RESUMO
The rare inherited form of Parkinson's disease (PD), PARK5, is caused by a missense mutation in ubiquitin carboxy-terminal hydrolase-L1 (UCH-L1) gene, resulting in Ile93Met substitution in its gene product (UCH-L1(Ile93Met)). PARK5 is inherited in an autosomal-dominant mode, but whether the Ile93Met mutation gives rise to a gain-of-toxic-function or loss-of-function of UCH-L1 protein remains controversial. Here, we investigated the selective vulnerabilities of dopaminergic (DA) neurons in UCH-L1-transgenic (Tg) and spontaneous UCH-L1-null gracile axonal dystrophy mice to an important PD-causing insult, abnormal accumulation of alpha-synuclein (alphaSyn). Immunohistochemistry of midbrain sections of a patient with sporadic PD showed alphaSyn- and UCH-L1-double-positive Lewy bodies in nigral DA neurons, suggesting physical and/or functional interaction between the two proteins in human PD brain. Recombinant adeno-associated viral vector-mediated over-expression of alphaSyn for 4 weeks significantly enhanced the loss of nigral DA cell bodies in UCH-L1(Ile93Met)-Tg mice, but had weak effects in age-matched UCH-L1(wild-type)-Tg mice and non-Tg littermates. In contrast, the extent of alphaSyn-induced DA cell loss in gracile axonal dystrophy mice was not significantly different from wild-type littermates at 13-weeks post-injection. Our results support the hypothesis that PARK5 is caused by a gain-of-toxic-function of UCH-L1(Ile93Met) mutant, and suggest that regulation of UCH-L1 in nigral DA cells could be a future target for treatment of PD.
Assuntos
Química Encefálica/genética , Predisposição Genética para Doença/genética , Doença de Parkinson/metabolismo , Ubiquitina Tiolesterase/metabolismo , alfa-Sinucleína/metabolismo , Idoso , Animais , Morte Celular/genética , Modelos Animais de Doenças , Dopamina/metabolismo , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Mutação/genética , Degeneração Neural/genética , Degeneração Neural/metabolismo , Degeneração Neural/fisiopatologia , Neurônios/metabolismo , Neurônios/patologia , Doença de Parkinson/genética , Doença de Parkinson/fisiopatologia , Substância Negra/metabolismo , Substância Negra/patologia , Substância Negra/fisiopatologia , Ubiquitina Tiolesterase/genética , alfa-Sinucleína/genéticaRESUMO
Enhancement of neurogenesis could be a suitable treatment approach to up-regulate dopaminergic neurons in Parkinson's disease (PD). In the present study, we focused on the kinetics of the subventricular zone (SVZ) in a mouse model of PD induced by MPTP injection. We showed recently the proliferation potential of neuronal stem cells (NSCs) prepared from the olfactory bulb of an animal model of PD [Hayakawa, H., Hayashita-Kinoh, H., Nihira, T., Seki, T., Mizuno, Y., Mochizuki, H., 2007. The isolation of neural stem cells from the OB of Parkinson's disease model. Neurosci. Res.]. In this study, we examined the relationship between proliferation and differentiation of NSCs in SVZ of both acute and chronic PD models. Only acute MPTP treatment significantly increased the areas of glial fibrillary acidic protein (GFAP)-expressing cells and decreased the areas of polysialylated neural cell adhesion molecule (PSA-NCAM)-expressing cells in the SVZ. In the case of caspase-11 knockout mice, MPTP did not induce alteration in the areas of GFAP-expressing cells and PSA-NCAM-expressing cells. Our results suggest that neuroinflammation related to the caspase-11 cascade in the striatum regulates differentiation of neural stem cells in the SVZ of our mouse model of PD.
Assuntos
Caspases/metabolismo , Diferenciação Celular/fisiologia , Encefalite/metabolismo , Transtornos Parkinsonianos/metabolismo , Células-Tronco/metabolismo , Telencéfalo/metabolismo , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina , Doença Aguda , Animais , Biomarcadores/metabolismo , Caspases/genética , Caspases Iniciadoras , Contagem de Células , Morte Celular/efeitos dos fármacos , Morte Celular/fisiologia , Diferenciação Celular/efeitos dos fármacos , Movimento Celular/fisiologia , Proliferação de Células/efeitos dos fármacos , Doença Crônica , Modelos Animais de Doenças , Encefalite/fisiopatologia , Proteína Glial Fibrilar Ácida/metabolismo , Ventrículos Laterais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Regeneração Nervosa/efeitos dos fármacos , Regeneração Nervosa/fisiologia , Molécula L1 de Adesão de Célula Nervosa/metabolismo , Neurotoxinas , Transtornos Parkinsonianos/fisiopatologia , Recuperação de Função Fisiológica/efeitos dos fármacos , Recuperação de Função Fisiológica/fisiologia , Ácidos Siálicos/metabolismo , Células-Tronco/citologia , Telencéfalo/fisiopatologiaRESUMO
We developed a new method for comparing immunopositive cell densities across groups of animals and creating statistical parametric maps on standardized sections. As an example, we compared Iba-1 (microglial marker) positive cell densities in rats with (n=6) and without (n=6) unilateral injection of 1-methyl-4-phenylpyridinium salt (MPP+). Immunopositive cells were automatically counted in each animal over a coronal section in the midbrain (bregma -5.9 mm) and a positive cell density map was created for each animal. After the positive cell density map was normalized to a template section from an atlas, positive cell densities of the two groups were compared in each pixel over the section and a statistical parameter (p-value from t-test) was mapped on each pixel. We were able to detect significant increases of microglias in the side of MPP+ injection not only in the substantia nigra pars compacta but also in adjacent white matter. We also applied the same analysis to tyrosine hydroxylase stained sections and detected significant decreases of dopamine neurons in the side of MPP+ injection. The new method was proven to be useful for detecting significant changes of cell densities over the entire area of immunostained sections.
Assuntos
Mapeamento Encefálico/métodos , Imuno-Histoquímica , Substância Negra/citologia , 1-Metil-4-fenilpiridínio/metabolismo , Animais , Biomarcadores/metabolismo , Contagem de Células , Dopamina/metabolismo , Masculino , Microglia/citologia , Ratos , Ratos Sprague-Dawley , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Loss-of-function mutations in the ubiquitin ligase parkin are the major cause of recessively inherited early-onset Parkinson disease (PD). Impairment of parkin activity caused by nitrosative or dopamine-related modifications may also be responsible for the loss of dopaminergic (DA) neurons in sporadic PD. Previous studies have shown that viral vector-mediated delivery of parkin prevented DA neurodegeneration in several animal models, but little is known about the neuroprotective actions of parkin in vivo. Here, we investigated mechanisms of neuroprotection of overexpressed parkin in a modified long-term mouse model of PD using osmotic minipump administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Recombinant adeno-associated viral vector-mediated intranigral delivery of parkin prevented motor deficits and DA cell loss in the mice. Ser129-phosphorylated α-synuclein-immunoreactive cells were increased in the substantia nigra of parkin-treated mice. Moreover, delivery of parkin alleviated the MPTP-induced decrease of the active phosphorylated form of Akt. On the other hand, upregulation of p53 and mitochondrial alterations induced by chronic MPTP administration were barely suppressed by parkin. These results suggest that the neuroprotective actions of parkin may be impaired in severe PD.
Assuntos
Dopamina/metabolismo , Intoxicação por MPTP/complicações , Mesencéfalo/patologia , Degeneração Neural/prevenção & controle , Neurônios/fisiologia , Ubiquitina-Proteína Ligases/uso terapêutico , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/administração & dosagem , Análise de Variância , Animais , Contagem de Células/métodos , Cromatografia Líquida de Alta Pressão/métodos , Corpo Estriado/metabolismo , Corpo Estriado/patologia , Modelos Animais de Doenças , Regulação da Expressão Gênica/efeitos dos fármacos , Vetores Genéticos/fisiologia , Proteínas de Fluorescência Verde/genética , Humanos , Intoxicação por MPTP/induzido quimicamente , Intoxicação por MPTP/metabolismo , Intoxicação por MPTP/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microinjeções/métodos , Atividade Motora/efeitos dos fármacos , Degeneração Neural/etiologia , Degeneração Neural/patologia , Neurotoxinas/administração & dosagem , Proteína Oncogênica v-akt/metabolismo , Teste de Desempenho do Rota-Rod , Transdução de Sinais/efeitos dos fármacos , Estatística como Assunto , Transdução Genética/métodos , Proteína Supressora de Tumor p53/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , alfa-Sinucleína/metabolismo , Proteína X Associada a bcl-2/metabolismoRESUMO
parkin is the most frequent causative gene among familial Parkinson's disease (PD). Although parkin deficiency induces autosomal recessive juvenile parkinsonism (AR-JP, PARK2) in humans, parkin knockout (PKO) mice consistently show few signs of dopaminergic degeneration. We aimed to directly measure evoked extracellular dopamine (DA) overflow in the striatum with in vivo voltammetry. The amplitude of evoked DA overflow was low in PKO mice. The half-life time of evoked DA overflow was long in PKO mice suggesting lower release and uptake of dopamine. Facilitation of DA overflow by repetitive stimulation enhanced in the older PKO mice. Decreased dopamine release and uptake in young PKO mice suggest early pre-symptomatic changes in dopamine neurotransmission, while the enhanced facilitation in the older PKO mice may reflect a compensatory adaptation in dopamine function during the late pre-symptomatic phase of Parkinson's disease. Our results showed parkin deficiency may affect DA release in PKO mice, although it does not cause massive nigral degeneration or parkinsonian symptoms as in humans.
Assuntos
Corpo Estriado/fisiologia , Dopamina/metabolismo , Ubiquitina-Proteína Ligases/deficiência , Ácido 3,4-Di-Hidroxifenilacético/metabolismo , Envelhecimento/fisiologia , Animais , Peso Corporal , Ácido Homovanílico/metabolismo , Ácido Hidroxi-Indolacético/metabolismo , Camundongos , Camundongos Knockout , Atividade Motora/fisiologia , Fibras Nervosas/efeitos dos fármacos , Fibras Nervosas/fisiologia , Nomifensina/farmacologia , Prosencéfalo/efeitos dos fármacos , Prosencéfalo/fisiologiaRESUMO
Oxidative stress is involved in the degeneration of the nigrostriatal dopaminergic system in Parkinson's disease (PD). Vitamin E (alpha-tocopherol) is a potent antioxidant in the cell membrane that can trap free radicals and prohibit lipid peroxidation. The retention and secretion of vitamin E are regulated by alpha-tocopherol transfer protein (TTP) in the brain and liver. Dysfunction of TTP results in systemic deficiency of vitamin E in humans and mice, and increased oxidative stress in mouse brain. In this study, we investigated the effect of vitamin E deficiency in PD development by generating an 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD using TTP knockout (TTP-/-) mice. Vitamin E concentration in the brains of TTP+/- mice was half that in TTP+/+ mice, and in TTP-/- mice, was undetectable. MPTP treatment tended to decrease striatal dopamine, but the effect was comparable and not significant in any of the three genotypes. Furthermore, the extent of loss of dopaminergic cell bodies in the substantia nigra did not differ among the groups. One the other hand, oral administration of vitamin E resulted in the partial protection of striatal dopaminergic terminals against MPTP toxicity. Our results suggest that vitamin E does not play a major protective role in MPTP-induced nigrostriatal dopaminergic neurodegeneration in the brain.
Assuntos
1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina , Encéfalo/fisiopatologia , Antagonistas de Dopamina , Neurotoxinas , Transtornos Parkinsonianos/induzido quimicamente , Deficiência de Vitamina E/fisiopatologia , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/antagonistas & inibidores , 1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/farmacologia , Administração Oral , Animais , Corpo Estriado/metabolismo , Suscetibilidade a Doenças , Antagonistas de Dopamina/farmacologia , Genótipo , Glutationa/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurotoxinas/antagonistas & inibidores , Neurotoxinas/farmacologia , Substância Negra/metabolismo , Superóxido Dismutase/metabolismo , Superóxido Dismutase-1 , Vitamina E/administração & dosagem , Vitamina E/farmacologia , Deficiência de Vitamina E/genéticaRESUMO
Granulocyte colony-stimulating factor (G-CSF) has been used for the treatment of neutropenia in hematologic disorders. The neuroprotective effects of G-CSF were reported in neurological disease models. In the present study, we examined whether G-CSF can protect dopaminergic neurons against MPTP-induced cell death in a mouse model of Parkinson's disease. Mice of one group were injected intraperitoneally with MPTP for five consecutive days, those of another group with MPTP and intraperitoneal G-CSF at 2 days and 1 day before the first MPTP injection, and 30 min before each MPTP injection, while control mice received saline injections. Immunohistochemistry, western blotting analysis, and HPLC were performed to evaluate damage of substantia nigra dopaminergic neurons and expression of Bcl-2 and Bax protein. MPTP induced dopaminergic cell death in the substantia nigra. G-CSF significantly prevented MPTP-induced loss of tyrosine hydroxylase-positive neurons (p < 0.05), increased Bcl-2 protein and decreased Bax protein expression. Our findings indicate that G-CSF provides neuroprotection against MPTP-induced cell death and this effect is mediated by increasing Bcl-2 expression levels and decreasing Bax expression levels in C57BL/6 mice.
Assuntos
1-Metil-4-Fenil-1,2,3,6-Tetra-Hidropiridina/antagonistas & inibidores , Dopamina/fisiologia , Genes bcl-2/efeitos dos fármacos , Fator Estimulador de Colônias de Granulócitos/farmacologia , Proteína X Associada a bcl-2/biossíntese , Proteína X Associada a bcl-2/genética , Animais , Morte Celular/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Immunoblotting , Imuno-Histoquímica , Marcação In Situ das Extremidades Cortadas , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neostriado/efeitos dos fármacos , Neostriado/metabolismo , Doença de Parkinson Secundária/induzido quimicamente , Doença de Parkinson Secundária/metabolismo , Doença de Parkinson Secundária/patologia , Proteínas Recombinantes , Tirosina 3-Mono-Oxigenase/metabolismoRESUMO
Recent studies of enhanced hippocampal neurogenesis by antidepressants suggest enhancement of neurogenesis is a potentially effective therapy in neurodegenerative diseases. In this study, we evaluated nigral neurogenesis in animals and autopsy brains including patients with Parkinson's disease (PD). First, proliferating cells in substantia nigra were labeled with retroviral transduction of green fluorescent protein, which is an efficient method to label neuronal stem cells. Subsequent differentiation of labeled cells was followed; many transduced cells became microglia, but no differentiation into tyrosine hydroxylase-positive neurons was detected at 4 weeks after injection, in both intact rodents and those treated with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Second, polysialic acid (PSA)-like immunoreactivity, indicative of newly differentiated neurons, was detected in the substantia nigra of rodent, primate, and human midbrains. A large number of PSA-positive cells were detected in the substantia nigra pars reticulata of some patients with PD. In rats and a macaque monkey, the dopamine-depleted hemispheres showed more PSA staining than the intact side. A small number of tyrosine hydroxylase-positive cells were PSA-positive. Our results suggest enhanced neural reconstruction in PD, which may be important in the design of new therapies against the progression of PD.