Notes: Complement 3a (C3a) receptor agonist binds the G protein-coupled C3a receptors (C3aRs) in the immune system complement pathway.{33705} Activation of C3aR prevents neutrophils from being mobilized in a model of intestinal ischemia-reperfusion injury.{33708} C3aRs are expressed on neural progenitor cells and immature neurons in adult mice. C3a stimulates differentiation of neural progenitor cells in vitro.{33706,33707}