Characteristics of home cage locomotion in cynomolgus monkeys

The profiles of home cage locomotor activity and its rhythmicity were investigated using a camera system for 4 consecutive days in cynomolgus monkeys. Nine male and nine female cynomolgus monkeys were used in this study, and were found to have the same profile in nocturnal behavior in that they were mostly inactive during the night. The locomotor activity of both sexes showed a normal activity and inactivity rhythm, which had an inverse relationship between normal activity and inactivity, showing a fluctuation profile of being higher in the light cycle and lower in the dark cycle. The four-day locomotion time of the females was higher than that of the males in the dark period. The females also showed a higher locomotion count and D/L ratio in the dark period than the males during the 4 consecutive days. These findings indicate that the females have greater locomotor activity in the dark period than that of the males. The present findings may serve as useful basic data for the behavioral assessment of overall animal movements in toxicological studies using monkeys.