Final answer:
Botulinum toxin targets neurons at the neuromuscular junction, preventing acetylcholine release and causing flaccid paralysis. Tetanus toxin targets inhibitory interneurons, preventing them from releasing neurotransmitters that inhibit muscle contractions, leading to spastic paralysis.
Step-by-step explanation:
Botulinum toxin and tetanus toxin target different cells within the neuromuscular system. Botulinum toxin, which is produced by Clostridium botulinum, focuses on the neurons that are responsible for muscle contraction. It does this by binding to the neurons at the neuromuscular junction and then cleaving proteins that are essential for the release of acetylcholine, the neurotransmitter responsible for inducing muscle contractions. As these proteins are broken down, synaptic vesicle fusion is prevented, and acetylcholine release is inhibited. This results in muscle relaxation and can lead to flaccid paralysis. On the other hand, tetanus toxin, produced by Clostridium tetani, targets inhibitory interneurons. These interneurons typically release inhibitory neurotransmitters, glycine and gamma-aminobutyric acid (GABA), that prevent the excessive release of acetylcholine. Tetanus toxin inhibits the release of these inhibitory neurotransmitters, which otherwise help in the normal mechanism for preventing uncontrollable muscle contraction. The absence of this inhibition causes constant stimulation of muscles, leading to spastic paralysis and symptoms such as lockjaw and later, potentially life-threatening complications like respiratory failure.