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Acetylcholine
 
 
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The chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 acetylcholine (often abbreviated ACh) is a neurotransmitter
Neurotransmitter

Neurotransmitters are chemistry which relay, amplify and modulate signals between a neuron and another cell . Neurotransmitters are packaged into vesicles that cluster beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side of...
 in both the peripheral nervous system
Peripheral nervous system

The peripheral nervous system resides or extends outside the central nervous system , which consists of the brain and spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs....
 (PNS) and central nervous system
Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
 (CNS) in many organisms including humans. Acetylcholine is one of many neurotransmitters in the autonomic nervous system
Autonomic nervous system

The autonomic nervous system is the part of the peripheral nervous system that acts as a control system, maintaining human homeostasis in the body....
 (ANS) and the only neurotransmitter used in the somatic nervous system
Somatic nervous system

The somatic nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements through the action of skeletal muscles, and with sensory receptor of external stimulus, which helps keep the body in touch with its surroundings ....
. It is also the neurotransmitter in all autonomic ganglia.

ylcholine (ACh) was first identified in 1914 by Henry Hallett Dale
Henry Hallett Dale

Sir Henry Hallett Dale, Order of Merit , Order of British Empire, Royal Society was an England pharmacologist. For his study of acetylcholine as agent in the chemical transmission of nerve impulses he shared the 1936 Nobel Prize in Physiology or Medicine with Otto Loewi....
 for its actions on heart tissue.






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Encyclopedia


The chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 acetylcholine (often abbreviated ACh) is a neurotransmitter
Neurotransmitter

Neurotransmitters are chemistry which relay, amplify and modulate signals between a neuron and another cell . Neurotransmitters are packaged into vesicles that cluster beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side of...
 in both the peripheral nervous system
Peripheral nervous system

The peripheral nervous system resides or extends outside the central nervous system , which consists of the brain and spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs....
 (PNS) and central nervous system
Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
 (CNS) in many organisms including humans. Acetylcholine is one of many neurotransmitters in the autonomic nervous system
Autonomic nervous system

The autonomic nervous system is the part of the peripheral nervous system that acts as a control system, maintaining human homeostasis in the body....
 (ANS) and the only neurotransmitter used in the somatic nervous system
Somatic nervous system

The somatic nervous system is the part of the peripheral nervous system associated with the voluntary control of body movements through the action of skeletal muscles, and with sensory receptor of external stimulus, which helps keep the body in touch with its surroundings ....
. It is also the neurotransmitter in all autonomic ganglia.

History

Acetylcholine (ACh) was first identified in 1914 by Henry Hallett Dale
Henry Hallett Dale

Sir Henry Hallett Dale, Order of Merit , Order of British Empire, Royal Society was an England pharmacologist. For his study of acetylcholine as agent in the chemical transmission of nerve impulses he shared the 1936 Nobel Prize in Physiology or Medicine with Otto Loewi....
 for its actions on heart tissue. It was confirmed as a neurotransmitter by Otto Loewi
Otto Loewi

Otto Loewi was a Germany pharmacology whose discovery of acetylcholine helped enhance medical therapy. The discovery earned for him the Nobel Prize in Physiology or Medicine in 1936 which he shared with Sir Henry Dale....
 who initially gave it the name vagusstoff
Vagusstoff

Vagusstoff refers to the substance released by stimulation of the vagus nerve which causes a reduction in the heart rate. Discovered in 1921 by physiologist Otto Loewi, vagusstoff was the first confirmation of chemical synapse and the first neurotransmitter ever discovered....
 because it was released from the vagus nerve
Vagus nerve

The vagus nerve is the tenth of twelve paired cranial nerves, and is the only nerve that starts in the brainstem and extends, through the jugular foramen, down below the head , to the neck, chest and abdomen, where it contributes to the innervation of the viscera....
. Both received the 1936 Nobel Prize in Physiology or Medicine
Nobel Prize in Physiology or Medicine

The Nobel Prize in Physiology or Medicine is awarded once a year by the Swedish Karolinska Institutet. It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895, awarded for outstanding contributions in Nobel Prize in Physics, Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Physiology or Medic...
 for their work. Acetylcholine was also the first neurotransmitter
Neurotransmitter

Neurotransmitters are chemistry which relay, amplify and modulate signals between a neuron and another cell . Neurotransmitters are packaged into vesicles that cluster beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side of...
 to be identified.

Chemistry

Acetylcholine is an ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
 of acetic acid
Acetic acid

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment , and freezes at 16.7 Celsius to a colourless crystalline solid....
 and choline
Choline

Choline is an organic compound, classified as a water-soluble essential nutrient and usually grouped within the Vitamin B complex. This natural amine is found in the lipids that make up cell membranes and in the neurotransmitter acetylcholine....
 with chemical formula
Chemical formula

A chemical formula is a way of expressing information about the atoms that constitute a particular chemical compound, and how the relationship between those atoms changes in chemical reactions....
 CH3CO
Acetyl

In organic chemistry, acetyl , is a functional group, the acyl of acetic acid, with chemical formula -CarbonOxygenCarbonHydrogen3. It is sometimes abbreviated as Ac ....
O
Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
CH2
Methylene

Methylene is the chemical species, R2C:, named after methane, in which two of the carbon atom's valence electrons form no bonds. The word is applicable to:...
CH2
Methylene

Methylene is the chemical species, R2C:, named after methane, in which two of the carbon atom's valence electrons form no bonds. The word is applicable to:...
N
Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
+(CH3)3. This structure is reflected in the systematic name, 2-acetoxy-N,N,N-trimethylethanaminium.

Function

Acetylcholine has functions both in the peripheral nervous system
Peripheral nervous system

The peripheral nervous system resides or extends outside the central nervous system , which consists of the brain and spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs....
 (PNS) and in the central nervous system
Central nervous system

The central nervous system is the part of the nervous system that functions to coordinate the activity of all parts of the bodies of multicellular organisms....
 (CNS) as a neuromodulator.

In the PNS, acetylcholine activates muscles, and is a major neurotransmitter in the autonomic nervous system.

In the CNS, acetylcholine and the associated neurons form a neurotransmitter system, the cholinergic system, which tends to cause excitatory actions.

In PNS

In the peripheral nervous system
Peripheral nervous system

The peripheral nervous system resides or extends outside the central nervous system , which consists of the brain and spinal cord. The main function of the PNS is to connect the CNS to the limbs and organs....
, acetylcholine activates muscles, and is a major neurotransmitter in the autonomic nervous system. When acetylcholine binds to acetylcholine receptor
Acetylcholine receptor

An acetylcholine receptor is an integral membrane protein that responds to the binding of the neurotransmitter acetylcholine....
s on skeletal muscle
Skeletal muscle

They generally contract voluntarily , although they can contract involuntarily through Reflex action. The whole muscle is wrapped in a special type of connective tissue, epimysium....
 fibers, it opens ligand gated sodium channels in the cell membrane
Cell membrane

The cell membrane is the interface between the cellular machinery inside the cell and the fluid outside.It is a semipermeable lipid bilayer found in all cell ....
. Sodium ions then enter the muscle cell, stimulating muscle contraction. Acetylcholine, while inducing contraction of skeletal muscles, instead induces decreased contraction in cardiac muscle
Cardiac muscle

Cardiac muscle is a type of involuntary sarcomere muscle found in the walls of the heart, specifically the wikt:myocardium. Cardiac muscle cells are known as cardiac myocytes ....
 fibers. This distinction is attributed to differences in receptor structure between skeletal and cardiac fibers.

In the autonomic nervous system
Autonomic nervous system

The autonomic nervous system is the part of the peripheral nervous system that acts as a control system, maintaining human homeostasis in the body....
, acetylcholine is released in the following sites:
  • all pre- and post-ganglionic parasympathetic
    Parasympathetic nervous system

    The parasympathetic nervous system is a division of the autonomic nervous system , along with the sympathetic nervous system and enteric nervous system ....
     neurons
  • all preganglionic sympathetic
    Sympathetic nervous system

    The Sympathetic Nervous System is a branch of the autonomic nervous system along with the enteric nervous system and parasympathetic nervous system....
     neurons
    • preganglionic sympathetic fibers to suprarenal medulla, the modified sympathetic ganglion; on stimulation by acetylcholine, the suprarenal medulla releases epinephrine
      Epinephrine

      Epinephrine is a hormone and neurotransmitter.Epinephrine increases the "fight or flight" response of the Sympathetic nervous system of the autonomic nervous system....
       and norepinephrine
      Norepinephrine

      Norepinephrine or noradrenaline is a catecholamine with dual roles as a hormone and a neurotransmitter.As a stress hormone, norepinephrine affects parts of the brain where attention and responding actions are controlled....
  • some postganglionic sympathetic fibers
    • sudomotor neurons to sweat gland
      Sweat gland

      The skin contains two different groups of sweat glands: apocrine sweat glands and merocrine sweat glands. Both gland types contain myoepithelial cells , specialized epithelial cells located between the gland cells and the underlying basal lamina....
      s.


In CNS

In the central nervous system, ACh has a variety of effects as a neuromodulator, e.g., for plasticity and excitability. Other effects are arousal and reward
Reward system

In neuroscience, the reward system is a collection of brain structures which attempts to regulate and control behavior by inducing pleasurable effects....
. Damage to the cholinergic system in the brain has been suggested to play a role in the memory deficits associated with Alzheimer's Disease
Alzheimer's disease

Alzheimer's disease , also called Alzheimer disease, Senile Dementia of the Alzheimer Type or simply Alzheimer's, is the most common form of dementia....
.

Structure
Acetylcholine and the associated neurons form a neurotransmitter system, the cholinergic system. It originates mainly in pontomesencephalotegmental complex, basal optic nucleus of Meynert
Basal optic nucleus of Meynert

N. Basalis of Meynert is a group of nerve cells in the substantia innominata of the basal forebrain that has wide projections to the neocortex and is rich in acetylcholine and choline acetyltransferase....
 and medial septal nucleus, and projects axons to vast areas of the brain:
  • The pontomesencephalotegmental complex acts mainly on M1 receptors in the brainstem .
  • Basal optic nucleus of Meynert
    Basal optic nucleus of Meynert

    N. Basalis of Meynert is a group of nerve cells in the substantia innominata of the basal forebrain that has wide projections to the neocortex and is rich in acetylcholine and choline acetyltransferase....
     acts mainly on M1 receptors in the neocortex
    Neocortex

    The neocortex is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI ....
    .
  • Medial septal nucleus acts mainly on M1 receptors in the hippocampus
    Hippocampus

    The hippocampus is a brain structure located inside the medial temporal lobe of the cerebral cortex, and therefore is part of the telencephalon ....
     and neocortex
    Neocortex

    The neocortex is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI ....
    .


Plasticity
ACh is involved with synaptic plasticity
Synaptic plasticity

In neuroscience, synaptic plasticity is the ability of the connection, or synapse, between two neurons to change in Synapse#Synaptic strength. There are several underlying mechanisms that cooperate to achieve synaptic plasticity, including changes in the quantity of neurotransmitters released into a synapse and changes in how effectively cell...
, specifically in learning
Learning

Learning is acquiring new knowledge, behaviors, skills, Value s, preferences or understanding, and may involve synthesizing different types of information....
 and short-term memory
Memory

In psychology, memory is an organism's mental ability to store, retain and recall information. Traditional studies of memory began in the fields of philosophy, including techniques of mnemonic....
.

Acetylcholine has been shown to enhance the amplitude of synaptic potentials following long-term potentiation
Long-term potentiation

In neuroscience, long-term potentiation is the long-lasting improvement in communication between two neurons that results from stimulating them simultaneously....
 in many regions, including the dentate gyrus
Dentate gyrus

The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memory as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult humans, ....
, CA1, piriform cortex
Piriform cortex

In anatomy of animals, the piriform cortex, or pyriform cortex is a region in the brain. The piriform cortex is part of the rhinencephalon situated in the telencephalon....
, and neocortex
Neocortex

The neocortex is a part of the brain of mammals. It is the outer layer of the cerebral hemispheres, and made up of six layers, labelled I to VI ....
. This effect most likely occurs either through enhancing currents through NMDA
NMDA

NMDA is an amino acid derivative acting as a specific agonist at the NMDA receptor, and therefore mimics the action of the neurotransmitter glutamate on that receptor....
 receptors or indirectly by suppressing adaptation
Neural adaptation

Neural adaptation or sensory adaptation is a change over time in the responsiveness of the sensory system to a constant Stimulus . It is usually perception as a change in the stimulus....
. The suppression of adaptation has been shown in brain slices of regions CA1, cingulate cortex
Cingulate cortex

The cingulate cortex is a part of the brain situated in the medial aspect of the Cerebral cortex. It is extended from the corpus callosum below to the cingulate sulcus above, at least anteriorly....
, and piriform cortex, as well as in vivo
In vivo

In vivo means that which takes place inside an organism. In science, in vivo refers to experimentation done in or on the living tissue of a whole, living organism as opposed to a partial or dead one or a in vitro....
 in cat somatosensory and motor cortex
Motor cortex

Motor cortex is a term that describes regions of the cerebral cortex involved in the planning, control, and execution of voluntary motion functions....
 by decreasing the conductance of voltage-dependent M currents and Ca2+
Calcium in biology

Calcium plays a pivotal role in the physiology and biochemistry of organisms and the cell . It plays an important role in signal transduction pathways, where it acts as a second messenger, in neurotransmitter release from neurons, contraction of all muscle cell types, and fertilization....
-dependent K+
Potassium in biology

Potassium is an essential mineral macronutrient and is the main intracellular ion for all types of cell s. It is important in maintaining fluid and electrolyte balance in the body....
 currents.

Excitability
Acetylcholine also has other effects on excitability of neurons. Its presence causes a slow depolarization
Depolarization

In biology, depolarization is a decrease in the absolute value of a cell's membrane potential. Thus, changes in membrane voltage in which the membrane potential becomes less positive or less negative are both depolarizations....
 by blocking a tonically-active K+ current, which increases neuronal excitability. It appears to be a paradox, however, that ACh increases spiking activity in inhibitory interneurons while decreasing strength of synaptic transmission from those cells. This decrease in synaptic transmission also occurs selectively at some excitatory cells: For instance, it has an effect on intrinsic and associational fibers in layer Ib of piriform cortex, but has no effect on afferent fibers in layer Ia. Similar laminar selectivity has been shown in dentate gyrus and region CA1 of the hippocampus. One theory to explain this paradox interprets acetylcholine neuromodulation in the neocortex as modulating the estimate of expected uncertainty, acting counter to norepinephrine
Norepinephrine

Norepinephrine or noradrenaline is a catecholamine with dual roles as a hormone and a neurotransmitter.As a stress hormone, norepinephrine affects parts of the brain where attention and responding actions are controlled....
 (NE) signals for unexpected uncertainty. Both would then decrease synaptic transition strength, but ACh would then be needed to counter the effects of NE in learning, a signal understood to be 'noisy'.

Synthesis and Degradation

Acetylcholine is synthesized in certain neuron
Neuron

Neurons are responsive cell in the nervous system that process and transmit information by electrochemical Signal . They are the core components of the brain, the vertebrate spinal cord, the invertebrate ventral nerve cord, and the peripheral nerves....
s by the enzyme
Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
 choline acetyltransferase
Choline acetyltransferase

Choline acetyltransferase is an enzyme that is synthesized within the body of a neuron. It is then transferred to the synapse via axoplasmic flow....
 from the compounds choline
Choline

Choline is an organic compound, classified as a water-soluble essential nutrient and usually grouped within the Vitamin B complex. This natural amine is found in the lipids that make up cell membranes and in the neurotransmitter acetylcholine....
 and acetyl-CoA
Acetyl-CoA

Acetyl-CoA is an important molecule in metabolism, used in many biochemical reactions. Its main use is to convey the carbon atoms within the acetyl group to the citric acid cycle to be oxidation for energy production....
.

The enzyme acetylcholinesterase
Acetylcholinesterase

Acetylcholinesterase, also known as AChE, is an enzyme that degrades the neurotransmitter acetylcholine, producing choline and an acetate group....
 converts acetylcholine into the inactive metabolites choline
Choline

Choline is an organic compound, classified as a water-soluble essential nutrient and usually grouped within the Vitamin B complex. This natural amine is found in the lipids that make up cell membranes and in the neurotransmitter acetylcholine....
 and acetate
Acetate

An acetate, or ethanoate, is either a salt or ester of acetic acid.In chemistry, the abbreviation Ac refers to the acetyl group. The anion and the functional group may be written as -OAc and AcO-, or OAc respectively....
. This enzyme is abundant in the synaptic cleft, and its role in rapidly clearing free acetylcholine from the synapse is essential for proper muscle function. Certain neurotoxins work by inhibiting acetylcholinesterase, thus leading to excess acetylcholine at the neuromuscular junction
Neuromuscular junction

A neuromuscular junction is the synapse or junction of the axon terminal of a motoneuron with the motor end plate, the highly-excitable region of muscle plasma membrane responsible for initiation of action potentials across the muscle's surface, ultimately causing the muscle to contract....
, thus causing paralysis of the muscles needed for breathing and stopping the beating of the heart.

Receptors

There are two main classes of acetylcholine receptor (AChR), nicotinic acetylcholine receptor
Nicotinic acetylcholine receptor

Nicotinic acetylcholine receptors, or nAChRs, are cholinergic receptors that form ligand-gated ion channels in the plasma membranes of certain neurons....
s (nAChR) and muscarinic acetylcholine receptor
Muscarinic acetylcholine receptor

Muscarinic receptors, or mAChRs, are G protein-coupled receptor acetylcholine receptors found in the plasma membranes of certain neurons and other Cell s....
s (mAChR). They are named for the ligands used to activate the receptors.

Myasthenia gravis
The disease myasthenia gravis
Myasthenia gravis

Myasthenia gravis is a neuromuscular disease leading to fluctuating muscle weakness and fatigue . It is an autoimmunity, in which weakness is caused by circulating antibody that block acetylcholine receptors at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine....
, characterized by muscle weakness and fatigue, occurs when the body inappropriately produces antibodies
Antibody

Antibodies are gamma globulin proteins that are found in blood or other bodily fluids of vertebrates, and are used by the immune system to identify and neutralize foreign objects, such as bacterium and viruses....
 against acetylcholine nicotinic receptors, and thus inhibits proper acetylcholine signal transmission. Over time, the motor end plate is destroyed. Drugs that competitively inhibit acetylcholinesterase (e.g., neostigmine, physostigmine, or primarily pyridostigmine) are effective in treating this disorder. They allow endogenously-released acetylcholine more time to interact with its respective receptor before being inactivated by acetylcholinesterase in the gap junction.

Nicotinic

Nicotinic AChRs are ionotropic receptors
Ligand-gated ion channel

Ligand-gated ion channels , also referred to as ionotropic receptors or channel-linked receptors, are a group of transmembrane ion channels that are opened or closed in response to the binding of a chemical messenger , such as a neurotransmitter....
 permeable to sodium
Sodium

Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" ....
, potassium
Potassium

Potassium is a chemical element. It has the symbol K , atomic number 19, and atomic mass 39.0983. Potassium was first isolated from potash, hence the name....
, and chloride
Chloride

The chloride ion is formed when the chemical element chlorine picks up one electron to form an anion Cl−....
 ions. They are stimulated by nicotine
Nicotine

Nicotine is an alkaloid found in the nightshade family of plants which constitutes approximately 0.6?3.0% of dry weight of tobacco, with biosynthesis taking place in the roots, and accumulating in the leaves....
 and acetylcholine. They are of two main types, muscle type and neuronal type. The former can be selectively blocked by curare
Curare

Curare [koo rah ree] is a common name for various arrow poisons originating from South America. The three main types of curare are:* tube curarine ....
 and the latter by hexamethonium
Hexamethonium

Hexamethonium is a ganglionic blocker, a neuronal acetylcholine receptor receptor Receptor antagonist which acts in autonomic ganglia by binding mostly in or on the NN receptor, and not the acetylcholine binding site itself....
. The main location of nicotinic AChRs is on muscle
MUSCLE

MUSCLE is public domain, multiple sequence alignment software for protein and nucleotide sequences.MUSCLE is integrated into UGENE bioinformatics tool as a plugin....
 end plates, autonomic ganglia (both sympathetic and parasympathetic), and in the CNS.

Muscarinic

Muscarinic receptors are metabotropic, and affect neurons over a longer time frame. They are stimulated by muscarine
Muscarine

Muscarine, L--muscarine, or muscarin is a Secondary metabolite found in certain mushrooms, particularly in Inocybe and Clitocybe species, such as the deadly Clitocybe dealbata....
 and acetylcholine, and blocked by atropine
Atropine

Atropine is a tropane alkaloid extracted from deadly nightshade , jimsonweed , Mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a hard drug with a wide variety of effects....
. Muscarinic receptors are found in both the central nervous system and the peripheral nervous system, in heart, lungs, upper GI tract and sweat glands. Extracts from the plant Deadly nightshade
Deadly nightshade

Atropa belladonna or Atropa bella-donna, commonly known as belladonna or deadly nightshade, is a perennial plant herbaceous plant in the family Solanaceae, native to Europe, North Africa, and Western Asia....
 included this compound (atropine), and the blocking of the muscarinic AChRs increases pupil size as used for attractiveness in many European cultures in the past. Now, ACh is sometimes used during cataract
Cataract

A cataract is a clouding that develops in the lens of the eye or in its envelope, varying in degree from slight to complete Opacity and obstructing the passage of light....
 surgery to produce rapid constriction of the pupil. It must be administered intraocularly because cornea
Cornea

The cornea is the transparency front part of the eye that covers the Iris , pupil, and anterior chamber. Together with the cilliary muscles, the cornea reflects light, and as a result helps the eye to dilate, accounting for approximately two-thirds of the eye's total optical power....
l cholinesterase metabolizes topically-administered ACh before it can diffuse into the eye. It is sold by the trade name Miochol-E (CIBA Vision). Similar drugs are used to induce mydriasis
Mydriasis

Mydriasis is an excessive dilation of the pupil due to disease, Physical trauma, or the use of drugs. Normally, the pupil dilates in the dark and constriction in the light to improve vividity at night and to protect the retina from sunlight damage during the day....
 (dilation of the pupil), in cardiopulmonary resuscitation
Cardiopulmonary resuscitation

Cardiopulmonary resuscitation is an emergency medical procedure for a victim of cardiac arrest or, in some circumstances, respiratory arrest. CPR is performed in hospitals, or in the community by layman or by emergency response professionals....
 and many other situations.

Drugs Acting on the ACh System

Blocking, hindering or mimicking the action of acetylcholine has many uses in medicine. Drugs acting on the acetylcholine system are either agonists to the receptors, stimulating the system, or antagonists, inhibiting it.

ACh Receptor Agonists

Acetylcholine receptor agonists can either have an effect directly on the receptors or exert their effects indirectly, e.g., by affecting the enzyme acetylcholinesterase
Acetylcholinesterase

Acetylcholinesterase, also known as AChE, is an enzyme that degrades the neurotransmitter acetylcholine, producing choline and an acetate group....
, which degrades the receptor ligand.

Associated disorders
ACh Receptor Agonists are used to treat myasthenia gravis
Myasthenia gravis

Myasthenia gravis is a neuromuscular disease leading to fluctuating muscle weakness and fatigue . It is an autoimmunity, in which weakness is caused by circulating antibody that block acetylcholine receptors at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine....
 and Alzheimer's disease
Alzheimer's disease

Alzheimer's disease , also called Alzheimer disease, Senile Dementia of the Alzheimer Type or simply Alzheimer's, is the most common form of dementia....
.

Alzheimer's disease
Since a shortage of acetylcholine in the brain
Brain

The brain is the center of the nervous system in all vertebrate, and most invertebrate, animals. Some primitive animals such as cnidarian and echinoderm have a decentralized nervous system without a brain, while sponges lack any nervous system at all....
 has been associated with Alzheimer's disease
Alzheimer's disease

Alzheimer's disease , also called Alzheimer disease, Senile Dementia of the Alzheimer Type or simply Alzheimer's, is the most common form of dementia....
, some drugs that inhibit acetylcholinesterase are used in the treatment of that disease.

Direct Acting
  • Acetylcholine
  • Bethanechol
    Bethanechol

    Bethanechol is a parasympathomimetic choline ester that selectively stimulates muscarinic acetylcholine receptor without any effect on nicotinic acetylcholine receptor....
  • Carbachol
    Carbachol

    Carbachol, also known as carbamylcholine , is a drug that binds and activates the acetylcholine receptor. Thus it is classified as a cholinergic agonist agonist....
  • Cevimeline
    Cevimeline

    Cevimeline is a parasympathomimetic and muscarinic agonist, with particular effect on M3 receptors. It is used in the treatment of xerostomia associated with Sj?gren's syndrome....
  • Pilocarpine
    Pilocarpine

    Pilocarpine is a muscarine alkaloid obtained from the leaves of tropical American shrubs from the genus Pilocarpus. It is a non-selective muscarinic receptor agonist in the parasympathetic nervous system, which acts therapeutically at the muscarinic acetylcholine receptor M3 due to its topical application, e.g....
  • Suberylcholine
  • Nicotine
    Nicotine

    Nicotine is an alkaloid found in the nightshade family of plants which constitutes approximately 0.6?3.0% of dry weight of tobacco, with biosynthesis taking place in the roots, and accumulating in the leaves....
     (in small doses)
  • Acetyl l-carnitine


Cholinesterase inhibitors
Most indirect acting ACh receptor agonists work by inhibiting the enzyme acetylcholinesterase
Acetylcholinesterase

Acetylcholinesterase, also known as AChE, is an enzyme that degrades the neurotransmitter acetylcholine, producing choline and an acetate group....
. The resulting accumulation of acetylcholine causes continuous stimulation of the muscles, glands, and central nervous system.

They are examples of enzyme inhibitors, and increase the action of acetylcholine by delaying its degradation; some have been used as nerve agent
Nerve agent

Nerve agents, also referred to as nerve gases though these chemicals are liquid at room temperature, are a class of phosphorus-containing organic chemistry that disrupt the mechanism by which nerves transfer messages to organs....
s (Sarin
Sarin

Sarin, also known by its NATO designation of GB, is an extremely toxic substance whose sole application is as a nerve agent. As a chemical weapons, it is classified as a weapon of mass destruction by the United Nations in UN Resolution 687....
 and VX
VX (nerve agent)

VX is an extremely toxic substance whose only application is in chemical warfare as a nerve agent. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations in UN Resolution 687....
 nerve gas) or pesticide
Pesticide

A pesticide is a substance or mixture of substances used to kill a pest .A pesticide may be a chemical substance, biological agent , antimicrobial, disinfectant or device used against any pest ....
s (organophosphates and the carbamates). In clinical use, they are administered to reverse the action of muscle relaxant
Muscle relaxant

A muscle relaxant is a drug which affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia....
s, to treat myasthenia gravis
Myasthenia gravis

Myasthenia gravis is a neuromuscular disease leading to fluctuating muscle weakness and fatigue . It is an autoimmunity, in which weakness is caused by circulating antibody that block acetylcholine receptors at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine....
, and to treat symptoms of Alzheimer's disease
Alzheimer's disease

Alzheimer's disease , also called Alzheimer disease, Senile Dementia of the Alzheimer Type or simply Alzheimer's, is the most common form of dementia....
 (rivastigmine
Rivastigmine

Rivastigmine is a parasympathomimetics or cholinergic agent for the treatment of mild to moderate Alzheimer's disease and dementia due to Parkinson's disease....
, which increases cholinergic activity in the brain).

Reversible
The following substances reversibly inhibit the enzyme acetylcholinesterase
Acetylcholinesterase

Acetylcholinesterase, also known as AChE, is an enzyme that degrades the neurotransmitter acetylcholine, producing choline and an acetate group....
 (which breaks down acetylcholine), thereby increasing acetylcholine levels.
  • Many medications in Alzheimer's disease
    Alzheimer's disease

    Alzheimer's disease , also called Alzheimer disease, Senile Dementia of the Alzheimer Type or simply Alzheimer's, is the most common form of dementia....
    • Donepezil
      Donepezil

      Donepezil , marketed under the trade name Aricept , , is a centrally acting reversible acetylcholinesterase inhibitor. Its main therapeutic use is in the treatment of Alzheimer's disease where it is used to increase cortical acetylcholine....
    • Galantamine
      Galantamine

      'Galantamine' is a drug used for the treatment of mild to moderate Alzheimer?s disease and various memory impairments. It is an alkaloid that is obtained synthetically or from the bulbs and flowers of the Caucasian snowdrop , Galanthus woronowii and related genera like Narcissus , Leucojum and Lycoris including Lycoris radi...
    • Rivastigmine
      Rivastigmine

      Rivastigmine is a parasympathomimetics or cholinergic agent for the treatment of mild to moderate Alzheimer's disease and dementia due to Parkinson's disease....
    • Tacrine
      Tacrine

      Tacrine is a parasympathomimetic and a centrally acting cholinesterase inhibitor . It was the first centrally-acting cholinesterase inhibitor approved for the treatment of Alzheimer's disease, and was marketed under the trade name Cognex....
  • Edrophonium
    Edrophonium

    Edrophonium is a readily reversible acetylcholinesterase inhibitor. It prevents breakdown of the neurotransmitter acetylcholine and acts by competitively inhibiting the enzyme acetylcholinesterase, mainly at the neuromuscular junction....
     (differs myasthenic and cholinergic crisis
    Cholinergic crisis

    A cholinergic crisis is an over-stimulation at a neuromuscular junction due to an excess of acetylcholine , as of a result of the inactivity of the AChE enzyme, which normally breaks down acetylcholine....
    )
  • Neostigmine
    Neostigmine

    Neostigmine is a Parasympathomimetic drug, specifically, a reversible cholinesterase inhibitor.Neostigmine is available under several trade names such as Prostigmin and Vagostigmin....
     (in myasthenia gravis
    Myasthenia gravis

    Myasthenia gravis is a neuromuscular disease leading to fluctuating muscle weakness and fatigue . It is an autoimmunity, in which weakness is caused by circulating antibody that block acetylcholine receptors at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine....
    )
  • Physostigmine
    Physostigmine

    Physostigmine is a parasympathomimetic, specifically, a reversible cholinesterase inhibitor alkaloid of the Calabar bean.The chemical was synthesized for the first time in 1935 by the chemists Percy Lavon Julian and Josef Pikl....
     (in glaucoma
    Glaucoma

    Glaucoma is a group of diseases of the optic nerve involving loss of ganglion cell in a characteristic pattern of optic atrophy. Raised intraocular pressure is a significant risk factor for developing glaucoma ....
     and anticholinergic
    Anticholinergic

    An anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central nervous system and the peripheral nervous system....
     drug overdoses)
  • Pyridostigmine
    Pyridostigmine

    Pyridostigmine is a parasympathomimetic and a reversible cholinesterase inhibitor. Since it is a quaternary amine, it is poorly absorbed in the gut and doesn't cross the blood-brain barrier, except possibly in stressful conditions....
     (in myasthenia gravis
    Myasthenia gravis

    Myasthenia gravis is a neuromuscular disease leading to fluctuating muscle weakness and fatigue . It is an autoimmunity, in which weakness is caused by circulating antibody that block acetylcholine receptors at the post-synaptic neuromuscular junction, inhibiting the stimulative effect of the neurotransmitter acetylcholine....
  • Carbamate
    Carbamate

    Carbamates, or urethanes, are a group of organic compounds sharing a common functional group with the general structure -NHO-. Carbamates are esters of carbamic acid, NH2COOH, an unstable compound....
     insecticides (e.g., Aldicarb
    Aldicarb

    Aldicarb is a carbamate insecticide with structural formula: 2-methyl-2-propanal O-oxime. Aldicarb is the active substance in Temik pesticide, which is effective against thrips, aphids, Red Spider Mites, lygus, fleahoppers, and leafminers but is primarily used as a nematicide....
    )
  • Huperzine A
    Huperzine A

    Huperzine A, is a naturally occurring sesquiterpene alkaloid found in the plant extracts of the firmoss Huperzia serrata.The botanical has been used in China for centuries for the treatment of swelling, fever and blood disorders....


Irreversible
Semi-permanently inhibit the enzyme acetylcholinesterase.
  • Echothiophate
    Echothiophate

    Ecothiopate iodide is a parasympathomimetic and organophosphate. It is a cholinesterase inhibitor....
  • Isofluorophate
  • Organophosphate
    Organophosphate

    An organophosphate is the general name for esters of phosphoric acid. Phosphates are probably the most pervasive organophosphorus compounds. Many of the most important biochemicals are organophosphates, including DNA and RNA as well as many cofactor s that are essential for life....
     Insecticides (Malathion
    Malathion

    Malathion is an organophosphate parasympathomimetic which binds irreversibly to cholinesterase. Malathion is an insecticide of relatively low human toxicity....
    , Parathion
    Parathion

    Parathion, also called parathion-ethyl or diethyl parathion, is an organophosphate compound. It is a potent insecticide and acaricide. It was originally developed by IG Farben in the 1940s....
    , Azinphos methyl, Chlorpyrifos
    Chlorpyrifos

    Chlorpyrifos is a toxic crystalline organophosphate insecticide that inhibits acetylcholinesterase and is used to control insect pests. Trade names include Dursban and Lorsban ....
    , among others)
  • Organophosphate-containing nerve agents (e.g., Sarin
    Sarin

    Sarin, also known by its NATO designation of GB, is an extremely toxic substance whose sole application is as a nerve agent. As a chemical weapons, it is classified as a weapon of mass destruction by the United Nations in UN Resolution 687....
    , VX
    VX (nerve agent)

    VX is an extremely toxic substance whose only application is in chemical warfare as a nerve agent. As a chemical weapon, it is classified as a weapon of mass destruction by the United Nations in UN Resolution 687....
    )


Victims of organophosphate-containing nerve agents commonly die of suffocation as they cannot relax their diaphragm
Thoracic diaphragm

In the anatomy of mammals, the thoracic diaphragm is a sheet of muscle extending across the bottom of the ribcage. The diaphragm separates the thoracic cavity from the abdominal cavity and performs an important function in Respiration ....
.

Reactivation of Acetylcholine Esterase
  • Pralidoxime
    Pralidoxime

    Pralidoxime belongs to a family of compounds called oximes that bind to organophosphate-inactivated acetylcholinesterase. It is used to combat Organophosphate poisoning or acetylcholinesterase inhibitors , in conjunction with atropine....


ACh Receptor Antagonists


Antimuscarinic Agents
  • Atropine
    Atropine

    Atropine is a tropane alkaloid extracted from deadly nightshade , jimsonweed , Mandrake and other plants of the family Solanaceae. It is a secondary metabolite of these plants and serves as a hard drug with a wide variety of effects....
  • Ipratropium
    Ipratropium

    Ipratropium is an anticholinergic drug....
  • Scopolamine
    Scopolamine

    Scopolamine, known by the names levo-duboisine and hyoscine, is a tropane alkaloid Medication with muscarinic antagonist effects. It is obtained from plants of the family Solanaceae , such as henbane, jimson weed and Angel's Trumpets , and corkwood ....
  • Tiotropium
    Tiotropium

    Tiotropium is a long-acting, 24 hour, anticholinergic bronchodilator used in the management of chronic obstructive pulmonary disease . Tiotropium bromide capsules for inhalation are co-marketed by Boehringer-Ingelheim and Pfizer Inc....


Ganglionic Blockers
  • Mecamylamine
    Mecamylamine

    Mecamylamine is a nicotinic Receptor antagonist that is well absorbed from the gastrointestinal tract and crosses the blood-brain barrier....
  • Hexamethonium
    Hexamethonium

    Hexamethonium is a ganglionic blocker, a neuronal acetylcholine receptor receptor Receptor antagonist which acts in autonomic ganglia by binding mostly in or on the NN receptor, and not the acetylcholine binding site itself....
  • Nicotine
    Nicotine

    Nicotine is an alkaloid found in the nightshade family of plants which constitutes approximately 0.6?3.0% of dry weight of tobacco, with biosynthesis taking place in the roots, and accumulating in the leaves....
     (in high doses)
  • Trimethaphan
    Trimethaphan

    Trimetaphan camsilate or trimethaphan camsylate , trade name Arfonad, is a drug that counteracts cholinergic transmission at the ganglion type receptor of nicotinic receptors of the autonomic ganglia and therefore blocks both the sympathetic nervous system and the parasympathetic nervous system....


Neuromuscular Blockers
  • Atracurium
    Atracurium

    Atracurium is a neuromuscular-blocking drugs or muscle relaxant in the category of non-depolarizing neuromuscular-blocking drugs, used adjunctively in anesthesia to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation....
  • Cisatracurium
    Cisatracurium

    Cisatracurium is a neuromuscular-blocking drug. It is one of the ten isomers of atracurium. Its active metabolites contain less laudanosine which cause hypotension, central nervous system excitement, and seizures than that of atracurium....
  • Doxacurium
  • Metocurine
    Metocurine

    Metocurine is a neuromuscular-blocking drug....
  • Mivacurium
    Mivacurium

    Mivacurium is a bisbenzylisoquinolinium based neuromuscular blocker or muscle relaxant.In the TV series "Nip Tuck", a serial rapist used "a modified form of mivacurium chloride" for disabling his victims while violating them....
  • Pancuronium
    Pancuronium

    Pancuronium is a chemical compound, used in medicine as the bromide salt pancuronium bromide. It has the brand name Pavulon . It is a muscle relaxant with various purposes....
  • Rocuronium
    Rocuronium

    Rocuronium is an aminosteroid non-depolarizing Neuromuscular-blocking drugs or muscle relaxant used in modern anaesthesia, to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation....
  • Succinylcholine
  • Tubocurarine
    Tubocurarine

    Tubocurarine chloride is an alkaloid of the benzylisoquinoline type. It is an Receptor antagonist of nicotinic neuromuscular acetylcholine receptors that is used to paralyse patients undergoing anaesthesia....
  • Vecuronium
    Vecuronium

    Vecuronium bromide is a muscle relaxant in the category of non-depolarizing blocking agent. Vecuronium bromide is indicated as an adjunct to general anesthesia, to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical...
  • HemiCholine
dupogimine

Synthesis inhibitors
Organic mercurial
Mercury (element)

Mercury , also called quicksilver or hydrargyrum , is a chemical element with the symbol Hg and atomic number 80. A heavy, silvery d-block metal, mercury is one of six elements that are liquid at or near room temperature and pressure....
 compounds have a high affinity for sulfhydryl groups
Thiol

In organic chemistry, a thiol is a compound that contains the functional group composed of a sulfur atom and a hydrogen atom . Being the sulfur analogue of an alcohol group , this functional group is referred to either as a thiol group or a sulfhydryl group....
, which causes dysfunction of the enzyme choline acetyltransferase. This inhibition may lead to acetylcholine deficiency, and can have consequences on motor function.

Release inhibitors
Botulin acts by suppressing the release of acetylcholine; where the venom from a black widow spider
Black widow spider

Latrodectus mactans, the Black widow, is a species of spider in the genus Latrodectus. They are well known for the distinctive black and red coloring of the female of the species and for the fact that she will occasionally eat her mate after reproduction....
 (alpha-latrotoxin
Alpha-latrotoxin

The best-studied latrotoxin is alpha-latrotoxin, which acts presynaptically to release neurotransmitters from sensory and motor neurons, as well as on endocrine cells ....
) has the reverse effect.

Other / Uncategorized / Unknown
  • surugatoxin
    Surugatoxin

    Surugatoxin is a type of venom found in the Japanese ivory mollusk . It functions as a ganglionic blocker.References ...
  • suxamethonium


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