PA-9 is a pituitary adenylate cyclase-activating polypeptide (PACAP) type I (PAC1) receptor antagonist. PA-9 dose dependently inhibits PACAP-induced cAMP elevation with an IC50 of 5.6 nM. PA-9 can be used for the research of neuropathic and/or inflammatory pain.In Vitro: PA-9 (10 pM to 10 nM; 30 minutes) dose dependently inhibits PACAP-induced (1 nM) CREB phosphorylation in the CHO cells expressing PAC1 receptors.In Vivo: PA-9 (100 pmol; co-injection with PACAP) attenuates the development of PACAP-induced (100 pmol/5 μL; intrathecal injection) aversive responses of mice.
PA-9 (100 pmol; co-injection with PACAP) significantly blocks the induction of PACAP-induced (100 pmol) mechanical allodynia.
PA-9 (100 pmol/5 μl; single intrathecal injection alone) does not induce aversive responses and mechanical allodynia of mice.
PA-9 is well accommodated in the subpocket formed by L80, F81, I83, G91, V92, P107, A112, and C113 of the PAC1 receptor, precipitating in hydrophobic interactions.