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Effects of Drugs on Visual Stimulus Control of Behavior in an Analog of a Drug‐Discrimination Procedure
Author(s) -
Katz Jonathan L.,
Newman Amy H.,
Campbell Bettye
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.a782-c
Subject(s) - stimulus control , stimulus (psychology) , pharmacology , pentobarbital , drug , chemistry , psychology , medicine , nicotine , psychotherapist
In drug discrimination (DD) the effects of novel drugs are assessed in subjects trained to discriminate a standard drug from vehicle, with results considered indices of the similarity in subjective effects of the drugs. The present study assessed whether partial substitution of test drugs might rather reflect a drug‐induced disruption in the stimulus control produced by DD training. Rats were trained to emit one response on a fixed‐ratio 20 schedule (response 20 → food) with houselight (HL) on, and another response under the schedule with HL off. Daily HL on or off sessions alternated in a mixed sequence. Pentobarbital (PB: 1–10 mg/kg) and chlorpromazine (CPZ: .1–1.7 mg/kg) had no effects on stimulus control at all but the highest doses. However, cocaine (.03–3 mg/kg) produced a graded decrease in stimulus control. A similar effect was obtained with the cocaine analog, WIN35,428 (.1–3 mg/kg). Analogs of benztropine (BZT) bind to the dopamine transporter like cocaine, but only partially substitute for cocaine possibly due to effects on stimulus control rather than differences in their cocaine‐like DD effects. The BZT analogs 4‐Cl‐BZT, 4′,4″‐diF‐BZT, and N‐allyl‐4′,4″‐diF‐BZT were assessed for their effects on stimulus control. Both 4‐Cl‐BZT and 4′,4″‐diF‐BZT had small effects on stimulus control at selected doses that were less than those of cocaine. N‐allyl‐4′,4″‐diF‐BZT only affected stimulus control at the highest dose. Thus, some drugs (e.g. cocaine and WIN35,428) but not others (PB, CPZ) may have effects on stimulus control in DD procedures that may be confounded with their similarity to training drugs. Further, the lack of a full cocaine‐like effect of the BZT analogs is unlikely due to an effect on stimulus control, and more likely reflects a difference between these drugs and cocaine with regard to their subjective effects. [Supported by NIDA‐IRP]