<prompt> Erythromycin acts on which receptor in GITract -MotilinMuscarinicNicotinicSerotonergic  <response>: Ans. is a i.e., Motilin Erythromycin stimulates motilin an upper gastrointestinal peptide hormone receptors in the g.i.t.--thereby induces gastric contractions, hastens gastric emptying and promotes intestinal motility without significant effect on colonic motility. On the basis of this action erythromycin has been occasionally used to afford short-term symptomatic relief in diabetic gastroparesis. However, tolerance quickly develops to this action probably due to receptor down- regulation and undesirable alteration of bacterial flora limit use of erythromycin as a prokinetic agent. Contribution of this action to the g.i. side effects of erythromycin is not known. 