Non-invasive Physiology in Conscious Mice

Abstract

Linking gene defect to disease phenotypes in mice has become an essential step in the development of new drugs. Yet, many in vitro and in vivo assays require anaesthetic and surgery or do not reflect physiologically relevant phenomena. The effects of genes or diseases may only become apparent with stressors. Here, we apply non-invasive ECG monitoring and gait imaging systems to describe changes in the electrocardiogram and in gait dynamics resulting from a doubling of the ambulatory speed of mice. We found that B6C3H mice (n = 5) take 3.6 ± 0.1 strides/second to walk 18cm/second and have a heart rate of 750 ± 2bpm after 1 minute of walking at this speed. These mice significantly increase stride frequency to 5.2 ± 0.1 strides/second in order to increase their speed to 36cm/second. The heart rate increased significantly (814 ± 9bpm, p < 0.05) after trotting at the higher speed for 90 seconds, and the QRS interval duration significantly decreased (9.4 ± 0.3ms vs. 10.4 ± 0.3ms, p < 0.05). We discuss the application of the ECG screening and gait imaging systems to mouse models of Duchenne muscular dystrophy, Down syndrome and amyotrophic lateral sclerosis, diseases in humans that are known to affect the heart and neuromuscular systems.

Osteoporotic bone recovery by a bamboo-structured bioceramic with controlled release of hydroxyapatite nanoparticles

“…A primary characteristic of successful biomaterials for osteoporotic bone repair is their bone formation ability under in vivo pathological conditions. Animal motor behaviour analysis, especially foot placement, is often used to assess the overall functional recovery of animals as a noninvasive technique [ 48 ]. In an osteoporotic rat femur defect model, we observed that the stride lengths of all groups were dramatically decreased one week after implantation, indicating severely impaired motor function after bone injury [ 49 ].…”

Phenotypic analysis of ataxia in spinocerebellar ataxia type 6 mice using DeepLabCut

“…BAS was developed to count paw slips comparable to a human rater, as well as analyze detailed gait parameters not typically investigated in the beamwalk test. It therefore sets itself apart from what one may obtain from performing the analysis with programs that target only gait parameters such as Visual Gait Lab 24 , LocoMouse 7 and DigiGait 4 . As these were developed to process videos of animals freely walking in arenas or on a treadmill where paw slips would not occur, it is highly unlikely that they could provide a proper analysis of paw slips.…”