Acetylcholine release process at the neuromuscular junction (None)

The acetylcholine release process at the neuromuscular junction is a multistep, highly regulated physiological event enabling communication between a motor neuron and a skeletal muscle fiber. The process begins with the arrival of a nerve action potential at the presynaptic terminal, leading to the opening of voltage-gated calcium channels. Calcium influx triggers fusion of synaptic vesicles (via the SNARE protein complex) with the presynaptic membrane, releasing acetylcholine into the synaptic cleft by exocytosis. Acetylcholine diffuses across the cleft and activates nicotinic acetylcholine receptors on the motor end plate of the muscle fiber, resulting in sodium influx, membrane depolarization, and creation of an end-plate potential that triggers muscle contraction. Termination of signaling occurs as acetylcholinesterase rapidly hydrolyzes acetylcholine. Each of these molecular steps is a potential disease locus or pharmacological intervention point, but the process itself is not a discrete molecular therapeutic target.

Other names

Neurotransmitter release at the neuromuscular junctionNMJ acetylcholine releaseSynaptic transmission at the motor end plate

Inhibition of acetylcholinesterase increases ACh presence in the synaptic cleft to improve neuromuscular transmission (used in myasthenia gravis). Blocking presynaptic exocytosis (botulinum toxin) prevents ACh release, leading to paralysis. Nicotinic receptor antagonists block post-synaptic transmission. Nicotinic receptor agonists cause prolonged depolarization, leading to paralysis.