Anxiety- and activity-related effects of diazepam and chlordiazepoxide in the rat light/dark and dark/light tests.
We have investigated, through factor analysis, anxiety- and activity-related variables in rats placed in the light/dark box. Thus, vehicle-, diazepam (DZ)-, and chlordiazepoxide (CDP)-treated rats were submitted 30 min later to 5-min light/dark or dark/light tests (initial placements in light or dark, respectively). Following this test, the animals were tested for 5 min in an automated activity monitor. Doses of DZ (0.75-3.0 mg/kg) and CDP (2.5-10.0 mg/kg) were based on preliminary evidence for 1.5 mg/kg of DZ and 5 mg/kg of CDP being anxiolytic in the elevated plus-maze. In the light/dark test, DZ increased the number of visits to and duration in the light compartment, and locomotor activity in the dark compartment; moreover, DZ decreased the latency to enter the light compartment. These effects were, however, significant for the highest dose only. Although CDP yielded similar behavioural effects, only the highest dose had a significant effect, namely, on latency to enter the light side. Conversely, none of the other variables were benzodiazepine-sensitive. Locomotion in the activity cages was decreased by DZ and CDP, an effect significant for the highest doses of benzodiazepines (dark/light test condition only). In both tests, factor analyses revealed an anxiety-related factor (to which all variables related to the visits in the light and part of the locomotion in the dark contributed), and an activity-related factor (upon which the latency to enter the dark and part of the locomotion in the dark loaded) in the light/dark test only. It is suggested that although the light/dark and dark/light tests capture an approach/avoidance dimension, DZ and CDP are more effective in the former test. Compared to the light/dark test, however, the plus-maze may be more sensitive to the anxiolytic effects of DZ and CDP.
Chaouloff
F
F
Génétique du Stress, INSERM CJF 94-05, INRA, Université Bordeaux II, France. francis.chaouloff@bordeaux.inserm.fr
Durand
M
M
Mormède
P
P
D000818:Animals; D014151:Anti-Anxiety Agents / Q000494:pharmacology* / Q000627:therapeutic use; D001007:Anxiety / Q000188:drug therapy / Q000523:psychology*; D002707:Chlordiazepoxide / Q000494:pharmacology* / Q000627:therapeutic use; D003624:Darkness; D003975:Diazepam / Q000494:pharmacology* / Q000627:therapeutic use; D008027:Light; D008297:Male; D009043:Motor Activity / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D014151:Anti-Anxiety Agents; D002707:Chlordiazepoxide; D003975:Diazepam