A new approach to the light/dark test procedure in mice

Area of Science:

• Neuroscience
• Pharmacology
• Behavioral Science

Background:

• Anxiety disorders are prevalent, necessitating reliable methods for evaluating anxiolytic and anxiogenic compounds.
• The two-compartment light/dark apparatus is a common tool for assessing anxiety-like behaviors in rodents.

Purpose of the Study:

• To evaluate the efficacy of the light/dark test in identifying anxiolytic and anxiogenic agents.
• To investigate the influence of psychostimulant drugs on anxiety indices.
• To assess the impact of apparatus modifications and strain differences on test reliability.

Main Methods:

• Utilized a fully automated, computer-integrated two-compartment light/dark apparatus.
• Tested known anxiolytics (diazepam, alprazolam), a putative anxiogenic (FG 7142), and psychostimulants (amphetamine, adrafinil, amineptine, caffeine).
• Incorporated modifications like a soiled apparatus and compared results with cleaned apparatus trials, also assessing Swiss and C57Bl/6J mouse strains.

Main Results:

• Diazepam and alprazolam demonstrated anxiolytic-like profiles, with time in the lit area and exploration being reliable indices.
• FG 7142 showed no intrinsic anxiogenic effect.
• Amphetamine was anxiogenic, while amineptine, adrafinil, and caffeine exhibited only psychostimulant effects.
• The Swiss mouse strain proved suitable for this test.

Conclusions:

• The light/dark test is valuable for screening potential anxiolytic and anxiogenic compounds.
• Control tests (e.g., open field, actimeter) are crucial to rule out sedation or altered exploration.
• The Swiss mouse strain is recommended for use in this anxiety test.