RESUMEN

Glutamate excitotoxicity accompanies numerous brain pathologies, including traumatic brain injury, ischemic stroke, and epilepsy. Disturbances of the ion homeostasis, mitochondria dysfunction, and further cell death are considered the main detrimental consequences of excitotoxicity. It is well known that neurons demonstrate different vulnerability to pathological exposures. In this regard, neurons containing calcium-permeable AMPA receptors (CP-AMPARs) may show higher susceptibility to excitotoxicity due to an additional pathway of Ca2+ influx. Here, we demonstrate that neurons containing CP-AMPARs are characterized by the higher amplitude of the glutamate-induced elevation of intracellular Ca2+ concentration ([Ca2+]i) and slower restoration of [Ca2+]i level compared to non-CP-AMPA neurons. Moreover, we have found that NASPM, an antagonist of CP-AMPARs, significantly decreases the amplitude of the [Ca2+]i elevation induced by glutamate or selective AMPARs agonist, 5-fluorowillardiine. In contrast, the antagonists of NMDARs or KARs affect insignificantly. We have also described some peculiarities of Na+, K+, and H+ intracellular dynamics in neurons containing CP-AMPARs. In particular, the amplitude of [Na+]i elevation was lower compared to non-CP-AMPA neurons, whereas the amplitude of [K+]i decrease was higher. We have shown the significant inverse correlation between [K+]i and [Ca2+]i and between intracellular pH and [Na+]i in CP-AMPARs-containing and non-CP-AMPA neurons upon glutamate excitotoxicity. Our data indicate that CP-AMPARs-mediated Ca2+ influx and slow removal of Ca2+ from the cytosol may underlie the vulnerability of the CP-AMPARs-containing neurons to glutamate excitotoxicity. Further studies of the mechanisms mediating the disturbances in ion homeostasis are crucial for developing new approaches for protecting these neurons at brain pathologies.

Asunto(s)

Calcio , Receptores AMPA , Receptores AMPA/fisiología , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiónico/metabolismo , Calcio/metabolismo , Neuronas/metabolismo , Ácido Glutámico/metabolismo , Homeostasis

RESUMEN

It is believed that degenerative conditions that give rise to neurological diseases may share an abnormal influx of Ca2+, mainly through glutamate receptors. Current research on the glutamatergic system indicates that the N-methyl-D-aspartate receptor (NMDAR) is not the only receptor permeable to Ca2+. Under certain conditions, α -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs) are able to rapidly and potently mediate a neurotoxic Ca2+ influx. AMPARs are encoded by four genes designated GluR 1-4. The presence of the edited GluA2 subunit makes the heteromeric AMPAR impermeable to Ca2+ (CI-AMPAR's). On the other hand, the lack of GluA2 or disruptions in its post-translational editing result in Ca2+-permeable AMPA receptors (CP-AMPARs). In addition to triggering behavioral changes, the increase in CP-AMPARs is documented in several neurodegenerative, neuroinflammatory and neurotoxic conditions, demonstrating that AMPAR changes may play a role in the emergence and evolution of pathological conditions of the central nervous system (CNS). Seeking to better understand how CP-AMPARs influence CNS neuropathology, and how it may serve as a pharmacological target for future molecules, in this article, we summarize and discuss studies investigating changes in the composition of AMPARs and their cellular and molecular effects, to improve the understanding of the therapeutic potential of the CP-AMPAR in neurodegenerative, neurotoxic and neuroinflammatory diseases.

Asunto(s)

Enfermedades Neuroinflamatorias , Receptores AMPA , Humanos , Receptores de N-Metil-D-Aspartato , Calcio/metabolismo

RESUMEN

Drugs of abuse, such as cocaine, produce aberrant changes in synaptic transmission and plasticity that emerge throughout withdrawal. One region of the brain that displays a high degree of synaptic plasticity, as well as connectivity with mesolimbic structures such as the nucleus accumbens, is the ventral hippocampus (vH). Here, we investigated the effects of an escalating cocaine dosing schedule on vH CA1 excitatory transmission by measuring place preference and recording excitatory postsynaptic currents (EPSCs) at three different withdrawal time points: withdrawal day (WD) 2, 9 or 28. Behaviourally, this escalating cocaine-conditioning protocol was capable of producing conditioned place preference that persisted through WD28. Physiologically, cocaine conditioning produced an increase in vH excitatory transmission on WD2 that appeared to be the result of an increase in calcium-impermeable (CI)-AMPA receptor density. Excitatory transmission was still enhanced in cocaine-treated animals on WD9; however, a significant increase in the contribution of calcium-permeable (CP)-AMPA receptors to EPSCs was detected as compared with WD2. By WD28, these CP-AMPA receptors provided a major contribution to vH CA1 excitatory transmission, resulting in synaptic responses distinct from WD2 and WD9. Taken together, these results highlight progressive changes in vH synaptic transmission during withdrawal that may enhance cocaine contextual associations.

Asunto(s)

Cocaína/farmacología , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Hipocampo/efectos de los fármacos , Receptores AMPA/efectos de los fármacos , Síndrome de Abstinencia a Sustancias/fisiopatología , Animales , Masculino , Ratones , Ratones Endogámicos C57BL , Plasticidad Neuronal/efectos de los fármacos , Factores de Tiempo

RESUMEN

AMPA receptors are tetrameric glutamate-gated ion channels that mediate a majority of fast excitatory neurotransmission in the brain. They exist as calcium-impermeable (CI-) and calcium-permeable (CP-) subtypes, the latter of which lacks the GluA2 subunit. CP-AMPARs display an array of distinctive biophysical and pharmacological properties that allow them to be functionally identified. This has revealed that they play crucial roles in diverse forms of central synaptic plasticity. Here we summarise the functional hallmarks of CP-AMPARs and describe how these are modified by the presence of auxiliary subunits that have emerged as pivotal regulators of AMPARs. A lasting change in the prevalence of GluA2-containing AMPARs, and hence in the fraction of CP-AMPARs, is a feature in many maladaptive forms of synaptic plasticity and neurological disorders. These include modifications of glutamatergic transmission induced by inflammatory pain, fear conditioning, cocaine exposure, and anoxia-induced damage in neurons and glia. Furthermore, defective RNA editing of GluA2 can cause altered expression of CP-AMPARs and is implicated in motor neuron damage (amyotrophic lateral sclerosis) and the proliferation of cells in malignant gliomas. A number of the players involved in CP-AMPAR regulation have been identified, providing useful insight into interventions that may prevent the aberrant CP-AMPAR expression. Furthermore, recent molecular and pharmacological developments, particularly the discovery of TARP subtype-selective drugs, offer the exciting potential to modify some of the harmful effects of increased CP-AMPAR prevalence in a brain region-specific manner.

Asunto(s)

Plasticidad Neuronal , Receptores AMPA , Canales de Calcio/metabolismo , Neuronas/metabolismo , Receptores AMPA/metabolismo , Transmisión Sináptica

RESUMEN

At present, role of the lateral habenula (LHb) calcium-permeable AMPA receptors (CP-AMPARs) in depression is not understood, particularly in Parkinson's disease-related depression. Here we found that lesions of the substantia nigra pars compacta (SNc) in rats induced depressive-like behaviors, and intra-LHb injection of CP-AMPAR antagonist Naspm produced antidepressant-like effects in SNc sham-lesioned and SNc-lesioned rats, however, the doses inducing these effects in SNc-lesioned rats were lower than that of SNc sham-lesioned rats. Blockade of LHb CP-AMPARs decreased the firing rate of the neurons and increased release of dopamine and serotonin in the medial prefrontal cortex (mPFC) in both groups, but the duration of Naspm action on the firing rate and release of the transmitters were prolonged in SNc-lesioned rats. These changes in SNc-lesioned rats were involved in increased expression of ßCaMKII and p-GluR1-S831 in the LHb. Intra-LHb injection of Naspm inhibited dopaminergic neurons in the anterior ventral tegmental area and serotonergic neurons in the dorsal raphe nucleus and excited dopaminergic neurons in the posterior ventral tegmental area (pVTA) and serotonergic neurons in the median raphe nucleus (MRN), and lesioning the GABAergic rostromedial tegmental nucleus (RMTg) decreased the percentages of excited pVTA dopaminergic neurons and MRN serotonergic neurons. Our findings indicate that blockade of LHb CP-AMPARs produces antidepressant-like effects, which attribute to decreased firing activity of LHb neurons and increased levels of dopamine and serotonin in the mPFC, and provide further evidence that LHb CP-AMPARs regulate the firing activity of pVTA dopaminergic neurons and MRN serotonergic neurons indirectly via the RMTg.

Asunto(s)

Antidepresivos/farmacología , Núcleo Dorsal del Rafe/fisiología , Habénula/fisiología , Oxidopamina/farmacología , Porción Compacta de la Sustancia Negra/fisiología , Receptores AMPA/antagonistas & inhibidores , Espermina/análogos & derivados , Potenciales de Acción/fisiología , Animales , Conducta Animal/efectos de los fármacos , Proteína Quinasa Tipo 2 Dependiente de Calcio Calmodulina/biosíntesis , Dopamina/metabolismo , Neuronas Dopaminérgicas , Habénula/metabolismo , Ácido Iboténico/farmacología , Masculino , Inhibición Neural/efectos de los fármacos , Porción Compacta de la Sustancia Negra/efectos de los fármacos , Fosforilación/efectos de los fármacos , Corteza Prefrontal/metabolismo , Ratas , Receptores AMPA/agonistas , Receptores AMPA/metabolismo , Neuronas Serotoninérgicas , Serotonina/metabolismo , Espermina/farmacología , Tegmento Mesencefálico/efectos de los fármacos , Área Tegmental Ventral/fisiología

RESUMEN

Dendritic spines influence synapse function by boosting synaptic potentials and sequestering synaptically generated second messengers. Spines have been extensively studied in densely spiny principal neurons, but little is known about how they expand the information-gathering capabilities of sparsely spiny interneurons (INs). We find in the mouse primary visual cortex, parvalbumin-positive INs have a low density of spines that enclose functional glutamatergic synapses. Both spine and dendritic synapses contain calcium-permeable AMPA receptors (CP-AMPARs) and NMDA receptors (NMDARs), but NMDARs are enriched at spine synapses. Glutamate-receptor-mediated Ca influx at proximal dendritic sites is bidirectionally modulated by the timing of action potentials (APs). Surprisingly, spine synapses are largely insensitive to APs, but coincident activity originating in the adjacent dendrite strongly influences spine NMDAR-mediated calcium influx. Thus, while glutamate receptors on spines and dendrites are modulated by the activity of the neuron, they are distinctive in the type of coincident activity detected.

Asunto(s)

Espinas Dendríticas/metabolismo , Interneuronas/metabolismo , Parvalbúminas/metabolismo , Sinapsis/metabolismo , Animales , Ratones

RESUMEN

The medial habenula (MHb) is an epithalamic hub contributing to expression and extinction of aversive states by bridging forebrain areas and midbrain monoaminergic centers. Although contradictory information exists regarding their synaptic properties, the physiology of the excitatory inputs to the MHb from the posterior septum remains elusive. Here, combining optogenetics-based mapping with ex vivo and in vivo physiology, we examine the synaptic properties of posterior septal afferents to the MHb and how they influence behavior. We demonstrate that MHb cells receive sparse inputs producing purely glutamatergic responses via calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), heterotrimeric GluN2A-GluN2B-GluN1 N-methyl-D-aspartate (NMDA) receptors, and inhibitory group II metabotropic glutamate receptors. We describe the complex integration dynamics of these components by MHb cells. Finally, we combine ex vivo data with realistic afferent firing patterns recorded in vivo to demonstrate that efficient optogenetic septal stimulation in the MHb induces anxiolysis and promotes locomotion, contributing long-awaited evidence in favor of the importance of this septo-habenular pathway.

Asunto(s)

Habénula/fisiopatología , Transmisión Sináptica/genética , Animales , Humanos , Ratones

RESUMEN

The medial habenula-interpeduncular nucleus (MHb-IPN) pathway, which connects the limbic forebrain to the midbrain, has recently been implicated in aversive behaviors. The MHb-IPN circuit is characterized by a unique topographical organization, an excitatory role of GABA, and a prominent co-release of neurotransmitters and neuropeptides. However, little is known about synaptic plasticity in this pathway. An application of a high-frequency stimulation resulted in a long-lasting potentiation of glutamate release in IPN neurons. Our experiments reveal that a Ca2+-permeable AMPA receptor (CPAR)-dependent release of GABA from IPN neurons and a retrograde activation of GABAB receptors on MHb terminals result in a long-lasting enhancement of glutamate release. Strikingly, adolescent IPN neurons lacked CPARs and exhibited an inability to undergo plasticity. In addition, fear conditioning suppressed an activity-dependent potentiation of MHb-IPN synapses, whereas fear extinction reversed this plasticity deficit, suggesting a role of the MHb-IPN synaptic plasticity in the regulation of aversive behaviors.

Asunto(s)

Núcleo Interpeduncular/metabolismo , Plasticidad Neuronal/fisiología , Receptores AMPA/metabolismo , Receptores de GABA-B/metabolismo , Sinapsis/metabolismo , Animales , Núcleo Interpeduncular/citología , Ratones , Ratones Transgénicos , Receptores AMPA/genética , Receptores de GABA-B/genética , Sinapsis/genética

RESUMEN

Addiction is a disease of altered behavior. Addicts use drugs compulsively and will continue to do so despite negative consequences. Even after prolonged periods of abstinence, addicts are at risk of relapse, particularly when cues evoke memories that are associated with drug use. Rodent models mimic many of the core components of addiction, from the initial drug reinforcement to cue-associated relapse and continued drug intake despite negative consequences. Rodent models have also enabled unprecedented mechanistic insight into addiction, revealing plasticity of glutamatergic synaptic transmission evoked by the strong activation of mesolimbic dopamine-a defining feature of all addictive drugs-as a neural substrate for these drug-adaptive behaviors. Cell type-specific optogenetic manipulations have allowed both identification of the relevant circuits and design of protocols to reverse drug-evoked plasticity and to establish links of causality with drug-adaptive behaviors. The emergence of a circuit model for addiction will open the door for novel therapies, such as deep brain stimulation.

Asunto(s)

Conducta Adictiva/fisiopatología , Trastornos Relacionados con Sustancias/fisiopatología , Animales , Encéfalo/fisiopatología , Dopamina/farmacología , Humanos , Plasticidad Neuronal/efectos de los fármacos , Transmisión Sináptica/efectos de los fármacos

RESUMEN

There is increasing evidence that diabetic retinopathy is a primary neuropathological disorder that precedes the microvascular pathology associated with later stages of the disease. Recently, we found evidence for altered functional properties of synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in A17, but not AII, amacrine cells in the mammalian retina, and the observed changes were consistent with an upregulation of the GluA2 subunit, a key determinant of functional properties of AMPA receptors, including Ca(2+) permeability and current-voltage (I-V) rectification properties. Here, we have investigated functional changes of extrasynaptic AMPA receptors in AII amacrine cells evoked by diabetes. With patch-clamp recording of nucleated patches from retinal slices, we measured Ca(2+) permeability and I-V rectification in rats with ∼3 wk of streptozotocin-induced diabetes and age-matched, noninjected controls. Under bi-ionic conditions (extracellular Ca(2+) concentration = 30 mM, intracellular Cs(+) concentration = 171 mM), the reversal potential (Erev) of AMPA-evoked currents indicated a significant reduction of Ca(2+) permeability in diabetic animals [Erev = -17.7 mV, relative permeability of Ca(2+) compared with Cs(+) (PCa/PCs) = 1.39] compared with normal animals (Erev = -7.7 mV, PCa/PCs = 2.35). Insulin treatment prevented the reduction of Ca(2+) permeability. I-V rectification was examined by calculating a rectification index (RI) as the ratio of the AMPA-evoked conductance at +40 and -60 mV. The degree of inward rectification in patches from diabetic animals (RI = 0.48) was significantly reduced compared with that in normal animals (RI = 0.30). These results suggest that diabetes evokes a change in the functional properties of extrasynaptic AMPA receptors of AII amacrine cells. These changes could be representative for extrasynaptic AMPA receptors elsewhere in AII amacrine cells and suggest that synaptic and extrasynaptic AMPA receptors are differentially regulated.

Asunto(s)

Células Amacrinas/metabolismo , Calcio/metabolismo , Retinopatía Diabética/metabolismo , Hiperglucemia/metabolismo , Receptores AMPA/metabolismo , Potenciales de Acción , Células Amacrinas/fisiología , Animales , Femenino , Ratas , Ratas Wistar , Sinapsis/metabolismo , Sinapsis/fisiología

RESUMEN

Diabetes leads to dysfunction of the neural retina before and independent of classical microvascular diabetic retinopathy, but previous studies have failed to demonstrate which neurons and circuits are affected at the earliest stages. Here, using patch-clamp recording and two-photon Ca(2+) imaging in rat retinal slices, we investigated diabetes-evoked changes in a microcircuit consisting of rod bipolar cells and their dyad postsynaptic targets, AII and A17 amacrine cells, which play an essential role in processing scotopic visual signals. AII amacrines forward their signals to ON- and OFF-cone bipolar cells and A17 amacrines provide GABAergic feedback inhibition to rod bipolar cells. Whereas Ca(2+)-permeable AMPA receptors mediate input from rod bipolar cells to both AII and A17 amacrines, diabetes changes the synaptic receptors on A17, but not AII amacrine cells. This was expressed as a change in pharmacological properties and single-channel conductance of the synaptic receptors, consistent with an upregulation of the AMPA receptor GluA2 subunit and reduced Ca(2+) permeability. In addition, two-photon imaging revealed reduced agonist-evoked influx of Ca(2+) in dendritic varicosities of A17 amacrine cells from diabetic compared with normal animals. Because Ca(2+)-permeable receptors in A17 amacrine cells mediate synaptic release of GABA, the reduced Ca(2+) permeability of these receptors in diabetic animals leads to reduced release of GABA, followed by disinhibition and increased release of glutamate from rod bipolar cells. This perturbation of neuron and microcircuit dynamics can explain the decreased dynamic range and sensitivity of scotopic vision that has been observed in diabetes.

Asunto(s)

Diabetes Mellitus Experimental/patología , Diabetes Mellitus Experimental/fisiopatología , Vías Nerviosas/patología , Células Fotorreceptoras Retinianas Bastones/patología , Adamantano/análogos & derivados , Adamantano/farmacología , Células Amacrinas/efectos de los fármacos , Células Amacrinas/metabolismo , Animales , Calcio/metabolismo , Diabetes Mellitus Experimental/metabolismo , Potenciales Postsinápticos Excitadores , Femenino , Ácido Glutámico/metabolismo , Ratas , Receptores AMPA/antagonistas & inhibidores , Receptores AMPA/biosíntesis , Receptores AMPA/metabolismo , Células Bipolares de la Retina/metabolismo , Células Bipolares de la Retina/patología , Células Fotorreceptoras Retinianas Bastones/metabolismo , Regulación hacia Arriba , Ácido gamma-Aminobutírico/metabolismo

RESUMEN

The local fast-spiking interneurons (FSINs) are considered to be crucial for the generation, maintenance, and modulation of neuronal network oscillations especially in the gamma frequency band. Gamma frequency oscillations have been associated with different aspects of behavior. But the prolonged effects of gamma frequency synaptic activity on the FSINs remain elusive. Using whole cell current clamp patch recordings, we observed a sustained decrease of intrinsic excitability in the FSINs of the dentate gyrus (DG) following repetitive stimulations of the mossy fibers at 30 Hz (gamma bursts). Surprisingly, the granule cells (GCs) did not express intrinsic plastic changes upon similar synaptic excitation of their apical dendritic inputs. Interestingly, pairing the gamma bursts with membrane hyperpolarization accentuated the plasticity in FSINs following the induction protocol, while the plasticity attenuated following gamma bursts paired with membrane depolarization. Paired pulse ratio measurement of the synaptic responses did not show significant changes during the experiments. However, the induction protocols were accompanied with postsynaptic calcium rise in FSINs. Interestingly, the maximum and the minimum increase occurred during gamma bursts with membrane hyperpolarization and depolarization respectively. Including a selective blocker of calcium-permeable AMPA receptors (CP-AMPARs) in the bath; significantly attenuated the calcium rise and blocked the membrane potential dependence of the calcium rise in the FSINs, suggesting their involvement in the observed phenomenon. Chelation of intracellular calcium, blocking HCN channel conductance or blocking CP-AMPARs during the experiment forbade the long lasting expression of the plasticity. Simultaneous dual patch recordings from FSINs and synaptically connected putative GCs confirmed the decreased inhibition in the GCs accompanying the decreased intrinsic excitability in the FSINs. Experimentally constrained network simulations using NEURON predicted increased spiking in the GC owing to decreased input resistance in the FSIN. We hypothesize that the selective plasticity in the FSINs induced by local network activity may serve to increase information throughput into the downstream hippocampal subfields besides providing neuroprotection to the FSINs.

Asunto(s)

Potenciales de Acción/fisiología , Calcio/metabolismo , Giro Dentado/citología , Potenciales Postsinápticos Excitadores/fisiología , Interneuronas/fisiología , Receptores AMPA/metabolismo , Anestésicos Locales/farmacología , Animales , Animales Recién Nacidos , Biofisica , Ácido Egtácico/análogos & derivados , Ácido Egtácico/farmacología , Estimulación Eléctrica , Fármacos actuantes sobre Aminoácidos Excitadores/farmacología , Potenciales Postsinápticos Excitadores/efectos de los fármacos , Técnicas In Vitro , Interneuronas/efectos de los fármacos , Lidocaína/análogos & derivados , Lidocaína/farmacología , Masculino , Modelos Neurológicos , Red Nerviosa/efectos de los fármacos , Red Nerviosa/fisiología , Técnicas de Placa-Clamp , Pirimidinas/farmacología , Ratas , Factores de Tiempo

RESUMEN

There is conflicting evidence regarding whether calcium-permeable receptors are removed during group I mGluR-mediated synaptic depression. In support of this hypothesis, AMPAR rectification, a correlative index of the synaptic expression of GluA2-lacking calcium-permeable AMPARs (CP-AMPARs), is known to decrease after the induction of several types of group I mGluR-mediated long-term depression (LTD), suggesting that a significant proportion of synaptic CP-AMPARs is removed during synaptic depression. We have previously demonstrated that fear conditioning-induced synaptic potentiation in the lateral amygdala is reversed by group 1 mGluR-mediated depotentiation. Here, we examined whether CP-AMPARs are removed by mGluR1-mediated depotentiation of fear conditioning-induced synaptic potentiation. The synaptic expression of CP-AMPARs was negligible before, increased significantly 12 h after, and returned to baseline 48 h after fear conditioning, as evidenced by the changes in the sensitivity of lateral amygdala synaptic responses to NASPM. Importantly, the sensitivity to NASPM was not altered after induction of depotentiation. Our findings, together with previous results, suggest that the removal of CP-AMPARs is not required for the depotentiation of fear conditioning-induced synaptic potentiation at lateral amygdala synapses.

RESUMEN

The inclusion of GluA2 subunits has a profound impact on the channel properties of AMPA receptors (AMPARs), in particular rendering them impermeable to calcium. While GluA2-containing AMPARs are the most abundant in the central nervous system, GluA2-lacking calcium-permeable AMPARs are also expressed in wide variety of neurons and glia. Accumulating evidence suggests that the dynamic control of the GluA2 content of AMPARs plays a critical role in development, synaptic plasticity, and diverse neurological conditions ranging from ischemia-induced brain damage to drug addiction. It is thus important to understand the molecular mechanisms involved in regulating the balance of AMPAR subtypes, particularly the role of their co-assembled auxiliary subunits. The discovery of transmembrane AMPAR regulatory proteins (TARPs), initially within the cerebellum, has transformed the field of AMPAR research. It is now clear that these auxiliary subunits play a key role in multiple aspects of AMPAR trafficking and function in the brain. Yet, their precise role in AMPAR subtype-specific regulation has only recently received particular attention. Here we review recent findings on the differential regulation of calcium-permeable (CP-) and -impermeable (CI-) AMPARs in cerebellar neurons and glial cells, and discuss the critical involvement of TARPs in this process. This article is part of the Special Issue entitled 'Glutamate Receptor-Dependent Synaptic Plasticity'.

Asunto(s)

Canales de Calcio/fisiología , Cerebelo/fisiología , Neuroglía/fisiología , Plasticidad Neuronal/fisiología , Subunidades de Proteína/metabolismo , Receptores AMPA/biosíntesis , Receptores AMPA/fisiología , Animales , Canales de Calcio/metabolismo , Cerebelo/metabolismo , Neuroglía/metabolismo , Receptores AMPA/metabolismo , Transmisión Sináptica/fisiología

RESUMEN

Experience shapes and molds the brain throughout life.These changes in neuronal circuits are produced by a myriad of molecular and cellular processes. Simplistically, circuits are modified through changes in neurotransmitter release or through neurotransmitter detection at synapses. The predominant neurotransmitter receptor in excitatory transmission, the AMPA-type glutamate receptor (AMPAR), is exquisitely sensitive to changes in experience and synaptic activity. These ion channels are usually impermeable to calcium, a property conferred by the GluA2 subunit. However, GluA2-lacking AMPARs are permeable to calcium and have recently been shown to play a unique role in synaptic function. In this review, I will describe new findings on the role of calcium permeable AMPARs (CP-AMPARs) in experience-dependent and synaptic plasticity.These studies suggest that CP-AMPARs play a prominent role in maintaining circuits in a labile state where further plasticity can occur, thus promoting metaplasticity. Moreover, the abnormal expression of CP-AMPARs has been implicated in drug addiction and memory disorders and thus may be a novel therapeutic target.