a-clinician-injects-a-very-small-localized-dose-of-a-neurotoxin-into-a-patients-

Question

A clinician injects a very small, localized dose of a neurotoxin into a patient’s facial muscle to temporarily reduce wrinkle formation. The treatment works by preventing communication between the motor neuron and the muscle fiber at the neuromuscular junction. Which molecular mechanism best explains how the injection reduces muscle contraction in that region?

Accepted Answer

Cleavage of SNARE proteins that are necessary for synaptic vesicle fusion in motor neurons

Answer

Activation of enzymes that rapidly degrade acetylcholine in the synaptic cleft

Answer

Blockage of voltage-gated sodium channels in the muscle cell membrane

Answer

Inhibition of actin–myosin cross-bridge formation within the muscle fiber