Age dependence of strain determinant on mice motor coordination.

Evaluation of motor coordination and motor learning in mice remains a challenge as many factors may interact with the different tests used. Among these factors, genetic background has been reported to be a major determinant of mice performances in motor coordination tests. However, it is not known if the strain dependence of motor coordination and motor learning remains constant through life. In order to assess this point, we tested during 5 days male and female mice of three different strains (NMRI, C57BL/6J, and C57BL/6J x 129OlaHsd) in runway, rotarod, and thin rod tests at juvenile (first day of testing = postnatal day 19) and adult (3 months) age. We found a strong strain effect on motor performances and motor learning at juvenile age (C57BL/6J performing more poorly than the two other strains), whatever the tests used. Interestingly, the C57BL/6J mice were the best performing mice at the adult age. These strain rankings were observed either in male and female groups. These results demonstrate that the strain determinant on mice performances and motor learning is highly age dependent.