Figure 4. A possible mechanism for BoNT effectiveness on pain.

(A) Process showing the transfer of sensory receptor from synaptic vesicle through regular fusion process. Exocytosis process at the synapse is not only involved in neurotransmitter release, but also populates presynaptic regions with several pain receptors. (B) Impairment of fusion process by BoNT toxin which ultimately stops the transfer of receptors to the membrane. Inhibition of fusion vesicles reduces number of pain receptors at the synapse.