Transport to the CNS inhibitory interneurons begins with the B-chain mediating the neurospecific binding of TeNT to the nerve terminal membrane.

[14][15] Once the toxin has been translocated into the cytosol, chemical reduction of the disulfide bond to separate thiols occurs, mainly by the enzyme NADPH-thioredoxin reductase-thioredoxin.

[16] Cleavage of synaptobrevin affects the stability of the SNARE core by restricting it from entering the low-energy conformation, which is the target for NSF binding.

The final target of TeNT is the cleavage of synaptobrevin and, even in low doses, has the effect of interfering with exocytosis of neurotransmitters from inhibitory interneurons.

The blockage of the neurotransmitters γ-aminobutyric acid (GABA) and glycine is the direct cause of the physiological effects that TeNT induces.

[20] The combined consequence is dangerous overactivity in the muscles from the smallest sensory stimuli, as the damping of motor reflexes is inhibited, leading to generalized contractions of the agonist and antagonist musculature, termed a "tetanic spasm".

With diminished inhibition, the resting firing rate of the alpha motor neuron increases, producing rigidity, unopposed muscle contraction and spasm.

Tetanospasmin appears to prevent the release of neurotransmitters by selectively cleaving a component of synaptic vesicles called synaptobrevin II.

The shorter nerves are the first to be inhibited, which leads to the characteristic early symptoms in the face and jaw, risus sardonicus and lockjaw.