What is Acetylcholine?
Acetylcholine is an active neurotransmitter that acts a chemical connection between neurons. It is synthesized in nerve terminals from acetyl coenzyme A (acetyl-CoA) and choline, by a transferase enzyme called Choline acetyltransferase (CAT). The neurotransmitter plays a crucial role in connecting nerves to each other by diffusing across the narrow gap between nerve cells, known as synapses. When acetylcholine travel between synapses, it binds to specific receptor sites. These receptor sites are designed to receive messages from specific chemicals. Once activated, it will either give off an excitatory response or an inhibitory response. Depending on the response, the user will experience different benefits and effects.
History of Acetylcholine
In the 1900s, scientists had a sensible understanding of the anatomy of the nervous system. It was acknowledged that neurons formed the basis of the nervous system. It was also acknowledged that nerve messages traveled in the form of an electrical signal along the length of a neuron and passed from the axon of one cell to the dendrites of a nearby cell (“Acetylcholine”, 2004). However, a problem remained which was the understanding of the mechanisms by which the nerve message travels across the narrow gap, the synapses, between two adjacent neurons (“Acetylcholine”, 2004). Thomas R. Elliott suggested that the nerve message is carried from one cell to another by means of a chemical compound, in 1903.
By 1914, Henry Dale isolated a compound from the fungus ergot that produces effects on organs similar to those produced by nerves (“Acetylcholine”, 2004). He called the compound acetylcholine. Likewise, in 1921, Otto Loewi found two chemical substance that secreted from the frog’s heart after he stimulated the nerves attached to it. The first substance was adrenalin and the second substance, in which he named, was Vagusstoffe. It was later proposed that Vagusstoffe is identical to acetylcholine which led both Henry Dale and Otto Loewi to share the 1936 Nobel Prize for physiology or medicine (“Acetylcholine”, 2004).
Other than unraveling the exact mechanism that carries messages across the synapses, John Carew Eccles and Bernard Katz further Henry Dale and Otto Loewi studies on acetylcholine. John Eccles developed a method for inserting microelectrodes into adjacent cells and then studying the chemical and physical changes that occur when a neurotransmitter passes through the synapse (“Acetylcholine”, n.d.). Bernard Katz discovered that neurotransmitters are released in small packages of a few thousand molecules each and characterized the release of the tiny packages in resting and active neurons (“Acetylcholine”, 2004). Due to their work on the neurotransmitter, John Eccles and Bernard Katz each received a Nobel Prize in physiology or medicine in 1963 and 1970 (“Acetylcholine”, 2004).
Functions of Acetylcholine
Acetylcholine transmits messages to various regions of the brain, including the basal forebrain and the hippocampus, two regions controlling memory and learning. It improves the encoding of memories in the perirhinal and entorhinal cortex and causes synaptogenesis (Whittaker, 1990). Synaptogenesis is the formation of synapses between neurons in the nervous system. Acetylcholine also aids other neurotransmitters to communicate messages by enhancing the intensity and quality of neuron signaling through the increase of theta waves (Colman, 2006). Other than improving concentration and memory, it creates protective benefits which helps reduce the effects of degenerative diseases and neurological decay.
Acetylcholine also acts as a vasodilator, initiate the dilation (widening) of blood vessels and decreases blood pressure, which affects the cardiovascular system. The vasodilation process improves the cerebral circulation of blood, nutrient, oxygen, and glucose throughout the body and brain resulting in energy generation and absorption efficiency. This is proven when small amounts of acetylcholine were injected into the brain. Blood pressure fell, slowing heartbeat, increased contraction of smooth muscle in many organs and copious secretion from exocrine glands (“Acetylcholine”, 2004).
Other functions of neurotransmitter include speeding up and slowing down nerve signals. Yet, acetylcholine gives off an excitatory response in the central nervous system majority of the time (Colman, 2006). This assists in arousal, learning, neuroplasticity, and engages in sensory function upon waking. Similarly, acetylcholine is involved in maintaining rapid eye movement sleep. This decreases the blood flow to the brain and redirects itself towards muscles, allowing the body and mind to recover and rest.
Additional Acetylcholine Findings
A study was done to investigate the level of acetylcholine release in the hippocampus in animals undergoing a cross-maze under two cue conditions, rich or poor extra maze. The findings showed that high levels of acetylcholine predicted quicker learning in cue-rich condition than in the cue-poor condition (Hasselmo, 1999). This suggests high levels of acetylcholine is detrimental if the environment constraints do not encourage hippocampal processing and the task can be solved by another neural system.
Some Ingredients found in Natural Nootropics that Increases Acetylcholine
Acetyl-L-Carnitine (ALCAR) is an amino acid that is essential for muscle movement, brain and heart function, and other body processes. It is considered a Natural Nootropic due to its ability to cross the blood-brain barrier to get from the bloodstream into the brain. In terms of cognitive enhancement, ALCAR produces acetylcholine, which is an essential neurotransmitter required for memory function and learning. Other benefits include improved processing speed, focus, memory, mood, alertness, clarity, and has a fast acting antidepressant properties.
Choline Bitrate is a molecule used to boost cognitive functions and is a direct precursor for acetylcholine. It is a nutrient naturally found in the body and can be found in broccoli, eggs, fish, meats, and peanuts. Choline is very safe, however, high doses can lead to dizziness, low blood pressure, and increase perspiration and salvation.
Huperzine A is Natural Nootropic ingredient purified and extracted from the Chinese club moss (Huperziceae family). It is known as an acetylcholinesterase inhibitor, which means that it stops an enzyme from breaking down acetylcholine which results in increases in acetylcholine. Additionally, it is beneficial for problems with loss of mental abilities (dementia) and memory.
Acetylcholine. (2004). In K. L. Lerner & B. W. Lerner (Eds.), The Gale Encyclopedia of Science (3rd ed.,
Vol. 1, pp. 15-16). Detroit: Gale. Retrieved from http://go.galegroup.com.ezproxy.lib.ryerson.ca/ ps/i.do?p=GVRL&sw=w&u=rpu_main&v=2.1&it=r&id=GALE%7CCX3418500022&sid=summon&asid=c47834a9eebb56ac4cd8adc80cc673b7
Colman, A. M. (2006). A dictionary of psychology (2nd ed.). Oxford: Oxford University Press.
Hasselmo, Michael. Neuromodulation: Acetylcholine And Memory Consolidation. 1st ed. Boston: Trends
in Cognitive Sciences, 1999. Print.
Whittaker, Victor. The Contribution Of Drugs And Toxins To Understanding Of Cholinergic Function. 1st
- New York: Elsevier Science Publishers Ltd., 1990. Print.
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