Botulinum toxin acts by:: (A) Presynaptic release of acetyl choline, (B) Presynaptic inhibition of release of acetylcholine, (C) GABA mimetic, (D) GABA antagonist
Answer is B. Ans.(b) Presynaptic inhibition of release of acetylcholineRef Katzung 10th ed. Ch 27* Botulinum toxin is a neuromascular blocking agent which act at neuromascular junction by blocking the presynaptic release of Ach vesicles.* Doing so, it reduces spasticity in a variety of neurologic conditions (ie, spasmolytics).* NOTE: Neuromuscular blocking drugs interfere with transmission at the neuromuscular end plate and lack central nervous system activity. Also KnowMOA of drugs and their siteDrugSite of ActionMoaLocal anestheticsNerve axonsBlock Na channelsHemicho- liniumAt cholinergic nerve terminalBlocks uptake of choline and slows synthesisVesamicolCholinergic terminal vesiclePrevents storage, depletesReserpineAdrenergic terminal vesiclePrevents storage, depletesTyramine, Ampheta- mineAdrenergic nerve terminalsPromote transmitter releaseBethanecholReceptors, parasympathetic effector cells (smooth muscle, glands)Binds and activates muscarinic receptorsAtropineReceptors, parasympathetic effector cellsBinds muscarinic receptors; prevents activatio