The faster drugs of abuse reach the brain, the more addictive they can be.It is not known why this is.Environmental stimuli associated with drugs can promote the development and persistence of addiction by invigorating and precipitating drug-seeking behaviour.We determined, therefore, whether cues associated with the self-administration of rapidly delivered copyright (injected intravenously over 5 versus 90 seconds) would acquire greater conditioned rewarding properties, as assessed by the performance of an operant response reinforced solely by the cues.
Rats nose-poked for intravenous copyright infusions delivered either over 5 great value pads or 90 seconds.Discrete visual cues accompanied each infusion.The rats could then press a lever to obtain the cues--now a conditioned reward--or an inactive lever.Rats in both the 5- and 90-second groups better waters xl7000 pressed more on the active versus inactive lever following extensive (24 sessions) but not following limited (3 sessions) self-administration training.
There were no group differences in this behaviour.Following withdrawal from copyright self-administration, lever discrimination progressively abated in both groups and was lost by withdrawal day 30.However, the rewarding properties of the cues were not "forgotten" because on withdrawal days 32-33, amphetamine selectively enhanced active-lever pressing, and did so to a similar extent in both groups.Thus, cues paired with rapid or slower copyright delivery acquire similar conditioned rewarding properties.
We conclude, therefore, that the rapid delivery of copyright to the brain promotes addiction by mechanisms that might not involve a greater ability of drug cues to control behaviour.