FG 7142 selectively decreases nonpunished responding, but has no anxiogenic effects on time allocation in a conflict schedule.
Previous work (Thomas et al. 1990) showed that an anxiolytic benzodiazepine increased the time allocated to responding in a conflict situation (where responses were both food-reinforced and shock-punished) versus a nonpunishment situation. The present experiment tested whether a benzodiazepine-receptor inverse agonist (FG 7142, 1-30 mg/kg) would have the opposite effect (i.e., decrease time spent responding in a punishment situation). Chain pulls determined whether a rat's lever presses were reinforced on 1) a lean variable-interval schedule, or 2) a richer variable-interval schedule in which responding also produced shock intermittently. FG 7142 dose-dependently decreased nonpunished lever responding, but did not affect punished responding. The drug nonselectively decreased chain pulling (the schedule-switching response). Like chlordiazepoxide, FG 7142 increased the time spent in the punishment component, showing that not all effects of benzodiazepine-receptor agonists and inverse agonists are opposite. These results are inconsistent with expectations that anxiogenic actions of FG 7142 should 1) decrease punished responding; 2) increase the rate of responses that terminate the punishment condition; and 3) decrease time spent in the punishment component. Rather, nonsuppressed responding seems most sensitive to decreases by FG 7142.
Panlilio
L V
LV
Department of Psychology, American University, Washington, DC 20016.
Weiss
S J
SJ
Thomas
D A
DA
Glowa
J R
JR
D000818:Animals; D001007:Anxiety / Q000139:chemically induced*; D002243:Carbolines / Q000494:pharmacology*; D002707:Chlordiazepoxide / Q000494:pharmacology; D003216:Conditioning, Operant / Q000187:drug effects*; D003220:Conflict, Psychological; D004305:Dose-Response Relationship, Drug; D008297:Male; D051381:Rats; D011963:Receptors, GABA-A / Q000187:drug effects*; D013997:Time Factors
D002243:Carbolines; D011963:Receptors, GABA-A; C035874:FG 7142; D002707:Chlordiazepoxide