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1.
J Physiol ; 599(20): 4643-4669, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34418097

RESUMEN

Cortical areas have the capacity of large-scale reorganization following sensory deafferentation. However, it remains unclear whether this phenomenon is a unique process that homogeneously affects the entire deprived cortical region or whether it is susceptible to changes depending on neuronal networks across distinct cortical layers. Here, we studied how the local circuitry within each layer of the deafferented cortex forms the basis for neuroplastic changes after immediate thoracic spinal cord injury (SCI) in anaesthetized rats. In vivo electrophysiological recordings from deafferented hindlimb somatosensory cortex showed that SCI induces layer-specific changes mediating evoked and spontaneous activity. In supragranular layer 2/3, SCI increased gamma oscillations and the ability of these neurons to initiate up-states during spontaneous activity, suggesting an altered corticocortical network and/or intrinsic properties that may serve to maintain the excitability of the cortical column after deafferentation. On the other hand, SCI enhanced the infragranular layers' ability to integrate evoked sensory inputs leading to increased and faster neuronal responses. Delayed evoked response onsets were also observed in layer 5/6, suggesting alterations in thalamocortical connectivity. Altogether, our data indicate that SCI immediately modifies the local circuitry within the deafferented cortex allowing supragranular layers to better integrate spontaneous corticocortical information, thus modifying column excitability, and infragranular layers to better integrate evoked sensory inputs to preserve subcortical outputs. These layer-specific neuronal changes may guide the long-term alterations in neuronal excitability and plasticity associated with the rearrangements of somatosensory networks and the appearance of central sensory pathologies usually associated with spinal cord injury. KEY POINTS: Sensory stimulation of forelimb produces cortical evoked responses in the somatosensory hindlimb cortex in a layer-dependent manner. Spinal cord injury favours the input statistics of corticocortical connections between intact and deafferented cortices. After spinal cord injury supragranular layers exhibit better integration of spontaneous corticocortical information while infragranular layers exhibit better integration of evoked sensory stimulation. Cortical reorganization is a layer-specific phenomenon.


Asunto(s)
Privación Sensorial , Traumatismos de la Médula Espinal , Animales , Plasticidad Neuronal , Neuronas , Ratas , Corteza Somatosensorial
2.
J Neurosci ; 36(37): 9683-95, 2016 09 14.
Artículo en Inglés | MEDLINE | ID: mdl-27629718

RESUMEN

UNLABELLED: Direction selectivity is a robust computation across a broad stimulus space that is mediated by activity of both rod and cone photoreceptors through the ON and OFF pathways. However, rods, S-cones, and M-cones activate the ON and OFF circuits via distinct pathways and the relative contribution of each to direction selectivity is unknown. Using a variety of stimulation paradigms, pharmacological agents, and knockout mice that lack rod transduction, we found that inputs from the ON pathway were critical for strong direction-selective (DS) tuning in the OFF pathway. For UV light stimulation, the ON pathway inputs to the OFF pathway originated with rod signaling, whereas for visible stimulation, the ON pathway inputs to the OFF pathway originated with both rod and M-cone signaling. Whole-cell voltage-clamp recordings revealed that blocking the ON pathway reduced directional tuning in the OFF pathway via a reduction in null-side inhibition, which is provided by OFF starburst amacrine cells (SACs). Consistent with this, our recordings from OFF SACs confirmed that signals originating in the ON pathway contribute to their excitation. Finally, we observed that, for UV stimulation, ON contributions to OFF DS tuning matured earlier than direct signaling via the OFF pathway. These data indicate that the retina uses multiple strategies for computing DS responses across different colors and stages of development. SIGNIFICANCE STATEMENT: The retina uses parallel pathways to encode different features of the visual scene. In some cases, these distinct pathways converge on circuits that mediate a distinct computation. For example, rod and cone pathways enable direction-selective (DS) ganglion cells to encode motion over a wide range of light intensities. Here, we show that although direction selectivity is robust across light intensities, motion discrimination for OFF signals is dependent upon ON signaling. At eye opening, ON directional tuning is mature, whereas OFF DS tuning is significantly reduced due to a delayed maturation of S-cone to OFF cone bipolar signaling. These results provide evidence that the retina uses multiple strategies for computing DS responses across different stimulus conditions.


Asunto(s)
Orientación/fisiología , Retina/citología , Células Fotorreceptoras Retinianas Conos/fisiología , Células Fotorreceptoras Retinianas Bastones/fisiología , Vías Visuales/fisiología , Potenciales de Acción , Animales , Opsinas de los Conos/metabolismo , Luz , Fototransducción/efectos de los fármacos , Ratones , Ratones Endogámicos C57BL , Ratones Transgénicos , Estimulación Luminosa , Receptores AMPA/genética , Receptores AMPA/metabolismo , Receptores de Interleucina-2/genética , Receptores de Interleucina-2/metabolismo , Receptores de Hormona Liberadora de Tirotropina/genética , Receptores de Hormona Liberadora de Tirotropina/metabolismo , Células Ganglionares de la Retina , Opsinas de Bastones/metabolismo , Potenciales Sinápticos/fisiología , Rayos Ultravioleta
3.
Vis Neurosci ; 32: E003, 2015 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-25873107

RESUMEN

Early in development, before the onset of vision, the retina establishes direction-selective responses. During this time period, the retina spontaneously generates bursts of action potentials that propagate across its extent. The precise spatial and temporal properties of these "retinal waves" have been implicated in the formation of retinal projections to the brain. However, their role in the development of direction selective circuits within the retina has not yet been determined. We addressed this issue by combining multielectrode array and cell-attached recordings to examine mice that lack the CaV3.2 subunit of T-type Ca2+ channels (CaV3.2 KO) because these mice exhibit disrupted waves during the period that direction selective circuits are established. We found that the spontaneous activity of these mice displays wave-associated bursts of action potentials that are altered from that of control mice: the frequency of these bursts is significantly decreased and the firing rate within each burst is reduced. Moreover, the projection patterns of the retina demonstrate decreased eye-specific segregation in the dorsal lateral geniculate nucleus (dLGN). However, after eye-opening, the direction selective responses of CaV3.2 KO direction selective ganglion cells (DSGCs) are indistinguishable from those of wild-type DSGCs. Our data indicate that although the temporal properties of the action potential bursts associated with retinal waves are important for activity-dependent refining of retinal projections to central targets, they are not critical for establishing direction selectivity in the retina.


Asunto(s)
Potenciales de Acción/genética , Canales de Calcio Tipo T/deficiencia , Retina/patología , Retina/fisiopatología , Trastornos de la Visión , Animales , Animales Recién Nacidos , Canales de Calcio Tipo T/genética , Cuerpos Geniculados/patología , Técnicas In Vitro , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Orientación , Células Ganglionares de la Retina/patología , Trastornos de la Visión/genética , Trastornos de la Visión/patología , Trastornos de la Visión/fisiopatología , Vías Visuales/fisiología
4.
STAR Protoc ; 5(2): 102972, 2024 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-38502685

RESUMEN

Studies on sensory information processing typically focus on whisker-related tactile information, overlooking the question of how sensory inputs from other body areas are processed at cortical levels. Here, we present a protocol for stimulating specific rodent limb receptive fields while recording in vivo somatosensory-evoked activity. We describe steps for localizing cortical-hindlimb coordinates using acute peripheral stimulation, electrode placement, and the application of electrical stimulation. This protocol overcomes the challenge of inducing a reproducible and consistent stimulation of specific limbs. For complete details on the use and execution of this protocol, please refer to Miguel-Quesada et al.1.


Asunto(s)
Estimulación Eléctrica , Potenciales Evocados Somatosensoriales , Corteza Somatosensorial , Animales , Potenciales Evocados Somatosensoriales/fisiología , Estimulación Eléctrica/métodos , Corteza Somatosensorial/fisiología , Ratas , Ratones , Extremidades/fisiología , Roedores , Miembro Posterior/fisiología , Vibrisas/fisiología
5.
Exp Neurol ; 369: 114504, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37591355

RESUMEN

The complete or partial damage of ascending somatosensory pathways produced by a spinal cord injury triggers changes in the somatosensory cortex consisting in a functional expansion of activity from intact cortical regions towards deafferented ones, a process known as cortical reorganization. However, it is still unclear whether cortical reorganization depends on the severity of the spinal cord damage or if a spinal cord injury always leads to a similar cortical reorganization process in the somatosensory cortex. To answer these open questions in the field, we obtained longitudinal somatosensory evoked responses from bilateral hindlimb and forelimb cortex from animals with chronic full-transection or contusive spinal cord injury at thoracic level (T9-T10) to induce sensory deprivation of hindlimb cortex while preserving intact the forelimb cortex. Electrophysiological recordings from the four locations were obtained before lesion and weekly for up to 4 weeks. Our results show that cortical reorganization depends on the type of spinal cord injury, which tends to be more bilateral in full transection while is more unilateral in the model of contusive spinal cord injury. Moreover, in full transection of spinal cord, the deafferented and intact cortex exhibited similar increments of somatosensory evoked responses in both models of spinal cord injury - a feature observed in about 80% of subjects. The other 20% were unaffected by the injury indicating that cortical reorganization does not undergo in all subjects. In addition, we demonstrated an increased probability of triggered up-states in animals with spinal cord injury. This data indicates increased cortical excitability that could be proposed as a new feature of cortical reorganization. Finally, decreased levels of GABA marker GAD67 across cortical layers were only found in those animals with increased somatosensory evoked responses, but not in the unaffected population. In conclusion, cortical reorganization depends on the types of spinal cord injuries, and suggest that the phenomenon is strongly determined by cortical circuits. Moreover, changes in GABAergic transmission at the deprived cortex may be considered one of the mechanisms underlying the process of cortical reorganization and increased excitability.

6.
Clin Neurophysiol ; 149: 18-24, 2023 05.
Artículo en Inglés | MEDLINE | ID: mdl-36867915

RESUMEN

OBJECTIVE: Focal application of transcranial static magnetic field stimulation (tSMS) is a neuromodulation technique, with predominantly inhibitory effects when applied to the motor, somatosensory or visual cortex. Whether this approach can also transiently interact with dorsolateral prefrontal cortex (DLPFC) function remains unclear. The suppression of habitual or competitive responses is one of the core executive functions linked to DLPFC function. This study aimed to assess the impact of tSMS on the prefrontal contributions to inhibitory control and response selection by means of a RNG task. METHODS: We applied 20 min of tSMS over the left DLPFC of healthy subjects, using a real/sham cross-over design, during performance of a RNG task. We used an index of randomness calculated with the measures of entropy and correlation to assess the impact of stimulation on DLPFC function. RESULTS: The randomness index of the sequences generated during the tSMS intervention was significantly higher compared to those produced in the sham condition. CONCLUSIONS: Our results indicate that application of tSMS transiently modulates specific functional brain networks in DLPFC, which indicate a potential use of tSMS for treatment of neuropsychiatric disorders. SIGNIFICANCE: This study provides evidence for the capacity of tSMS for modulating DLPFC function.


Asunto(s)
Estimulación Transcraneal de Corriente Directa , Corteza Visual , Humanos , Corteza Prefontal Dorsolateral , Estimulación Magnética Transcraneal/métodos , Función Ejecutiva , Campos Magnéticos , Corteza Prefrontal/fisiología , Estimulación Transcraneal de Corriente Directa/métodos
7.
Cell Rep ; 42(8): 112950, 2023 08 29.
Artículo en Inglés | MEDLINE | ID: mdl-37543946

RESUMEN

Cortical neuron-astrocyte communication in response to peripheral sensory stimulation occurs in a topographic-, frequency-, and intensity-dependent manner. However, the contribution of this functional interaction to the processing of sensory inputs and consequent behavior remains unclear. We investigate the role of astrocytes in sensory information processing at circuit and behavioral levels by monitoring and manipulating astrocytic activity in vivo. We show that astrocytes control the dynamic range of the cortical network activity, optimizing its responsiveness to incoming sensory inputs. The astrocytic modulation of sensory processing contributes to setting the detection threshold for tactile and thermal behavior responses. The mechanism of such astrocytic control is mediated through modulation of inhibitory transmission to adjust the gain and sensitivity of responding networks. These results uncover a role for astrocytes in maintaining the cortical network activity in an optimal range to control behavior associated with specific sensory modalities.


Asunto(s)
Astrocitos , Corteza Somatosensorial , Astrocitos/fisiología , Vías Nerviosas , Calcio/metabolismo , Neuronas/fisiología , Electrofisiología , Animales , Ratones , Corteza Somatosensorial/citología , Corteza Somatosensorial/fisiología , Percepción Olfatoria , Percepción del Tacto
8.
Am J Physiol Cell Physiol ; 301(1): C86-98, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21451100

RESUMEN

Calcium (Ca(2+))-dependent endocytosis has been linked to preferential Ca(2+) entry through the L-type (α(1D), Ca(V)1.3) of voltage-dependent Ca(2+) channels (VDCCs). Considering that the Ca(2+)-dependent exocytotic release of neurotransmitters is mostly triggered by Ca(2+) entry through N-(α(1B), Ca(V)2.2) or PQ-VDCCs (α(1A), Ca(V)2.1) and that exocytosis and endocytosis are coupled, the supposition that the different channel subtypes are specialized to control different cell functions is attractive. Here we have explored this hypothesis in primary cultures of bovine adrenal chromaffin cells where PQ channels account for 50% of Ca(2+) current (I(Ca)), 30% for N channels, and 20% for L channels. We used patch-clamp and fluorescence techniques to measure the exo-endocytotic responses triggered by long depolarizing stimuli, in 1, 2, or 10 mM concentrations of extracellular Ca(2+) ([Ca(2+)](e)). Exo-endocytotic responses were little affected by ω-conotoxin GVIA (N channel blocker), whereas ω-agatoxin IVA (PQ channel blocker) caused 80% blockade of exocytosis as well as endocytosis. In contrast, nifedipine (L channel blocker) only caused 20% inhibition of exocytosis but as much as 90% inhibition of endocytosis. Conversely, FPL67146 (an activator of L VDCCs) notably augmented endocytosis. Photoreleased caged Ca(2+) caused substantially smaller endocytotic responses compared with those produced by K(+) depolarization. Using fluorescence antibodies, no colocalization between L, N, or PQ channels with clathrin was found; a 20-30% colocalization was found between dynamin and all three channel antibodies. This is incompatible with the view that L channels are coupled to the endocytotic machine. Data rather support a mechanism implying the different inactivation rates of L (slow-inactivating) and N/PQ channels (fast-inactivating). Thus a slow but more sustained Ca(2+) entry through L channels could be a requirement to trigger endocytosis efficiently, at least in bovine chromaffin cells.


Asunto(s)
Canales de Calcio Tipo L/fisiología , Calcio/metabolismo , Endocitosis/fisiología , Exocitosis/fisiología , Animales , Bloqueadores de los Canales de Calcio/farmacología , Canales de Calcio Tipo L/efectos de los fármacos , Bovinos , Células Cultivadas , Células Cromafines/metabolismo , Células Cromafines/fisiología , Clatrina/fisiología , Conotoxinas/farmacología , Dinaminas/fisiología , Endocitosis/efectos de los fármacos , Exocitosis/efectos de los fármacos , Técnica del Anticuerpo Fluorescente , Nifedipino/farmacología , Técnicas de Placa-Clamp
9.
Biochem Biophys Res Commun ; 410(2): 307-11, 2011 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-21663733

RESUMEN

Ca(2+) entry through the L-subtype (α(1D), Ca(v)1,3) of voltage-dependent calcium channels (VDCCs) seems to selectively regulate the endocytotic response after the application of a single depolarizing pulse to voltage-clamped bovine chromaffin cells. Here we have found that L channel blockade with nifedipine transformed the exocytotic responses elicited by a double-pulse protocol, from depression to facilitation. This apparent paradoxical effect was mimicked by pharmacological interventions that directly block endocytosis namely, dynasore, calmidazolium, GTP-γS and GDP-ßS. This reinforces our view that Ca(2+) entry through PQ channels (α(1A); Ca(v)2.1) regulates fast exocytosis while Ca(2+) entry through L channels preferentially controls rapid endocytosis.


Asunto(s)
Bloqueadores de los Canales de Calcio/farmacología , Canales de Calcio Tipo L/metabolismo , Células Cromafines/efectos de los fármacos , Exocitosis/efectos de los fármacos , Animales , Calcio/metabolismo , Canales de Calcio Tipo L/efectos de los fármacos , Bovinos , Células Cultivadas , Células Cromafines/metabolismo , Guanosina 5'-O-(3-Tiotrifosfato)/análogos & derivados , Guanosina 5'-O-(3-Tiotrifosfato)/farmacología , Hidrazonas/farmacología , Imidazoles/farmacología , Nifedipino/farmacología
10.
Br J Pharmacol ; 178(17): 3395-3413, 2021 09.
Artículo en Inglés | MEDLINE | ID: mdl-33830504

RESUMEN

BACKGROUND AND PURPOSE: Activation of astrocytes contributes to synaptic remodelling, tissue repair and neuronal survival following traumatic brain injury (TBI). The mechanisms by which these cells interact to resident/infiltrated inflammatory cells to rewire neuronal networks and repair brain functions remain poorly understood. Here, we explored how TLR4-induced astrocyte activation modified synapses and cerebrovascular integrity following TBI. EXPERIMENTAL APPROACH: To determine how functional astrocyte alterations induced by activation of TLR4 pathway in inflammatory cells regulate synapses and neurovascular integrity after TBI, we used pharmacology, genetic approaches, live calcium imaging, immunofluorescence, flow cytometry, blood-brain barrier (BBB) integrity assessment and molecular and behavioural methods. KEY RESULTS: Shortly after a TBI, there is a recruitment of excitable and reactive astrocytes mediated by TLR4 pathway activation with detrimental effects on post-synaptic density-95 (PSD-95)/vesicular glutamate transporter 1 (VGLUT1) synaptic puncta, BBB integrity and neurological outcome. Pharmacological blockage of the TLR4 pathway with resatorvid (TAK-242) partially reversed many of the observed effects. Synapses and BBB recovery after resatorvid administration were not observed in IP3 R2-/- mice, indicating that effects of TLR4 inhibition depend on the subsequent astrocyte activation. In addition, TBI increased the astrocytic-protein thrombospondin-1 necessary to induce a synaptic recovery in a sub-acute phase. CONCLUSIONS AND IMPLICATIONS: Our data demonstrate that TLR4-mediated signalling, most probably through microglia and/or infiltrated monocyte-astrocyte communication, plays a crucial role in the TBI pathophysiology and that its inhibition prevents synaptic loss and BBB damage accelerating tissue recovery/repair, which might represent a therapeutic potential in CNS injuries and disorders.


Asunto(s)
Astrocitos , Lesiones Traumáticas del Encéfalo , Animales , Astrocitos/metabolismo , Barrera Hematoencefálica/metabolismo , Ratones , Microglía/metabolismo , Neuronas/metabolismo , Receptor Toll-Like 4/metabolismo
11.
Biomaterials ; 279: 121186, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34700221

RESUMEN

Progress in the clinical application of recording and stimulation devices for neural diseases is still limited, mainly because of suboptimal material engineering and unfavorable interactions with biological entities. Nanotechnology is providing upgraded designs of materials to better mimic the native extracellular environment and attain more intimate contacts with individual neurons, besides allowing for the miniaturization of the electrodes. However, little progress has been done to date on the understanding of the biological impact that such neural interfaces have on neural network maturation and functionality. In this work, we elucidate the effect of a gold (Au) highly ordered nanostructure on the morphological and functional interactions with neural cells and tissues. Alumina-templated Au nanostructured electrodes composed of parallel nanowires of 160 nm in diameter and 1.2 µm in length (Au-NWs), with 320 nm of pitch, are designed and characterized. Equivalent non-structured Au electrodes (Au-Flat) are used for comparison. By using diverse techniques in in vitro cell cultures including live calcium imaging, we found that Au-NWs interfaced with primary neural cortical cells for up to 14 days allow neural networks growth and increase spontaneous activity and ability of neuronal synchronization, thus indicating that nanostructured features favor neuronal network. The enhancement in the number of glial cells found is hypothesized to be behind these beneficial functional effects. The in vivo effect of the implantation of these nanostructured electrodes and its potential relevance for future clinical applicability has been explored in an experimental model of rat spinal cord injury. Subacute responses to implanted Au-NWs show no overt reactive or toxic biological reactions besides those triggered by the injury itself. These results highlight the translational potential of Au-NWs electrodes for in vivo applications as neural interfaces in contact with central nervous tissues including the injured spinal cord.


Asunto(s)
Nanoestructuras , Nanocables , Animales , Electrodos , Oro , Nanotecnología , Ratas
12.
Biomedicines ; 9(6)2021 May 25.
Artículo en Inglés | MEDLINE | ID: mdl-34070533

RESUMEN

Traumatic brain injury (TBI) is one of the leading causes of mortality and disability worldwide without any validated biomarker or set of biomarkers to help the diagnosis and evaluation of the evolution/prognosis of TBI patients. To achieve this aim, a deeper knowledge of the biochemical and pathophysiological processes triggered after the trauma is essential. Here, we identified the serum amyloid A1 protein-Toll-like receptor 4 (SAA1-TLR4) axis as an important link between inflammation and the outcome of TBI patients. Using serum and mRNA from white blood cells (WBC) of TBI patients, we found a positive correlation between serum SAA1 levels and injury severity, as well as with the 6-month outcome of TBI patients. SAA1 levels also correlate with the presence of TLR4 mRNA in WBC. In vitro, we found that SAA1 contributes to inflammation via TLR4 activation that releases inflammatory cytokines, which in turn increases SAA1 levels, establishing a positive proinflammatory loop. In vivo, post-TBI treatment with the TLR4-antagonist TAK242 reduces SAA1 levels, improves neurobehavioral outcome, and prevents blood-brain barrier disruption. Our data support further evaluation of (i) post-TBI treatment in the presence of TLR4 inhibition for limiting TBI-induced damage and (ii) SAA1-TLR4 as a biomarker of injury progression in TBI patients.

13.
Pflugers Arch ; 460(5): 901-14, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20640579

RESUMEN

Sphingosine has been shown to modulate neurotransmitter release. Because membrane fusion and fission involve lipid metabolism, we asked here whether sphingosine had a role in regulating endocytosis. To explore this hypothesis, we monitored changes of membrane capacitance (Cm) to study the effects of intracellular sphingosine on membrane retrieval after chromaffin cell stimulation with depolarising pulses (DPs). We found that: (1) sphingosine dialysis through the patch-clamp pipette (SpD) using the whole-cell configuration of the patch-clamp technique (WCC) favours the appearance of a pronounced endocytotic response; (2) SpD-elicited endocytosis was Ca(2+)-dependent but Ba(2+) did not substitute Ca(2+); (3) under WCC, such endocytotic response disappeared with repetitive DPs; (4) in cells preincubated with sphingomyelinase to augment endogenous sphingosine synthesis, and then voltage-clamped under the perforated-patch configuration of the patch-clamp technique (PPC), endocytosis decayed little with repeated stimulation; (5) sphingosine-1-phosphate (S1P), a metabolite of sphingosine, had a meagre effect on endocytosis; and (6) neither dynamin inhibitor dynasore nor calmodulin blocker calmidazolium affected the sphingosine elicited endocytosis. We believe this is the first report showing that sphingosine plays a permissive role in activating Ca(2+)-dependent endocytosis during cell depolarisation. This effect requires high subplasmalemmal cytosolic Ca(2+) concentrations and a cytosolic factor(s) that is dialysed with the pipette solution. Independence of dynamin and calmodulin suggests that sphingosine-dependent endocytosis could be a novel, more direct pathway for vesicle recycling under mild depolarisation stimuli.


Asunto(s)
Calcio/fisiología , Células Cromafines/fisiología , Endocitosis/efectos de los fármacos , Esfingosina/farmacología , Animales , Bario/farmacología , Carbonil Cianuro p-Trifluorometoxifenil Hidrazona/farmacología , Bovinos , Células Cromafines/efectos de los fármacos , Endocitosis/fisiología , Hidrazonas/farmacología , Imidazoles/farmacología , Lisofosfolípidos/farmacología , Técnicas de Placa-Clamp , Esfingomielina Fosfodiesterasa/metabolismo , Esfingosina/análogos & derivados
14.
Chem Biol Interact ; 328: 109195, 2020 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-32707044

RESUMEN

A previous study demonstrated that glutathione (GSH) produces specific antidepressant-like effect in the forced swimming test (FST), a predictive test of antidepressant activity. The present study investigated the involvement of multiple cellular targets implicated in the antidepressant-like effect of GSH in the FST. The antidepressant-like effect of GSH (300 nmol/site, icv) lasted up to 3 h when mice were submitted to FST. The central administration of oxidized GSH (GSSG, 3-300 nmol/site) did not alter the behavior of mice submitted to the FST. Furthermore, the combined treatment of sub-effective doses of GSH (100 nmol/site, icv) with a sub-effective dose of classical antidepressants (fluoxetine 10 mg/kg, and imipramine 5 mg/kg, ip) presented synergistic effect by decreasing the immobility time in the FST. The antidepressant-like effect of GSH was abolished by prazosin (1 mg/kg, ip, α1-adrenoceptor antagonist), baclofen (1 mg/kg, ip, GABAB receptor agonist), bicuculline (1 mg/kg, ip, GABAA receptor antagonist), l-arginine (750 mg/kg, ip, NO precursor), SNAP (25 µg/site, icv, NO donor), but not by yohimbine (1 mg/kg, ip, α2-adrenoceptor antagonist). The NMDA receptor antagonists, MK-801(0.001 mg/kg, ip) or GMP (0.5 mg/kg, ip), potentiated the effect of a sub-effective dose of GSH in the FST. These results suggest that the antidepressant-like effect induced by GSH is connected to the activation of α1 adrenergic and GABAA receptors, as well as the inhibition of GABAB and NMDA receptors and NO biosyntesis. We speculate that redox-mediated signaling on the extracelular portion of cell membrane receptors would be a common mechanism of action of GSH.


Asunto(s)
Antidepresivos/farmacología , Glutatión/farmacología , Terapia Molecular Dirigida , Antagonistas Adrenérgicos/farmacología , Animales , Arginina/farmacología , Sinergismo Farmacológico , Femenino , Glutatión/administración & dosificación , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Inmovilización , Masculino , Ratones , Receptores Adrenérgicos/metabolismo , Receptores de GABA/metabolismo , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidores , Receptores de N-Metil-D-Aspartato/metabolismo , S-Nitroso-N-Acetilpenicilamina/farmacología , Natación
15.
Pflugers Arch ; 458(4): 795-807, 2009 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-19347353

RESUMEN

Why adrenal chromaffin cells express various subtypes of voltage-dependent Ca(2+) channels and whether a given channel is specialized to perform a specific function are puzzling and unanswered questions. In this study, we have used the L Ca(2+) channel activator FPL64176 (FPL) to test the hypothesis that enhanced Ca(2+) entry through this channel favors the inhibition of N and PQ channels in voltage-clamped bovine adrenal chromaffin cells. Using 2 mM Ca(2+) as charge carrier and under the perforated-patch configuration (PPC) of the patch-clamp technique, FPL caused a paradoxical inhibition of the whole-cell inward Ca(2+) current (I (Ca)). Such inhibition turned on into an augmentation upon cell loading with EGTA-AM. Also, under the whole-cell configuration (WCC) of the patch-clamp technique, FPL decreased I (Ca) in the absence of EGTA from the pipette solution and increased the current in its presence. Using 2 mM Ba(2+) as charge carrier, FPL augmented the Ba(2+) current under both recording conditions, WCC and PPC. FPL augmented the residual current remaining after blockade of N and PQ channels with omega-conotoxin MVIIC or by holding the membrane potential at -50 mV. The data support the view that Ca(2+) entering the cell through the lesser inactivating L channels serves to modulate the more inactivating N and PQ channels. They also suggest a close colocalization of L and N/PQ Ca(2+) channels. This kind of L channel specialization may be relevant to cell excitability, exocytosis, and cell survival mechanisms.


Asunto(s)
Canales de Calcio/fisiología , Señalización del Calcio/fisiología , Calcio/metabolismo , Células Cromafines/fisiología , Activación del Canal Iónico/fisiología , Potenciales de la Membrana/fisiología , Animales , Bovinos , Células Cultivadas
16.
Br J Pharmacol ; 176(15): 2764-2779, 2019 08.
Artículo en Inglés | MEDLINE | ID: mdl-31074003

RESUMEN

BACKGROUND AND PURPOSE: Ischaemic stroke is a leading cause of death, disability, and a high unmet medical need. Post-reperfusion inflammation and an up-regulation of toll-like receptor 4 (TLR4), an upstream sensor of innate immunity, are associated with poor outcome in stroke patients. Here, we identified the therapeutic effect of targeting the LPS/TLR4 signal transduction pathway. EXPERIMENTAL APPROACH: We tested the effect of the TLR4 inhibitor, eritoran (E5564) in different in vitro ischaemia-related models: human organotypic cortex culture, rat organotypic hippocampal cultures, and primary mixed glia cultures. We explored the therapeutic window of E5564 in the transient middle cerebral artery occlusion model of cerebral ischaemia in mice. KEY RESULTS: In vivo, administration of E5564 1 and 4 hr post-ischaemia reduced the expression of different pro-inflammatory chemokines and cytokines, infarct volume, blood-brain barrier breakdown, and improved neuromotor function, an important clinically relevant outcome. In the human organotypic cortex culture, E5564 reduced the activation of microglia and ROS production evoked by LPS. CONCLUSION AND IMPLICATIONS: TLR4 signalling has a causal role in the inflammation associated with a poor post-stroke outcome. Importantly, its inhibition by eritoran (E5564) provides neuroprotection both in vitro and in vivo, including in human tissue, suggesting a promising new therapeutic approach for ischaemic stroke.


Asunto(s)
Antiinflamatorios/farmacología , Antiinflamatorios/uso terapéutico , Isquemia Encefálica/tratamiento farmacológico , Lípido A/análogos & derivados , Fármacos Neuroprotectores/farmacología , Fármacos Neuroprotectores/uso terapéutico , Receptor Toll-Like 4/antagonistas & inhibidores , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Isquemia Encefálica/metabolismo , Isquemia Encefálica/fisiopatología , Línea Celular , Citocinas/genética , Citocinas/metabolismo , Modelos Animales de Enfermedad , Femenino , Humanos , Lípido A/farmacología , Lípido A/uso terapéutico , Masculino , Ratones Endogámicos C57BL , Microglía/efectos de los fármacos , Microglía/metabolismo , Fenotipo , Ratas Sprague-Dawley , Especies Reactivas de Oxígeno/metabolismo , Receptor Toll-Like 4/metabolismo
17.
Neuron ; 90(2): 308-19, 2016 04 20.
Artículo en Inglés | MEDLINE | ID: mdl-27068790

RESUMEN

In daylight, the input to the retinal circuit is provided primarily by cone photoreceptors acting as band-pass filters, but the retinal output also contains neuronal populations transmitting sustained signals. Using in vivo imaging of genetically encoded calcium reporters, we investigated the circuits that generate these sustained channels within the inner retina of zebrafish. In OFF bipolar cells, sustained transmission was found to depend on crossover inhibition from the ON pathway through GABAergic amacrine cells. In ON bipolar cells, the amplitude of low-frequency signals was regulated by glycinergic amacrine cells, while GABAergic inhibition regulated the gain of band-pass signals. We also provide the first functional description of a subset of sustained ON bipolar cells in which synaptic activity was suppressed by fluctuations at frequencies above ∼0.2 Hz. These results map out the basic circuitry by which the inner retina generates sustained visual signals and describes a new function of crossover inhibition.


Asunto(s)
Células Amacrinas/fisiología , Inhibición Neural/fisiología , Retina/fisiología , Células Bipolares de la Retina/fisiología , Visión Ocular/fisiología , Células Amacrinas/metabolismo , Animales , Neuronas GABAérgicas/fisiología , Glicina/metabolismo , Glicina/fisiología , Estimulación Luminosa , Transmisión Sináptica/fisiología , Pez Cebra
18.
Elife ; 42015 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-26274565

RESUMEN

Neuron-glia interactions play a critical role in the maturation of neural circuits; however, little is known about the pathways that mediate their communication in the developing CNS. We investigated neuron-glia signaling in the developing retina, where we demonstrate that retinal waves reliably induce calcium transients in Müller glial cells (MCs). During cholinergic waves, MC calcium transients were blocked by muscarinic acetylcholine receptor antagonists, whereas during glutamatergic waves, MC calcium transients were inhibited by ionotropic glutamate receptor antagonists, indicating that the responsiveness of MCs changes to match the neurotransmitter used to support retinal waves. Using an optical glutamate sensor we show that the decline in MC calcium transients is caused by a reduction in the amount of glutamate reaching MCs. Together, these studies indicate that neurons and MCs exhibit correlated activity during a critical period of retinal maturation that is enabled by neurotransmitter spillover from retinal synapses.


Asunto(s)
Neuroglía/fisiología , Neuronas/fisiología , Neurotransmisores/metabolismo , Retina/embriología , Transducción de Señal , Animales , Ratones
19.
Curr Biol ; 24(19): R964-6, 2014 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-25291639

RESUMEN

The number of synaptic inputs onto retinal bipolar cells is influenced by transmitter release from neighboring bipolar cells, implicating a new form of population-based retrograde plasticity in the development of these neural circuits.


Asunto(s)
Ácido Glutámico/metabolismo , Plasticidad Neuronal , Retina/fisiología , Células Bipolares de la Retina/fisiología , Animales
20.
Behav Brain Res ; 253: 165-72, 2013 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-23850355

RESUMEN

Glutathione (GSH) displays a broad range of functions, among them a role as a neuromodulator with some neuroprotective properties. Taking into account that oxidative stress has been associated with depressive disorders, this study investigated the possibility that GSH, a major cell antioxidant, elicits an antidepressant-like effect in mice. Thus, GSH was administered by i.c.v. route to mice that were tested in the forced swimming test and in the tail suspension test, two predictive tests for antidepressant drug activity. In addition, GSH metabolism and the redox environment were modulated in order to study the possible mechanisms underlying the effects of GSH in the forced swimming test. The administration of GSH decreased the immobility time in the forced swimming test (300-3000nmol/site) and tail suspension test (100-1000nmol/site), consistent with an antidepressant-like effect. GSH depletion elicited by l-buthionine sulfoximine (3.2µmol/site, i.c.v.) did not alter the antidepressant-like effect of GSH, whereas the inhibition of extracellular GSH catabolism by acivicin (100nmol/site, i.c.v.) prevented the antidepressant-like effect of GSH. Moreover, a sub-effective dose (0.01nmol/site, i.c.v.) of the oxidizing agent DTNB (5,5'-dithiobis(2-nitrobenzoic acid)) potentiated the effect of GSH (100nmol/site, i.c.v.), while the pretreatment (25-100mg/kg, i.p.) with the reducing agent DTT (dl-dithiothreitol) prevented the antidepressant-like effect of GSH (300nmol/site, i.c.v.). DTNB (0.1nmol/site, i.c.v.), produced an antidepressant-like effect, per se, which was abolished by DTT (25mg/kg, i.p.). The results show, for the first time, that centrally administered GSH produces an antidepressant-like effect in mice, which can be modulated by the GSH metabolism and the thiol/disulfide reagents. The redox environment may constitute a new venue for future antidepressant-drug development.


Asunto(s)
Antidepresivos , Depresión/psicología , Glutatión/farmacología , Natación/psicología , Animales , Antimetabolitos/farmacología , Antioxidantes/metabolismo , Butionina Sulfoximina/farmacología , Ácido Ditionitrobenzoico/farmacología , Ditiotreitol/farmacología , Femenino , Glutatión/administración & dosificación , Glutatión/metabolismo , Glutatión Peroxidasa/metabolismo , Glutatión Reductasa/metabolismo , Glutatión Transferasa/metabolismo , Suspensión Trasera/psicología , Inyecciones Intraventriculares , Masculino , Ratones , Actividad Motora/efectos de los fármacos , Oxidación-Reducción , gamma-Glutamiltransferasa/metabolismo
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