Botulinum toxin, or "botox," has become popular for cosmetic surgery. The toxin prevents neurosecretory vesicles from docking at the plasma membrane and releasing neurotransmitter. How would this toxin affect the neuromuscular junction?

The toxin does not allow the neurosecretory vesicles to fuse with plasma membrane and thereby prevents the release of acetylcholine in synaptic cleft.

Explanation:

The release of neurosecretory vesicles and their fusion with the plasma membrane is followed by the release of neurotransmitters into the synaptic cleft. The neurotransmitter molecules fuse with receptors present in the plasma membrane of postsynaptic neurons to produce the postsynaptic potential.

Botulinum toxin or Botox is a diluted form of the toxin. Botulinum toxin serves to block the release of acetylcholine into the synaptic cleft and thereby causes muscle paralysis. Without the release of neurotransmitter (acetylcholine) in the synaptic cleft, the muscles can not contract and are said to be paralyzed. Botulinum toxin is injected into the skin to paralyze skeletal muscles of the face. As soon as the muscles are paralyzed, the facial wrinkles disappear gradually.