Research report
Anxiety- and activity-related effects of diazepam and chlordiazepoxide in the rat light/dark and dark/light tests

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Abstract

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.

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Cited by (150)

  • Exploring the light/dark box test: Protocols and implications for neuroscience research

    2023, Journal of Neuroscience Methods
    Citation Excerpt :

    This paradigm is widely used in anxiety models such as the elevated plus maze (EPM), the open-field test (OFT), and the light-dark box test (LDB) (Ohl, 2003). Anxiolytic drugs increase the exploration of aversive areas and/or decrease the avoidance of such areas depending on the apparatus (Chaouloff et al., 1997; Bilkei-Gorzó et al., 1998; Griebel et al., 1994; Merlo Pich and Samanin, 1989). Stressful experiences may also induce anxiety-like states in rodents (Padovan and Guimarães, 2000; Novaes et al., 2017; Calvo et al., 1998; Lazarini-Lopes et al., 2020) and humans (Grillon et al., 2007).

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