Unitat d'Histologia i Neurobiologia (UHNeurob), Facultat de Medicina i Ciències de la Salut, Universitat Rovira i Virgili, Sant Llorenç 21, 43201 Reus, Spain.
MoBioFood Research Group, Campus Sescelades, Universitat Rovira i Virgili, Marcel.lí Domingo 1, 43007 Tarragona, Spain.
Int J Mol Sci. 2024 Jul 23;25(15):8018. doi: 10.3390/ijms25158018.
Age-related conditions, such as sarcopenia, cause physical disabilities for an increasing section of society. At the neuromuscular junction, the postsynaptic-derived neurotrophic factors brain-derived neurotrophic factor (BDNF) and neurotrophin 4 (NT-4) have neuroprotective functions and contribute to the correct regulation of the exocytotic machinery. Similarly, presynaptic muscarinic signalling plays a fundamental modulatory function in this synapse. However, whether or not these signalling pathways are compromised in ageing neuromuscular system has not yet been analysed. The present study analyses, through Western blotting, the differences in expression and activation of the main key proteins of the BDNF/NT-4 and muscarinic pathways related to neurotransmission in young versus ageing (EDL) rat muscles. The main results show an imbalance in several sections of these pathways: (i) a change in the stoichiometry of BDNF/NT-4, (ii) an imbalance of Tropomyosin-related kinase B receptor (TrkB)-FL/TrkB-T1 and neurotrophic receptor p 75 (p75), (iii) no changes in the cytosol/membrane distribution of phosphorylated downstream protein kinase C (PKC)βI and PKCε, (iv) a reduction in the M2-subtype muscarinic receptor and P/Q-subtype voltage-gated calcium channel, (v) an imbalance of phosphorylated mammalian uncoordinated-18-1 (Munc18-1) (S313) and synaptosomal-associated protein 25 (SNAP-25) (S187), and (vi) normal levels of molecules related to the management of acetylcholine (Ach). Based on this descriptive analysis, we hypothesise that these pathways can be adjusted to ensure neurotransmission rather than undergoing negative alterations caused by ageing. However, further studies are needed to assess this hypothetical suggestion. Our results contribute to the understanding of some previously described neuromuscular functional age-related impairments. Strategies to promote these signalling pathways could improve the neuromuscular physiology and quality of life of older people.
与年龄相关的病症(如肌肉减少症)会导致社会中越来越多的人群出现身体残疾。在神经肌肉接头处,突触后衍生的神经营养因子脑源性神经营养因子(BDNF)和神经营养因子 4(NT-4)具有神经保护功能,并有助于正确调节胞吐机制。同样,突触前毒蕈碱信号在这个突触中起着基本的调节功能。然而,这些信号通路在衰老的神经肌肉系统中是否受到损害尚未进行分析。本研究通过 Western blot 分析了年轻(EDL)大鼠肌肉中与神经传递相关的 BDNF/NT-4 和毒蕈碱途径的主要关键蛋白的表达和激活的差异。主要结果表明这些途径的几个部分存在不平衡:(i)BDNF/NT-4 的比例发生变化,(ii)Tropomyosin-related kinase B receptor(TrkB)-FL/TrkB-T1 和神经营养受体 p75(p75)的平衡失调,(iii)磷酸化下游蛋白激酶 C(PKC)βI 和 PKCε 的细胞质/膜分布没有变化,(iv)M2 型毒蕈碱受体和 P/Q 型电压门控钙通道减少,(v)磷酸化哺乳动物非协调蛋白 18-1(Munc18-1)(S313)和突触相关蛋白 25(SNAP-25)(S187)的失衡,以及(vi)乙酰胆碱(Ach)管理相关分子的正常水平。基于这种描述性分析,我们假设这些途径可以进行调整以确保神经传递,而不是由于衰老而发生负面改变。然而,需要进一步的研究来评估这一假设。我们的研究结果有助于理解一些先前描述的与年龄相关的神经肌肉功能障碍。促进这些信号通路的策略可以改善老年人的神经肌肉生理学和生活质量。