PAC1R antagonist 1 is an orally active PAC1 receptor antagonist that inhibits abnormal pain induced by pituitary adenylate cyclase-activating polypeptide (PACAP) and nerve damage, and may be used in the study of neoplasms and immune-related disorders.

PACAP (1-38), human, ovine, rat (Pituitary Adenylate Cyclase Activating Polypeptide 38) is a neuropeptide with 38 amino acid residues.

PACAP (6-38), human, ovine, rat acetate is a potent PACAP receptor antagonist with IC50s of 30, 600, and 40 nM for PACAP type I receptor, PACAP type II receptor VIP1, and PACAP type II receptor VIP2, respectively.

PACAP-related peptide (PRP) is an endogenous 29-amino acid peptide that belongs to the secretin/glucagon superfamily of peptides, which includes secretin , glucagon , glucagon-like peptide-1 , GLP-2 , and pituitary adenylate cyclase-activating polypeptide . It is expressed in normal human pancreas and adrenal gland tissue and in some tumors that produce vasoactive intestinal peptide (VIP). PRP (1-29) is secreted by CHO-K1 cells that express human recombinant preproPACAP.

Pituitary adenylate cyclase-activating peptide (PACAP) (6-27) is a PACAP receptor antagonist with IC50 values of 1,500, 600, and 300 nM, respectively, for rat PAC1, rat VPAC1, and human VPAC2 recombinant receptors expressed in CHO cells. It binds to PACAP receptors on SH-SY5Y and SK-N-MC human neuroblastoma and T47D human breast cancer cells (IC50s = 24.5, 106, and 105 nM, respectively) and inhibits cAMP accumulation induced by PACAP (1-38) (Kis = 457, 102, and 283 nM, respectively, in SH-SY5Y, SK-N-MC, and T47D cells). In vivo, in newborn pigs, PACAP (6-27) (10 μM) inhibits vasodilation of pial arterioles induced by PACAP (1-27) and PACAP (1-38) . It also inhibits PACAP (1-27)-stimulated increases in plasma insulin and glucagon levels and pancreatic venous blood flow in dogs when administered locally to the pancreas at a dose of 500 μg.