The phenomenon of one-trial tolerance to the anxiolytic effect of chlordiazepoxide in the elevated plus-maze test is abolished by previous administration of chlordiazepoxide or buspirone.
It has been repeatedly reported that the anxiolytic action of benzodiazepines in the elevated plus-maze test is abolished in rats that have received a single prior experience of the test apparatus (one-trial tolerance effect). To analyze whether the one-trial tolerance effect of chlordiazepoxide can be influenced by administration of chlordiazepoxide or buspirone on trial 1, male Wistar rats received an IP injection of vehicle, chlordiazepoxide (8 mg/kg) or buspirone (2.5 mg/kg) 30 min. before testing for 5 min. in the plus-maze (trial 1). Seventy-two hours later, the rats received vehicle or chlordiazepoxide 30 min. before the re-exposure to the plus-maze for 5 min. (trial 2). Groups injected with chlordiazepoxide or buspirone on trial 1 and with chlordiazepoxide on trial 2 showed an anxiolytic effect of chlordiazepoxide on trial 2, as opposed to rats injected with vehicle on trial 1 and with chlordiazepoxide on trial 2. As opposed to previous studies, the present results suggest that the influence of prior experience with the plus-maze on the anxiolytic action of chlordiazepoxide during re-exposure seems to depend critically on the drug state in which trial 1 is experienced. These results are discussed with respect to the hypothesis proposed to explain the phenomenon of one-trial tolerance.
Escarabajal
M D
MD
Area de Psicobiología, Universidad de Jaén, Paraje Las Lagunillas s/n. 23071 Jaén, Spain. descara@ujaen.es
Torres
C
C
Flaherty
C F
CF
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D001007:Anxiety / Q000523:psychology*; D001522:Behavior, Animal / Q000187:drug effects*; D002065:Buspirone / Q000494:pharmacology*; D002707:Chlordiazepoxide / Q000494:pharmacology*; D004361:Drug Tolerance; D007274:Injections, Intraperitoneal; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar
D014151:Anti-Anxiety Agents; D002707:Chlordiazepoxide; D002065:Buspirone