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1.
Ann N Y Acad Sci ; 1488(1): 3-15, 2021 03.
Artigo em Inglês | MEDLINE | ID: mdl-33040338

RESUMO

The neuromuscular junction (NMJ) is a specialized structure that works as an interface to translate the action potential of the presynaptic motor neuron (MN) in the contraction of the postsynaptic myofiber. The design of appropriate experimental models is essential to have efficient and reliable approaches to study NMJ development and function, but also to generate conditions that recapitulate distinct features of diseases. Initial studies relied on the use of tissue slices maintained under the same environment and in which single motor axons were difficult to trace. Later, MNs and muscle cells were obtained from primary cultures or differentiation of progenitors and cocultured as monolayers; however, the tissue architecture was lost. Current approaches include self-assembling 3D structures or the incorporation of biomaterials with cells to generate engineered tissues, although the incorporation of Schwann cells remains a challenge. Thus, numerous investigations have established different NMJ models, some of which are quite complex and challenging. Our review summarizes the in vitro models that have emerged in recent years to coculture MNs and skeletal muscle, trying to mimic the healthy and diseased NMJ. We expect our review may serve as a reference for choosing the appropriate experimental model for the required purposes of investigation.


Assuntos
Potenciais de Ação/fisiologia , Neurônios Motores/fisiologia , Doenças da Junção Neuromuscular/fisiopatologia , Junção Neuromuscular/fisiologia , Junção Neuromuscular/fisiopatologia , Células de Schwann/fisiologia , Animais , Humanos , Músculo Esquelético/fisiologia , Músculo Esquelético/fisiopatologia , Doenças da Junção Neuromuscular/diagnóstico
2.
Neuron ; 51(5): 601-12, 2006 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-16950158

RESUMO

An important step for cholinergic transmission involves the vesicular storage of acetylcholine (ACh), a process mediated by the vesicular acetylcholine transporter (VAChT). In order to understand the physiological roles of the VAChT, we developed a genetically altered strain of mice with reduced expression of this transporter. Heterozygous and homozygous VAChT knockdown mice have a 45% and 65% decrease in VAChT protein expression, respectively. VAChT deficiency alters synaptic vesicle filling and affects ACh release. Whereas VAChT homozygous mutant mice demonstrate major neuromuscular deficits, VAChT heterozygous mice appear normal in that respect and could be used for analysis of central cholinergic function. Behavioral analyses revealed that aversive learning and memory are not altered in mutant mice; however, performance in cognitive tasks involving object and social recognition is severely impaired. These observations suggest a critical role of VAChT in the regulation of ACh release and physiological functions in the peripheral and central nervous system.


Assuntos
Encéfalo/metabolismo , Doenças da Junção Neuromuscular/etiologia , Junção Neuromuscular/metabolismo , Reconhecimento Psicológico/fisiologia , Proteínas Vesiculares de Transporte de Acetilcolina/deficiência , Acetilcolina/análise , Acetilcolina/metabolismo , Animais , Northern Blotting , Southern Blotting , Encéfalo/patologia , Encéfalo/fisiopatologia , Química Encefálica , Cromatografia Líquida de Alta Pressão , Feminino , Masculino , Potenciais da Membrana/fisiologia , Camundongos , Camundongos Transgênicos , Microdiálise , Atividade Motora/fisiologia , Junção Neuromuscular/patologia , Junção Neuromuscular/fisiopatologia , Doenças da Junção Neuromuscular/patologia , Doenças da Junção Neuromuscular/fisiopatologia , Reação em Cadeia da Polimerase , RNA Mensageiro/análise , Transmissão Sináptica/fisiologia , Proteínas Vesiculares de Transporte de Acetilcolina/genética
3.
Ann N Y Acad Sci ; 998: 11-7, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-14592858

RESUMO

Different types of voltage-activated Ca(2+) channels have been established based on their molecular structure and pharmacological and biophysical properties. One of them, the P/Q-type, is the main channel involved in nerve-evoked neurotransmitter release at neuromuscular junctions and the immunological target in Eaton-Lambert Syndrome. At adult neuromuscular junctions, L- and N-type Ca(2+) channels become involved in transmitter release only under certain experimental or pathological conditions. In contrast, at neonatal rat neuromuscular junctions, nerve-evoked synaptic transmission depends jointly on both N- and P/Q-type channels. Synaptic transmission at neuromuscular junctions of the ataxic P/Q-type Ca(2+) channel knockout mice is also dependent on two different types of channels, N- and R-type. At both neonatal and P/Q knockout junctions, the K(+)-evoked increase in miniature endplate potential frequency was not affected by N-type channel blockers, but strongly reduced by both P/Q- and R-type channel blockers. These differences could be accounted for by a differential location of the channels at the release site, being either P/Q- or R-type Ca(2+) channels located closer to the release site than N-type Ca(2+) channels. Thus, Ca(2+) channels may be recruited to mediate neurotransmitter release where P/Q-type channels seem to be the most suited type of Ca(2+) channel to mediate exocytosis at neuromuscular junctions.


Assuntos
Envelhecimento/fisiologia , Canais de Cálcio Tipo N/fisiologia , Doenças da Junção Neuromuscular/fisiopatologia , Junção Neuromuscular/fisiologia , Transmissão Sináptica/fisiologia , Adulto , Animais , Animais Recém-Nascidos , Canais de Cálcio Tipo L/efeitos dos fármacos , Canais de Cálcio Tipo L/metabolismo , Canais de Cálcio Tipo N/classificação , Canais de Cálcio Tipo N/deficiência , Feto , Humanos , Camundongos , Junção Neuromuscular/efeitos dos fármacos , Junção Neuromuscular/genética , Neurotransmissores/metabolismo , Potássio/farmacologia , Ratos , Membranas Sinápticas/efeitos dos fármacos , Membranas Sinápticas/metabolismo , Transmissão Sináptica/efeitos dos fármacos
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