Continuous measurement of locomotor activity during convalescence and acclimation in group-housed rats.

Locomotor activity is affected by a range of factors in addition to experimental treatment, including the breeding environment. Appropriate convalescence and acclimation are important for animal experiments, because environmental changes and physical burden can result from surgery, transportation, and cage exchange. However, the duration that locomotor activity is affected by these factors is currently unclear, because it has traditionally been difficult to measure locomotor activity in multiple group-housed animals in any location other than the analysis room. In the present study, we analyzed the locomotor activity of group-housed rats using a nano tag after surgery, transportation, and cage exchange. The nano tag, a new device for analyzing activity, can measure locomotor activity in laboratory animals with no limitation on the number of animals in same cage. Any type of cage can be used for analysis, at any time of day, and in any location. Nano tags were subcutaneously implanted in male rats (F344/NSlc, 6 weeks of age) and locomotor activity was continuously measured after surgery, transportation, and cage exchange. Significant activity changes were observed in rats after transportation and cage exchange, 9 days and 3 h after the event, respectively. The results suggest that continuous measurement of locomotor activity with nano tags can be used to monitor changes in activity induced by environmental changes, and will be helpful for designing animal experiments analyzing locomotor activity.