Cholinergic Transmission

Cholinergic transmission occurs in many steps;

Synthesis

• It takes place in neurons.
• Choline is taken up by active transport from outside.
• Choline combines with acetyl-coA with the help of enzyme choline acetyl transferase (CAT) also called as choline acetylase. This enzyme is present inside the nerve fibers.
• In this way, acetylecholine is synthesized. Hemicholinine can stop the uptake of choline.

Storage

Acetylcholine molecules are stored inside vesicles in the nerve endings.

Release

• Storage vesicles empty Ach into synaptic cleft. Opening of ca channels occur and there is influx of calcium ions which help in release of Ach from the vesicles.
• Drugs also work in the same way. E.g. carbachol
• Some factors decrease this release. E.g. calcium deficiency

Binding

Ach binds with receptors on post-synaptic membrane and stimulates these receptors.

Removal

Ach is removed with the help of enzyme acetylcholinesterase (AchE).
Ach----------------------------------------choline + acetate.
This reaction occurs in the presence of Acetylcholinesterase.