Figure 2. Behavioral analysis of conditional R1441C LRRK2 transgenic mice.

(A) Body weight of male and female transgenic mice was measured at 20 months (n = 6 mice/genotype). (B) Olfactory function was assessed by an odor detection test on transgenic mice at 20 months whereby the latency to retrieve hidden food stimuli was recorded (n = 6 mice/genotype). (C) Motor coordination and balance of transgenic mice were evaluated by their performance on the rotarod at 6 (open circles) and 19 months (closed circles) of age. Testing was performed over 4 consecutive days using an accelerating rotation paradigm (5 to 50 rpm over 5 min). The latency of mice to fall from the rotating rod was recorded (n = 6 animals/genotype). (D-E) Transgenic mice at 10 (open rectangles) and 20 months (closed rectangles) were tested in the open field quadrant to assess their locomotor activity and anxiety-like behavior in a novel environment. Locomotor activity was measured by the total distance covered in the open field over 20 min as well as distance and speed every 5 minutes following introduction into the arena (n = 6 animals/genotype) (D). The time spent in the central zone of the open field arena was recorded as an index of anxiety (E). (F-H) Gait profiling of 11 and 20 month-old transgenic mice was performed with an automated gait analysis method. The temporal parameters calculated were the time for each animal to cross the walkway (F), the pace of walking (calculated as distance covered / sec), and variation in walking speed, as well as cadence which reflects the frequency of steps during the trial (G). (H) The relative spatial relationship between paws was assessed by calculating the base of support (the distance between the front paws or hind paws during walking) and print position (the distance between the hind paw and the previously placed ipsilateral front paw). The interlimb coordination is reflected on the step-sequence pattern that the mice employed while crossing the walkway (n = 6 animals/genotype). Data on all graphs represent the mean ± SEM. Comparisons between groups for each time-point were assessed by unpaired, two-tailed Student's t-test ns, non-significant.