Comprehensive characterization of motor and coordination functions in three adolescent wild-type mouse strains

Abstract

Neuropsychiatric disorders are often associated with motor and coordination abnormalities that have important implications on the etiology, pathophysiology, and management of these disorders. Although the onset of many neuropsychiatric disorders including autism spectrum disorder, schizophrenia, and attention-deficit hyperactivity disorder emerges mainly during infancy and adolescence, most of the behavioral studies in mice modeling neuropsychiatric phenotypes are performed in adult animals, possibly missing valuable phenotypic information related to the effect of synaptic maturation during development. Here, we examined which behavioral tests assessing both motor and coordination functions can be performed in mice at two different adolescent stages. As strain and sex affect mouse behavior, our experiments covered both male and female mice of three inbred wild-type strains, C57BL/6N, DBA/2, and FVB/N. Adolescent mice of both postnatal days (P)22-30 and P32-40 developmental stages were capable of mastering common motor and coordination tests. However, results differed significantly between strains and sexes. Moreover, the 10-day interval between the two tested cohorts uncovered a strong difference in the behavioral results, confirming the significant impact of maturation on behavioral patterns. Interestingly, the results of distinct behavioral experiments were directly correlated with the weight of mice, which may explain the lack of reproducibility of some behavioral results in genetically-modified mice. Our study paves the way for better reproducibility of behavioral tests by addressing the effect of the developmental stage, strain, sex, and weight of mice on achieving the face validity of neuropsychiatric disorder-associated motor dysfunctions.

Figure 1

Coordination function in the P22–30 cohort of C57BL/6N, DBA/2, and FVB/N strains. (a) The grip strength test revealed increased grip strength for FVB/N mice compared to C57BL/6N and DBA/2 mice. (b) The beam balance rod test showed no difference between the three investigated strains. (c) DBA/2 mice displayed the lowest latency to fall off the grid in the inverted screen test. (d) In the cliff avoidance reaction test, DBA/2 mice exhibited the lowest latency to fall off the cliff (left) and the highest number of falls (right) compared to C57BL/6N and FVB/N mice. Two-way ANOVA followed by Tukey post hoc test, *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001. A black rectangle indicates a significant difference between sexes within a strain (see Supplementary Table 2). Blue and red dots refer to males and females, respectively. Error bars indicate the standard error of the mean (SEM).

Figure 2

Motor activity in the P22–30 cohort of C57BL/6N, DBA/2, and FVB/N strains. (a) In the rotarod test, DBA/2 mice exhibited the lowest duration on the rotarod compared to C57BL/6N and FVB/N mice. For the detailed comparison between male and female mice within each strain, see Supplementary Fig. 2. (b) C57BL/6N mice showed a significant better learning ability in the rotarod test compared to DBA/2 mice. (c) In the voluntary wheel running test, no difference between the three investigated strains was revealed. Two-way ANOVA followed by Tukey post hoc test, !p ≤ 0.05, !!p ≤ 0.01 and !!!p ≤ 0.001 for DBA/2 versus C57BL/6N; ~ p ≤ 0.05 and ~~~ p ≤ 0.001 for DBA/2 versus FVB/N; $ p ≤ 0.001 C57BL/6N versus FVB/N; **p ≤ 0.01. Blue and red dots refer to males and females, respectively. Error bars indicate the standard error of the mean (SEM).

Figure 3

Coordination function in the P32–40 cohort of C57BL/6N, DBA/2, and FVB/N strains. (a) The grip strength test revealed FVB/N displaying the most powerful grip strength, DBA/2 showing the least grip strength with C57BL/6N being intermediate. (b) FVB/N displayed the lowest score in the beam balance rod test compared to C57BL/6N and DBA/2. (c) DBA/2 mice had the lowest latency to fall off a grid in the inverted screen test and reached significance compared to FVB/N mice. (d) In the cliff avoidance reaction test, no difference in the latency to fall off a cliff (left) or the number of falls (right) between the three investigated strains. Two-way ANOVA followed by Tukey post hoc test, *p ≤ 0.05, ***p ≤ 0.001. A black rectangle indicates a significant difference between sexes within a strain (see Supplementary Table 2). Blue and red dots refer to males and females, respectively. Error bars indicate the standard error of the mean (SEM).

Figure 4

Motor activity in the P32–40 cohort of C57BL/6N, DBA/2, and FVB/N strains. (a) In the rotarod test, DBA/2 mice exhibited the lowest duration on the rotarod compared to C57BL/6N and FVB/N mice. For the detailed comparison between male and female mice within each strain, see Supplementary Fig. 3. (b) C57BL/6N mice showed a significant better learning ability in the rotarod test compared to DBA/2 mice. C) In the voluntary wheel running test, DBA/2 mice displayed the lowest number of rotations. Two-way ANOVA followed by Tukey post hoc test, !p ≤ 0.05 and !!!p ≤ 0.001 for DBA/2 versus C57BL/6N; ~ p ≤ 0.05, ~~ p ≤ 0.01 and ~~~ p ≤ 0.001 for DBA/2 versus FVB/N; *p ≤ 0.05, ***p ≤ 0.001. A black rectangle indicates a significant difference between sexes within a strain (see Supplementary Table 2). Blue and red dots refer to males and females, respectively. Error bars indicate the standard error of the mean (SEM).

Figure 5

Comparison between the P22–30 and P32–40 cohorts within C57BL/6N, DBA/2, and FVB/N strains. (a) The grip strength was increased with age in the three investigated strains. (b) In the beam balance rod test, only FVB/N mice showed a decreased score in older mice. (c) The latency to fall off a grid in the inverted screen test was increased in older DBA/2 mice. (d) In the cliff avoidance reaction test, FVB/N mice exhibited lower latency to fall off a cliff (left) and DBA/2 showed a decreased number of falls (right). e) The voluntary wheel running test revealed inconsistent results in different strains with C57BL/6N and FVB/N mice showing an increase in the number of rotations with age in contrast to DBA/2 mice. Two-way ANOVA followed by Tukey post hoc test,*p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001. Error bars indicate the standard error of the mean (SEM).