RESUMO
Lafora disease is a rare and fatal form of progressive myoclonic epilepsy typically occurring early in adolescence. The disease results from mutations in the EPM2A gene, encoding laforin, or the EPM2B gene, encoding malin. Laforin and malin work together in a complex to control glycogen synthesis and prevent the toxicity produced by misfolded proteins via the ubiquitin-proteasome system. Disruptions in either protein cause alterations in this complex, leading to the formation of Lafora bodies containing abnormal, insoluble, and hyperphosphorylated forms of glycogen. We used the Epm2a-/- knockout mouse model of Lafora disease to apply gene therapy by administering intracerebroventricular injections of a recombinant adeno-associated virus carrying the human EPM2A gene. We evaluated the effects of this treatment through neuropathological studies, behavioral tests, video-electroencephalography, electrophysiological recordings, and proteomic/phosphoproteomic analysis. Gene therapy ameliorated neurological and histopathological alterations, reduced epileptic activity and neuronal hyperexcitability, and decreased the formation of Lafora bodies. Moreover, differential quantitative proteomics and phosphoproteomics revealed beneficial changes in various molecular pathways altered in Lafora disease. Our results represent proof of principle for gene therapy with the coding region of the human EPM2A gene as a treatment for EPM2A-related Lafora disease.
Assuntos
Dependovirus , Modelos Animais de Doenças , Terapia Genética , Doença de Lafora , Camundongos Knockout , Proteínas Tirosina Fosfatases não Receptoras , Doença de Lafora/terapia , Doença de Lafora/genética , Doença de Lafora/metabolismo , Animais , Terapia Genética/métodos , Proteínas Tirosina Fosfatases não Receptoras/genética , Proteínas Tirosina Fosfatases não Receptoras/metabolismo , Camundongos , Dependovirus/genética , Humanos , Vetores Genéticos/genética , Vetores Genéticos/administração & dosagem , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Eletroencefalografia , Proteômica/métodosRESUMO
Amyloid beta 1-42 (Aß42) aggregates acutely impair hippocampal long-term potentiation (LTP) of synaptic transmission, and 17ß-estradiol is crucial for hippocampal LTP. We tested whether boosting the synthesis of neural-derived 17ß-estradiol (nE2) saves hippocampal LTP by the neurotoxic action of Aß42. Electrophysiological recordings were performed to measure dentate gyrus (DG) LTP in rat hippocampal slices. Using a pharmacological approach, we tested the ability of nE2 to counteract the LTP impairment caused by acute exposure to soluble Aß42 aggregates. nE2 was found to be required for LTP in DG under physiological conditions. Blockade of steroid 5α-reductase with finasteride, by increasing nE2 synthesis from testosterone (T), completely recovered LTP in slices treated with soluble Aß42 aggregates. Modulation of the glutamate N-methyl-D aspartate receptor (NMDAR) by memantine effectively rescued the LTP deficit observed in slices exposed to Aß42, and memantine prevented LTP reduction observed under the blocking of nE2 synthesis. nE2 is able to counteract Aß42-induced synaptic dysfunction. This effect depends on a rapid, non-genomic mechanism of action of nE2, which may share a common pathway with glutamate NMDAR signaling.
Assuntos
Estradiol , Potenciação de Longa Duração , Ratos , Animais , Estradiol/farmacologia , Estradiol/metabolismo , Peptídeos beta-Amiloides/metabolismo , Memantina/farmacologia , Hipocampo/metabolismo , Glutamatos/metabolismoRESUMO
Lafora disease is a rare recessive form of progressive myoclonic epilepsy, usually diagnosed during adolescence. Patients present with myoclonus, neurological deterioration, and generalized tonic-clonic, myoclonic, or absence seizures. Symptoms worsen until death, usually within the first ten years of clinical onset. The primary histopathological hallmark is the formation of aberrant polyglucosan aggregates called Lafora bodies in the brain and other tissues. Lafora disease is caused by mutations in either the EPM2A gene, encoding laforin, or the EPM2B gene, coding for malin. The most frequent EPM2A mutation is R241X, which is also the most prevalent in Spain. The Epm2a-/- and Epm2b-/- mouse models of Lafora disease show neuropathological and behavioral abnormalities similar to those seen in patients, although with a milder phenotype. To obtain a more accurate animal model, we generated the Epm2aR240X knock-in mouse line with the R240X mutation in the Epm2a gene, using genetic engineering based on CRISPR-Cas9 technology. Epm2aR240X mice exhibit most of the alterations reported in patients, including the presence of LBs, neurodegeneration, neuroinflammation, interictal spikes, neuronal hyperexcitability, and cognitive decline, despite the absence of motor impairments. The Epm2aR240X knock-in mouse displays some symptoms that are more severe that those observed in the Epm2a-/- knock-out, including earlier and more pronounced memory loss, increased levels of neuroinflammation, more interictal spikes and increased neuronal hyperexcitability, symptoms that more precisely resemble those observed in patients. This new mouse model can therefore be specifically used to evaluate how new therapies affects these features with greater precision.
Assuntos
Disfunção Cognitiva , Doença de Lafora , Animais , Camundongos , Disfunção Cognitiva/genética , Doença de Lafora/genética , Doença de Lafora/patologia , Camundongos Knockout , Doenças Neuroinflamatórias , Proteínas Tirosina Fosfatases não Receptoras/genética , Ubiquitina-Proteína Ligases/genéticaRESUMO
Human mutations and haploinsufficiency of the SHANK family genes are associated with autism spectrum disorders (ASD) and intellectual disability (ID). Complex phenotypes have been also described in all mouse models of Shank mutations and deletions, consistent with the heterogeneity of the human phenotypes. However, the specific role of Shank proteins in synapse and neuronal functions remain to be elucidated. Here, we generated a new mouse model to investigate how simultaneously deletion of Shank1 and Shank3 affects brain development and behavior in mice. Shank1-Shank3 DKO mice showed a low survival rate, a developmental strong reduction in the activation of intracellular signaling pathways involving Akt, S6, ERK1/2, and eEF2 during development and a severe behavioral impairments. Our study suggests that Shank1 and Shank3 proteins are essential to developmentally regulate the activation of Akt and correlated intracellular pathways crucial for mammalian postnatal brain development and synaptic plasticity. Therefore, Akt function might represent a new therapeutic target for enhancing cognitive abilities of syndromic ASD patients.
Assuntos
Transtorno do Espectro Autista , Proteínas Proto-Oncogênicas c-akt , Animais , Transtorno do Espectro Autista/genética , Humanos , Camundongos , Camundongos Knockout , Proteínas dos Microfilamentos , Proteínas do Tecido Nervoso/genética , SinapsesRESUMO
Misfolding and aggregation of α-synuclein are specific features of Parkinson's disease and other neurodegenerative diseases defined as synucleinopathies. Parkinson's disease progression has been correlated with the formation and extracellular release of α-synuclein aggregates, as well as with their spread from neuron to neuron. Therapeutic interventions in the initial stages of Parkinson's disease require a clear understanding of the mechanisms by which α-synuclein disrupts the physiological synaptic and plastic activity of the basal ganglia. For this reason, we identified two early time points to clarify how the intrastriatal injection of α-synuclein-preformed fibrils in rodents via retrograde transmission induces time-dependent electrophysiological and behavioural alterations. We found that intrastriatal α-synuclein-preformed fibrils perturb the firing rate of dopaminergic neurons in the substantia nigra pars compacta, while the discharge of putative GABAergic cells of the substantia nigra pars reticulata is unchanged. The α-synuclein-induced dysregulation of nigrostriatal function also impairs, in a time-dependent manner, the two main forms of striatal synaptic plasticity, long-term potentiation and long-term depression. We also observed an increased glutamatergic transmission measured as an augmented frequency of spontaneous excitatory synaptic currents. These changes in neuronal function in the substantia nigra pars compacta and striatum were observed before overt neuronal death occurred. In an additional set of experiments, we were able to rescue α-synuclein-induced alterations of motor function, striatal synaptic plasticity and increased spontaneous excitatory synaptic currents by subchronic treatment with l-DOPA, a precursor of dopamine widely used in the therapy of Parkinson's disease, clearly demonstrating that a dysfunctional dopamine system plays a critical role in the early phases of the disease.
Assuntos
Plasticidade Neuronal/fisiologia , Doença de Parkinson/fisiopatologia , Substância Negra/fisiopatologia , Transmissão Sináptica/fisiologia , alfa-Sinucleína/toxicidade , Animais , Dopamina/metabolismo , Neurônios Dopaminérgicos/metabolismo , Neurônios Dopaminérgicos/patologia , Masculino , Doença de Parkinson/metabolismo , Ratos , Ratos Wistar , Substância Negra/metabolismo , alfa-Sinucleína/metabolismoRESUMO
Amyloid-ß (Aß) 1-40 and 1-42 peptides are key mediators of synaptic and cognitive dysfunction in Alzheimer's disease (AD). Whereas in AD, Aß is found to act as a pro-epileptogenic factor even before plaque formation, amyloid pathology has been detected among patients with epilepsy with increased risk of developing AD. Among Aß aggregated species, soluble oligomers are suggested to be responsible for most of Aß's toxic effects. Aß oligomers exert extracellular and intracellular toxicity through different mechanisms, including interaction with membrane receptors and the formation of ion-permeable channels in cellular membranes. These damages, linked to an unbalance between excitatory and inhibitory neurotransmission, often result in neuronal hyperexcitability and neural circuit dysfunction, which in turn increase Aß deposition and facilitate neurodegeneration, resulting in an Aß-driven vicious loop. In this review, we summarize the most representative literature on the effects that oligomeric Aß induces on synaptic dysfunction and network disorganization.
Assuntos
Doença de Alzheimer/genética , Peptídeos beta-Amiloides/genética , Sinapses/genética , Transmissão Sináptica/genética , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Peptídeos beta-Amiloides/efeitos adversos , Peptídeos beta-Amiloides/ultraestrutura , Proteínas Amiloidogênicas/efeitos adversos , Proteínas Amiloidogênicas/genética , Animais , Humanos , Fragmentos de Peptídeos/genética , Fragmentos de Peptídeos/metabolismo , Multimerização Proteica/genética , Sinapses/metabolismoRESUMO
Energy depletion caused by ischemic brain insults may result in persistent neuronal depolarization accompanied by hyper-stimulation of ionotropic glutamate receptors and excitotoxic phenomena, possibly leading to cell death. The use of glutamate receptor antagonists, such as the AMPARs antagonist Perampanel (PER), might be a pharmacological approach to counteract the excessive over-activation of glutamate receptors providing neuroprotective effects. Using electrophysiological and molecular analyses, we investigated the effect of PER against in vitro ischemia obtained by oxygen and glucose deprivation (OGD) in rat slices of two brain structures particularly sensitive to ischemic insults, the nucleus striatum and the hippocampus. We found that in these regions PER was able to avoid the OGD-induced neuronal suffering, at low doses not reducing basal excitatory synaptic transmission and not altering long-term potentiation (LTP) induction. Furthermore, in both the analysed regions, PER blocked a pathological form of LTP, namely ischemic LTP (iLTP). Finally, we hypothesized that the protective effect of PER against OGD was due to its capability to normalize the altered synaptic localization and function of AMPAR subunits, occuring after an ischemic insult. Taken together these findings support the idea that PER is a drug potentially effective to counteract ischemic damage.
Assuntos
Isquemia Encefálica/fisiopatologia , Hipocampo/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Piridonas/farmacologia , Receptores de AMPA/metabolismo , Animais , Morte Celular , Corpo Estriado/metabolismo , Antagonistas de Aminoácidos Excitatórios/farmacologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Fármacos Neuroprotetores , Nitrilas , Ratos , Ratos Wistar , Receptores de Glutamato/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Transmissão Sináptica/fisiologiaRESUMO
OBJECTIVE: Spreading depolarization (SD) is a transient self-propagating wave of neuronal and glial depolarization coupled with large membrane ionic changes and a subsequent depression of neuronal activity. Spreading depolarization in the cortex is implicated in migraine, stroke, and epilepsy. Conversely, spreading depolarization in the striatum, a brain structure deeply involved in motor control and in Parkinson's disease (PD) pathophysiology, has been poorly investigated. METHODS: We characterized the participation of glutamatergic and dopaminergic transmission in the induction of striatal spreading depolarization by using a novel approach combining optical imaging, measurements of endogenous DA levels, and pharmacological and molecular analyses. RESULTS: We found that striatal spreading depolarization requires the concomitant activation of D1-like DA and N-methyl-d-aspartate receptors, and it is reduced in experimental PD. Chronic l-dopa treatment, inducing dyskinesia in the parkinsonian condition, increases the occurrence and speed of propagation of striatal spreading depolarization, which has a direct impact on one of the signaling pathways downstream from the activation of D1 receptors. CONCLUSION: Striatal spreading depolarization might contribute to abnormal basal ganglia activity in the dyskinetic condition and represents a possible therapeutic target. © 2019 International Parkinson and Movement Disorder Society.
Assuntos
Corpo Estriado/fisiopatologia , Neurônios Dopaminérgicos/fisiologia , Discinesia Induzida por Medicamentos/fisiopatologia , Levodopa/farmacologia , Neurônios/fisiologia , Transtornos Parkinsonianos/fisiopatologia , Transmissão Sináptica/fisiologia , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/metabolismo , Antiparkinsonianos/farmacologia , Corpo Estriado/efeitos dos fármacos , Compostos de Mostarda Nitrogenada/metabolismo , Prednisolona/metabolismo , Procarbazina/metabolismo , Ratos , Ratos Wistar , Vincristina/metabolismoRESUMO
The α3ß4 subtype is the predominant neuronal nicotinic acetylcholine receptor present in the sensory and autonomic ganglia and in a subpopulation of brain neurons. This subtype can form pentameric receptors with either 2 or 3 ß4 subunits that have different pharmacologic and functional properties. To further investigate the role of the fifth subunit, we coexpressed a dimeric construct coding for a single polypeptide containing the ß4 and α3 subunit sequences, with different monomeric subunits. With this strategy, which allowed the formation of single populations of receptors with unique stoichiometry, we demonstrated with immunofluorescence and biochemical and functional assays that only the receptors with 3 ß4 subunits are efficiently expressed at the plasma membrane. Moreover, the LFM export motif of ß4 subunit in the fifth position exerts a unique function in the regulation of the intracellular trafficking of the receptors, their exposure at the cell surface, and consequently, their function, whereas the same export motif present in the ß4 subunits forming the acetylcholine binding site is dispensable.-Crespi, A., Plutino, S., Sciaccaluga, M., Righi, M., Borgese, N., Fucile, S., Gotti, C., Colombo, S. F. The fifth subunit in α3ß4 nicotinic receptor is more than an accessory subunit.
Assuntos
Subunidades Proteicas/metabolismo , Receptores Nicotínicos/metabolismo , Sítios de Ligação/fisiologia , Membrana Celular/metabolismo , Células Cultivadas , HumanosRESUMO
OBJECTIVE: γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in adult central nervous system, and profound alterations of GABA receptor functions are linked to temporal lobe epilepsy (TLE). Here we describe the functional relationships between GABA receptors type B (GABAB R) and type A (GABAA R) in human temporal cortex and how TLE affects this aspect of GABAergic signaling. METHODS: Miniature inhibitory postsynaptic currents (mIPSCs) were recorded by patch-clamp techniques from human L5 pyramidal neurons in slices from temporal cortex tissue obtained from surgery. RESULTS: We describe a constitutive functional crosstalk between GABAB Rs and GABAA Rs in human temporal layer 5 pyramidal neurons, which is lost in epileptic tissues. The activation of GABAB Rs by baclofen, in addition to the expected reduction of mIPSC frequency, produced, in cortex of nonepileptic patients, the prolongation of mIPSC rise and decay times, thus increasing the inhibitory net charge associated with a single synaptic event. Block of K+ channels did not prevent the increase of decay time and charge. Protein kinase A (PKA) blocker KT5720 and pertussis toxin inhibited the action of baclofen, whereas 8Br-cAMP mimicked the GABAB R action. The same GABAB R-mediated modulation of GABAA Rs was observed in pyramidal neurons of rat temporal cortex, with both PKA and PKC involved in the process. In cortices from TLE patients and epileptic rats, baclofen lost its ability to modulate mIPSCs. SIGNIFICANCE: Our results highlight the association of TLE with functional changes of GABAergic signaling that may be related to seizure propagation, and suggest that the selective activation of a definite subset of nonpresynaptic GABAB Rs may be therapeutically useful in TLE.
Assuntos
Epilepsia do Lobo Temporal/metabolismo , Neocórtex/metabolismo , Células Piramidais/metabolismo , Receptores de GABA-A/metabolismo , Receptores de GABA-B/metabolismo , Lobo Temporal/metabolismo , 8-Bromo Monofosfato de Adenosina Cíclica/farmacologia , Adolescente , Adulto , Animais , Baclofeno/farmacologia , Carbazóis/farmacologia , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Modelos Animais de Doenças , Epilepsia Resistente a Medicamentos/metabolismo , Epilepsia Resistente a Medicamentos/fisiopatologia , Epilepsia Resistente a Medicamentos/cirurgia , Inibidores Enzimáticos/farmacologia , Epilepsia/induzido quimicamente , Epilepsia/metabolismo , Epilepsia/fisiopatologia , Epilepsia do Lobo Temporal/fisiopatologia , Epilepsia do Lobo Temporal/cirurgia , Feminino , Agonistas dos Receptores de GABA-B/farmacologia , Humanos , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/fisiologia , Masculino , Pessoa de Meia-Idade , Agonistas Muscarínicos/toxicidade , Neocórtex/efeitos dos fármacos , Neocórtex/fisiopatologia , Técnicas de Patch-Clamp , Toxina Pertussis/farmacologia , Pilocarpina/toxicidade , Proteína Quinase C/metabolismo , Células Piramidais/efeitos dos fármacos , Pirróis/farmacologia , Ratos , Lobo Temporal/efeitos dos fármacos , Lobo Temporal/fisiopatologiaRESUMO
Neuronal nicotinic acetylcholine receptors (nAChRs) containing the α5 subunit modulate nicotine consumption, and the human CHRNA5 rs16969968 polymorphism, causing the replacement of the aspartic acid residue at position 398 with an asparagine (α5DN), has recently been associated with increased use of tobacco and higher incidence of lung cancer. We show that in ventral midbrain neurons, the α5 subunit is essential for heteromeric nAChR-induced intracellular-free Ca(2+) concentration elevations and that in α5(-/-) mice, a class of large-amplitude nicotine-evoked currents is lost. Furthermore, the expression of the α5DN subunit is not able to restore nicotinic responses, indicating a loss of function by this subunit in native neurons. To understand how α5DN impairs heteromeric nAChR functions, we coexpressed α4, α5, or α5DN subunits with a dimeric concatemer (ß2α4) in a heterologous system, to obtain nAChRs with fixed stoichiometry. Both α5(ß2α4)2 and α5DN(ß2α4)2 nAChRs yielded similar levels of functional expression and Ca(2+) permeability, measured as fractional Ca(2+) currents (8.2 ± 0.7% and 8.0 ± 1.9%, respectively), 2-fold higher than α4(ß2α4)2. Our results indicate that the loss of function of nicotinic responses observed in α5DN-expressing ventral midbrain neurons is neither due to an intrinsic inability of this subunit to form functional nAChRs nor to an altered Ca(2+) permeability but likely to intracellular modulation.
Assuntos
Cálcio/metabolismo , Mesencéfalo/metabolismo , Neurônios/metabolismo , Subunidades Proteicas/metabolismo , Receptores Nicotínicos/metabolismo , Animais , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Nicotina/metabolismoRESUMO
The swelling-activated chloride current (I Cl,Vol) is abundantly expressed in glioblastoma (GBM) cells, where it controls cell volume and invasive migration. The transduction pathway mediating I Cl,Vol activation in GBM cells is, however, poorly understood. By means of pharmacological and electrophysiological approaches, on GL-15 human GBM cells we found that I Cl,Vol activation by hypotonic swelling required the activity of a U73122-sensitive phospholipase C (PLC). I Cl,Vol activation could also be induced by the membrane-permeable diacylglycerol (DAG) analog OAG. In contrast, neither calcium (Ca(2+)) chelation by BAPTA-AM nor changes in PKC activity were able to affect I Cl,Vol activation by hypotonic swelling. We further found that R59022, an inhibitor of diacylglycerol kinase (DGK), reverted I Cl,Vol activation, suggesting the involvement of phosphatidic acid. In addition, I Cl,Vol activation required the activity of a EHT1864-sensitive Rac1 small GTPase and the resulting actin polymerization, as I Cl,Vol activation was prevented by cytochalasin B. We finally show that I Cl,Vol can be activated by the promigratory fetal calf serum in a PLC- and DGK-dependent manner. This observation is potentially relevant because blood serum can likely come in contact with glioblastoma cells in vivo as a result of the tumor-related partial breakdown of the blood-brain barrier. Given the relevance of I Cl,Vol in GBM cell volume regulation and invasiveness, the several key signaling molecules found in this study to be involved in the activation of the I Cl,Vol may represent potential therapeutic targets against this lethal cancer.
Assuntos
Canais de Cloreto/metabolismo , Glioblastoma/metabolismo , Transdução de Sinais , Actinas/metabolismo , Linhagem Celular Tumoral , Cloretos/metabolismo , Diacilglicerol Quinase/metabolismo , Diglicerídeos/biossíntese , Humanos , Pressão Osmótica , Multimerização Proteica , Fosfolipases Tipo C/metabolismo , Proteínas rac de Ligação ao GTP/metabolismoRESUMO
INTRODUCTION: Developmental epileptic encephalopathies (DEEs) pose significant challenges due to their refractory nature and limited treatment options. Despite advancements in genetic understanding, effective therapies targeting underlying pathophysiology are lacking. Serotoninergic dysfunction has been implicated in epilepsy, sparking interest in serotonin as a therapeutic target. AREA COVERED: This article explores the potential of bexicaserin, a selective 5-HT2C receptor agonist, as an adjunctive antiseizure medication in DEEs. Bexicaserin is thought to modulate GABAergic neurotransmission, suppressing central hyperexcitability. Preclinical studies demonstrate its efficacy across various seizure models. Clinical trials, including the Pacific Study, reveal promising results in reducing motor seizures. However, challenges such as adverse effects and treatment discontinuation underscore the need for further investigation. EXPERT OPINION: The efficacy of 5-HT2C serotoninergic agonists, validated in preclinical and clinical studies, highlights serotonin's role in DEEs. Bexicaserin offers new therapeutic possibilities, potentially synergizing with existing antiseizure medications. Polypharmacotherapy, targeting distinct pathways, may enhance therapeutic outcomes. Monitoring pharmacological interactions and addressing central nervous system comorbidities are crucial for optimizing treatment strategies. Further research is needed to elucidate bexicaserin's mechanisms and potential antiepileptogenic effects.
Assuntos
Anticonvulsivantes , Agonistas do Receptor 5-HT2 de Serotonina , Humanos , Anticonvulsivantes/uso terapêutico , Anticonvulsivantes/farmacologia , Animais , Agonistas do Receptor 5-HT2 de Serotonina/uso terapêutico , Agonistas do Receptor 5-HT2 de Serotonina/farmacologia , Epilepsia/tratamento farmacológico , Espasmos Infantis/tratamento farmacológicoRESUMO
INTRODUCTION: The landscape of epilepsy treatment has undergone a significant transformation with the emergence of cannabidiol as a potential therapeutic agent. Epidiolex, a pharmaceutical formulation of highly purified CBD, garnered significant attention not just for its therapeutic potential but also for being the first cannabis-derived medication to obtain approval from regulatory bodies. AREA COVERED: In this narrative review the authors explore the intricate landscape of CBD as an antiseizure medication, deepening into its pharmacological mechanisms and clinical trials involving various epileptic encephalopathies. This exploration serves as a comprehensive guide, shedding light on a compound that holds promise for individuals contending with the significant challenges of drug-resistant epilepsy. EXPERT OPINION: Rigorous studies highlight cannabidiol's efficacy, safety profile, and potential cognitive benefits, warranting further exploration for its approval in various drug-resistant epilepsy forms. As a promising therapeutic option, cannabidiol not only demonstrates efficacy in seizure control but also holds the potential for broader enhancements in the quality of life, especially for patients with epileptic encephalopathies.
Assuntos
Canabidiol , Epilepsia Resistente a Medicamentos , Epilepsia , Humanos , Canabidiol/efeitos adversos , Anticonvulsivantes/efeitos adversos , Qualidade de Vida , Epilepsia/tratamento farmacológico , Epilepsia Resistente a Medicamentos/tratamento farmacológico , Resultado do TratamentoRESUMO
Muscarinic receptors, expressed in several primary and metastatic tumours, appear to be implicated in their growth and propagation. In this work we have demonstrated that M2 muscarinic receptors are expressed in glioblastoma human specimens and in glioblastoma cell lines. Moreover, we have characterized the effects of the M2 agonist arecaidine on cell growth and survival both in two different glioblastoma cell lines (U251MG and U87MG) and in primary cultures obtained from different human biopsies. Cell growth analysis has demonstrated that the M2 agonist arecaidine strongly decreased cell proliferation in both glioma cell lines and primary cultures. This effect was dose and time dependent. FACS analysis has confirmed cell cycle arrest at G1/S and at G2/M phase in U87 cells and U251 respectively. Cell viability analysis has also shown that arecaidine induced severe apoptosis, especially in U251 cells. Chemosensitivity assays have, moreover, shown arecaidine and temozolomide similar effects on glioma cell lines, although IC50 value for arecaidine was significantly lower than temozolomide. In conclusion, we report for the first time that M2 receptor activation has a relevant role in the inhibition of glioma cell growth and survival, suggesting that M2 may be a new interesting therapeutic target to investigate for glioblastoma therapy.
Assuntos
Antineoplásicos/farmacologia , Arecolina/análogos & derivados , Pontos de Checagem do Ciclo Celular , Sobrevivência Celular/efeitos dos fármacos , Receptor Muscarínico M2/agonistas , Apoptose , Arecolina/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Glioblastoma , Humanos , Concentração Inibidora 50 , Agonistas Muscarínicos/farmacologia , Antagonistas Muscarínicos/farmacologia , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Receptor Muscarínico M2/metabolismo , Transdução de SinaisRESUMO
The binding mode of nicotinic agonists has been thoroughly investigated in the last decades. It is now accepted that the charged amino group is bound by a cation-π interaction to a conserved tryptophan residue, and that the aromatic moiety is projected into a hydrophobic pocket deeply located inside the binding cleft. A hydrogen bond donor/acceptor, maybe a water molecule solvating this receptor subsite, contributes to further stabilize the nicotinic ligands. The position of this water molecule has been established by several X-ray structures of the acetylcholine-binding protein. In this study, we computationally analyzed the role of this water molecule as a putative hydrogen bond donor/acceptor moiety in the agonist binding site of the three most relevant heteromeric (α4ß2, α3ß4) and homomeric (α7) neuronal nicotinic acetylcholine receptor (nAChR) subtypes. Our theoretical investigation made use of epibatidine 1 and deschloroepibatidine 2 as molecular probes, and was then extended to their analogues 3 and 4, which were subsequently synthesized and tested at the three target receptor subtypes. Although the pharmacological data for the new ligands 3 and 4 indicated a reduction of the affinity at the studied nAChRs with respect to reference agonists, a variation of the selectivity profile was clearly evidenced.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/química , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Agonistas Nicotínicos/química , Agonistas Nicotínicos/farmacologia , Piridinas/química , Piridinas/farmacologia , Receptores Colinérgicos/metabolismo , Água/química , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , Humanos , Ligação de Hidrogênio , Modelos Moleculares , Sondas Moleculares/química , Dados de Sequência Molecular , Receptores Colinérgicos/químicaRESUMO
Despite the wide range of compounds currently available to treat epilepsy, there is still no drug that directly tackles the physiopathological mechanisms underlying its development. Indeed, antiseizure medications attempt to prevent seizures but are inefficacious in counteracting or rescuing the physiopathological phenomena that underlie their onset and recurrence, and hence do not cure epilepsy. Classically, the altered excitation/inhibition balance is postulated as the mechanism underlying epileptogenesis and seizure generation. This oversimplification, however, does not account for deficits in homeostatic plasticity resulting from either insufficient or excessive compensatory mechanisms in response to a change in network activity. In this respect, both neurodevelopmental epilepsies and those associated with neurodegeneration may share common underlying mechanisms that still need to be fully elucidated. The understanding of these molecular mechanisms shed light on the identification of new classes of drugs able not only to suppress seizures, but also to present potential antiepileptogenic effects or "disease-modifying" properties.
Assuntos
Anticonvulsivantes , Epilepsia , Animais , Humanos , Anticonvulsivantes/farmacologia , Anticonvulsivantes/uso terapêutico , Epilepsia/tratamento farmacológico , Epilepsia/prevenção & controle , Modelos Animais de DoençasRESUMO
Pathological accumulation of Aß oligomers has been linked to neuronal networks hyperexcitability, potentially underpinned by glutamatergic AMPA receptors (AMPARs) dysfunction. We aimed to investigate whether the non-competitive block of AMPARs was able to counteract the alteration of hippocampal epileptic threshold, and of synaptic plasticity linked to Aß oligomers accumulation, being this glutamate receptor a valuable specific therapeutic target. In this work, we showed that the non-competitive AMPARs antagonist perampanel (PER) which, per se, did not affect physiological synaptic transmission, was able to counteract Aß-induced hyperexcitability. Moreover, AMPAR antagonism was able to counteract Aß-induced hippocampal LTP impairment and hippocampal-based cognitive deficits in Aß oligomers-injected mice, while retaining antiseizure efficacy. Beside this, AMPAR antagonism was also able to reduce the increased expression of proinflammatory cytokines in this mice model, also suggesting the presence of an anti-inflammatory activity. Thus, targeting AMPARs might be a valuable strategy to reduce both hippocampal networks hyperexcitability and synaptic plasticity deficits induced by Aß oligomers accumulation.
Assuntos
Angiopatia Amiloide Cerebral , Disfunção Cognitiva , Antagonistas de Aminoácidos Excitatórios , Hipocampo , Receptores de AMPA , Animais , Camundongos , Ácido alfa-Amino-3-hidroxi-5-metil-4-isoxazol Propiônico , Peptídeos beta-Amiloides/metabolismo , Cognição/efeitos dos fármacos , Antagonistas de Aminoácidos Excitatórios/farmacologia , Hipocampo/efeitos dos fármacos , Hipocampo/fisiopatologia , Receptores de AMPA/antagonistas & inibidores , Angiopatia Amiloide Cerebral/terapia , Disfunção Cognitiva/terapiaRESUMO
The GL15 glioblastoma cell line undergoes viability loss upon treatment with bromopyruvate. The biochemical mechanisms triggered by the antiglycolytic agent indicate the activation of an autophagic pathway. Acridine orange stains acidic intracellular vesicles already 60 min after bromopyruvate treatment, whereas autophagosomes engulfing electron dense material are well evidenced 18 h later. The autophagic process is accompanied by the expression of the early autophagosomal marker Atg5 and by LC3-II formation, a late biochemical marker associated with autophagosomes. In agreement with the autophagic route activation, the inhibitory and the activator Akt and ERK signaling pathways are depressed and enhanced, respectively. In spite of the energetic collapse suffered by bromopyruvate-treated cells, MALDI-TOF mass spectrometry lipid analysis does not evidence a decrease of the major phospholipids, in accordance with the need of phospholipids for autophagosomal membranes biogenesis. Contrarily, mitochondrial cardiolipin decreases, accompanied by monolyso-cardiolipin formation and complete cytochrome c degradation, events that could target mitochondria to autophagy. However, in our experimental conditions cytochrome c degradation seems to be independent of the autophagic process.
Assuntos
Antineoplásicos Alquilantes/farmacologia , Autofagia/efeitos dos fármacos , Cardiolipinas/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Glioblastoma/metabolismo , Piruvatos/farmacologia , Laranja de Acridina , Proteína 5 Relacionada à Autofagia , Western Blotting , Linhagem Celular Tumoral , Vesículas Citoplasmáticas/metabolismo , Humanos , Microscopia Eletrônica de Transmissão , Proteínas Associadas aos Microtúbulos/metabolismo , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por MatrizRESUMO
The literature on epileptic seizures in Alzheimer's disease has significantly increased over the past decades. Remarkably, several studies suggest a bi-directional link between these two common neurological diseases, with either condition carrying a nearly 2-fold risk of contracting the other in comparison to healthy subjects. In this respect, evidence from both clinical and preclinical studies indicates that epileptogenesis and neurodegeneration possibly share common underlying mechanisms. However, the precise association between epileptogenesis and neurodegeneration still needs to be fully elucidated. Targeted intervention to reduce abnormal network hyperexcitability might constitute a therapeutic strategy to postpone the onset of later neurodegenerative changes and consequent cognitive decline by many years in patients. By virtue of this, an early diagnosis and treatment of seizures in patients with Alzheimer's disease should be pursued. To date, no guidelines are available for treating epileptic activity in this context, largely due to the paucity of studies sufficient to answer the related questions. Accordingly, clinical trials are mandatory, not only to inform clinicians about symptomatic management of seizures in Alzheimer's disease patients but also to detect if treatment with antiseizure medications could have disease-modifying effects. Moreover, it will be fundamental to expand the application of animal models of Alzheimer's disease to comorbid conditions, such as epilepsy both to reveal the mechanisms underlying seizure onset and to better define their role in cognitive decline. Such models could also be useful to identify pharmacological compounds having therapeutically effectiveness as well as reliable early biomarkers for seizures in Alzheimer's disease.