A fully automated apparatus for a light/dark test measuring anxiolytic or anxiogenic effects of drugs in mice.

Abstract

We developed a fully automated light/dark apparatus which detects locomotion, rearing and time spent in light and dark zones, and shuttle crossing of mice. This apparatus is controlled by a personal computer and detects these parameters by using infrared beamsensors. We used this apparatus to investigate the effects of the anxiolytics, diazepam (DZP) and pentobarbital (PB); the putative anxiolytic, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT); and the anxiogenics, picrotoxin, methyl-beta-carboline-3-carboxylate (beta-CCM), and ethyl-beta-carboline-3-carboxylate (beta-CCE), on each parameter measured by a light/dark test in mice. DZP (5 mg/kg) and 8-OH-DPAT (0.1 and 0.2 mg/kg) significantly increased the time spent in the light zone. PB (10 mg/kg) also significantly increased the number of shuttle crossings between the dark and light zones. Conversely, picrotoxin (1 and 2 mg/kg) significantly decreased locomotion, rearing and time spent in the light zone. beta-CCM (10 mg/kg) and beta-CCE (5 mg/kg) also significantly decreased rearing and time spent in the light zone. Although the same dose of beta-CCE significantly decreased shuttle crossing and rearing in the dark zone, beta-CCE did not change locomotion in either zone. Our results indicate that this apparatus is useful for the assessment of the anxiolytic and anxiogenic activities of drugs in mice.