RESUMO
Deficits in hippocampal synaptic plasticity result in cognitive impairment in Huntington's disease (HD). Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide that exerts neuroprotective actions, mainly through the PAC1 receptor. However, the role of PACAP in cognition is poorly understood, and no data exists in the context of Huntington's disease (HD). Here, we investigated the ability of PACAP receptor stimulation to enhance memory development in HD. First, we observed a hippocampal decline of all three PACAP receptor expressions, i.e., PAC1, VPAC1, and VPAC2, in two different HD mouse models, R6/1 and HdhQ7/Q111, from the onset of cognitive dysfunction. In hippocampal post-mortem human samples, we found a specific decrease of PAC1, without changes in VPAC1 and VPAC2 receptors. To determine whether activation of PACAP receptors could contribute to improve memory performance, we conducted daily intranasal administration of PACAP38 to R6/1 mice at the onset of cognitive impairment for seven days. We found that PACAP treatment rescued PAC1 level in R6/1 mice, promoted expression of the hippocampal brain-derived neurotrophic factor, and reduced the formation of mutant huntingtin aggregates. Furthermore, PACAP administration counteracted R6/1 mice memory deficits as analyzed by the novel object recognition test and the T-maze spontaneous alternation task. Importantly, the effect of PACAP on cognitive performance was associated with an increase of VGlut-1 and PSD95 immunolabeling in hippocampus of R6/1 mice. Taken together, these results suggest that PACAP, acting through stimulation of PAC1 receptor, may have a therapeutic potential to counteract cognitive deficits induced in HD.
Assuntos
Hipocampo/fisiopatologia , Doença de Huntington/fisiopatologia , Memória/fisiologia , Plasticidade Neuronal/efeitos dos fármacos , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/farmacologia , Administração Intranasal , Animais , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Transtornos Cognitivos/fisiopatologia , Modelos Animais de Doenças , Proteína 4 Homóloga a Disks-Large/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Hipocampo/patologia , Humanos , Proteína Huntingtina/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pessoa de Meia-Idade , Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/administração & dosagem , Agregados Proteicos , Receptores de Polipeptídeo Hipofisário Ativador de Adenilato Ciclase/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/metabolismoAssuntos
Anticorpos/sangue , Encéfalo/metabolismo , Encefalite/sangue , Encefalite/imunologia , Receptores de AMPA/imunologia , Idoso , Encéfalo/patologia , Encéfalo/fisiopatologia , Linhagem Celular Transformada , Encefalite/tratamento farmacológico , Encefalite/patologia , Feminino , Humanos , Pessoa de Meia-Idade , Transfecção/métodosRESUMO
Dysregulation of gene expression is one of the mechanisms involved in the pathophysiology of Huntington's disease (HD). Here, we examined whether mutant huntingtin regulates the levels of PH domain leucine-rich repeat protein phosphatase 1 (PHLPP1), a phosphatase that specifically dephosphorylates Akt at Ser473. Our results show decreased PHLPP1 protein levels in knock-in models (Hdh(Q111/Q111) mouse striatum and STHdh(Q111/Q111) cells), in the striatum of N-terminal exon-1 mutant huntingtin transgenic mouse models (R6/1; R6/1 : BDNF + or - , R6/2 and Tet/HD94) and in the putamen of HD patients. Quantitative PCR analysis revealed a reduction in PHLPP1 mRNA levels in the striatum of R6/1 compared with wild-type mice. Coincident with reduced PHLPP1 protein levels, we observed increased phosphorylated Akt (Ser473) levels specifically in the striatum. The analysis of the conditional mouse model Tet/HD94 disclosed that after mutant huntingtin shutdown PHLPP1 levels returned to wild-type levels whereas phospho-Akt levels were partially reduced. In conclusion, our results show that mutant huntingtin downregulates PHLPP1 expression. In the striatum, these reduced levels of PHLPP1 can contribute to maintain high levels of activated Akt that may delay cell death and allow the recovery of neuronal viability after mutant huntingtin silencing.
Assuntos
Corpo Estriado/enzimologia , Doença de Huntington/enzimologia , Proteínas Nucleares/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Fosfoproteínas Fosfatases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Adulto , Idoso , Animais , Morte Celular/fisiologia , Linhagem Celular Transformada , Núcleo Celular/metabolismo , Corpo Estriado/patologia , Citosol/metabolismo , Modelos Animais de Doenças , Éxons/genética , Feminino , Técnicas de Introdução de Genes , Humanos , Doença de Huntington/genética , Doença de Huntington/patologia , Masculino , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Neurotoxinas/metabolismo , Proteínas Nucleares/química , Proteínas Nucleares/genética , Fosfoproteínas Fosfatases/química , Fosfoproteínas Fosfatases/genética , Fosforilação/fisiologia , Estrutura Terciária de ProteínaRESUMO
Antibodies against neuronal surface antigens (NSA-ab) have been described in pediatric opsoclonus-myoclonus syndrome (OMS). We analyzed the presence of NSA-ab by flow cytometry and immunocytochemistry of live cerebellar granular neurons (CGN) in the serum of 25 adult patients with idiopathic (14) and paraneoplastic (11) OMS. Paraneoplastic, but not idiopathic, OMS sera showed a CGN surface binding by flow cytometry higher than that of controls (mean MFI (median fluorescence intensity): 29+/-6.9 vs. 20+/-5.8; p=0.001) but only one serum had a binding greater than three standard deviations of controls. OMS sera did not label live CGN by immunocytochemistry. Unlike pediatric OMS, NSA-ab were not detected in adult cases suggesting that the immunity to NSA in OMS is heterogeneous.