Unraveling the causes of sarcopenia: Roles of neuromuscular junction impairment and mitochondrial dysfunction

Abstract

Sarcopenia is a systemic skeletal muscle disease characterized by a decline in skeletal muscle mass and function. Originally defined as an age‐associated condition, sarcopenia presently also encompasses muscular atrophy due to various pathological factors, such as intensive care unit‐acquired weakness, inactivity, and malnutrition. The exact pathogenesis of sarcopenia is still unknown; herein, we review the pathological roles of the neuromuscular junction and mitochondria in this condition. Sarcopenia is caused by complex and interdependent pathophysiological mechanisms, including aging, neuromuscular junction impairment, mitochondrial dysfunction, insulin resistance, lipotoxicity, endocrine factors, oxidative stress, and inflammation. Among these, neuromuscular junction instability and mitochondrial dysfunction are particularly significant. Dysfunction in neuromuscular junction can lead to muscle weakness or paralysis. Mitochondria, which are plentiful in neurons and muscle fibers, play an important role in neuromuscular junction transmission. Therefore, impairments in both mitochondria and neuromuscular junction may be one of the key pathophysiological mechanisms leading to sarcopenia. Moreover, this article explores the structural and functional alterations in the neuromuscular junction and mitochondria in sarcopenia, suggesting that a deeper understanding of these changes could provide valuable insights for the prevention or treatment of sarcopenia.

Proteomic reference map for sarcopenia research: mass spectrometric identification of key muscle proteins of organelles, cellular signaling, bioenergetic metabolism and molecular chaperoning

“… 83 This is important, since mitochondrial abnormalities and oxidative stress have been implicated in sarcopenia of old age. 84 , 85 The identified mitochondrial markers encompass the voltage-dependent anion-selective channel VDAC1, NADH dehydrogenase, succinate dehydrogenase, cytochrome b-c1, cytochrome c oxidase, ATP synthase subunit beta and isocitrate dehydrogenase of the outer membrane, inner membrane complexes I to V and the mitochondrial matrix, respectively. 86 The presence of glycolytic enzymes and other components involved in glucose metabolism were clearly revealed by proteomics.…”