Synthesis, Packaging, and Reuptake of Acetylcholine (Essay Sample)

Synthesis, Packaging, and Reuptake of Acetylcholine
Acetylcholine (ACh) is among the most common neurotransmitters, known for a wide range of functions within the brain and other body organ systems. ACh is an ester of acetic acid and choline and acts as a chemical messenger that mediates communication between neurons, together with other specialized cells like the myocytes ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"B2Z4kGRS","properties":{"formattedCitation":"(Sam and Bordoni, 2021)","plainCitation":"(Sam and Bordoni, 2021)","noteIndex":0},"citationItems":[{"id":3584,"uris":["http://zotero.org/users/4013864/items/U93MH63G"],"uri":["http://zotero.org/users/4013864/items/U93MH63G"],"itemData":{"id":3584,"type":"chapter","abstract":"Acetylcholine is a neurochemical that has a wide variety of functions in the brain and other organ systems of the body. Specifically, it is a neurotransmitter that acts as a chemical message that is released by neurons and allows them to communicate with one another as well as other specialized cells such as myocytes and cells found in glandular tissues. The name \"acetylcholine\" is derived from its chemical structure, as it is an ester of acetic acid and choline. Tissues of the body that use this chemical messenger or are responsive to it are referred to as cholinergic. There is a class of chemicals called anticholinergics that interfere with acetylcholine's action on tissues as well.  While ACh operates as a neurotransmitter in many parts of the body, it is most commonly associated with the neuromuscular junction. The neuromuscular junction is where motor neurons located in the ventral spinal cord synapse with muscles in the body to activate them. Acetylcholine also functions as a neurotransmitter in the autonomic nervous system, acting both as the neurotransmitter between preganglionic and postganglionic neurons as well as being the final release product from parasympathetic postganglionic neurons.[1]","call-number":"NBK557825","container-title":"StatPearls","event-place":"Treasure Island (FL)","language":"eng","note":"PMID: 32491757","publisher":"StatPearls Publishing","publisher-place":"Treasure Island (FL)","source":"PubMed","title":"Physiology, Acetylcholine","URL":"http://www.ncbi.nlm.nih.gov/books/NBK557825/","author":[{"family":"Sam","given":"Christian"},{"family":"Bordoni","given":"Bruno"}],"accessed":{"date-parts":[["2021",5,10]]},"issued":{"date-parts":[["2021"]]}}}],"schema":"https://github.com/citation-style-language/schema/raw/master/csl-citation.json"} (Sam and Bordoni, 2021). Furthermore, ACh is commonly associated with the neuromuscular junction, despite being versatile in many other parts of the body. According to ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"jQZgOPwQ","properties":{"formattedCitation":"(Brown, 2019)","plainCitation":"(Brown, 2019)","noteIndex":0},"citationItems":[{"id":3587,"uris":["http://zotero.org/users/4013864/items/957B435E"],"uri":["http://zotero.org/users/4013864/items/957B435E"],"itemData":{"id":3587,"type":"article-journal","abstract":"This review provides a distillate of the advances in knowledge about the neurotransmitter functions of acetylcholine over the 50-year period between 1967 and 2017, together with incremental information about the cognate nicotinic and muscarinic acetylcholine receptors, and some brief comments on possible advances in the near future. The text is supplemented by a timelines figure indicating the dates of some key advances in knowledge about acetylcholine receptors and a box-figure providing a snapshot of selected papers about acetylcholine published in the year 1967.","container-title":"Brain and Neuroscience Advances","DOI":"10.1177/2398212818820506","ISSN":"2398-2128","journalAbbreviation":"Brain Neurosci Adv","language":"eng","note":"PMID: 32166177\nPMCID: PMC7058246","page":"2398212818820506","source":"PubMed","title":"Acetylcholine and cholinergic receptors","volume":"3","author":[{"family":"Brown","given":"David A."}],"issued":{"date-parts":[["2019",12]]}}}],"schema":"https://github.com/citation-style-language/schema/raw/master/csl-citation.json"} Brown (2019), ACh was officially confirmed in 1967 after it was detected following stimulation of vagal parasympathetic nerves, preganglionic sympathetic nerves, as well as somatic motor nerves. In this paper, the mechanism of acetylcholine synthesis, packaging, and reuptake under normal physiology is explicitly discussed.
Acetylcholine Synthesis
The mechanism of acetylcholine synthesis follows a strictly enzyme-controlled process. Naturally, acetylcholine is synthesised from acetyl coenzyme (acetyl CoA) that is normally found at the nerve terminals and choline, following catalysis by choline acetyltransferase (CAT) ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"2j3fPVGw","properties":{"formattedCitation":"(Purves et al., 2001)","plainCitation":"(Purves et al., 2001)","noteIndex":0},"citationItems":[{"id":3590,"uris":["http://zotero.org/users/4013864/items/KGXZU6G2"],"uri":["http://zotero.org/users/4013864/items/KGXZU6G2"],"itemData":{"id":3590,"type":"article-journal","abstract":"Acetylcholine is the neurotransmitter at neuromuscular junctions, at synapses in the ganglia of the visceral motor system, and at a variety of sites within the central nervous system. Whereas a great deal is known about the function of cholinergic transmission at the neuromuscular junction and at ganglionic synapses, the actions of ACh in the central nervous system are not as well understood.","container-title":"Neuroscience. 2nd edition","language":"en","note":"publisher: Sinauer Associates","source":"www.ncbi.nlm.nih.gov","title":"Acetylcholine","URL":"https://www.ncbi.nlm.nih.gov/books/NBK11143/","author":[{"family":"Purves","given":"Dale"},{"family":"Augustine","given":"George J."},{"family":"Fitzpatrick","given":"David"},{"family":"Katz","given":"Lawrence C."},{"family":"LaMantia","given":"Anthony-Samuel"},{"family":"McNamara","given":"James O."},{"family":"Williams","given":"S. Mark"}],"accessed":{"date-parts":[["2021",5,10]]},"issued":{"date-parts":[["2001"]]}}}],"schema":"https://github.com/citation-style-language/schema/raw/master/csl-citation.json"} (Purves et al., 2001). Thus, neurons that possess CAT are deemed to utilise ACh as one of their neurotransmitters. Choline has the capacity to cross the blood-brain barrier and is absorbed by the cholinergic nerve terminals by the use of sodium-dependent channels ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"AUD2Mwzp","properties":{"formattedCitation":"(Radziejewska and Chmurzynska, 2019)","plainCitation":"(Radziejewska and Chmurzynska, 2019)","noteIndex":0},"citationItems":[{"id":3594,"uris":["http://zotero.org/users/4013864/items/4CSFDWQ3"],"uri":["http://zotero.org/users/4013864/items/4CSFDWQ3"],"itemData":{"id":3594,"type":"article-journal","abstract":"SCOPE: In this review, we attempt to assess how choline and folate transporters affect fetal development. We focus on how the expression of these transporters in response to choline and folate intake affects transport effectiveness. We additionally describe allelic variants of the genes encoding these transporters and their phenotypic effects.\nMETHODS AND RESULTS: We made an extensive review of recent articles describing role of choline and folate - with particularly emphasize on their transporters - in fetal development. Folate and choline are necessary for the proper functioning of the cell and body. During pregnancy, the requirements of these nutrients increase because of elevated maternal demand and the rapid division of fetal cells. The concentrations of folate and choline in cells depend on food intake, the absorption of nutrients, and the cellular transport system, which is tissue-specific and developmentally regulated. Relatively few studies have investigated the role of choline transporters in fetal development.\nCONCLUSIONS: In this review we show relations between functioning of folate and choline transporters and fetal development.","container-title":"Biochimie","DOI":"10.1016/j.biochi.2018.12.002","ISSN":"1638-6183","journalAbbreviation":"Biochimie","language":"eng","note":"PMID: 30529042","page":"10-19","source":"PubMed","title":"Folate and choline absorption and uptake: Their role in fetal development","title-short":"Folate and choline absorption and uptake","volume":"158","author":[{"family":"Radziejewska","given":"Anna"},{"family":"Chmurzynska","given":"Agata"}],"issued":{"date-parts":[["2019",3]]}}}],"schema":"https://github.com/citation-style-language/schema/raw/master/csl-citation.json"} (Radziejewska and Chmurzynska, 2019). The synthesis process is controlled by the available amounts of acetate (from mitochondrial acetyl CoA) and choline from plasma or synaptic cleft. As Hedtke and Bakovic (2019) explained, the body cannot synthesise choline and, therefore, dietary supply is vital for maintaining all associated processes. On the other hand, acetyl CoA is derived from the mitochondria found in large numbers at the nerve endings. Following its synthesis in the cytoplasm of the nerve terminals, acetylcholine is actively transported out of the cytosol for packaging and release.
Packaging of Acetylcholine
After synthesis, the packaging of acetylcholine is essential before it is released. Primarily, the packaging of acetylcholine is mediated by the vesicular acetylcholine transporter (VAChT) ADDIN ZOTERO_ITEM CSL_CITATION {"citationID":"Ubd488Uj","properties":{"formattedCitation":"(Boppana et al., 2017)","plainCitation":"(Boppana et al., 2017)","noteIndex":0},"citationItems":[{"id":3603,"uris":["http://zotero.org/users/4013864/items/Z6UWYISM"],"uri":["http://zotero.org/users/4013864/items/Z6UWYISM"],"itemData":{"id":3603,"type":"article-journal","abstract":"Vesicular acetylcholine transporter (VAChT) function is essential for organismal survival, mediating th...