RESUMO
INTRODUCTION: Reduced expression of the vesicular acetylcholine transporter (VAChT) leads to changes in the distribution and shape of synaptic vesicles (SVs) at neuromuscular junctions (NMJs), suggesting vesicular acetylcholine (ACh) as a key component of synaptic structure and function. It is poorly understood how long-term changes in cholinergic transmission contribute to age- and disease-related degeneration in the motor system. METHODS: In this study we performed confocal imaging, electrophysiology, electron microscopy, and analyses of respiratory mechanics of the diaphragm NMJ components in 12-month-old wild-type (WT) and VAChTKDHOM mice. RESULTS: Diaphragms of NMJs of the VAChTKDHOM mice were similar to those in WT mice in number, colocalization, and fragmentation of pre-/postsynaptic components. However, they had increased spontaneous SV exocytosis, miniature endplate potential frequency, and diminished MEPP amplitude. No impairment in respiratory mechanics at rest was observed, probably due to the large neurotransmission safety factor of the diaphragm. DISCUSSION: The present findings help us to understand the consequences of reduced ACh release at the NMJs during aging.
Assuntos
Envelhecimento/patologia , Diafragma/ultraestrutura , Síndromes Miastênicas Congênitas/patologia , Junção Neuromuscular/ultraestrutura , Vesículas Sinápticas/ultraestrutura , Acetilcolina/metabolismo , Envelhecimento/metabolismo , Animais , Diafragma/metabolismo , Diafragma/fisiopatologia , Modelos Animais de Doenças , Endocitose , Potenciais Pós-Sinápticos Excitadores/fisiologia , Exocitose , Técnicas de Silenciamento de Genes , Camundongos , Microscopia Confocal , Microscopia Eletrônica de Transmissão , Placa Motora , Síndromes Miastênicas Congênitas/genética , Síndromes Miastênicas Congênitas/metabolismo , Síndromes Miastênicas Congênitas/fisiopatologia , Junção Neuromuscular/metabolismo , Junção Neuromuscular/fisiopatologia , Mecânica Respiratória/fisiologia , Transmissão Sináptica , Vesículas Sinápticas/metabolismo , Proteínas Vesiculares de Transporte de Acetilcolina/genéticaRESUMO
Huntington's disease (HD) is a rare neurodegenerative disease characterized by motor, cognitive, and psychiatric symptoms. Inflammasomes are multiprotein complexes capable of sensing pathogen-associated and damage-associated molecular patterns, triggering innate immune pathways. Activation of inflammasomes results in a pro-inflammatory cascade involving, among other molecules, caspases and interleukins. NLRP3 (nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain-containing 3) is the most studied inflammasome complex, and its activation results in caspase-1 mediated cleavage of the pro-interleukins IL-1ß and IL-18 into their mature forms, also inducing a gasdermin D mediated form of pro-inflammatory cell death, i.e. pyroptosis. Accumulating evidence has implicated NLRP3 inflammasome complex in neurodegenerative diseases. The evidence in HD is still scant and mostly derived from pre-clinical studies. This review aims to present the available evidence on NLRP3 inflammasome activation in HD and to discuss whether targeting this innate immune system complex might be a promising therapeutic strategy to alleviate its symptoms.