The Mechanism Of Central CCK System In Methamphetamine-induced Addictive Behavior

Background: Drugs seriously threaten people's health and public safety.Methamphetamine(METH)has become the most abused drug in China.It is highly addictive and causes severe damage to the central nervous system,however the mechanism of action has not been fully understood.Octapeptide cholecystokinin(CCK-8),as a neuropeptide,plays an important role in oxidative stress and reward effect.CCK-8 can function through CCK1 receptor(CCK1R)or CCK2 receptor(CCK2R).Our previous research confirmed that CCK-8 can inhibit morphine-induced conditioned place preference(CPP)and METH-induced behavioral sensitization(BS),but the mechanisms of receptors and post-receptors in METH addiction remain unclear.?-arrestin is a negative feedback regulating protein for G protein-coupled receptor(GPCR)signaling.In recent years,it has been discovered that ?-arrestin can also be used as a scaffold protein to produce a variety of functions.For example,?-arrestin can form Akt-?-arrestin/PP2 A complex to regulate Akt signaling pathway and affect DA-induced behavioral changes.Therefore,we considered whether CCK-8 can activate ?-arrestin signaling to perform special role to activating Gq and Gs pathways through CCK receptors(one of the types of GPCR)in addition.Objective: This study intends to explore the role of central CCK system in addiction induced by METH through CCK receptors and ?-arresstin2 knockout mice,using CPP and BS models induced by METH,and further explain the role of ?-arrestin2 in addiction induced by METH.This experiment is expected to provide new ideas for the prevention and treatment of addiction.Methods: First,the CPP and BS model of C57BL/6N were constructed by intraperitoneal injection of 1 mg/kg METH.Afterwards,the lateral ventricle was catheterized,and CPP training was conducted 7 days after the operation.CCK-8 was injected into the posterior ventricle every day to observe the effect of CCK-8 at different concentrations on CPP induced by 1 mg/kg METH in C57BL/6N mice.CCK1 R,CCK2R and ?-arrestin2 knockout mice were used to observe the role of CCK receptors and ?-arrestin2 in addiction induced by METH.Results:1.The CPP score was significantly higher than the pre-conditioning induced by 1 mg/kg METH,the CPP model was successfully established.The total distance in the expression stage significantly higher than that in the formation stage of BS induced by 1 mg/kg METH,and the BS model was successfully established.2.CCK2 R knockout inhibited CPP and BS induced by METH,but CCK1 R knockout had no effect on the formation of CPP and BS.3.0.1 and 1 ?g CCK-8 significantly reduced the score,while 0.01 ?g CCK-8 had no effect on CPP score;0.1 ?g CCK-8 significantly reduced CPP score 1 h after METH training,while no significant change was observed after 6 h.4.CCK2 R knockout blocked the inhibitory effect of exogenous CCK-8 on CPP formation,while CCK1 R knockout was not affected.The inhibitory effect of exogenous CCK-8 on CPP formation disappeared after ?-arrestin2 was knockout,knocking out ?-arrestin2 promotes CPP formation induced by METH.Conclusions:1.Endogenous CCK-8 can promote the formation of CPP and BS induced by METH through CCK2 R.2.Exogenous CCK-8 may inhibit the formation of CPP induced by METH by activating ?-arrestin2 through CCK2 R.3.CCK2 R can play a bidirectional regulating role in the formation of CPP induced by METH through different signaling pathways.