Activation of the following type of receptors present on myenteric neurons by metoclopramide is primarily responsible for the enhanced acetylcholine release and improving gastric motility:: (A) Muscarine M1, (B) Serotonergic 5-HT3, (C) Serotonergic 5-HT4, (D) Dopaminergic D2
Answer is C. (Ref: KDT 6/e p646, 647) Gastric motility is increased by ACh. Release of this neurotransmitter is enhanced by 5HT4 receptor stimulation and 5HT3 and D2 receptor antagonism.