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The development of predictive in vitro sensing tools able to provide rapid information on the different bioactivities of a sample is of pivotal importance, not only to monitor environmental toxicants, but also to understand their mechanisms of action on diverse molecular pathways. This mechanistic understanding is highly important for the characterization of toxicological hazards, and for the risk assessment of chemicals and environmental samples such as surface waters and effluents. Prompted by this need, we developed and optimized a straightforward bioluminescent multiplexed assay which enables the measurement of four bioactivities, selected for their relevance from a toxicological perspective, in bioluminescent microtissues. The assay was developed to monitor inflammatory, antioxidant, and toxic activity, and the presence of heavy metals, and was successfully applied to the analysis of river water samples, showing potential applicability for environmental analyses. The assay, which does not require advanced equipment, can be easily implemented in general laboratories equipped with basic cell culture facilities and a luminometer.
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Metales Pesados , Bioensayo , Agua Dulce , Mediciones LuminiscentesRESUMEN
Malignant Pleural Mesothelioma (MPM) is a rare malignancy with an overall poor prognosis. The standard therapeutic strategy in early-stage disease is trimodality therapy. In this publication, we report the preliminary toxicity results of the first 20 patients treated with accelerated hypofractionated radiotherapy. Between July 2017 to June 2019, 20 MPM patients were enrolled and treated with accelerated hypofractionated radiotherapy using helical tomotherapy and intensity-modulated arc therapy. The prescription dose was 30 Gy in five daily fractions, while an inhomogeneous dose escalation to 40 Gy was prescribed based solely upon the presence of gross residual tumor. Only one case of G3 toxicity was reported, which was a bilateral pneumonitis that occurred two years after treatment probably due to superinfection. Median Time to Progression reached 18.2 months while one- and three-year Overall Survival rates were 85% (95% CI:60.4-94.9) and 49.5% (95% CI:26.5-68.9), respectively. Treatment of the intact lung with pleural intensity-modulated arc irradiation is a novel treatment strategy that appears to be safe, feasible, and without a high grade of lung toxicity. Survival rates and Time to Progression are encouraging.
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Human immunodeficiency virus-1 (HIV-1)-encoded transactivator of transcription (Tat) potentiated the depolarization-evoked exocytosis of [(3)H]D-aspartate ([(3)H]D-ASP) from human neocortical terminals. The metabotropic glutamate (mGlu) 1 receptor antagonist 7-(hydroxyimino)cyclopropa[b]chromen-1a-carboxylate ethyl ester (CPCCOEt) prevented this effect, whereas the mGlu5 receptor antagonist 2-methyl-6-(phenylethynyl) pyridine hydrochloride (MPEP) was ineffective. Western blot analysis showed that human neocortex synaptosomes possess mGlu1 and mGlu5 receptors. Tat potentiated the K(+)-evoked release of [(3)H]D-ASP or of endogenous glutamate from mouse neocortical synaptosomes in a CPCCOEt-sensitive and MPEP-insensitive manner. Deletion of mGlu1 receptors (crv4/crv4 mice) or mGlu5 receptors (mGlu5(-/-)mouse) silenced Tat effects. Tat enhanced inositol 1,4,5-trisphosphate production in human and mouse neocortical synaptosomes, consistent with the involvement of group I mGlu receptors. Tat inhibited the K(+)-evoked release of [(3)H]gamma-aminobutyric acid ([(3)H]GABA) from human synaptosomes and that of endogenous GABA or [(3)H]GABA from mouse nerve terminals; the inhibition was insensitive to CPCCOEt or MPEP. Tat-induced effects were retained by Tat(37-72) but not by Tat(48-85). In mouse neocortical slices, Tat facilitated the K(+)- and the veratridine-induced release of [(3)H]D-ASP in a CPCCOEt-sensitive manner and was ineffective in crv4/crv4 mouse slices. These observations are relevant to the comprehension of the pathophysiological effects of Tat in central nervous system and may suggest new potential therapeutic approaches to the cure of HIV-1-associated dementia.
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Regulación hacia Abajo/fisiología , Exocitosis/fisiología , Ácido Glutámico/metabolismo , Neocórtex/metabolismo , Terminales Presinápticos/metabolismo , Regulación hacia Arriba/fisiología , Ácido gamma-Aminobutírico/metabolismo , Productos del Gen tat del Virus de la Inmunodeficiencia Humana/fisiología , Adulto , Anciano , Animales , Antagonistas de Aminoácidos Excitadores/farmacología , Humanos , Masculino , Ratones , Ratones Endogámicos BALB C , Persona de Mediana Edad , Neocórtex/citología , Técnicas de Cultivo de Órganos , Fragmentos de Péptidos/farmacología , Potasio/toxicidad , Transmisión Sináptica/efectos de los fármacos , Transmisión Sináptica/fisiología , Sinaptosomas/metabolismo , Adulto JovenRESUMEN
BACKGROUND: Chemotherapy and radiotherapy followed by durvalumab is currently the standard treatment for locally advanced node-positive non-small-cell lung cancer (NSCLC). We describe the case of a patient with locally advanced node-positive NSCLC (LA-NSCLC) treated in a phase II prospective protocol with chemotherapy, accelerated hypofractionated radiotherapy (AHRT) and surgery in the pre-immunotherapy era. CASE SUMMARY: A 69-year-old male, ex-smoker (20 PY), with a Karnofsky performance status of 90, was diagnosed with locally advanced squamous cell lung carcinoma. He was staged by total body computed tomography (CT) scanning, and integrated 18F-fluorodeoxyglucose positron emission tomography/CT scan [cT4 cN3 cM0, stage IIIC according to TNM (tumor-node-metastasis) 8th edition] and received AHRT between chemotherapy cycles, in accordance with the study protocol (EudractCT registration 2008-006525-14). At the end of the study the patient underwent surgery, which was not part of the protocol, and showed a complete pathological response. CONCLUSION: This case report confirms that AHRT can be used successfully to treat primary LA-NSCLC with bilateral mediastinal lymph node involvement. Our case is of particular interest because of the pathological response after AHRT and the lack of surgical complications. We hypothesize that this radiotherapeutic approach, with its proven efficacy, could be delivered as a short course reducing treatment costs, increasing patient compliance and reducing toxicity. We are currently investigating the possibility of combining hypofractionation, chemotherapy and immunotherapy for patients with LA-NSCLC.
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In locally advanced pancreatic cancer (LAPC), the combination of chemotherapy and radiotherapy is a widely used treatment option. We performed a pooled analysis, including an exploratory analysis for prognostic and predictive factors, of two phase 2 trials including 73 patients with LAPC, treated with gemcitabine and oxaliplatin (GEMOX) and hypofractionated tomotherapy. With a median follow-up of 36 months (range 1-65), median progression-free (PFS) and overall survival (OS) were 10.2 (95% confidence interval [CI] 7.8-13.2) and 14.3 (95% CI 12.0-18.1) months, respectively. The overall resectability rate was 23.3% (95% CI 13.6-33.0), and the R0 resection rate was 13.7% (95% CI 5.8-21.6). In the multivariate analysis, ECOG performance status (PS) 0 and low levels of CA 19-9 were associated with improved OS and PFS. Concerning OS, log(CA19-9) resulted in a hazard ratio (HR) of 1.20 (95% CI 1.02-1.42), p = 0.027. For ECOG PS 0, HR was 1.00; for PS 1, HR was 2.69 (95% CI 1.46-4.96); for PS 2, HR was 4.18 (95% CI 0.90-19.46); p = 0.003. Low CA19-9 levels were also predictive for resection, with an odds ratio of 0.71 (95% CI 0.52-0.97), p = 0.034. In conclusion, GEMOX and hypofractionated radiotherapy is a treatment option in LAPC. Further studies are needed to identify differences in tumor biology, which may help to predict resectability and prognosis.
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Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Ensayos Clínicos Fase II como Asunto/métodos , Desoxicitidina/análogos & derivados , Neoplasias Pancreáticas/tratamiento farmacológico , Neoplasias Pancreáticas/radioterapia , Radioterapia de Intensidad Modulada/métodos , Adulto , Anciano , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Terapia Combinada/métodos , Desoxicitidina/administración & dosificación , Desoxicitidina/efectos adversos , Fatiga/inducido químicamente , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Neutropenia/inducido químicamente , Compuestos Organoplatinos/administración & dosificación , Compuestos Organoplatinos/efectos adversos , Neoplasias Pancreáticas/diagnósticoRESUMEN
BACKGROUND: The presence of hypoxic cells in high-grade glioma (HGG) is one of major reasons for failure of local tumour control with radiotherapy (RT). The use of hyperbaric oxygen therapy (HBO) could help to overcome the problem of oxygen deficiency in poorly oxygenated regions of the tumour. We propose an innovative approach to improve the efficacy of hypofractionated stereotactic radiotherapy (HSRT) after HBO (HBO-RT) for the treatment of recurrent HGG (rHGG) and herein report the results of an ad interim analysis. METHODS: We enrolled a preliminary cohort of 9 adult patients (aged >18 years) with a diagnosis of rHGG. HSRT was administered in daily 5-Gy fractions for 3-5 consecutive days a week. Each fraction was delivered up to maximum of 60 minutes after HBO. RESULTS: Median follow-up from re-irradiation was 11.6 months (range: 3.2-11.6 months). The disease control rate (DCR) 3 months after HBO-RT was 55.5% (5 patients). Median progression-free survival (mPFS) for all patients was 5.2 months (95%CI: 1.34-NE), while 3-month and 6-month PFS was 55.5% (95%CI: 20.4-80.4) and 27.7% (95%CI: 4.4-59.1), respectively. Median overall survival (mOS) of HBO-RT was 10.7 months (95% CI: 7.7-NE). No acute or late neurologic toxicity >grade (G)2 was observed in 88.88% of patients. One patient developed G3 radionecrosis. CONCLUSIONS: HSRT delivered after HBO appears to be effective for the treatment of rHGG, it could represent an alternative, with low toxicity, to systemic therapies for patients who cannot or refuse to undergo such treatments. CLINICAL TRIAL REGISTRATION: www.ClinicalTrials.gov, identifier NCT03411408.
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Neboglamine is a functional modulator of the glycine site on the N-methyl-d-aspartate (NMDA) receptor. Dysfunction of this receptor has been associated with negative and cognitive symptoms in schizophrenia. Thus, we tested the hypothesis that neboglamine behaves as a potential antipsychotic. We compared the effects of neboglamine, D-serine, clozapine, and haloperidol on the expression of Fos-like immunoreactivity (FLI), a marker of neuronal activation, in rat forebrain. We also studied the effects of these agents on phencyclidine (PCP)-induced behaviour in rats, a model predictive of potential antipsychotic activity. Neboglamine, like haloperidol and clozapine, significantly increased the number of FLI-positive cells in the prefrontal cortex, nucleus accumbens, and lateral septal nucleus (3.2-, 4.8-, and 4.5-fold over control, respectively). Haloperidol dramatically increased FLI (390-fold over control) in the dorsolateral striatum, a brain region in which neboglamine and clozapine had no effect. The pattern of FLI induced by neboglamine closely matched that of d-serine, an endogenous agonist at the glycine site of NMDA receptors. Consistent with this finding, neboglamine restored NMDA-mediated neurotransmitter release in frontal cortex punches exposed to the NMDA antagonist PCP. In the behavioural model, all test compounds significantly inhibited PCP-induced hyperlocomotion. Unlike haloperidol and clozapine, neither neboglamine nor D-serine affected the basal levels of locomotor activity. Moreover, oral neboglamine dose-dependently inhibited both the hyperlocomotion and the frequency of rearing behaviour induced by PCP. These results, while confirming that the NMDA glycine site is a feasible target for activating the frontostriatal system, support the clinical evaluation of neboglamine as a treatment for schizophrenia.
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Antipsicóticos/farmacología , Conducta Animal/efectos de los fármacos , Ácidos Pentanoicos/farmacología , Receptores de N-Metil-D-Aspartato/efectos de los fármacos , Animales , Clozapina/farmacología , Relación Dosis-Respuesta a Droga , Alucinógenos/antagonistas & inhibidores , Alucinógenos/farmacología , Haloperidol/farmacología , Inmunohistoquímica , Masculino , Actividad Motora/efectos de los fármacos , Fenciclidina/antagonistas & inhibidores , Fenciclidina/farmacología , Prosencéfalo/efectos de los fármacos , Prosencéfalo/metabolismo , Proteínas Proto-Oncogénicas c-fos/metabolismo , Ratas , Ratas Wistar , Receptores de Glicina/efectos de los fármacos , Serina/metabolismoRESUMEN
The authors wish to make the following corrections to this paper [...].
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AIMS: This study aims to evaluate the safety and efficacy of a new neoadjuvant regimen (FOLFOX4 plus hypofractionated tomotherapy) in patients with locally advanced rectal cancer. METHODS: Patients with stage II-III rectal cancer were treated with the pre-operative chemoradiotherapy regimen comprising FOLFOX4 (two cycles), TomoTherapy (25 Gy in five consecutive fractions, one fraction per day in 5 days on the clinical target volume at the isodose of 95% of the total dose), FOLFOX4 (two cycles), followed by surgery with total mesorectal excision and adjuvant chemotherapy with FOLFOX4 (eight cycles). The primary endpoint was pathological complete response (pCR). RESULTS: Fifty-two patients were enrolled and 50 patients were evaluable. A total of 46 (92%) patients completed chemoradiotherapy according to the study protocol and 49 patients underwent surgery. Overall, 12 patients achieved a pCR (24.5%, 95% CI 12.5-36.5). The most common grade 3 or more adverse events were neutropenia and alteration of the alvus. Adverse reactions due to radiotherapy, mainly grade 1-2 dermatitis, tenesmus, urinary dysfunction and pain, were tolerable and fully reversible. The most important surgical complications included infection, anastomotic leakage and fistula, all resolved with conservative treatment. CONCLUSION: FOLFOX and hypofractionated TomoTherapy is effective and safe in patients with locally advanced rectal cancer. Long-term efficacy needs to be further evaluated. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT02000050 (registration date: 26 November 2013) https://clinicaltrials.gov/ct2/show/NCT02000050.
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The effects of the recombinant chemokine human RANTES (hRANTES) on the release of glutamate from human neocortex glutamatergic nerve endings were investigated. hRANTES facilitated the spontaneous release of d [(3)H]D-aspartate ([(3)H]DASP-) by binding Pertussis toxin-sensitive G-protein-coupled receptors (GPCRs), whose activation caused Ca(2+) mobilization from inositol trisphosphate-sensitive stores and cytosolic tyrosine kinase-mediated phosphorylations. Facilitation of release switched to inhibition when the effects of hRANTES on the 12 mM K(+)-evoked [(3)H]D-ASP exocytosis were studied. Inhibition of exocytosis relied on activation of Pertussis toxin-sensitive GPCRs negatively coupled to adenylyl cyclase. Both hRANTES effects were prevented by met-RANTES, an antagonist at the chemokine receptors (CCRs) of the CCR1, CCR3, and CCR5 subtypes. Interestingly, human neocortex glutamatergic nerve endings seem to possess all three receptor subtypes. Blockade of CCR1 and CCR5 by antibodies against the extracellular domain of CCRs prevented both the hRANTES effect on [(3)H]D-ASP release, whereas blockade of CCR3 prevented inhibition, but not facilitation, of release. The effects of RANTES on the spontaneous and the evoked release of [(3)H]D-ASP were also observed in experiments with mouse cortical synaptosomes, which may therefore represent an appropriate animal model to study RANTES-induced effects on neurotransmission. It is concluded that glutamate transmission can be modulated in opposite directions by RANTES acting at distinct CCR receptor subtypes coupled to different transduction pathways, consistent with the multiple and sometimes contrasting effects of the chemokine.
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Quimiocina CCL5/farmacología , Ácido Glutámico/metabolismo , Neocórtex/efectos de los fármacos , Neocórtex/metabolismo , Adulto , Anciano , Análisis de Varianza , Animales , Ácido Aspártico/farmacología , Calcio/metabolismo , Quimiocina CCL5/antagonistas & inhibidores , Ácido D-Aspártico/metabolismo , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/farmacología , Femenino , Humanos , Técnicas In Vitro , Compuestos Macrocíclicos/farmacología , Masculino , Ratones , Persona de Mediana Edad , Oxazoles/farmacología , Receptores CCR/metabolismo , Sinaptosomas/efectos de los fármacos , Sinaptosomas/metabolismo , Factores de Tiempo , Tritio/metabolismo , Adulto JovenRESUMEN
The aim of the study was to evaluate the safety and efficacy of a new chemo-radiotherapy regimen for patients with locally advanced pancreatic cancer (LAPC). Patients were treated as follows: gemcitabine 1000 mg/m2 on day 1, and oxaliplatin 100 mg/m2 on day 2, every two weeks (GEMOX regimen) for 4 cycles, 15 days off, hypofractionated radiotherapy (35 Gy in 7 fractions in 9 consecutive days), 15 days off, 4 additional cycles of GEMOX, restaging. From April 2011 to August 2016, a total of 42 patients with non resectable LAPC were enrolled. Median age was 67 years (range 41-75). Radiotherapy was well tolerated and the most frequently encountered adverse events were mild to moderate nausea and vomiting, abdominal pain and fatigue. In total, 9 patients underwent surgical laparotomy (5 radical pancreatic resection 1 thermoablation and 3 explorative laparotomy), 1 patient became operable but refused surgery. The overall resectability rate was 25%, while the R0 resection rate was 12.5%. At a median follow-up of 50 months, the median progression-free survival and overall survival were 9.3 (95% CI 6.2-14.9) and 15.8 (95% CI 8.2-23.4) months, respectively. The results demonstrate the feasibility of a new chemo-radiotherapy regimen as a potential treatment for unresectable LAPC.
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The effects of mGlu1 and mGlu5 receptor activation on the depolarization-evoked release of [3H]d-aspartate ([3H]D-ASP) from mouse cortical synaptosomes were investigated. The mGlu1/5 receptor agonist 3,5-DHPG (0.1-100microM) potentiated the K+(12mM)-evoked [3H]D-ASP overflow. The potentiation occurred in a concentration-dependent manner showing a biphasic pattern. The agonist potentiated [3H]D-ASP exocytosis when applied at 0.3microM; the efficacy of 3,5-DHPG then rapidly declined and reappeared at 30-100microM. The fall of efficacy of agonist at intermediate concentration may be consistent with 3,5-DHPG-induced receptor desensitization. Facilitation of [3H]D-ASP exocytosis caused by 0.3microM 3,5-DHPG was prevented by the selective mGlu5 receptor antagonist MPEP, but was insensitive to the selective mGlu1 receptor antagonist CPCCOEt. In contrast, CPCCOEt prevented the potentiation by 50microM 3,5-DHPG, while MPEP had minimal effect. Unexpectedly, LY 367385 antagonized both the 3,5-DHPG-induced effects. A total of 0.3microM 3,5-DHPG failed to facilitate the K+-evoked [3H]D-ASP overflow from mGlu5 receptor knockout (mGlu5-/-) cortical synaptosomes, but not from nerve terminals prepared from the cortex of animals lacking the mGlu1 receptors, the crv4/crv4 mice. On the contrary, 50microM 3,5-DHPG failed to affect the [3H]D-ASP exocytosis from cortical synaptosomes obtained from crv4/crv4 and mGlu5-/-mice. Western blot analyses in subsynaptic fractions support the existence of both mGlu1 and mGlu5 autoreceptors located presynaptically, while immunocytochemistry revealed their presence at glutamatergic terminals. We propose that mGlu1 and mGlu5 autoreceptors exist on mouse glutamatergic cortical terminals; mGlu5 receptors may represent the "high affinity" binding sites for 3,5-DHPG, while mGlu1 autoreceptors represent the "low affinity" binding sites.
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Corteza Cerebral/citología , Exocitosis/fisiología , Ácido Glutámico/metabolismo , Terminales Presinápticos/fisiología , Receptores de Glutamato Metabotrópico/fisiología , Animales , Ácido Aspártico/metabolismo , Relación Dosis-Respuesta a Droga , Interacciones Farmacológicas , Fármacos actuantes sobre Aminoácidos Excitadores/farmacología , Exocitosis/efectos de los fármacos , Expresión Génica/fisiología , Glicina/análogos & derivados , Glicina/farmacología , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Noqueados , Cloruro de Potasio/farmacología , Receptor del Glutamato Metabotropico 5 , Receptores de Glutamato Metabotrópico/deficiencia , Resorcinoles/farmacología , Sinaptosomas/efectos de los fármacos , Sinaptosomas/metabolismo , Sintaxina 1/metabolismo , Tritio/metabolismo , Proteína 1 de Transporte Vesicular de Glutamato/metabolismoRESUMEN
We investigated the effects of salvinorin A on the basal and the 12 mM K(+)-evoked release of preloaded [(3)H]noradenaline ([(3)H]NA) and [(3)H]serotonin ([(3)H]5-HT) from mouse hippocampal nerve terminals (synaptosomes), as well as on the basal and 12mM K(+)-evoked release of preloaded [(3)H]dopamine ([(3)H]DA) from mouse striatal and prefrontal cortex (PFc) synaptosomes. Salvinorin A (0.1-1000 nM) failed to affect the basal release of amines, but inhibited the 12 mM K(+)-evoked, Ca(2+)-dependent, exocytotic-like release of [(3)H]5-HT and [(3)H]DA. At the same concentration, salvinorin A facilitated the 12 mM K(+)-evoked, Ca(2+)-dependent, exocytotic-like release of [(3)H]NA. These effects could not be observed in pertussis toxin (PTx) entrapped synaptosomes. The broad spectrum kappa-opioid receptor (KOR) antagonist norbinaltorphimine (norBNI, 1-100 nM) antagonized the inhibition of [(3)H]5-HT and [(3)H]DA exocytosis as well as the facilitation of [(3)H]NA overflow induced by 100 nM salvinorin A. The KOR agonist U69593 (1-100 nM) mimicked salvinorin A in inhibiting [(3)H]5-HT and of [(3)H]DA exocytosis, its effect being prevented by norBNI, but leaving unchanged the K(+)-evoked release of [(3)H]NA. The effects of Salvinorin A on neurotransmitter exocytosis were not prevented by the selective mu opioid (MOR) receptor antagonist CTAP (10-100 nM), whereas facilitation of [(3)H]NA exocytosis, but not inhibition of [(3)H]5-HT and [(3)H]DA K(+)-evoked release, was counteracted by the delta opioid receptor (DOR) antagonist naltrindole (1-100 nM). We conclude that salvinorin A presynaptically modulates central NA, 5-HT, and DA exocytosis evoked by a mild depolarizing stimulus by acting at presynaptic opioid receptors having different pharmacological profiles.
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Fármacos del Sistema Nervioso Central/farmacología , Diterpenos de Tipo Clerodano/farmacología , Exocitosis/efectos de los fármacos , Neurotransmisores/metabolismo , Terminales Presinápticos/efectos de los fármacos , Animales , Calcio/metabolismo , Cuerpo Estriado/efectos de los fármacos , Cuerpo Estriado/fisiología , Dopamina/metabolismo , Exocitosis/fisiología , Hipocampo/efectos de los fármacos , Hipocampo/fisiología , Masculino , Ratones , Antagonistas de Narcóticos , Neuronas/efectos de los fármacos , Neuronas/fisiología , Norepinefrina/metabolismo , Potasio/metabolismo , Corteza Prefrontal/efectos de los fármacos , Corteza Prefrontal/fisiología , Terminales Presinápticos/fisiología , Receptores Opioides/metabolismo , Serotonina/metabolismo , Sinaptosomas/efectos de los fármacos , Sinaptosomas/fisiologíaRESUMEN
Human immunodeficiency virus 1 (HIV-1)-associated dementia (HAD) represents a common complication of HIV-1 infection. Antiretroviral therapy has diminished its incidence, but it is insufficient to eradicate the problem. HAD depends on the presence of the virus in central nervous system (CNS), but the molecular mechanisms involved are not completely understood. It is widely accepted that proteins shed by the virus, such as the envelope glycoprotein gp120 and the nonstructural viral protein Tat, may themselves cause alterations to CNS. By one side, viral proteins are toxic to neurons because of their ability (1) to act as excitotoxins and (2) to evoke the release of endogenous neurotoxins and/or proinflammatory cytokines. By the other side, evidences are emerging that viral components can alter neuronal functions either by modifying the release of neurotransmitters or by influencing the functions of classical receptors controlling central neurotransmission. We here review some results concerning the effects of Tat on cholinergic and noradrenergic neurotransmission in human and rat cortex. The protein can induce the release of acetylcholine from both human and rat cortical cholinergic nerve terminals in a specie-specific manner. In human cholinergic terminals, Tat-mediated releasing effect depends on activation of receptors belonging to I group of metabotropic glutamate receptors (mGluRs), while in rat terminals Tat-induced effect involves the activation of a so far unknown receptor. The protein, unable on its own to release noradrenaline from human and rat cortical noradrenergic nerve endings, potentiates the release of amine induced by presynaptic NMDA receptors. Also in this case, Tat effect involves activation of a receptor belonging to the group I mGluRs, in particular of the mGluR1 subtype. The finding that group I mGluRs may represent a preferential target of the protein in CNS may be relevant to the proposal of new therapeutic approaches for the cure of HAD.
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Productos del Gen tat/farmacología , VIH-1/metabolismo , Receptores de Glutamato Metabotrópico/fisiología , Transmisión Sináptica/fisiología , Animales , Sistema Nervioso Central/efectos de los fármacos , Sistema Nervioso Central/metabolismo , Productos del Gen tat/genética , Humanos , Neurotransmisores/metabolismo , Receptores de Glutamato Metabotrópico/efectos de los fármacos , Receptores Presinapticos/efectos de los fármacos , Transmisión Sináptica/efectos de los fármacos , Productos del Gen tat del Virus de la Inmunodeficiencia HumanaRESUMEN
Presynaptic NMDA autoreceptors regulating glutamate release have rarely been investigated. High-micromolar N-methyl-D-aspartate (NMDA) was reported to elicit glutamate release from hippocampal synaptosomes in a Ca(2+)-independent manner by reversal of excitatory amino acid transporters. The aim of this work was to characterize excitatory amino acid release evoked by low-micromolar NMDA from glutamatergic axon terminals. Purified rat hippocampal synaptosomes were prelabelled with [(3)H]D-aspartate ([(3)H]D-ASP) and exposed in superfusion to varying concentrations of NMDA in the presence of 1 microM glycine. The release of [(3)H]D-ASP and also that of endogenous glutamate provoked by 10 microM NMDA were external Ca(2+) dependent and sensitive to the NMDA channel blocker MK-801 but insensitive to the glutamate transporter inhibitor DL-TBOA, which, on the contrary, prevented the Ca(2+)-independent release evoked by 100 microM NMDA. The NMDA (10 microM) response was blocked by 1 nM Zn(2+) and 1 microM ifenprodil, compatible with the involvement of a NR1/NR2A/NR2B assembly, although the presence of two separate receptor populations, i.e., NR1/NR2A and NR1/NR2B, cannot be excluded. This response was strongly antagonized by submicromolar (0.01-1 microM) concentrations of kynurenic acid and was mimicked by quinolinic acid (1-100 microM) plus 1 microM glycine. Finally, the HIV-1 protein gp120 potently mimicked the NMDA co-agonists glycine and D-serine, being significantly effective at 30 pM. In conclusion, glutamatergic nerve terminals possess NMDA autoreceptors mediating different types of release when activated by different agonist concentrations: low-micromolar glutamate would potentiate glutamate exocytosis, whereas higher glutamate concentrations would also provoke carrier-mediated release.