Effects of thenorphine on methamphetamine-induced behavioral sensitization in mice

Objective:To investigate the effects of thenorphine,a new partial agonist of opiatereceptors,on the process of methamphetamine (MA)-induced behavioral sensitization in mice.Meth-ods:Locomotor activity was detected after administration with thenorphine or co-administration ofthenorphine with MA in mice.Mice were induced behavioral sensitization to MA by intraperitoneal in-jection of 2mg·kg~(-1) MA once daily for 7 days,and administered with the combination of MA andthenorphine to observe the effects of thenorphine on behavioral sensitization to MA.Results:A singleadministration of thenorphine (0.0625～1.0mg·kg~(-1)) could dose-dependently inhibit the locomotoractivity in mice (P0.05) and the effects of thenorphine on locomotor activity developed tolerance,instead of sensitization after repeated administration.Co-administration of thenorphine couldn't inhibitthe MA -induced hyperactivity in mice.Although thenorphine couldn't inhibit the development andexpression of MA sensitization,it could dose-dependently suppress the transfer of MA sensitization(P0.05 or P0.01).Conclusions:Thenorphine could suppress the central nervous system and thetransfer of MA sensitization in mice,suggesting that thenorphine may be effective against the addictionof MA.