RESUMO
Synucleinopathies encompass several neurodegenerative diseases, which include Parkinson's disease, dementia with Lewy bodies and multiple system atrophy. These diseases are characterized by the deposit of α-synuclein aggregates in intracellular inclusions in neurons and glial cells. Unlike Parkinson's disease and dementia with Lewy bodies, where aggregates are predominantly neuronal, multiple system atrophy is associated with α-synuclein cytoplasmic inclusions in oligodendrocytes. Glial cytoplasmic inclusions are the pathological hallmark of multiple system atrophy and are associated with neuroinflammation, modest demyelination and, ultimately, neurodegeneration. To evaluate the possible pathogenic role of glial cytoplasmic inclusions, we inoculated glial cytoplasmic inclusion-containing brain fractions obtained from multiple system atrophy patients into the striatum of non-human primates. After a 2-year in vivo phase, extensive histochemical and biochemical analyses were performed on the whole brain. We found loss of both nigral dopamine neurons and striatal medium spiny neurons, as well as loss of oligodendrocytes in the same regions, which are characteristics of multiple system atrophy. Furthermore, demyelination, neuroinflammation and α-synuclein pathology were also observed. These results show that the α-synuclein species in multiple system atrophy-derived glial cytoplasmic inclusions can induce a pathological process in non-human primates, including nigrostriatal and striatofugal neurodegeneration, oligodendroglial cell loss, synucleinopathy and gliosis. The present data pave the way for using this experimental model for MSA research and therapeutic development.
Assuntos
Doenças Desmielinizantes , Doença por Corpos de Lewy , Atrofia de Múltiplos Sistemas , Doença de Parkinson , Sinucleinopatias , Animais , Encéfalo/patologia , Doenças Desmielinizantes/patologia , Humanos , Corpos de Inclusão/metabolismo , Doença por Corpos de Lewy/patologia , Atrofia de Múltiplos Sistemas/patologia , Doença de Parkinson/patologia , alfa-Sinucleína/metabolismoRESUMO
In Parkinson's disease, synucleinopathy is hypothesized to spread from the enteric nervous system, via the vagus nerve, to the central nervous system. Recent evidences collected in non-human primates challenge however the hypothesis of a transmission of α-synuclein (α-syn) pathology through the vagus nerve. Would the hypothesis whereby the bloodstream acts as a route for long-distance transmission of pathological α-syn hold true, an inter-individual transmission of synucleinopathy could occur via blood contact. Here, we used a parabiosis approach to join the circulatory systems of wild type and GFP transgenic C57BL/6 J mice, for which one of the partners parabiont received a stereotaxic intranigral injection of patient-derived α-syn aggregates. While the Lewy Body-receiving mice exhibited a loss of dopamine neurons and an increase in nigral S129 phosphorylated α-syn immunoreactivity, their parabiotic bloodstream-sharing partners did not show any trend for a lesion or change in S129 phosphorylated-α-syn levels. Altogether, our study suggests that, in the patient-derived α-synuclein aggregates-injected mouse model and within the selected time frame, the disease is not "transmitted" through the bloodstream.
Assuntos
Corpos de Lewy/transplante , Neostriado/patologia , Neurônios/patologia , Parabiose , Agregados Proteicos , Agregação Patológica de Proteínas/metabolismo , Substância Negra/patologia , alfa-Sinucleína/metabolismo , Animais , Camundongos , Camundongos Transgênicos , Técnicas Estereotáxicas , alfa-Sinucleína/sangueRESUMO
In Parkinson's disease, synucleinopathy is hypothesized to spread from the enteric nervous system, via the vagus nerve, to the CNS. Here, we compare, in baboon monkeys, the pathological consequences of either intrastriatal or enteric injection of α-synuclein-containing Lewy body extracts from patients with Parkinson's disease. This study shows that patient-derived α-synuclein aggregates are able to induce nigrostriatal lesions and enteric nervous system pathology after either enteric or striatal injection in a non-human primate model. This finding suggests that the progression of α-synuclein pathology might be either caudo-rostral or rostro-caudal, varying between patients and disease subtypes. In addition, we report that α-synuclein pathological lesions were not found in the vagal nerve in our experimental setting. This study does not support the hypothesis of a transmission of α-synuclein pathology through the vagus nerve and the dorsal motor nucleus of the vagus. Instead, our results suggest a possible systemic mechanism in which the general circulation would act as a route for long-distance bidirectional transmission of endogenous α-synuclein between the enteric and the central nervous systems. Taken together, our study provides invaluable primate data exploring the role of the gut-brain axis in the initiation and propagation of Parkinson's disease pathology and should open the door to the development and testing of new therapeutic approaches aimed at interfering with the development of sporadic Parkinson's disease.
Assuntos
Encéfalo/patologia , Neuroimunomodulação/fisiologia , Doença de Parkinson/fisiopatologia , Nervo Vago/patologia , alfa-Sinucleína/toxicidade , Idoso , Animais , Sistema Nervoso Entérico/efeitos dos fármacos , Sistema Nervoso Entérico/metabolismo , Sistema Nervoso Entérico/patologia , Feminino , Humanos , Corpos de Lewy/metabolismo , Corpos de Lewy/patologia , Masculino , Papio , alfa-Sinucleína/administração & dosagemRESUMO
OBJECTIVE: Whether the basal ganglia are involved in the cortical synchronization during focal seizures is still an open question. In the present study, we proposed to synchronize cortico-striatal activities acutely inducing striatal disinhibition, performing GABA-antagonist injections within the putamen in primates. METHOD: Experiments were performed on three fascicularis monkeys. During each experimental session, low volumes of bicuculline (0.5-4 µL) were injected at a slow rate of 1 µL/min. Spontaneous behavioral changes were classified according to Racine's scale modified for primates. These induced motor behaviors were correlated with electromyographic, electroencephalographic, and putaminal and pallidal local field potentials changes in activity. RESULTS: acute striatal desinhibition induced focal motor seizures. Seizures were closely linked to cortical epileptic activity synchronized with a striatal paroxysmal activity. These changes in striatal activity preceded the cortical epileptic activity and the induced myoclonia, and both cortical and subcortical activities were coherently synchronized during generalized seizures. INTERPRETATION: Our results strongly suggest the role of the sensorimotor striatum in the regulation and synchronization of cortical excitability. These dramatic changes in the activity of this "gating" pathway might influence seizure susceptibility by modulating the threshold for the initiation of focal motor seizures.
Assuntos
Córtex Cerebral/fisiopatologia , Sincronização Cortical , Putamen/fisiopatologia , Convulsões/fisiopatologia , Animais , Bicuculina/administração & dosagem , Feminino , Antagonistas de Receptores de GABA-A/administração & dosagem , Macaca fascicularis , Masculino , Vias Neurais/fisiopatologia , Putamen/efeitos dos fármacos , Ratos Sprague-Dawley , Convulsões/etiologiaRESUMO
Parkinson's disease motor symptoms are treated with levodopa, but long-term treatment leads to disabling dyskinesia. Altered synaptic transmission and maladaptive plasticity of corticostriatal glutamatergic projections play a critical role in the pathophysiology of dyskinesia. Because the noble gas xenon inhibits excitatory glutamatergic signaling, primarily through allosteric antagonism of the N-methyl-d-aspartate receptors, we aimed to test its putative antidyskinetic capabilities. We first studied the direct effect of xenon gas exposure on corticostriatal plasticity in a murine model of levodopa-induced dyskinesia We then studied the impact of xenon inhalation on behavioral dyskinetic manifestations in the gold-standard rat and primate models of PD and levodopa-induced dyskinesia. Last, we studied the effect of xenon inhalation on axial gait and posture deficits in a primate model of PD with levodopa-induced dyskinesia. This study shows that xenon gas exposure (1) normalized synaptic transmission and reversed maladaptive plasticity of corticostriatal glutamatergic projections associated with levodopa-induced dyskinesia, (2) ameliorated dyskinesia in rat and nonhuman primate models of PD and dyskinesia, and (3) improved gait performance in a nonhuman primate model of PD. These results pave the way for clinical testing of this unconventional but safe approach. © 2018 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.
Assuntos
Antiparkinsonianos/efeitos adversos , Discinesia Induzida por Medicamentos/tratamento farmacológico , Levodopa/efeitos adversos , Transtornos Parkinsonianos/tratamento farmacológico , Xenônio/uso terapêutico , Administração por Inalação , Animais , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Discinesia Induzida por Medicamentos/etiologia , Transtornos Neurológicos da Marcha/tratamento farmacológico , Transtornos Neurológicos da Marcha/etiologia , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Intoxicação por MPTP/tratamento farmacológico , Camundongos , Camundongos Transgênicos , Oxidopamina/toxicidade , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/complicações , Ratos , Transtornos de Sensação/tratamento farmacológico , Transtornos de Sensação/etiologia , Simpatolíticos/toxicidade , Fatores de TempoRESUMO
Long-term l-3,4-dihydroxyphenylalanine (l-DOPA) treatment in Parkinson's disease (PD) leads to l-DOPA-induced dyskinesia (LID), a condition thought to primarily involve the dopamine D1 receptor-expressing striatal medium spiny neurons. Activation of the D1 receptor results in increased expression of several molecular markers, in particular the members of the immediate-early gene (IEG) family, a class of genes rapidly transcribed in response to an external stimulus. However, several dopaminoceptive structures in the brain that are likely to be affected by the exogenously produced DA have received little attention although they might play a key role in mediating those l-DOPA-induced abnormal behaviours. ΔFosB, ARC, FRA2 and Zif268 IEGs expression patterns were thus characterised, using unbiased stereological methods, in the whole brain of dyskinetic and non-dyskinetic rats to identify brain nuclei displaying a transcriptional response specifically related to LID. Within the basal ganglia, the striatum and the substantia nigra pars reticulata showed an increased expression of all four IEGs in dyskinetic compared to non-dyskinetic rats. Outside the basal ganglia, there was a striking increased expression of the four IEGs in the motor cortex, the bed nucleus of the stria terminalis, the dorsal hippocampus, the pontine nuclei, the cuneiform nucleus and the pedunculopontine nuclei. Moreover, the zona incerta and the lateral habenula displayed an overexpression of ΔFosB, ARC and Zif268. Among these structures, the IEG expression in the striatum, the bed nucleus of the stria terminalis, the lateral habenula, the pontine nuclei and the cuneiform nucleus correlate with LID severity. These results illustrate a global transcriptional response to a dyskinetic state in the whole brain suggesting the possible involvement of these structures in LID.
Assuntos
Antiparkinsonianos/toxicidade , Gânglios da Base/metabolismo , Encéfalo/metabolismo , Discinesia Induzida por Medicamentos/metabolismo , Proteínas Imediatamente Precoces/metabolismo , Levodopa/toxicidade , Animais , Proteínas do Citoesqueleto/metabolismo , Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Antígeno 2 Relacionado a Fos/metabolismo , Masculino , Proteínas do Tecido Nervoso/metabolismo , Proteínas Proto-Oncogênicas c-fos/metabolismo , Ratos , Ratos Sprague-DawleyRESUMO
Decades of research have identified the pathological and pathophysiological hallmarks of Parkinson's disease (PD): profound deficit in brain dopamine and other monoamines, pathological α-synuclein aggregation, synaptic and neuronal network dysfunction, aberrant proteostasis, altered energy homeostasis, inï¬ammation, and neuronal cell death. The purpose of this contribution is to present the phenocopy aspect, pathogenic, and etiologic nonhuman primate (NHP) models of PD to readers with limited prior knowledge of PD so that they are ready to start working on PD. How NHPs, the closest species to man on which we can model diseases, contribute to the knowledge progress and how these models represent an invaluable translational step in therapeutic development are highlighted.
RESUMO
Aberrant membrane localization of dopamine D(1) receptor (D1R) is associated with L-DOPA-induced dyskinesia (LID), a major complication of L-DOPA treatment in Parkinson's disease (PD). Since the proteasome plays a central role in modulating neuronal response through regulation of neurotransmitter receptor intraneuronal fate, we hypothesized that the ubiquitine-proteasome proteolytic pathway could be impaired in LID. Those LIDs are actually associated with a striatum-specific decrease in proteasome catalytic activity and accumulation of polyubiquitinated proteins in experimental rodent and monkey parkinsonism. We then demonstrated that such decreased proteasome catalytic activity (1) results from D1R activation and (2) feed-back the D1R abnormal trafficking, i.e., its exaggerated cell surface abundance. We further showed that the genetic invalidation of the E3 ubiquitin-protein ligase parkin PD gene leads to exaggerated abnormal involuntary movements compared with wild-type mice. We thus established in an unprecedented series of experimental models that impairment of the ubiquitine-proteasome system at specific nodes (E3 ligase parkin, polyubiquitination, proteasome catalytic activity) leads to the same phenomenon, i.e., aberrant behavioral response to dopamine replacement therapy in PD, highlighting the intimate interplay between dopamine receptor and proteasome activity in a nondegenerative context.
Assuntos
Discinesia Induzida por Medicamentos/metabolismo , Levodopa/toxicidade , Transtornos Parkinsonianos/tratamento farmacológico , Transtornos Parkinsonianos/metabolismo , Complexo de Endopeptidases do Proteassoma/metabolismo , Inibidores de Proteassoma , Receptores de Dopamina D1/agonistas , Animais , Modelos Animais de Doenças , Agonistas de Dopamina/toxicidade , Discinesia Induzida por Medicamentos/fisiopatologia , Feminino , Macaca mulatta , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Técnicas de Cultura de Órgãos , Transtornos Parkinsonianos/enzimologia , Ratos , Ratos Sprague-Dawley , Receptores de Dopamina D1/fisiologiaRESUMO
The serotonin (5-hydroxytryptamine [5HT]) system has recently emerged as an important player in the appearance of l-3,4-dihydroxyphenylalanine (levodopa [l-dopa])-induced dyskinesia in animal models of Parkinson's disease. In fact, dopamine released as a false transmitter from serotonin neurons appears to contribute to the pulsatile stimulation of dopamine receptors, leading to the appearance of the abnormal involuntary movements. Thus, drugs able to dampen the activity of serotonin neurons hold promise for the treatment of dyskinesia. The authors investigated the ability of the mixed 5-HT 1A/1B receptor agonist eltoprazine to counteract l-dopa-induced dyskinesia in 6-hydroxydopamine-lesioned rats and in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treated macaques. The data demonstrated that eltoprazine is extremely effective in suppressing dyskinesia in experimental models, although this effect was accompanied by a partial worsening of the therapeutic effect of l-dopa. Interestingly, eltoprazine was found to (synergistically) potentiate the antidyskinetic effect of amantadine. The current data indicated that eltoprazine is highly effective in counteracting dyskinesia in preclinical models. However, the partial worsening of the l-dopa effect observed after eltoprazine administration represents a concern; whether this side effect is due to a limitation of the animal models or to an intrinsic property of eltoprazine needs to be addressed in ongoing clinical trials. The data also suggest that the combination of low doses of eltoprazine with amantadine may represent a valid strategy to increase the antidyskinetic effect and reduce the eltoprazine-induced worsening of l-dopa therapeutic effects.
Assuntos
Discinesia Induzida por Medicamentos/tratamento farmacológico , Piperazinas/uso terapêutico , Agonistas do Receptor de Serotonina/uso terapêutico , Amantadina/uso terapêutico , Anfetamina , Animais , Apomorfina/farmacologia , Modelos Animais de Doenças , Dopaminérgicos/efeitos adversos , Discinesia Induzida por Medicamentos/etiologia , Feminino , Levodopa/efeitos adversos , Macaca fascicularis , Feixe Prosencefálico Mediano/fisiologia , Atividade Motora/efeitos dos fármacos , Oxidopamina/toxicidade , Doença de Parkinson/tratamento farmacológico , Doença de Parkinson/etiologia , Transtornos Parkinsonianos/tratamento farmacológico , Desempenho Psicomotor/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Fatores de Tempo , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Aggregation of α-synuclein (α-syn) is the cornerstone of neurodegenerative diseases termed synucleinopathies, which include Parkinson's Disease (PD), Dementia with Lewy Bodies (DLB), and Multiple System Atrophy (MSA). These synucleinopathies are characterized by the deposit of aggregated α-syn in intracellular inclusions observable in neurons and glial cells. In PD and DLB, these aggregates, predominantly located in neurons, are called Lewy Bodies (LBs). These LBs are one of the pathological hallmarks of PD and DLB, alongside dopaminergic neuron loss in the substantia nigra. Previous studies have demonstrated the ability of PD patient-derived LB fractions to induce nigrostriatal neurodegeneration and α-syn pathology when injected into the striatum or the enteric nervous system of non-human primates. Here, we report the pathological consequences of injecting these LB fractions into the cortex of non-human primates. To this end, we inoculated mesencephalic PD patient-derived LB fractions into the prefrontal cortex of baboon monkeys terminated one year later. Extensive analyses were performed to evaluate pathological markers known to be affected in LB pathologies. We first assessed the hypothesized presence of phosphorylated α-syn at S129 (pSyn) in the prefrontal cortices. Second, we quantified the neuronal, microglial, and astrocytic cell survival in the same cortices. Third, we characterized these cortical LB injections' putative impact on the integrity of the nigrostriatal system. Overall, we observed pSyn accumulation around the injection site in the dorsal prefrontal cortex, in connected cortical regions, and further towards the striatum, suggesting α-syn pathological propagation. The pathology was also accompanied by neuronal loss in these prefrontal cortical regions and the caudate nucleus, without, however, loss of nigral dopamine neurons. In conclusion, this pilot study provides novel data demonstrating the toxicity of patient-derived extracts, their potential to propagate from the cortex to the striatum in non-human primates, and a possible primate model of DLB.
RESUMO
Morphine is endogenously synthesized in the central nervous system and endogenous dopamine is thought to be necessary for endogenous morphine formation. As Parkinson's disease results from the loss of dopamine and is associated with central pain, we considered how endogenous morphine is regulated in the untreated and l-DOPA-treated parkinsonian brain. However, as the cellular origin and overall distribution of endogenous morphine remains obscure in the pathological adult brain, we first characterized the distribution of endogenous morphine-like compound immunoreactive cells in the rat striatum. We then studied changes in the endogenous morphine-like compound immunoreactivity of medium spiny neurons in normal, Parkinson's disease-like and l-DOPA-treated Parkinson's disease-like conditions in experimental (rat and monkey) and human Parkinson's disease. Our results reveal an unexpected dramatic upregulation of neuronal endogenous morphine-like compound immunoreactivity and levels in experimental and human Parkinson's disease, only partially normalized by l-DOPA treatment. Our data suggest that endogenous morphine formation is more complex than originally proposed and that the parkinsonian brain experiences a dramatic upregulation of endogenous morphine immunoreactivity. The functional consequences of such endogenous morphine upregulation are as yet unknown, but based upon the current knowledge of morphine signalling, we hypothesize that it is involved in fatigue, depression and pain symptoms experienced by patients with Parkinson's disease.
Assuntos
Encéfalo/metabolismo , Transtornos Parkinsonianos/metabolismo , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Idoso , Análise de Variância , Animais , Encéfalo/efeitos dos fármacos , Encéfalo/patologia , Encéfalo/ultraestrutura , Colina O-Acetiltransferase/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Dendritos/metabolismo , Dendritos/ultraestrutura , Modelos Animais de Doenças , Dopamina/metabolismo , Dopaminérgicos/farmacologia , Proteínas da Membrana Plasmática de Transporte de Dopamina/deficiência , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Fosfoproteína 32 Regulada por cAMP e Dopamina/metabolismo , Inibidores Enzimáticos/farmacologia , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Lateralidade Funcional , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/genética , Proteína Glial Fibrilar Ácida/metabolismo , Glutamato Descarboxilase/metabolismo , Humanos , Levodopa/farmacologia , Macaca fascicularis , Masculino , Feixe Prosencefálico Mediano/efeitos dos fármacos , Feixe Prosencefálico Mediano/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Microscopia Imunoeletrônica/métodos , Pessoa de Meia-Idade , Fatores de Crescimento Neural/metabolismo , Compostos Orgânicos/metabolismo , Oxidopamina/efeitos adversos , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/tratamento farmacológico , Transtornos Parkinsonianos/patologia , Mudanças Depois da Morte , Ratos , Ratos Sprague-Dawley , Receptores de Dopamina D2/metabolismo , Subunidade beta da Proteína Ligante de Cálcio S100 , Proteínas S100/metabolismo , Espectrometria de Massas em Tandem , alfa-Metiltirosina/farmacologiaRESUMO
Woodchuck Hepatitis Virus Post-transcriptional Regulatory Element (WPRE) is thought to enhance transgene expression of target genes delivered by adeno-associated viral (AAV) vectors. This study assessed the protein expression of α-synuclein, phosphorylated α-synuclein at Serine 129, extent of nigrostriatal degeneration as well as subsequent behavioral deficits induced by unilateral intranigral stereotactic injection in male adult C57BL/6J mice of an AAV2/9 expressing A53T human α-synuclein under the control of the synapsin promoter in presence or absence of the WPRE. The presence of WPRE enabled to achieve greater nigrostriatal degeneration and synucleinopathy which was concomitant with worsened forelimb use asymmetry. This work refines a mouse Parkinson's disease model in which anatomo-pathology is related to behavioral deficits.
RESUMO
Adenosine A1/A2A receptors (A1R/A2AR) represent targets in nondopaminergic treatment of motor disorders such as Parkinson's disease (PD). As an innovative strategy, multitargeting ligands (MTLs) were developed to achieve comprehensive PD therapies simultaneously addressing comorbid symptoms such as sleep disruption. Recognizing the wake-promoting capacity of histamine H3 receptor (H3R) antagonists in combination with the "caffeine-like effects" of A1R/A2AR antagonists, we designed A1R/A2AR/H3R MTLs, where a piperidino-/pyrrolidino(propyloxy)phenyl H3R pharmacophore was introduced with overlap into an adenosine antagonist arylindenopyrimidine core. These MTLs showed distinct receptor binding profiles with overall nanomolar H3R affinities (Ki < 55 nM). Compound 4 (ST-2001, Ki (A1R) = 11.5 nM, Ki (A2AR) = 7.25 nM) and 12 (ST-1992, Ki (A1R) = 11.2 nM, Ki (A2AR) = 4.01 nM) were evaluated in vivo. l-DOPA-induced dyskinesia was improved after administration of compound 4 (1 mg kg-1, i.p. rats). Compound 12 (2 mg kg-1, p.o. mice) increased wakefulness representing novel pharmacological tools for PD therapy.
Assuntos
Antagonistas do Receptor A1 de Adenosina/uso terapêutico , Antagonistas do Receptor A2 de Adenosina/uso terapêutico , Antagonistas dos Receptores Histamínicos H3/uso terapêutico , Doença de Parkinson Secundária/tratamento farmacológico , Antagonistas do Receptor A1 de Adenosina/síntese química , Antagonistas do Receptor A1 de Adenosina/metabolismo , Antagonistas do Receptor A2 de Adenosina/síntese química , Antagonistas do Receptor A2 de Adenosina/metabolismo , Animais , Discinesias/tratamento farmacológico , Antagonistas dos Receptores Histamínicos H3/síntese química , Antagonistas dos Receptores Histamínicos H3/metabolismo , Humanos , Levodopa/farmacologia , Masculino , Camundongos Endogâmicos C57BL , Simulação de Acoplamento Molecular , Oxidopamina , Doença de Parkinson Secundária/induzido quimicamente , Piperidinas/síntese química , Piperidinas/metabolismo , Piperidinas/uso terapêutico , Pirimidinas/síntese química , Pirimidinas/metabolismo , Pirimidinas/uso terapêutico , Pirrolidinas/síntese química , Pirrolidinas/metabolismo , Pirrolidinas/uso terapêutico , Ratos Sprague-Dawley , Receptor A2A de Adenosina/metabolismo , Receptores Histamínicos H3/metabolismo , Vigília/efeitos dos fármacosRESUMO
We have associated behavioral, pharmacological, and quantitative immunohistochemical study in a rat analog of l-DOPA-induced dyskinesia to understand whether alterations in dopamine receptor fate in striatal neurons may be involved in mechanisms leading to movement abnormalities. Detailed analysis at the ultrastructural level demonstrates specific alterations of dopamine D(1) receptor (D(1)R) subcellular localization in striatal medium spiny neurons in l-DOPA-treated 6-hydroxydopamine-lesioned rats with abnormal involuntary movements (AIMs). This includes exaggerated D(1)R expression at the plasma membrane. However, D(1)R retains ability of internalization, as a challenge with the potent D(1)R agonist SKF-82958 induces a strong decrease of labeling at membrane in animals with AIMs. Since a functional cross talk between D(1)R and D(3)R has been suggested, we hypothesized that their coactivation by dopamine derived from l-DOPA might anchor D(1)R at the membrane. Accordingly, cotreatment with l-DOPA and the D(3)R antagonist ST 198 restores normal level of membrane-bound D(1)R. Together, these results demonstrate that AIMs are related to abnormal D(1)R localization at the membrane and intraneuronal trafficking dysregulation, and suggest that strategies aiming at disrupting the D(1)R-D(3)R cross talk might reduce l-DOPA-induced dyskinesia by reducing D(1)R availability at the membrane.
Assuntos
Discinesia Induzida por Medicamentos/metabolismo , Levodopa/análogos & derivados , Levodopa/toxicidade , Neurônios/metabolismo , Receptores de Dopamina D1/metabolismo , Animais , Discinesia Induzida por Medicamentos/patologia , Masculino , Neurônios/efeitos dos fármacos , Neurônios/ultraestrutura , Transtornos Parkinsonianos/metabolismo , Transtornos Parkinsonianos/patologia , Ratos , Ratos Sprague-Dawley , Receptor Cross-Talk/efeitos dos fármacos , Receptores de Dopamina D1/ultraestrutura , Receptores de Dopamina D3/agonistas , Receptores de Dopamina D3/antagonistas & inibidores , Receptores de Dopamina D3/metabolismoRESUMO
Chronic L-dopa treatment of Parkinson's disease (PD) often leads to debilitating involuntary movements, termed L-dopa-induced dyskinesia (LID), mediated by dopamine (DA) receptors. RGS9-2 is a GTPase accelerating protein that inhibits DA D2 receptor-activated G proteins. Herein, we assess the functional role of RGS9-2 on LID. In monkeys, Western blot analysis of striatal extracts shows that RGS9-2 levels are not altered by MPTP-induced DA denervation and/or chronic L-dopa administration. In MPTP monkeys with LID, striatal RGS9-2 overexpression--achieved by viral vector injection into the striatum--diminishes the involuntary movement intensity without lessening the anti-parkinsonian effects of the D1/D2 receptor agonist L-dopa. In contrasts, in these animals, striatal RGS9-2 overexpression diminishes both the involuntary movement intensity and the anti-parkinsonian effects of the D2/D3 receptor agonist ropinirole. In unilaterally 6-OHDA-lesioned rats with LID, we show that the time course of viral vector-mediated striatal RGS9-2 overexpression parallels the time course of improvement of L-dopa-induced involuntary movements. We also find that unilateral 6-OHDA-lesioned RGS9-/- mice are more susceptible to L-dopa-induced involuntary movements than unilateral 6-OHDA-lesioned RGS9+/+ mice, albeit the rotational behavior--taken as an index of the anti-parkinsonian response--is similar between the two groups of mice. Together, these findings suggest that RGS9-2 plays a pivotal role in LID pathophysiology. However, the findings also suggest that increasing RGS9-2 expression and/or function in PD patients may only be a suitable therapeutic strategy to control involuntary movements induced by nonselective DA agonist such as L-dopa.
Assuntos
Di-Hidroxifenilalanina/efeitos adversos , Dopaminérgicos/efeitos adversos , Discinesias/etiologia , Discinesias/fisiopatologia , Proteínas RGS/metabolismo , Comportamento Estereotipado/fisiologia , Análise de Variância , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Corpo Estriado/metabolismo , Corpo Estriado/fisiopatologia , Modelos Animais de Doenças , Discinesias/terapia , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/fisiologia , Intoxicação por MPTP/tratamento farmacológico , Macaca fascicularis , Camundongos , Camundongos Knockout , Oxidopamina/farmacologia , Proteínas RGS/administração & dosagem , Comportamento Estereotipado/efeitos dos fármacos , Simpatolíticos/farmacologiaRESUMO
Dopamine agonists used to manage Parkinsonian motor symptoms have been suggested to be neuroprotective. The study was designed to assess the neuroprotective potential of the D(3)/D(2)/D(1) dopamine receptor agonist rotigotine in the acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned (MPTP) mouse model of Parkinson's disease by measuring mesencephalic degenerating neurons using FluoroJade staining and the remaining dopaminergic nerve endings in the striatum using dopamine transporter binding. Continuous administration of rotigotine at a dose of 3mg/kg significantly attenuated MPTP-induced acute cell degeneration in the FluoroJade-staining paradigm. Rotigotine (0.3-3mg/kg) partially protected dopamine nerve endings from MPTP-induced degeneration in a dose-dependent manner. These data suggest that rotigotine, at the doses employed, significantly protected dopamine neurons from degeneration in an acute mouse model of MPTP intoxication.
Assuntos
Agonistas de Dopamina/farmacologia , Fármacos Neuroprotetores/farmacologia , Transtornos Parkinsonianos/tratamento farmacológico , Transtornos Parkinsonianos/prevenção & controle , Tetra-Hidronaftalenos/farmacologia , Tiofenos/farmacologia , Doença Aguda , Administração Cutânea , Animais , Corpo Estriado/efeitos dos fármacos , Corpo Estriado/metabolismo , Relação Dose-Resposta a Droga , Radioisótopos do Iodo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Degeneração Neural/tratamento farmacológico , Degeneração Neural/prevenção & controle , Ensaio Radioligante , Receptores Dopaminérgicos/metabolismo , Substância Negra/efeitos dos fármacos , Substância Negra/metabolismoRESUMO
BACKGROUND: The brain bioavailability of novel small molecules developed to address central nervous system disease is classically documented through ex vivo or in vivo analyses conducted in rodent models. Data acquired in rodent models are, however, not easily transferrable to human as the pharmacokinetic and pharmacodynamics profiles of the species are quite different. METHODS: Using drugs selected for their differential transport across the blood-brain barrier, we here demonstrate the feasibility of brain microdialysis in normal vigil macaque monkey by measuring brain extracellular fluid bioavailability of carbamazepine, digoxin, oxycodone, and quinidine. RESULTS: All drugs, but digoxin, were found in dialysate samples. Drugs that are substrate of P-glycoprotein show a difference of bioavailability or brain pharmacokinetic parameters between rodents and primates. CONCLUSION: Data suggest that brain microdialysis in vigil macaque monkey, the species of choice for classic pharmacokinetic/pharmacodynamics studies could help predicting human brain bioavailability of a small molecule depending on the protein involved in the efflux transport from the brain.
RESUMO
INTRODUCTION: Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons as well as the presence of proteinaceous inclusions named Lewy bodies. α-synuclein (α-syn) is a major constituent of Lewy bodies, and the first disease-causing protein characterized in PD. Several α-syn-based animal models of PD have been developed to investigate the pathophysiology of PD, but none of them recapitulate the full picture of the disease. Ageing is the most compelling and major risk factor for developing PD but its impact on α-syn toxicity remains however unexplored. In this study, we developed and exploited a recombinant adeno-associated viral (AAV) vector of serotype 9 overexpressing mutated α-syn to elucidate the influence of ageing on the dynamics of PD-related neurodegeneration associated with α-syn pathology in different mammalian species. RESULTS: Identical AAV pseudotype 2/9 vectors carrying the DNA for human mutant p.A53T α-syn were injected into the substantia nigra to induce neurodegeneration and synucleinopathy in mice, rats and monkeys. Rats were used first to validate the ability of this serotype to replicate α-syn pathology and second to investigate the relationship between the kinetics of α-syn-induced nigrostriatal degeneration and the progressive onset of motor dysfunctions, strikingly reminiscent of the impairments observed in PD patients. In mice, AAV2/9-hα-syn injection into the substantia nigra was associated with accumulation of α-syn and phosphorylated hα-syn, regardless of mouse strain. However, phenotypic mutants with either accelerated senescence or resistance to senescence did not display differential susceptibility to hα-syn overexpression. Of note, p-α-syn levels correlated with nigrostriatal degeneration in mice. In monkeys, hα-syn-induced degeneration of the nigrostriatal pathway was not affected by the age of the animals. Unlike mice, monkeys did not exhibit correlations between levels of phosphorylated α-syn and neurodegeneration. CONCLUSIONS: In conclusion, AAV2/9-mediated hα-syn induces robust nigrostriatal neurodegeneration in mice, rats and monkeys, allowing translational comparisons among species. Ageing, however, neither exacerbated nigrostriatal neurodegeneration nor α-syn pathology per se. Our unprecedented multi-species investigation thus favours the multiple-hit hypothesis for PD wherein ageing would merely be an aggravating, additive, factor superimposed upon an independent disease process.
Assuntos
Envelhecimento , Intoxicação por MPTP/patologia , Degeneração Estriatonigral/patologia , Substância Negra/metabolismo , alfa-Sinucleína/metabolismo , Animais , Fenômenos Biomecânicos , Callithrix , Modelos Animais de Doenças , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Intoxicação por MPTP/induzido quimicamente , Camundongos , Atividade Motora , Análise de Componente Principal , Desempenho Psicomotor/fisiologia , Ratos , Degeneração Estriatonigral/etiologia , Fatores de Tempo , Transdução Genética , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
During recent years, much attention has been devoted at investigating the modulatory role of central 5-HT(2C) receptors on dopamine (DA) neuron activity, and it has been proposed that these receptors modulate selectively DA exocytosis associated with increased firing of DA neurons. In the present study, using in vivo microdialysis in the nucleus accumbens (NAc) and the striatum of halothane-anesthetized rats, we addressed this hypothesis by assessing the ability of 5-HT(2C) agents to modulate the increase in DA outflow induced by haloperidol and cocaine, of which the effects on DA outflow are associated or not with an increase in DA neuron firing, respectively. The intraperitoneal administration of cocaine (10-30 mg/kg) induced a dose-dependent increase in DA extracellular levels in the NAc and the striatum. The effect of 15 mg/kg cocaine was potentiated by the mixed 5-HT(2C/2B) antagonist SB 206553 (5 mg/kg i.p.) and the selective 5-HT(2C) antagonist SB 242084 (1 mg/kg i.p.) in both brain regions. The mixed 5-HT(2C/2B) agonist, Ro 60-0175 (1 mg/kg i.p.), failed to affect cocaine-induced DA outflow, but reduced significantly the increase in DA outflow induced by the subcutaneous administration of 0.1 mg/kg haloperidol. The obtained results provide evidence that 5-HT(2C) receptors exert similar effects in both the NAc and the striatum, and they modulate DA exocytosis also when its increase occurs independently from an increase in DA neuron impulse activity. Furthermore, they show that 5-HT(2C) agonists, at variance with 5-HT(2C) antagonists, exert a preferential control on the impulse-stimulated release of DA.