to assess the possible role of endogenous opioids on spatial memory , rats were administered morphine ( 1-15 mg/kg ) , naloxone ( 1-10 mg/kg ) , or naltrexone ( 0.1-10 mg/kg ) at varying times after or prior to completing the first 4 choices in an 8 arm radial maze .
C0027358
naloxone
C0027360
naltrexone