The temporal dynamics of swimming in rats as a possible index of the circadian mobility of the animals

: By the time course of forced swimming all rats may be separated in several groups with typical patterns of circadian motility. In case when active swimming movements and reduced immobility predominated, invert type of daily chronogram with low activity at the night hours and high sensitivity to chronic imipramine treatment were observed. Considerable immobility correlates with clear circadian rhythm and weak response to antidepressant. It is suggested that rhythmical pattern of the forced swimming may be used as predicator of circadian motility type.