The two receptors that VIP binds to—found throughout the body, they mediate VIP’s effects on blood flow, inflammation, and gut function.VPAC1 (vasoactive intestinal peptide receptor 1) and VPAC2 are class B GPCRs that signal primarily through Gs/cAMP/PKA. VPAC1 is widely expressed in the CNS, liver, lung, and immune cells; VPAC2 predominates in smooth muscle, pancreatic beta cells, and circadian pacemaker neurons. VIP and PACAP are the primary endogenous ligands—VIP binds both receptors with similar affinity, while PACAP preferentially activates PAC1 with higher affinity. The pleiotropic effects of VIP (vasodilation, anti-inflammation, circadian regulation) reflect this broad receptor distribution.W↑ Top