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BACKGROUND: ALS is a heterogeneous disease in which different factors such as mitochondrial phenotypes act in combination with a genetic predisposition. This study addresses the question of whether homoplasmic (total mitochondrial genome of a sample is affected) and/or heteroplasmic mutations (wildtype and mutant mitochondrial DNA molecules coexist) might play a role in familial ALS. Blood was drawn from familial ALS patients with a possible maternal pattern of inheritance according to their pedigrees, which was compared to blood of ALS patients without maternal association as well as age-matched controls. In two cohorts, we analyzed the mitochondrial genome from whole blood or isolated white blood cells and platelets using a resequencing microarray (Affymetrix MitoChip v2.0) that is able to detect homoplasmic and heteroplasmic mitochondrial DNA mutations and allows the assessment of low-level heteroplasmy. RESULTS: We identified an increase in homoplasmic ND5 mutations, a subunit of respiratory chain complex I, in whole blood of ALS patients that allowed maternal inheritance. This effect was more pronounced in patients with bulbar onset. Heteroplasmic mutations were significantly increased in different mitochondrial genes in platelets of patients with possible maternal inheritance. No increase of low-level heteroplasmy was found in maternal ALS patients. CONCLUSION: Our results indicate a contribution of homoplasmic ND5 mutations to maternally associated ALS with bulbar onset. Therefore, it might be conceivable that specific maternally transmitted rather than randomly acquired mitochondrial DNA mutations might contribute to the disease process. This stands in contrast with observations from Alzheimer's and Parkinson's diseases showing an age-dependent accumulation of unspecific mutations in mitochondrial DNA.
Assuntos
Esclerose Lateral Amiotrófica , Genoma Mitocondrial , Humanos , Genoma Mitocondrial/genética , Herança Materna/genética , Esclerose Lateral Amiotrófica/genética , DNA Mitocondrial/genética , Mitocôndrias/genética , MutaçãoRESUMO
BACKGROUND: During aging, both the brain and the immune system undergo a progressive impairment of physiological functions. Microglia, the immunocompetent cells of the central nervous system, shift towards a chronic mild inflammatory state that impacts brain homeostasis. Extracellular vesicles (EVs) released by microglia transport packages of molecular information that mirror the inflammatory status of donor cells and modulate the inflammatory phenotype of recipient microglia and other cell types. RESULTS: We demonstrated that intranasal administration of EVs derived from microglial-like BV2 cells to late adult mice (16-20 months of age) shifts microglia toward a "juvenile" morphology affecting their inflammatory profile. Mice treated with BV2-derived EVs have a reduction of anxiety-like behavior and an increased spatial learning, with sex-dependent differences. Further, BV2-derived EVs increased neuronal plasticity both in male and female mice. These findings suggest the involvement of microglial cells in vesicles-mediated anti-aging effect. CONCLUSIONS: Our data indicate that BV2-derived EVs could represent a resource to slow down age-dependent inflammation in the mouse brain.
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Gamma-aminobutyric acid (GABA), the principal inhibitory neurotransmitter in the brain, affects numerous immune cell functions. Microglia, the brain's resident innate immune cells, regulate GABA signaling through GABA receptors and express the complete GABAergic machinery for GABA synthesis, uptake, and release. Here, the use of primary microglial cell cultures and ex vivo brain tissue sections allowed for demonstrating that treatment with lipopolysaccharide (LPS) increased microglial GABA uptake as well as GABA transporter (GAT)-1 trafficking. This effect was not entirely abolished by treatment with GAT inhibitors (GAT-Is). Notably, LPS also induced microglial upregulation of bestrophin-1 (BEST-1), a Ca2+ -activated Cl- channel permeable to GABA. Combined administration of GAT-Is and a BEST-1 inhibitor completely abolished LPS-induced microglial GABA uptake. Interestingly, increased microglial GAT-1 membrane turnover via syntaxin 1A was detected in LPS-treated cultures after BEST-1 blockade. Altogether, these findings provided evidence for a novel mechanism through which LPS may trigger the inflammatory response by directly altering microglial GABA clearance and identified the GAT-1/BEST-1 interplay as a potential novel mechanism involved in brain inflammation.
Assuntos
Lipopolissacarídeos , Microglia , Microglia/metabolismo , Lipopolissacarídeos/farmacologia , Proteínas da Membrana Plasmática de Transporte de GABA/metabolismo , Bestrofinas/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
Glutamate levels and lifetime in the brain extracellular space are dinamically regulated by a family of Na+- and K+-dependent glutamate transporters, which thereby control numerous brain functions and play a role in numerous neurological and psychiatric diseases. Migraine is a neurological disorder characterized by recurrent attacks of typically throbbing and unilateral headache and by a global dysfunction in multisensory processing. Familial hemiplegic migraine type 2 (FHM2) is a rare monogenic form of migraine with aura caused by loss-of-function mutations in the α2 Na/K ATPase (α2NKA). In the adult brain, this pump is expressed almost exclusively in astrocytes where it is colocalized with glutamate transporters. Knockin mouse models of FHM2 (FHM2 mice) show a reduced density of glutamate transporters in perisynaptic astrocytic processes (mirroring the reduced expression of α2NKA) and a reduced rate of glutamate clearance at cortical synapses during neuronal activity and sensory stimulation. Here we review the migraine-relevant alterations produced by the astrocytic glutamate transport dysfunction in FHM2 mice and their underlying mechanisms, in particular regarding the enhanced brain susceptibility to cortical spreading depression (the phenomenon that underlies migraine aura and can also initiate the headache mechanisms) and the enhanced algesic response to a migraine trigger.
Assuntos
Transtornos de Enxaqueca , Enxaqueca com Aura , Camundongos , Animais , Astrócitos/metabolismo , Transtornos de Enxaqueca/metabolismo , Enxaqueca com Aura/genética , ATPase Trocadora de Sódio-Potássio/metabolismo , Ácido Glutâmico/metabolismoRESUMO
Migraine is a common but poorly understood sensory circuit disorder. Mouse models of familial hemiplegic migraine (FHM, a rare monogenic form of migraine with aura) show increased susceptibility to cortical spreading depression (CSD, the phenomenon that underlies migraine aura and can activate migraine headache mechanisms), allowing an opportunity to investigate the mechanisms of CSD and migraine onset. In FHM type 2 (FHM2) knock-in mice with reduced expression of astrocytic Na+, K+-ATPases, the reduced rate of glutamate uptake into astrocytes can account for the facilitation of CSD initiation. Here, we investigated the underlying mechanisms and show that the reduced rate of glutamate clearance in FHM2 mice results in increased amplitude and slowing of rise time and decay of the NMDA receptor (NMDAR) excitatory postsynaptic current (EPSC) elicited in layer 2/3 pyramidal cells by stimulation of neuronal afferents in somatosensory cortex slices. The relative increase in NMDAR activation in FHM2 mice is activity-dependent, being larger after high-frequency compared to low-frequency afferent activity. Inhibition of GluN1-N2B NMDARs, which hardly affected the NMDAR EPSC in wild-type mice, rescued the increased and prolonged activation of NMDARs as well as the facilitation of CSD induction and propagation in FHM2 mice. Our data suggest that the enhanced susceptibility to CSD in FHM2 is mainly due to specific activation of extrasynaptic GluN1-N2B NMDARs and point to these receptors as possible therapeutic targets for prevention of CSD and migraine.
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Astrócitos/metabolismo , Depressão Alastrante da Atividade Elétrica Cortical/fisiologia , Ácido Glutâmico/metabolismo , Transtornos de Enxaqueca/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Animais , Espaço Extracelular/metabolismo , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Transtornos de Enxaqueca/genética , Proteínas do Tecido Nervoso/genética , Técnicas de Cultura de Órgãos , Receptores de N-Metil-D-Aspartato/genética , Córtex Somatossensorial/metabolismoRESUMO
Failure of anti-amyloid-ß peptide (Aß) therapies against Alzheimer's disease (AD), a neurodegenerative disorder characterized by high amounts of the peptide in the brain, raised the question of the physiological role of Aß released at low concentrations in the healthy brain. To address this question, we studied the presynaptic and postsynaptic mechanisms underlying the neuromodulatory action of picomolar amounts of oligomeric Aß42 (oAß42) on synaptic glutamatergic function in male and female mice. We found that 200 pm oAß42 induces an increase of frequency of miniature EPSCs and a decrease of paired pulse facilitation, associated with an increase in docked vesicle number, indicating that it augments neurotransmitter release at presynaptic level. oAß42 also produced postsynaptic changes as shown by an increased length of postsynaptic density, accompanied by an increased expression of plasticity-related proteins such as cAMP-responsive element binding protein phosphorylated at Ser133, calcium-calmodulin-dependent kinase II phosphorylated at Thr286, and brain-derived neurotrophic factor, suggesting a role for Aß in synaptic tagging. These changes resulted in the conversion of early into late long-term potentiation through the nitric oxide/cGMP/protein kinase G intracellular cascade consistent with a cGMP-dependent switch from short- to long-term memory observed in vivo after intrahippocampal administration of picomolar amounts of oAß42 These effects were present upon extracellular but not intracellular application of the peptide and involved α7 nicotinic acetylcholine receptors. These observations clarified the physiological role of oAß42 in synaptic function and memory formation providing solid fundamentals for investigating the pathological effects of high Aß levels in the AD brains.SIGNIFICANCE STATEMENT High levels of oligomeric amyloid-ß42 (oAß42) induce synaptic dysfunction leading to memory impairment in Alzheimer's disease (AD). However, at picomolar concentrations, the peptide is needed to ensure long-term potentiation (LTP) and memory. Here, we show that extracellular 200 pm oAß42 concentrations increase neurotransmitter release, number of docked vesicles, postsynaptic density length, and expression of plasticity-related proteins leading to the conversion of early LTP into late LTP and of short-term memory into long-term memory. These effects require α7 nicotinic acetylcholine receptors and are mediated through the nitric oxide/cGMP/protein kinase G pathway. The knowledge of Aß function in the healthy brain might be useful to understand the causes leading to its increase and detrimental effect in AD.
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Peptídeos beta-Amiloides/administração & dosagem , Líquido Extracelular/fisiologia , Memória/fisiologia , Neurotransmissores/administração & dosagem , Fragmentos de Peptídeos/administração & dosagem , Terminações Pré-Sinápticas/fisiologia , Sinapses/fisiologia , Animais , Líquido Extracelular/efeitos dos fármacos , Feminino , Hipocampo/efeitos dos fármacos , Hipocampo/fisiologia , Injeções Intraventriculares , Masculino , Memória/efeitos dos fármacos , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Técnicas de Cultura de Órgãos , Terminações Pré-Sinápticas/efeitos dos fármacos , Ratos , Ratos Wistar , Sinapses/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologiaRESUMO
Microglial cells are the immune cells of the brain that, by sensing the microenvironment, permit a correct brain development and function. They communicate with other glial cells and with neurons, releasing and responding to a number of molecules that exert effects on surrounding cells. Among these, neurotransmitters and, in particular, gamma-aminobutyric acid (GABA) has recently gained interest in this context. We demonstrated the expression of GABA transporter 1 (GAT-1) in microglial cells both in soma and cell processes. We show that microglial cell treatment with 1,2,5,6-tetrahydro-1-[2-[[(diphenylmethylene)amino]oxy]ethyl]-3-pyridinecarboxylic acid hydrochloride (NNC-711), a potent and selective GAT-1 inhibitor, significantly reduced Na+ -dependent GABA uptake. On the other hand, GABA uptake was significantly increased by cell treatment with (S)-1-[2-[tris(4-methoxyphenyl)methoxy]ethyl]-3-piperidinecarboxylic acid (SNAP-5114), a GAT-2/3 inhibitor, and this effect was completely blocked by the botulinum toxin BoNT/C1, that specifically cleaves and inactives syntaxin 1A (STX1A). Overall, these findings show that microglial cells express GAT-1 and indicate that STX1A plays an important role in the regulation of GAT-1-dependent GABA uptake in microglia.
Assuntos
Córtex Cerebral/metabolismo , Proteínas da Membrana Plasmática de Transporte de GABA/metabolismo , Microglia/metabolismo , Sintaxina 1/metabolismo , Animais , Neurônios/metabolismo , Ácidos Nipecóticos/metabolismo , Transmissão Sináptica/fisiologia , Ácido gama-Aminobutírico/metabolismoRESUMO
GLT-1, the major glutamate transporter, is expressed at perisynaptic astrocytic processes (PAP) and axon terminals (AxT). GLT-1 is coupled to Na+/K+-ATPase (NKA) α1-3 isoforms, whose subcellular distribution and spatial organization in relationship to GLT-1 are largely unknown. Using several microscopy techniques, we showed that at excitatory synapses α1 and α3 are exclusively neuronal (mainly in dendrites and in some AxT), while α2 is predominantly astrocytic. GLT-1 displayed a differential colocalization with α1-3. GLT-1/α2 and GLT-1/α3 colocalization was higher in GLT-1 positive puncta partially (for GLT-1/α2) or almost totally (for GLT-1/α3) overlapping with VGLUT1 positive terminals than in nonoverlapping ones. GLT-1 colocalized with α2 at PAP, and with α1 and α3 at AxT. GLT-1 and α2 gold particles were â¼1.5-2 times closer than GLT-1/α1 and GLT-1/α3 particles. GLT-1/α2 complexes (edge to edge interdistance of gold particles ≤50 nm) concentrated at the perisynaptic region of PAP membranes, whereas neuronal GLT-1/α1 and GLT-1/α3 complexes were fewer and more uniformly distributed in AxT. These data unveil different composition of GLT-1 and α subunits complexes in the glial and neuronal domains of excitatory synapses. The spatial organization of GLT-1/α1-3 complexes suggests that GLT-1/NKA interaction is more efficient in astrocytes than in neurons, further supporting the dominant role of astrocytic GLT-1 in glutamate homeostasis.
Assuntos
Astrócitos/metabolismo , Transportador 2 de Aminoácido Excitatório/metabolismo , Neurônios/metabolismo , ATPase Trocadora de Sódio-Potássio/metabolismo , Sinapses/metabolismo , Animais , Western Blotting , Extensões da Superfície Celular/metabolismo , Córtex Cerebral/citologia , Córtex Cerebral/metabolismo , Dendritos/metabolismo , Imuno-Histoquímica , Camundongos , Terminações Pré-Sinápticas/metabolismo , Ratos , Ratos Sprague-Dawley , Proteína Vesicular 1 de Transporte de Glutamato/metabolismoRESUMO
BACKGROUND: Mitochondrial DNA (mtDNA) mutations are considered as a possible primary cause of age-associated neurodegenerative disorders like Parkinson's disease (PD). AIMS: To analyze, along the whole mtDNA sequence of PD patients, the presence of non-reference alleles compared to reference alleles, as defined in the revised Cambridge Reference Sequence (rCRS). METHODS: mtDNA was extracted from whole blood of PD and control groups, and was sequenced using a chip-based resequencing system. RESULTS: 58 nucleotide positions (np) exhibited a different allelic distribution in the two groups; in 81% of them the non-reference alleles were over-represented in PD patients, similar to findings reported in patients with Alzheimer's disease, albeit in reduced proportion. Closer analysis of the 58 np in PD group showed that they were characterized by low-level heteroplasmy, and that the nucleotide substitutions determined an amino acid change in 84% of cases. CONCLUSIONS: These results suggest that mtDNA allelic changes are increased in PD and that age-related neurodegenerative diseases could share a common mechanism involving mtDNA.
Assuntos
DNA Mitocondrial/genética , Mitocôndrias , Doença de Parkinson/genética , Idoso , Idoso de 80 Anos ou mais , Alelos , Feminino , Humanos , Masculino , Mitocôndrias/metabolismo , MutaçãoRESUMO
In patients with Alzheimer's disease (AD), synaptic plasticity seems to be involved in cognitive improvement induced by cognitive training. The platelet amyloid precursor protein (APP) ratio (APPr), i.e., the ratio between two APP isoforms, may be a useful peripheral biomarker to investigate synaptic plasticity pathways. This study evaluates the changes in neuropsychological/cognitive performance and APPr induced by cognitive training in AD patients participating in the "My Mind Project". Neuropsychological/cognitive variables and APPr were evaluated in the trained group (n = 28) before a two-month experimental protocol, immediately after its termination at follow-up 1 (FU1), after 6 months at follow-up 2 (FU2), and after 24 months at follow-up 3 (FU3). The control group (n = 31) received general psychoeducational training for two months. Some memory and attention parameters were significantly improved in trained vs. control patients at FU1 and FU2 compared to baseline (Δ values). At FU3, APPr and Mini Mental State Examination (MMSE) scores decreased in trained patients. Δ APPr correlated significantly with the Δ scores of (i) MMSE at FU1, (ii) the prose memory test at FU2, and (iii) Instrumental Activities of Daily Living (IADL), the semantic word fluency test, Clinical Dementia Rating (CDR), and the attentive matrices test at FU3. Our data demonstrate that the platelet APPr correlates with key clinical variables, thereby proving that it may be a reliable biomarker of brain function in AD patients.
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Doença de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Cognição , Atividades Cotidianas , Idoso , Doença de Alzheimer/patologia , Doença de Alzheimer/fisiopatologia , Biomarcadores/metabolismo , Plaquetas/metabolismo , Plaquetas/patologia , Feminino , Humanos , Masculino , Memória , Plasticidade NeuronalRESUMO
A wide agreement exists that environmental enrichment (EE) is most beneficial if introduced early in life, but numerous studies reported that also aged animals remain responsive. As age-related memory and cognition impairments are not uniform, an open question is whether EE might exert different effects in animals with different age-related deficits. A 12-week EE protocol was applied to late adult rats pretested for habituation and aversive memory. Animals were classified as low (LP) and high (HP) performers according to percent exploration change in Open Field test (OF) and as impaired (I) and not impaired (NI) according to latency in Step-through Passive Avoidance test (PA). Standard housing (SH) animals pretested by OF and PA, and naïve (non-pretested) EE and SH rats were used as controls. In comparison to pretest, after the housing protocol, EE LP ameliorated while EE HP and both SH HP and LP worsened their habituation pattern. The positive influence of EE on LP was probably due to the more active interaction with and the faster adaptation to surroundings promoted by continuous, multiple stimuli provided during the enriched housing. Regarding HP, EE did not boost the basal behavior, which likely represented the maximum achievable for that age, and the post housing exploration change dropped, as in SH animals, because of the retesting. After EE, a significant percentage of NI animals became I and a significant percentage of I animals became NI. The changes evidenced in the NI group likely depended on EE-related reduction of anxiety and the consequent more efficient coping with fearful situations. This hypothesis was strengthened by the observation that naïve EE animals were almost all I. Pretested EE I rats were not influenced by the rearing condition: their behavior was comparable to SH animals' behavior and determined by retesting. In conclusion, these results demonstrated that, when applied to aging rats, EE produces different effects based on pre-housing cognitive performances. The issue needs further analyses, but the observation that not all animals are able to take advantage of EE to the same extent suggests the opportunity to design individually tailored approaches to optimize their efficacy and minimize possible unwanted consequences.
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Envelhecimento/fisiologia , Aprendizagem da Esquiva/fisiologia , Disfunção Cognitiva/fisiopatologia , Disfunção Cognitiva/reabilitação , Habituação Psicofisiológica/fisiologia , Desempenho Psicomotor/fisiologia , Animais , Comportamento Animal/fisiologia , Modelos Animais de Doenças , Meio Ambiente , Masculino , Ratos , Ratos Sprague-Dawley , Meio SocialRESUMO
Stimulated by the results of a recent paper on the effects of tiagabine, a selective inhibitor of the main GABA transporter GAT-1, on oligodendrogenesis, we verified the possibility that GAT-1 may be expressed in oligodendrocytes using immunocytochemical methods and functional assays. Light microscopic analysis of the subcortical white matter of all animals revealed the presence of numerous GAT-1+ cells of different size (from 3 to 29 µm) and morphology. An electron microscope analysis revealed that, besides fibrous astrocytes and interstitial neurons, GAT-1 immunoreactivity was present in immature and mature oligodendrocytes. Co-localization studies between GAT-1 and markers specific for oligodendrocytes (NG2 and RIP) showed that about 12% of GAT-1 positive cells in the white matter were immature oligodendrocytes, while about 15% were mature oligodendrocytes. In vitro functional assays showed that oligodendrocytes exhibit tiagabine-sensitive Na+ -dependent GABA uptake. Although relationships between GABA and oligodendrocytes have been known for many years, this is the first demonstration that GAT-1 is expressed in oligodendrocytes. The present results on the one hand definitely closes the era of "neuronal" and "glial" GABA transporters, on the other they suggest that oligodendrocytes may contribute to pathophysiology of the several diseases in which GAT-1 have been implicated to date. GLIA 2017;65:514-522.
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Proteínas da Membrana Plasmática de Transporte de GABA/metabolismo , Oligodendroglia/metabolismo , Animais , Animais Recém-Nascidos , Antígenos/metabolismo , Encéfalo/citologia , Células Cultivadas , Masculino , Microscopia Confocal , Microscopia Imunoeletrônica , Inibidores da Captação de Neurotransmissores/farmacologia , Ácidos Nipecóticos/farmacologia , Oligodendroglia/efeitos dos fármacos , Oligodendroglia/ultraestrutura , Nervo Óptico/citologia , Proteoglicanas/metabolismo , Ratos , Ratos Sprague-Dawley , Proteína Serina-Treonina Quinases de Interação com Receptores/metabolismo , Sódio/metabolismo , Tiagabina , Trítio/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
In adult neocortex, VGLUT1 (also known as SLC17A7), the main glutamate vesicular transporter, and VGAT (also known as SLC32A1), the γ-aminobutyric acid (GABA) vesicular transporter, are co-expressed in a subset of axon terminals forming both symmetric and asymmetric synapses, where they are sorted into the same vesicles. However, the functional consequence of this colocalization in cortical neurons has not been clarified. Here, we tested the hypothesis that cortical axon terminals co-expressing VGLUT1 and VGAT can evoke simultaneously monosynaptic glutamate and GABA responses, and investigated whether the amount of terminals co-expressing VGLUT1 and VGAT is affected by perturbations of excitation-inhibition balance. In rat primary cortical neurons, we found that a proportion of synaptic and autaptic responses were indeed sensitive to consecutive application of selective glutamate and GABAA receptor blockers. These 'mixed' synapses exhibited paired-pulse depression. Notably, reducing the activity of the neuronal network by treatment with glutamate receptor antagonists decreased the amount of 'mixed' synapses, whereas reducing spontaneous inhibition by treatment with bicuculline increased them. These synapses might contribute to homeostatic regulation of excitation-inhibition balance.
Assuntos
Córtex Cerebral/citologia , Ácido Glutâmico/metabolismo , Neurônios/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/metabolismo , Proteínas Vesiculares de Transporte de Aminoácidos Inibidores/metabolismo , Ácido gama-Aminobutírico/metabolismo , Potenciais de Ação , Animais , Interneurônios/fisiologia , Terminações Pré-Sinápticas/metabolismo , Ratos Sprague-Dawley , Sinapses/metabolismoRESUMO
Amyotrophic lateral sclerosis (ALS) is a late-onset fatal neurodegenerative disease reflecting degeneration of upper and lower motoneurons (MNs). The cause of ALS and the mechanisms of neuronal death are still largely obscure, thus impairing the establishment of efficacious therapies. Glutamate (Glu)-mediated excitotoxicity plays a major role in MN degeneration in ALS. We recently demonstrated that the activation of Group I metabotropic Glu autoreceptors, belonging to both type 1 and type 5 receptors (mGluR1 and mGluR5), at glutamatergic spinal cord nerve terminals, produces excessive Glu release in mice over-expressing human superoxide-dismutase carrying the G93A point mutation (SOD1(G93A)), a widely used animal model of human ALS. To establish whether these receptors are implicated in ALS, we generated mice expressing half dosage of mGluR1 in the SOD1(G93A) background (SOD1(G93A)Grm1(crv4/+)), by crossing the SOD1(G93A) mutant mouse with the Grm1(crv4/+) mouse, lacking mGluR1 because of a spontaneous recessive mutation. SOD1(G93A)Grm1(crv4/+) mice showed prolonged survival probability, delayed pathology onset, slower disease progression and improved motor performances compared to SOD1(G93A) mice. These effects were associated to reduction of mGluR5 expression, enhanced number of MNs, decreased astrocyte and microglia activation, normalization of metallothionein and catalase mRNA expression, reduced mitochondrial damage, and decrease of abnormal Glu release in spinal cord of SOD1(G93A)Grm1(crv4/+)compared to SOD1(G93A) mice. These results demonstrate that a lower constitutive level of mGluR1 has a significant positive impact on mice with experimental ALS, thus providing the rationale for future pharmacological approaches to ALS by selectively blocking Group I metabotropic Glu receptors.
Assuntos
Esclerose Lateral Amiotrófica/metabolismo , Receptores de Glutamato Metabotrópico/metabolismo , Superóxido Dismutase/metabolismo , Esclerose Lateral Amiotrófica/patologia , Animais , Astrócitos/metabolismo , Astrócitos/patologia , Catalase/metabolismo , Progressão da Doença , Transportador 2 de Aminoácido Excitatório/metabolismo , Ácido Glutâmico/metabolismo , Metalotioneína/metabolismo , Camundongos , Camundongos Transgênicos , Microglia/metabolismo , Microglia/patologia , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Atividade Motora , Neurônios Motores/metabolismo , Neurônios Motores/patologia , Mutação Puntual , RNA Mensageiro/metabolismo , Receptor de Glutamato Metabotrópico 5/metabolismo , Receptores de Glutamato Metabotrópico/genética , Índice de Gravidade de Doença , Medula Espinal/metabolismo , Medula Espinal/patologia , Superóxido Dismutase/genética , Superóxido Dismutase-1 , Análise de SobrevidaRESUMO
The Na+, K+ ATPases play a fundamental role in the homeostatic functions of astrocytes. After a brief historic prologue and discussion of the subunit composition and localization of the astrocytic Na+, K+ ATPases, the review focuses on the role of the astrocytic Na+, K+ pumps in extracellular K+ and glutamate homeostasis, intracellular Na+ and Ca2+ homeostasis and signaling, regulation of synaptic transmission and neurometabolic coupling between astrocytes and neurons. Loss-of-function mutations in the gene encoding the astrocytic α2 Na+, K+ ATPase cause a rare monogenic form of migraine with aura (familial hemiplegic migraine type 2). On the other hand, the α2 Na+, K+ ATPase is upregulated in spinal cord and brain samples from amyotrophic lateral sclerosis and Alzheimer disease patients, respectively. In the last part, the review focuses on i) the migraine relevant phenotypes shown by familial hemiplegic migraine type 2 knock-in mice with 50 % reduced expression of the astrocytic α2 Na+, K+ ATPase and the insights into the pathophysiology of migraine obtained from these genetic mouse models, and ii) the evidence that upregulation of the astrocytic α2 Na+, K+ ATPase in mouse models of amyotrophic lateral sclerosis and Alzheimer disease promotes neuroinflammation and contributes to progressive neurodegeneration.
Assuntos
Doença de Alzheimer , Esclerose Lateral Amiotrófica , Enxaqueca com Aura , Humanos , Camundongos , Animais , ATPase Trocadora de Sódio-Potássio/genética , ATPase Trocadora de Sódio-Potássio/metabolismo , Enxaqueca com Aura/genética , Enxaqueca com Aura/metabolismo , Astrócitos/metabolismo , Doença de Alzheimer/metabolismo , Esclerose Lateral Amiotrófica/genética , Esclerose Lateral Amiotrófica/metabolismoRESUMO
Anxiety significantly diminishes the quality of life in older adults, and the drugs used for its treatment often come with risky side effects. Non-pharmacological protocols could be valuable, but more research is needed in this area. Environmental enrichment induces positive effects on anxiety-like behavior in young and adult animals; whether the same happens in aged animals is still elusive. The aged brain undergoes changes that contribute to make it "fragile" and consequently even mild, potentially positive stimuli can trigger dyshomeostasis, worsening rather than ameliorating functioning. Here, by combining behavioral analysis and measurement of serum and brain corticosterone levels, we show that late-life environmental enrichment can induce eustress or distress, depending on sex and hypothalamic-pituitary-adrenal axis function. These findings pave the way for optimizing outcomes and minimizing undesired effects in the clinical setting, underscoring the need to overcome the limits of gender medicine and emphasizing the crucial role of individually tailored therapies.
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Astrocytes play a key role in modulating synaptic transmission by controlling extracellular gamma-aminobutyric acid (GABA) levels via GAT-1 and GAT-3 GABA transporters (GATs). Using primary cultures of rat astrocytes, we show here that a further level of regulation of GABA uptake occurs via modulation of the GATs by the adenosine A1 (A1R) and A2A (A2AR) receptors. This regulation occurs through A1R-A2AR heteromers that signal via two different G proteins, Gs and Gi/0, and either enhances (A2AR) or inhibits (A1R) GABA uptake. These results provide novel mechanistic insight into how GPCR heteromers signal. Furthermore, we uncover a previously unknown mechanism where adenosine, in a concentration-dependent manner, acts via a heterocomplex of adenosine receptors in astrocytes to significantly contribute to neurotransmission at the tripartite (neuron-glia-neuron) synapse.
Assuntos
Astrócitos/metabolismo , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/metabolismo , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Receptor A1 de Adenosina/metabolismo , Receptor A2A de Adenosina/metabolismo , Ácido gama-Aminobutírico/metabolismo , Adenosina/metabolismo , Animais , Western Blotting , Feminino , Proteínas da Membrana Plasmática de Transporte de GABA/metabolismo , Células HEK293 , Humanos , Imuno-Histoquímica , Masculino , Ensaio Radioligante , Ratos , Ratos Wistar , Transmissão Sináptica/fisiologia , TransfecçãoRESUMO
BACKGROUND: Numerous mouse models of Alzheimer's disease (AD) are available, but all suffer from certain limitations, thus prompting further attempts. To date, no one model exists with amyloidopathy in a BALB/c strain. OBJECTIVE: To generate and characterize the C.B6/J-APPswe mouse, a model of AD with a mutated human gene for the amyloid-ß protein precursor (AßPP) inserted in a BALB/c background. METHODS: We analyzed five groups at different ages (3, 6, 9, 12, and 16-18 months) of C.B6/J-APPswe and wild-type mice (50% males and 50% females) for the main hallmarks of AD by western blotting, amyloid-ß (Aß) ELISA, immunocytochemistry, electrophysiology, and behavioral tests. RESULTS: The C.B6/J-APPswe mouse displays early AßPP and Aß production, late amyloid plaques formation, high level of Tau phosphorylation, synaptic deficits (reduced density and functional impairment due to a reduced post-synaptic responsiveness), neurodegeneration caused by apoptosis and necroptosis/necrosis, microgliosis, astrocytic abnormalities, and sex-related differences in explorative behavior, anxiety-like behavior, and spatial long-term and working memories. Social housing is feasible despite the intra-cage aggressiveness of male animals. CONCLUSION: C.B6/J-APPswe mice develop most of the distinctive features of AD and is a suitable model for the study of brain atrophy mechanisms and of the differences between males and females in the onset of cognitive/non-cognitive deficits.
Assuntos
Doença de Alzheimer , Feminino , Camundongos , Masculino , Humanos , Animais , Doença de Alzheimer/metabolismo , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Modelos Animais de Doenças , Camundongos Transgênicos , Peptídeos beta-Amiloides/metabolismoRESUMO
Astrocytes play a key role in modulating synaptic transmission by controlling the available extracellular GABA via the GAT-1 and GAT-3 GABA transporters (GATs). Using primary cultures of rat astrocytes, we show here that an additional level of regulation of GABA uptake occurs via modulation of the GATs by the adenosine A(1) (A(1)R) and A(2A) (A(2A)R) receptors. This regulation occurs through a complex of heterotetramers (two interacting homodimers) of A(1)R-A(2A)R that signal via two different G-proteins, G(s) and G(i/o), and either enhances (A(2A)R) or inhibits (A(1)R) GABA uptake. These results provide novel mechanistic insight into how G-protein-coupled receptor heteromers signal. Furthermore, we uncover a previously unknown mechanism in which adenosine, in a concentration-dependent manner, acts via a heterocomplex of adenosine receptors in astrocytes to significantly contribute to neurotransmission at the tripartite (neuron-glia-neuron) synapse.