Which toxin inhibits the release of GABA from Renshaw cells?

The correct answer, tetanus toxin, is known for its specific action on the nervous system, particularly its ability to inhibit the release of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) from Renshaw cells in the spinal cord. This occurs due to the toxin's proteolytic effects on proteins involved in the neurotransmitter release process, effectively blocking the normal inhibitory signals that would control motor neuron activity. As a result, muscle spasms and rigidity can occur, which are characteristic symptoms of tetanus.

In contrast, botulinum toxin primarily acts at the neuromuscular junction by preventing the release of acetylcholine, leading to muscle paralysis rather than inhibition of GABA. Cholera toxin targets intestinal epithelial cells, affecting fluid secretion and electrolyte balance rather than directly impacting neuronal inhibition. Diphtheria toxin affects protein synthesis in cells but does not have the specific action on GABAergic transmission that tetanus toxin does.