Vasoactive intestinal polypeptide receptor 1 also known as VPAC<sub>1</sub>, is a protein, that in humans is encoded by the VIPR1 gene. VPAC<sub>1</sub> is expressed in the brain (cerebral cortex, hippocampus, amygdala), lung, prostate, peripheral blood leukocytes, liver, small intestine, heart, spleen, placenta, kidney, thymus and testis.
VPAC<sub>1</sub> is a receptor for vasoactive intestinal peptide (VIP), a small neuropeptide. Vasoactive intestinal peptide is involved in smooth muscle relaxation, exocrine and endocrine secretion, and water and ion flux in lung and intestinal epithelia. Its actions are effected through integral membrane receptors associated with a guanine nucleotide binding protein which activates adenylate cyclase.
VIP acts in an autocrine fashion via VPAC<sub>1</sub>1 to inhibit megakaryocyte proliferation and induce proplatelet formation.
Patients with idiopathic achalasia show a significant difference in the distribution of SNPs affecting VIPR1.
VIP and PACAP levels were decreased in anterior vaginal wall of stress urinary incontinence and pelvic organ prolapse patients, they may participate in the pathophysiology of these diseases.