Acetylcholine is a neurotransmitter that functions in both the peripheral and central nervous systems. It is synthesized from choline and acetyl-CoA by the enzyme cholinesterase and is broken down by acetylcholinesterase. Acetylcholine is distributed throughout the body, including in muscles, nerves, the brain, and at neuromuscular junctions. It is stored in vesicles and released into the synaptic cleft upon arrival of an action potential.

1. Acetylcholine
Acetylcholine
IUPAC name 2-Acetoxy-N,N,N-trimethylethanaminium
Abbreviation ACh
Sources motor neurons, parasympathetic nervous system, brain
Targets skeletal muscles, brain, many other organs
Receptors nicotinic, muscarinic
Agonists nicotine, muscarine, cholinesterase inhibitors
Antagonists tubocurarine, atropine
Precursor choline, acetyl-CoA
Synthesizing enzyme choline acetyltransferase
Metabolizing enzyme acetylcholinesterase

2. Acetylcholine
• Acetylcholine is an organic chemical that
functions in the brain and body of many type of
animals, as a
• Neurotransmitter- a chemical released by nerve
cells to send signals to other cells.
• Also used as a neurotransmitter in the
autonomic nervous system.
• Its name is derived from its chemical structure: it
is ester acetic acid and choline.

3. Function Of Ach
• Acetylcholine has functions both in the peripheral
nervous system and CNS.
• In the peripheral nervous system, Ach activates
muscles, and is a major neurotransmitter in the
ANS.
• In the CNS, cholinergic projections from the basal
forebrain to the cerebral cortex and hippocampus
support the congnitive functions of those target
areas.

4. Synthesis Of Acetylcholine

5. Synthesis
• Acetylcholine is synthesized from its two immediate precursors,
choline and acetyl coenzyme A
• The synthesis reaction is a single step catalyzed by the enzyme ChAT
Choline+Acetyl coenzyme A⇌Acetylcoline+Coenzyme A
• Choline present in tissues has two origins :
exogenous, in food( folic acid, vitamin B12) and
endogenous , by biosynthesis from glycine.
• Acetylcholinesterase (ACHE), Also known as AChE
OR acetylhydrolase , is the primary cholinesterase
in the body, it is an enzyme that catalyzes the
breakdown of acetylcholine and some other choline
esters that function as neurotransmitter.

6. Distribution Of Ach
Tissue distribution of acetylcholine is very broad ,it
is present:
• In the central nervous system: brain , spinal cord ,
nerve
• In the vegetative nervous system: in sympathetic
and parasympathetic ganglia and in
parasympathetic terminations.
• In presynaptic termination of neuromuscular
junctions.

7. Release OF Ach
• In presynaptic termination, acetylcholine is
contained in vesicles.
• Nervous impulse, i.e. action potential, induces
migration of vesicles towards the membrane and
releases of acetylcholine into the synaptic cleft
• The stimulation of pre synaptic muscarinic
receptors inhibits acetylcholine release and ,
conversely, their inhibition increases it.
• Botulinum toxins is an inhibitor of the acetylcholine
releases.

8. Storage Of Acetylcholine
• After its synthesis, acetylcholine is packaged into
vesicles.
• Ach is transported from the cytoplasm into
individual vesicles by means of a carrier protein on
the vesicle membrane called vesicular Ach
transport (VACHT)
• VAchT is an antiporter that couples an influx of ACH
with an efflux of protein(H).
• Once packaged in a vesicles, acetylcholine is stored
at the nerve ending until an action potential arrives
and allows for its release into the synaptic cleft.