<prompt> Mechanism of action of tetanospasmin isInhibition of GABA releaseInhibition cAMPInactivation of Ach receptorsActivation of cAMP  <response>: Tetanus toxin acts presynaptically. It specifically blocks synaptic inhibition in the spinal cord, presumably at inhibitory terminals that use glycine and GABA as neurotransmitters. The abolition of spinal inhibition causes the uncontrollrd spread of impulses initiated anywhere in the central nervous system. This results in muscle rigidity and spasms. Reference: Textbook of Microbiology; Anathanarayan and panikers; 10th edition; Page no: 265 