Meeting Abstract
119.6 Tuesday, Jan. 7 11:30 Gait characteristics of mice bred for high voluntary wheel running CLAGHORN, GC*; THOMPSON, Z; KAY, JC; HAMPTON, TG; GARLAND JR, T; Univ. of California, Riverside; Univ. of California, Riverside; Univ. of California, Riverside; Mouse Specifics Inc; Univ. of California, Riverside gclag001@ucr.edu
Mice from lines that have been selectively bred for nearly 70 generations for high levels of voluntary wheel running (HR lines) show many differences from their non-selected control (C) lines, including more symmetrical hindlimb bones, greater treadmill endurance, and higher voluntary running speeds and daily distances on wheels. Despite continued selection, wheel running reached an apparent plateau at ~ generation 20. One proposed physical limit is the maximum limb-cycling frequency at the highest speeds during wheel running. We explored gait differences between HR and C mice, as well as differences related to the mini-muscle phenotype, characterized by a 50% mass reduction in the triceps surae and total hindlimb muscle mass, which has increased in frequency within 2 of the 4 HR lines. The unique DigiGait Imaging System (Mouse Specifics Inc) captured and analyzed high-speed, high-resolution, ventral-plane videos, and automatically calculated over 30 metrics of posture and locomotion to characterize the gait. Young adult mice were tested on the DigiGait treadmill at speeds of 30, 50, 70 and 90 cm/s. After 6 days of wheel access, the mice were retested. We analyzed several characteristics of gait, including stride length, stride frequency, stance width, and paw area using a nested ANCOVA with body size as a covariate. Preliminary analyses indicate that HR mice have decreased stance width following wheel access, mini-muscle mice have a larger paw area following wheel access than normal-muscled HR or C mice, the relative size of male and female paw areas changes with wheel access, and males take longer, less frequent strides . Supported by NSF GRFP to GC and IOS-1121273 to TG.
