Acetylcholine
Published: Jul 10, 2023
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Updated: Aug 7, 2023
Written by Oseh Mathias
Founder, SpeechFit
Acetylcholine is a neurotransmitter produced in neurons in the brain and peripheral nervous system. In the electron micrograph image above, you can see an acetylcholine receptor in the mouse sternomastoid muscle[1].
Acetylcholine's primary function is associated with motor function, memory, arousal, and attention. In the peripheral nervous system, acetylcholine acts at the neuromuscular junction to activate muscles, enabling them to contract and make movement possible. In the central nervous system, it is involved in cognitive functions like learning and memory by acting in areas of the brain associated with attention and arousal, such as the cerebral cortex, the hippocampus, and the basal forebrain.[2]
Synthesis of acetylcholine takes place in cholinergic neurons by the action of the enzyme choline acetyltransferase. The precursor compounds for this synthesis are choline and acetyl-CoA. Choline is a nutrient that can be ingested with the diet, and acetyl-CoA is a molecule produced in the mitochondria from the breakdown of glucose. Once synthesized, acetylcholine is packaged into synaptic vesicles in preparation for release [3].
There are numerous regions in the brain where acetylcholine is produced and where its neurons are found. Some of the most notable include:
Basal forebrain: The basal forebrain contains the nucleus basalis, which sends cholinergic (acetylcholine-releasing) neurons to the cerebral cortex, contributing to cerebral cortical arousal. This area plays a significant role in attention and memory[4].
Medial septum and diagonal band of Broca: These areas send cholinergic projections to the hippocampus and parts of the limbic system, thus playing a role in memory and learning [5].
Pontomesencephalotegmental complex: Located in the pons and midbrain, these cholinergic neurons are involved in modulating the activity of the brain during sleep and wakefulness [6].
Once released, the action of acetylcholine is terminated by the enzyme acetylcholinesterase, which breaks it down into choline and acetate. This allows choline to be taken back up into the neuron and recycled, or returned to the bloodstream [7].
Oseh is a software engineer, entrepreneur and founder of SpeechFit. Oseh is passionate about improving health and wellbeing outcomes for neurodiverse people and healthcare providers alike.
References
Fertuck, H. C., & Salpeter, M. M. (1974). Localization of Acetylcholine Receptor by "25I-Labeled a-Bungarotoxin Binding at Mouse Motor Endplates (electron microscope autoradiography/junctional folds/sternomastoid muscle/neuromuscular junction). Proceedings of the National Academy of Sciences of the United States of America, 71(4), 1376-1378.
Bear, M. F., Connors, B. W., & Paradiso, M. A. (2020). Neuroscience: Exploring the Brain (5th ed.). Wolters Kluwer Health.
Purves, D., Augustine, G.J., Fitzpatrick, D., Hall, W.C., LaMantia, A.S., McNamara, J.O., & White, L.E. (2012). Neuroscience (5th ed.). Sinauer Associates.
Whitehouse, P.J., Price, D.L., Struble, R.G., Clark, A.W., Coyle, J.T., & Delon, M.R. (1982). Alzheimer's disease and senile dementia: loss of neurons in the basal forebrain. Science, 215(4537), 1237-1239.
Vertes, R.P. (2004). Differential projections of the infralimbic and prelimbic cortex in the rat. Synapse, 51(1), 32-58.
Steriade, M., & McCarley, R.W. (2005). Brainstem Control of Wakefulness and Sleep (2nd ed.). Springer.
Oda, Y. (2012). Choline acetyltransferase: the structure, distribution and pathologic changes in the central nervous system. Pathology International, 62(11), 665-674.