Muscarinic acetylcholine receptor

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Muscarinic acetylcholine receptors, or muscarinic receptors (mAChRs), are acetylcholine receptors that form G protein-coupled receptors in the cell membranes of certain neurons and other cells.[1] They play several roles, including acting as the main end-receptor stimulated by acetylcholine released from postganglionic fibers in the parasympathetic nervous system.[citation needed]

Subtypes[edit | edit source]

There are five muscarinic acetylcholine receptor subtypes:

  • M1 receptors, also known as simply mAChRs
  • M2 receptors
  • M3 receptors
  • M4 receptors
  • M5 receptors[2]

ME/CFS[edit | edit source]

In 2015, a relatively large German study found 29% of ME/CFS patients had elevated autoantibodies to M3 and M4 muscarinic acetylcholine receptors, as well as β2 adrenergic receptors.[3]

In 2020, a small Sweden study confirmed these results in two different patient cohorts.[2] The study assessed patients with moderate ME who met the Canadian and international consensus criteria for ME, plus the Systemic Exertion Intolerance Disease criteria, and found that the majority of patients had raised blood plasma concentration of β1 and β2 adrenergic receptor autoantibodies, and M3 and M4 muscarinic receptor autoantibodies. Levels in cerebral spinal fluid levels were normal. Only 25% of healthy controls had raised autoantibody levels.[2] These findings supported the autoimmune hypothesis for a subset of patients.

Notable studies[edit | edit source]

  • 2016, Antibodies to β adrenergic and muscarinic cholinergic receptors in patients with Chronic Fatigue Syndrome[3] - (Full text)
  • 2020, Autoantibodies to beta-adrenergic and muscarinic cholinergic receptors in Myalgic Encephalomyelitis (ME) patients – A validation study in plasma and cerebrospinal fluid from two Swedish cohorts[2] - (Full text)

Articles and blogs[edit | edit source]

See also[edit | edit source]

Learn more[edit | edit source]

References[edit | edit source]

  1. Aronstam, R. S.; Patil, P. (Jan 1, 2009). Squire, Larry R., ed. "Muscarinic Receptors: Autonomic Neurons". Oxford: Academic Press: 1141–1149. ISBN 978-0-08-045046-9. 
  2. 2.02.12.22.3 Bynke, Annie; Julin, Per; Gottfries, Carl-Gerhard; Heidecke, Harald; Scheibenbogen, Carmen; Bergquist, Jonas (Aug 1, 2020). "Autoantibodies to beta-adrenergic and muscarinic cholinergic receptors in Myalgic Encephalomyelitis (ME) patients – A validation study in plasma and cerebrospinal fluid from two Swedish cohorts". Brain, Behavior, & Immunity - Health. 7: 100107. doi:10.1016/j.bbih.2020.100107. ISSN 2666-3546. 
  3. 3.03.1 Loebel, Madlen; Grabowski, Patricia; Heidecke, Harald; Bauer, Sandra; Hanitsch, Leif G.; Wittke, Kirsten; Meisel, Christian; Reinke, Petra; Volk, Hans-Dieter (Feb 2016). "Antibodies to β adrenergic and muscarinic cholinergic receptors in patients with Chronic Fatigue Syndrome". Brain, Behavior, and Immunity. 52: 32–39. doi:10.1016/j.bbi.2015.09.013. ISSN 1090-2139. PMID 26399744. 

cell membrane - A very thin membrane, composed of lipids and protein, that surrounds the cytoplasm of a cell and controls the passage of substances into and out of the cell.

ME/CFS - An acronym that combines myalgic encephalomyelitis with chronic fatigue syndrome. Sometimes they are combined because people have trouble distinguishing one from the other. Sometimes they are combined because people see them as synonyms of each other.

plasma - The liquid part of blood, lymph, or milk after removing any suspended material. Most of the time, "plasma" simply refers to blood, after all the blood cells have been removed. If you also remove the clotting factors, then the plasma is referred to as "serum".

antibody - Antibodies or immunoglobulin refers to any of a large number of specific proteins produced by B cells that act against an antigen in an immune response.

chronic fatigue syndrome (CFS) - A fatigue-based illness. The term CFS was invented invented by the U.S. Centers for Disease Control as an replacement for myalgic encephalomyelitis (ME). Some view CFS as a neurological disease, others use the term for any unexplained long-term fatigue. Sometimes used as a the term as a synonym of myalgic encephalomyelitis, despite the different diagnostic criteria.

myalgic encephalomyelitis (ME) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

myalgic encephalomyelitis (ME) - A disease often marked by neurological symptoms, but fatigue is sometimes a symptom as well. Some diagnostic criteria distinguish it from chronic fatigue syndrome, while other diagnostic criteria consider it to be a synonym for chronic fatigue syndrome. A defining characteristic of ME is post-exertional malaise (PEM), or post-exertional neuroimmune exhaustion (PENE), which is a notable exacerbation of symptoms brought on by small exertions. PEM can last for days or weeks. Symptoms can include cognitive impairments, muscle pain (myalgia), trouble remaining upright (orthostatic intolerance), sleep abnormalities, and gastro-intestinal impairments, among others. An estimated 25% of those suffering from ME are housebound or bedbound. The World Health Organization (WHO) classifies ME as a neurological disease.

The information provided at this site is not intended to diagnose or treat any illness.
From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history.