This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
[{'content': 'Mechanism of action of tetanospasmin is \nSelect and explain. \nA. Inhibition of GABA release, B. Inhibition cAMP, C. Inactivation of Ach receptors, D. Activation of cAMP', 'role': 'user'}, {'content': "Answer: A \nExplanation: 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 paniker's; 10th edition; Page no: 265", 'role': 'assistant'}]