Abstract: Objective: To observe the selective alterations of endogenous pituitary adenylate cyclase-activating polypeptide(PACAP) and PAC1 receptor gene expression in PC12 cells induced by neurotoxin-Rotenone and neuropeptide-PACAP.Methods: Real-time polymerase chain reaction(RT-PCR) was performed to examine alterations of endogenous PACAP and PAC1 receptor gene expression in PC12 cells.Results: Our data demonstrated that rotenone significantly increased gene expression of endogenous PACAP and PAC1 receptor and only neuropeptide PACAP27 have no effects on the gene expressions of endogenous PACAP and PAC1 receptor;In base of rotenone-treatment,PACAP in presence of PAC1 antianognist,PACAP6-27 or without presence of it,promote increasing of PACAP expressions(P<0.01).Conclusions: Our study indicates that Our results indicated that Endogenous PACAP was shown to contribute to self-defense and compensatory mechanisms by regulating PACAP expression itself.