Mouse rota rod

Motor performance and coordination were investigated by means of rotarod test in 16‐month‐old NURR1‐KO (male n = 6; female n = 9) and their WT littermates (male n = 6; female n = 5) and in 3–5‐month‐old female NURR1‐KO (n = 14) and their WT (n = 7) littermates. Mice were tested for three consecutive days. In each day, after a 2 min training session at a constant speed (4 rpm), the mice received three test sessions (T) in which the rod (Mouse Rotarod, Ugo Basile Biological Research Apparatus, Comerio, Italy) accelerated continuously from 4 to 65 rpm over 350 s (Hoxha et al., 2013 (link); Montarolo et al., 2019 (link)). The latency to fall off the rod was recorded and reported as the mean of the third trials of each of the 3 days.

Motor coordination and learning were evaluated by using a mouse rotarod with adjustable speed and accelerating mode (Ugo Basile, Italy). Mice were habituated to the rod for 2 days prior to the test, by placing them on to non-rotating rod on the first day to test equilibrium (speed: 0 rotation per minute, 0 rmp) and then the second day on the rod rotating at a constant speed of rpm to evaluate basal motor coordination. The fall latency was recorded with a 180 s cut-off duration. Ina second study phase, motor synchronization learning was tested for three consecutive days by placing the mice on the rotating rod with an acceleration protocol (4 to 40 rpm in 5 min). Mice were submitted to five training sessions, one session on the first training day and then two daily sessions during day 2 and day 3. Each session was composed of five successive trials. Between each trial the mouse was placed back in its cage for a minimum of 5 min to recover from physical fatigue. The fall latency recorded during the five trials of a session was averaged for each mouse. Motor learning performance was assessed by comparing the changes in mean fall latency across the five successive sessions in the two genotypes.

Locomotor function was evaluated by using a mouse rotarod with adjustable speed and accelerating mode (catalog no. #47600, Ugo Basile, Italy). Three to five mice were tested in parallel; the apparatus was cleaned with 100% ethanol after each trial. On the first day between 9:00 a.m. to 1:00 p.m. (session 1), equilibrium was tested by placing each mouse on the non-rotating rod, with its body axis perpendicular to the rod longitudinal axis. The time the animal stayed on the rod was recorded and the trial stopped when the animal fell or after 180 s. In the afternoon between 1:00 p.m. and 5:00 p.m. (session 2), mice were placed on the rod rotating at a constant speed (4 rpm), its head directed against the direction of rotation so that it had to progress forward and synchronize its walk with the speed of the rod to maintain balance. Training consisted of five successive trials with a 15-min inter-trial interval (ITI); fall latency was recorded during each trial with a 180-s cutoff duration. Locomotor function was analyzed 24 h later (session 3) by placing mice on the rotating rod, which accelerated from 4 to 40 rpm in a 5-min trial. Evaluation then consisted of four successive trials with a 60-min ITI; fall latency was recorded during each trial with a 300-s cutoff duration, and a mean score was then calculated.