Myalgia! Where Does it Come From (Acta Neuro, Taiwan. Dec. 2023)

[shak8]

Lee, Chen (2023) Myalgia! Where does it come from? Acta Neurol Taiwan (IF: -1) 32(4) 230-239
Abstract

Myalgia (also called muscle pain or muscle ache) is a symptom associated with many diseases, including fibromyalgia, neurodegenerative diseases, degenerative spine diseases, etc. Myalgia is a major medical problem affecting 60~85% of the population (lifetime prevalence). However, our understanding of chronic myalgia is still limited and effective treatment for intractable myalgia like fibromyalgia is still lacking.

Although multifactorial, one known source of muscle pain is tissue acidosis. Experimental muscle pain can be induced by the intramuscular infusion of a buffered acidic solution in humans. As well, animal studies have revealed that acidic infusion activates chemosensitive nociceptors via the proton-sensing ion channels and receptors. Intriguingly, acid signaling in muscle afferents is promiscuous and could be either pro-nociceptive or antinociceptive, so we have coined the term sngception to describe the somatosensory function of acid sensation.

Recent single-cell RNAseq studies have shown proton-sensing ion channels and receptors are expressed in all subpopulations of the somatosensory neurons, including nociceptors and non-nociceptive mechanoreceptors. Here, we address how the acid signaling is integrated in muscle afferents and why muscle pain can be chronic and intractable in mouse models of fibromyalgia.

Besides acidosis, we have recently found oxidative stress can be another factor to activate proton-sensing ion channels and thus trigger fibromyalgia-like pain in mice. Together, understanding how the acid signaling works in muscle afferents will provide novel therapeutic strategies for myalgia.

https://pubmed.ncbi.nlm.nih.gov/37967833/

complete article: http://www.ant-tnsjournal.com/Mag_Files/32-4/N2023111691815.pdf

 

[SNT Gatchaman]

(I like the idea of acid signalling/sensation. For me the muscle sensation has never been "pain" per se, but more of the sensation of "lactic acid burn".)

We have thus coined the term sngception to address the somatosensory function of sensing acidosis, in which sng (pronounced as /səŋ/) is the corresponding perception of acid sensation. Sng is the Romanization form of a Taiwanese word 痠 (or equilibrium to soreness in English), which is commonly used to describe the specific acid-like phenotypes distinct from pain. In Taiwan, sng is typically used in muscle soreness associated with fatiguing exercise, virus infection, adverse effects of statin treatment, fibromyalgia, or degenerative spine diseases. Of note, soreness is defined as pain in English, so sng would be a better term to distinguish it from pain.

In individuals with fibromyalgia, sng and pain can be clearly diagnosed as 2 different symptoms and attributed to different metabolomic and proteomic alterations in serum and urine. In fibromyalgia, sng is more intractable than pain and the distribution of sng (or morbid soreness) is not associated with pain in most of the body regions. Also, fibromyalgia sng is associated with oxidative stress and LPC16:0 upregulation, suggesting the involvement of ASIC3-mediated signaling.

"Gretchen..."