A circadian rhythm in passive avoidance behavior: the effect of phase shift and the benzodiazepines

In CFLP mice, trained to a 12 hr light-12 hr dark cycle, a 24 hr variation in passive avoidance behaviour was found, which conformed to a mathematical model of a rhythm. Advancing the phase of the light cycle by 6 hr produced a transient period of disruption in the response, with maximal effect 5 days after phase shift, followed by resynchronization after 7 days. The presence of chlordiazepoxide and clobazam in the drinking water, during the days after phase-shift, in concentrations which did not affect locomotor activity in control animals (100 and 15 mu g/ml respectively), produced a dose-dependent reduction of the effects of phase-shift and a more rapid resynchronization to the new light cycle.