Botulinum toxin effects on muscles are to?

• A. It prevents signals from the brain from reaching the muscles.
• B. It increases muscle contractions.
• C. It causes rapid fever.
• D. It enhances nerve transmission.

Answer: (A)

Botulinum toxin blocks communication between nerves and muscles by preventing the nerve from releasing acetylcholine at the neuromuscular junction. Without acetylcholine, muscles can’t be stimulated to contract, so signals from the brain fail to produce movement, resulting in flaccid paralysis. This contrasts with the other options: the toxin does not increase contractions or enhance nerve transmission, and fever is not a primary effect. In wildlife, this loss of neural signaling manifests as weakness and inability to move or swallow, reflecting that the toxin’s action is to halt nerve-to-muscle communication.