VPAC1 is a membrane-associated protein and shares significant homology with members of the G-protein coupled class B receptor family, the most important of which is the presence of large N-terminal extracellular domains which contain 10 highly conserved amino acids including six cysteines, putative N-terminal leader sequences and several potential N-glycosylation sites4. In the CNS, VPAC1 receptors are abundantly localized in piriform cortex, cerebral cortex, suprachiasmatic nucleus, hippocampus, and pineal gland. In peripheral tissues, VPAC1 receptors have been found in breast, kidney, liver, lung, prostate, spleen, and mucosa of the gastrointestinal tract6. VPAC1 mediates a large array of VIP and PACAP actions on exocrine secretion, hormones release, muscle relaxation, metabolism, fetus growth, tumor cells and embryonic brain development