A Comparison between Wheel-running and Ambulatory Activities in Young, Adult and Old Rats Based on Long-term Observation

Abstract

It has been considered that spontaneous motor activity (SMA) represented by wheelrunning activity (WRA) or ambulatory activity (AA) is one of the most basic indicators in the behavioral-pharmacological test in small rodents. Since various differences are noticeable between WRA and AA in their characteristics or drug responses, both activities may be not considered as the same category of SMA. The main purpose of this study was to elucidate the background difference between WRA and AA in three different aged groups, based on their long-term observation. AA data obtained by Gundai type Ambulo-drinkometer were applied for comparison with WRA data obtained by Wheeldrinkometer. WRA, AA and drinking behavior all showed clear diurnal rhythms characterized by nocturnal animals under light-dark condition (LD=12: 12h) . WRA and AA, in particular the former, tended to decrease according to the aging. More than 30 days habituation was required in order to obtain stable daily WRA level in adult rats. AA of young rats was higher than the other aged rats. The present results suggest that indicators, conditions, measurement apparatus, age etc have to be considered in behavioral-pharmacological observations using WRA or AA.