RT Journal Article SR Electronic T1 Glycine receptor subunit-ß -deficiency in a mouse model of spasticity results in attenuated physical performance, growth and muscle strength JF bioRxiv FD Cold Spring Harbor Laboratory SP 2020.07.15.180976 DO 10.1101/2020.07.15.180976 A1 Rivares, Cintia A1 Vignaud, Alban A1 Noort, Wendy A1 Koopmans, Bastijn A1 Loos, Maarten A1 Kalinichev, Mikhail A1 Jaspers, Richard T YR 2020 UL http://biorxiv.org/content/early/2020/07/15/2020.07.15.180976.abstract AB Spasticity is the most common neurological disorder associated with increased muscle contraction causing impaired movement and gait. The aim of this study was to characterize physical performance and skeletal muscle function and phenotype of mice with a hereditary spastic mutation (B6.Cg-Glrbspa/J). Motor function, gait and physical activity of juvenile and adult spastic mice and the morphological, histological and mechanical characteristics of their soleus (SO) and gastrocnemius medialis (GM) muscles were compared with their wild-type (WT) littermates. Spastic mice showed attenuated growth, impaired motor function and low physical activity. Gait of spastic mice was characterized by a typical hopping pattern. Spastic mice showed lower muscle forces, which were related to the smaller physiological cross-sectional area of spastic muscles. The muscle-tendon complex length-force relationship of adult GM was shifted towards shorter lengths, which was explained by attenuated longitudinal tibia growth. Spastic GM was more fatigue resistant than WT GM. This was largely explained by a higher mitochondrial content in muscle fibers and relatively higher percentage of slow type muscle fibers. Muscles of juvenile spastic mice showed similar differences compared to WT juvenile mice, but these were less pronounced than between adult mice. This study shows that in spastic mice, disturbed motor function and gait is likely the result hyperactivity of skeletal muscle and impaired skeletal muscle growth, which progress with age.Competing Interest StatementThe authors declare that this study received funding from Ipsen Innovation.