Browsing by Subject "Neuromuscular junction"

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    Aerobic training attenuates nicotinic acetylcholine receptor changes in the diaphragm muscle during heart failure
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2015) de Souza, Paula Aiello Tomé; de Souza, Rodrigo Wagner Alves; Campos Soares, Luana; Piedade, Warlen Pereira; Campos, Dijon Henrique S.; Carvalho, Robson Francisco; Padovani, Carlos Roberto; Okoshi, Katashi; Cicogna, Antônio Carlos; Michelin Matheus, Selma Maria; Dal-Pai-Silva, Maeli
    Introduction: Heart failure (HF) is a progressive myopathy, with clinical signs of fatigue and limb weakness that can damage the nerve-muscle interaction, altering synaptic transmission and nicotinic acetylcholine receptors (nAChR) in neuromuscular junctions (NMJs). The diaphragm is composed of a mixed proportion of muscle fibres, and during HF, this muscle becomes slower and can alter its function. As exercise training is an accepted practice to minimise abnormalities of skeletal muscle during HF, in this study, we evaluated the hypothesis that aerobic training attenuates alterations in the expression of nAChR subunits in NMJs diaphragm during heart failure. Objective: The aim of this study was to evaluate the distribution and expression of nAChR subunits in the diaphragm muscle fibres of rats subjected to an aerobic training programme during HF. Methods: Control (Sham), control training (ShamTR), aortic stenosis (AS) and aortic stenosis training (ASTR) groups were evaluated. The expression of nAChR subunits (γ, α1, ε, β1 and δ) was determined by qRT-PCR, and NMJs were analysed using confocal microscopy. Results: We observed increased expression of the γ, α1 and β1 subunits in the AS group compared with the ASTR group. The distribution of NMJs was modulated in these groups. Discussion: HF alters the mRNA expression of nAChR subunits and the structural characteristics of diaphragm NMJs. In addition, aerobic training did notalter NMJs morphology but attenuated the alterations in heart structure and function and in nAChR subunit mRNA expression. Our findings demonstrate the beneficial effects of aerobic exercise training in maintaining the integrity of the neuromuscular system in the diaphragm muscle during HF and may be critical for non-pharmacological therapy to improve the quality of life for patients with this syndrome.
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    Topological differences along mammalian motor nerve terminals for spontaneous and alpha-Bungarotoxin-induced sprouting
    (Murcia : F. Hernández, 2000) Tomas, J.; Lanuza, M.A.; Santafe, M.; Fenoll-Brunet, M.R.; García, N .
    Spontaneous sproutings can be observed in end plates from normal adult vertebrate muscles and motor end plates develop increased growth signs and sprouts when target muscle cells become less active or paralysed. Nevertheless, very little is known about where in the motor nerve terminal arborization spontaneous and experimentally induced sprouts originate, their similarities and differences and also about their final maturation or elimination. In this study we investigate the topological properties of both spontaneous and alpha-bungarotoxin-induced sprouts (during different periods of intoxication and after recovery) along the motor nerve terminal branches of the Levator auris longus muscle of Swiss mice (between 48- 169 day old). Muscles were processed for immunocytochemistry to simultaneously detect postsynaptic AChRs and axons. This procedurk permits us to make an accurate identification of the fine sprouts and a morphometric study of the presynaptic branching pattern profile in control muscles, during the toxin action and after recovery from paralysis. The results show that in normal muscles, the initial and trunk segments (those between branch points) of the terminal arborization sprouted proportionally more branches when taking their relative lengths into account than the distal free-end segments. In contrast, every micrometer of alpha-bungarotoxin-treated muscles throughout the full terminal arborization have the same probability of generating a sprout. Moreover, the toxininduced sprouts can consolidate as new branches once recovered from the paralysis without changing the total length of the nerve terminal arborization.
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    Ultrastructural study of neuromuscular junction in rectus femoris muscle of streptozotocin-diabetic rats
    (Murcia : F. Hernández, 1992) Medina sánchez, M.; Rodríguez Sáchez, C.; Vega Alvarez, J.A.; Menéndez Peláez, A.
    The neuromuscular junctions (NMJ) from rectus femoris muscle in streptozotocin (STZ) -induced diabetic rats were examined by electron microscopy eight weeks after the STZ injection. When compared to controls and vehicle-injected groups, both the axon terminal and the junctional sarcoplasm showed serious alterations including mitochondrial degeneration, presence of myeloid bodies, breakdown of presynaptic membrane and changes in the form of the synaptic vesicles. The results suggest that NMJ can contribute to the pathogenesis of diabetic proximal myopathy.