Which of the following is the mechanism of action of tetanospasmin -

Ans. is 'a1 i.e.. Inhibition of release of GABA and glycinePathogenicityo CL tetani has little invasive property and is confined to the primary site of lodgment. Tetanus results from the action of the potent exotoxin it produces.Toxin (released in the wound)|binds to peripheral motor neuron terminals|Enters the axon|Transported to cell body in the brain stem and spinal cord by retrograde intraneural transport|Presynaptically blocks release of glycine & GABAToxinsTetanolysin (Hemolysin)Not relevant in the pathogenesis of tetanus.Tetanospasmin (neurotoxin)Responsible for tetanusIt is plasmid codedIn the brainstem and spinal cord it blocks release of the inhibitory neurotransmitter glycine and g-aminobutyric acid (GABA).It resembles strychnine in its effects, but it acts presynaptically, while strychnine acts postsynapticatly.Tetanus toxin and botulinum toxin resemble each other in their aminoacid sequences.Nonspasmogenic, peripherally active neurotoxin.Its role is not known.