in a first group of experiments posttraining administration of naloxone ( 2.0 and 4.0 but not 1.0 mg/kg ) and naltrexone ( 0.5 and 1.0 but not 0.25 mg/kg ) , as well as those of the gaba-antagonists picrotoxin ( 0.5 and 1.0 but not 0.25 mg/kg ) and bicuculline ( 0.25 and 0.5 but not 0.1 mg/kg ) enhanced , whereas those of the gaba-agonist muscimol ( 1.0 and 2.0 but not 0.5 mg/kg ) impaired retention on a 24-hr test .
C0027358
naloxone
C0027360
naltrexone