the following results were obtained with intraseptal injections 40-41 min after intraperitoneal morphine : ( 1 ) beta-endorphin and , to a lesser extent , fentanyl increased frequencies of locomotor patterns , ( 2 ) morphine and met-enkephalin were ineffective , ( 3 ) naloxone and naltrexone decreased frequencies of locomotor patterns in a dose-dependent way , ( 4 ) naloxone and naltrexone antagonized the effects of beta-endorphin and fentanyl , and ( 5 ) morphine did not attenuate the effect of naloxone .
C0027360
naltrexone
C0027358
naloxone