolismo , Receptores de Ácido Caínico/fisiologia , Ácido gama-Aminobutírico/metabolismo , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Células Cultivadas , Relação Dose-Resposta a Droga , Agonistas de Aminoácidos Excitatórios/farmacologia , Ativação do Canal Iônico/efeitos dos fármacos , Ativação do Canal Iônico/fisiologia , Ácido Caínico/farmacologia , Masculino , Células do Corno Posterior/efeitos dos fármacos , Terminações Pré-Sinápticas/efeitos dos fármacos , Ratos , Células Receptoras Sensoriais/efeitos dos fármacos , Células Receptoras Sensoriais/metabolismoRESUMO
N-methyl-D-aspartate (NMDA) receptors contribute to many brain functions. We studied the effect of forebrain-targeted overexpression of the NMDA receptor subunit NR2B on the response of mice to tissue injury and inflammation. Transgenic mice exhibited prominent NR2B expression and enhanced NMDA receptor-mediated synaptic responses in two pain-related forebrain areas, the anterior cingulate cortex and insular cortex, but not in the spinal cord. Although transgenic and wild type mice were indistinguishable in tests of acute pain, transgenic mice exhibited enhanced responsiveness to peripheral injection of two inflammatory stimuli, formalin and complete Freund's adjuvant. Genetic modification of forebrain NMDA receptors can therefore influence pain perception, which suggests that forebrain-selective NMDA receptor antagonists, including NR2B-selective agents, may be useful analgesics for persistent pain.
Assuntos
Encefalite/fisiopatologia , Dor/fisiopatologia , Prosencéfalo/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Animais , Formaldeído/farmacologia , Adjuvante de Freund/farmacologia , Membro Posterior , Injeções , Masculino , Camundongos , Camundongos Transgênicos/genética , Limiar da Dor/efeitos dos fármacos , Limiar da Dor/fisiologia , Receptores de N-Metil-D-Aspartato/genética , Valores de Referência , Sinapses/fisiologiaRESUMO
Silent synapses form between some primary sensory afferents and dorsal horn neurons in the spinal cord. Molecular mechanisms for activation or conversion of silent synapses to conducting synapses are unknown. Serotonin can trigger activation of silent synapses in dorsal horn neurons by recruiting AMPA receptors. AMPA-receptor subunits GluR2 and GluR3 interact via their cytoplasmic C termini with PDZ-domain-containing proteins such as GRIP (glutamate receptor interacting protein), but the functional significance of these interactions is unclear. Here we demonstrate that protein interactions involving the GluR2/3 C terminus are important for serotonin-induced activation of silent synapses in the spinal cord. Furthermore, PKC is a necessary and sufficient trigger for this activation. These results implicate AMPA receptor-PDZ interactions in mechanisms underlying sensory synaptic potentiation and provide insights into the pathogenesis of chronic pain.
Assuntos
Neurônios Aferentes/fisiologia , Estrutura Terciária de Proteína , Receptores de AMPA/fisiologia , Medula Espinal/fisiologia , Sinapses/fisiologia , Animais , Células Cultivadas , Ativação Enzimática , Técnicas In Vitro , Neurônios Aferentes/ultraestrutura , Proteína Quinase C/metabolismo , Ratos , Serotonina/farmacologia , Medula Espinal/ultraestruturaRESUMO
We report here the identification of one Mafa-DPA1 and four Mafa-DQB1 novel alleles of Vietnamese cynomolgus macaques.
Assuntos
Alelos , Éxons , Antígenos de Histocompatibilidade Classe II/genética , Macaca fascicularis/genética , Polimorfismo Genético , Sequência de Aminoácidos , Animais , Expressão Gênica , Genótipo , Haplótipos , Antígenos de Histocompatibilidade Classe II/classificação , Antígenos de Histocompatibilidade Classe II/imunologia , Teste de Histocompatibilidade , Macaca fascicularis/imunologia , Alinhamento de Sequência , Análise de Sequência de DNA , VietnãRESUMO
Five Mafa-DPB1, two Mafa-DQB1 and three Mafa-DRB novel alleles are identified in Vietnamese cynomolgus macaques.
Assuntos
Alelos , Antígenos de Histocompatibilidade Classe II/genética , Animais , Macaca fascicularis , VietnãRESUMO
Pancreatic cancer remains a worldwide issue and burden that is hard to resolve given its low resection rate and chemo-resistance. Early diagnosis and early treatment are critical for conquering pancreatic cancer. Therefore, new biomarkers for diagnosis and prognosis are urgently needed. Previously, researchers mainly focused on protein-coding genetic and epigenetic changes in many types of cancers, and regarded the noncoding part as waste. Recently, however, long non-coding RNA (lncRNA) has emerged as a major participant in carcinogenesis, as it regulates cell proliferation, migration, invasion, metastasis, chemo-resistance, etc. The underlying mechanisms are summarized as signaling, decoy, guide and scaffold, yet the specific regulation networks remain to be uncovered. Several studies have revealed that some lncRNAs are dysregulated in pancreatic cancer, participating in biological functions. In this review, we will briefly outline the functional lncRNAs in pancreatic cancer, decipher possible mechanisms of lncRNAs, and further explore their significance in pancreatic cancer.
Assuntos
Regulação Neoplásica da Expressão Gênica , Neoplasias Pancreáticas/genética , RNA Longo não Codificante/genética , Biomarcadores Tumorais , Carcinogênese/genética , Humanos , Neoplasias Pancreáticas/metabolismoRESUMO
Two forms of activity-dependent long-term depression (LTD) in the CNS, as defined by their sensitivity to the blockade of NMDA receptors, are thought to be important in learning, memory, and development. Here, we report that NMDA receptor-independent LTD is the major form of long-term plasticity in the anterior cingulate cortex (ACC). Both L-type voltage-gated calcium channels and metabotropic glutamate receptors are required for inducing LTD. Amputation of a third hindpaw digit in an adult rat induced rapid expression of immediate early genes in the ACC bilaterally and caused a loss of LTD that persisted for at least 2 weeks. Our results suggest that synaptic LTD in the ACC may contribute to enhanced neuronal responses to subsequent somatosensory stimuli after amputation.
Assuntos
Giro do Cíngulo/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Sinapses/fisiologia , Dedos do Pé/inervação , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Amputação Cirúrgica , Animais , Canais de Cálcio Tipo L/fisiologia , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/genética , Proteínas de Ligação a DNA/genética , Proteína 1 de Resposta de Crescimento Precoce , Estimulação Elétrica , D-Penicilina (2,5)-Encefalina/farmacologia , Potenciais Evocados/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Lateralidade Funcional , Regulação da Expressão Gênica , Giro do Cíngulo/efeitos dos fármacos , Membro Posterior , Proteínas Imediatamente Precoces/genética , Técnicas In Vitro , Masculino , Plasticidade Neuronal/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Picrotoxina/farmacologia , Proteínas Proto-Oncogênicas c-fos/genética , Ratos , Ratos Sprague-Dawley , Tempo de Reação , Receptores de Glutamato Metabotrópico/fisiologia , Sinapses/efeitos dos fármacos , Fatores de Transcrição/genéticaRESUMO
Small diameter dorsal root ganglion (DRG) neurons, which include cells that transmit nociceptive information into the spinal cord, are known to express functional kainate receptors. It is well established that exposure to kainate will depolarize C-fiber afferents arising from these cells. Although the role of kainate receptors on sensory afferents is unknown, it has been hypothesized that presynaptic kainate receptors may regulate glutamate release in the spinal cord. Here we show that kainate, applied at low micromolar concentrations in the presence of the AMPA-selective antagonist (RS)-4-(4-aminophenyl)-1, 2-dihydro-1-methyl-2-propyl-carbamoyl-6,7-methylenedioxyphthalazine++ +, suppressed spontaneous NMDA receptor-mediated EPSCs in cultures of spinal dorsal horn neurons. In addition, kainate suppressed EPSCs in dorsal horn neurons evoked by stimulation of synaptically coupled DRG cells in DRG-dorsal horn neuron cocultures. Interestingly, although the glutamate receptor subunit 5-selective kainate receptor agonist (RS)-2-alpha-amino-3-(3-hydroxy-5-tert-butylisoxazol-4-yl) propanoic acid (ATPA) (2 micrometer) was able to suppress DRG-dorsal horn synaptic transmission to a similar extent as kainate (10 micrometer), it had no effect on excitatory transmission between dorsal horn neurons. Agonist applications revealed a striking difference between kainate receptors expressed by DRG and dorsal horn neurons. Whereas DRG cell kainate receptors were sensitive to both kainate and ATPA, most dorsal horn neurons responded only to kainate. Finally, in recordings from dorsal horn neurons in spinal slices, kainate and ATPA were able to suppress NMDA and AMPA receptor-mediated EPSCs evoked by dorsal root fiber stimulation. Together, these data suggest that kainate receptor agonists, acting at a presynaptic locus, can reduce glutamate release from primary afferent sensory synapses.