A gardener was accidentally poisoned by a weed killer that inhibits acetylcholinesterase. Which of the following alterations in neurochemical transmission at brain cholinergic synapses is the most likely result of this poisoning?

Ans. C. A pileup of acetylcholine outside the cholinergic neuron (in the synaptic cleft)Acetylcholinesterase is the enzyme that breaks acetylcholine down into acetate and choline. The acetate diffuses away, and choline is taken back up into the presynaptic nerve terminal for the synthesis of more ACh. Blocking the function of acetylcholinesterase would prevent the breakdown of ACh, which would accumulate in the cleft because there is no uptake mechanism for ACh and it diffuses away more slowly than acetate.