Evidence of possible opiate dependence during the behavioral depressant action of a single dose of morphine

摘要: Abstract Rats were trained to lever press for food pellets under a 20 response fixed ratio (FR 20) schedule of reinforcement. A single injection 15 mg morphine SO4/kg suppressed operant behavior 1 2 –3 hrs , after which time responding resumed at reduced rate. When 0.25 naloxone HCl/kg was given during the recovery phase, behavioral depressant effect narcotic immediately reversed and performance returned predrug rates. In contrast, when 0.5 naloxone/kg this time, abolished least hr. Naloxone, these doses, did not affect in drug-naive subjects. These results suggest that single, relatively low dose can induce transient dependence is detectable several drug administration, acute pharmacological actions are still apparent.