Influence of cholinergic system on motor learning during aging in mice

Three, 12- and 20-month-old C57Bl6 mice, reared in standard conditions or i n an enriched environment, were administered subcutaneously either scopolam ine hydrobromide (SIGMA), 0.6 and 1.2 mg kg(-1), or physiological saline 15 min before testing their motor skills (muscular strength, dynamic equilibr ium and motor coordination) and motor learning abilities (number of trials needed to reach a learning criterion on a rotorod rotating at 27 revolution s per min). The results demonstrated a lack of correlation between motor sk ill scores and between motor skill and motor learning scores, suggesting th at the rotorod training procedure measures motor learning and not motor ski lls or is :insensitive to changes in motor skills. They also demonstrated t hat motor skills decreased with age but were insensitive to environmental r earing and to scopolamine. In contrast, the learning scores, which also dec reased with age, were very sensitive to scopolamine, particularly in the ol dest mice. These results are discussed according to the role of cholinergic system in motor learning during aging. (C) 2001 Elsevier Science B.V. All rights reserved.