Cholinergic Neurons: Neurotransmission

Cholinergic neurons synthesize acetylcholine for neurotransmission from choline and acetyl-CoA.

Acetyl-CoA is synthesized in the mitochondria by oxidation and decarboxylation reactions, while choline is transported within the presynaptic neuron via choline transporters.

Within the neuron, the enzyme ChAT catalyzes the acetylation of choline to yield acetylcholine. Next, the VAT transports acetylcholine from the cytoplasm into synaptic vesicles for storage. 

Upon arrival of an electrical impulse, Ca²⁺ enters the neurons through voltage-gated calcium channels. This triggers the exocytosis of acetylcholine.

The released acetylcholine binds to the postsynaptic receptors, such as the nicotinic or muscarinic receptors. This initiates a postsynaptic response.

Finally, the enzyme AChE hydrolyzes acetylcholine into choline and acetate.

Notably, certain organophosphates can irreversibly block AChE and inhibit the breakdown of acetylcholine.