Clobazam: Induction of hyperlocomotion in a new nonautomatized device for measuring motor activity and exploratory behavior in mice: Comparison with diazepam and critical evaluation of the results with an automatized hole‐board apparatus (“Planche á Trous”)

Clobazam, a 1,5-benzodiazepine, and diazepam, a 1,4-benzodiazepine, were tested for their influence on motor activity and exploratory behavior in mice in an automatized hole-board apparatus with two light beams (“Planche a trous”) and in a nonautomatized motility-exploration (MOTEX) device, designed by Weischer 1976. Clobazam at oral doses of 5 to 80 mg/kg caused a marked increase in locomotion (79% to 122%) under MOTEX conditions, whereas results with the hole-board device were inconsistent and misleading: Enhanced locomotion was represented as reduced motor activity in terms of light-beam crossings. Exploratory behavior was reduced by clobazam in both MOTEX and Planche a trous at ED50 values of 33 and 67 mg/kg orally (p.o.), respectively. Diazepam at oral doses of 1 to 10 mg/kg slightly but not significantly increased locomotion in MOTEX and reduced motor activity in the hold-board test (ED50 = 3.8 mg/kg). Exploratory behavior was inhibited under both conditions at ED50 values of 3.2 and 6.7 mg/kg p.o., respectively. The inability of a two light-beam system to properly examine locomotor activity (particularly when peripheral areas of the apparatus are favored by the animals) is considered the reason for misleading results obtained with clobazam in the hold-board test. The marked increase in locomotion induced by clobazam in a nonautomatized apparatus (MOTEX) is discussed in terms of disinhibitory effects in connection with the fact that clobazam does not induce amnesia in animals and man.