Proceedings of The Physiological Society

Europhysiology 2018 (London, UK) (2018) Proc Physiol Soc 41, PCB292

Poster Communications

Pathological changes in muscle signaling mechanisms in muscle contractures of children with cerebral palsy

J. Pingel1, M. Kampmann2, J. Andersen2, C. Wong3, C. Børsting2, J. Nielsen1

1. Department of Neuroscience, University of Copenhagen, Copenhagen N, Denmark. 2. Section of Forensic Genetics, Department of Forensic Medicine, University of Copenhagen, Copenhagen, Denmark. 3. Department of Orthopedic Surgery, Copenhagen University Hospital Hvidovre, Hvidovre, Denmark.

Background: Cerebral palsy (CP) is a non-progressive motor disorder that affects the posture and gait of the patients. One major complication in CP is the development of muscle contractures. The mechanisms behind contractures are still poorly understood. Aim: The aim of the present study was to elaborate whether specific signaling pathways in the muscle are correlated to increased passive stiffness and reflex activity in CP when compared with typical developing children (TD), and further to investigated sarcomere length and possible mitochondrial mutations in both groups. Methods: Next Generation Sequencing of 92 candidate targets was performed in muscle biopsies from the m. Gastrochnemius muscle in n=10 children with CP and n=10 TD children. In addition, stretch reflexes and passive stiffness was measured in the lower legs. The sarcomere length was measured using electron microscopy and the mitochondria were also sequenced in all samples. All participants gave informed consent and the protocol was approved by the Regional Ethics Committee for Copenhagen (H-4-2014-047), and the protocol was in compliance with the Helsinki Declaration. Results: The sequencing results from all candidate genes are shown if Figure 1. The red colour indicates a downregulation of the target in children with CP while the green colour indicates an upregulation in CP when compared to TD children. Passive stiffness was significantly correlated to mRNA expressions of HSPG2 (p=0.02; R2=0.67), PRELP (p=0.002; R2=0.84), RYR3 (p=0.04; R2=0.66), COL5A3 (p=0.0007; R2=0.88), ASPH (p=0.002; R2=0.82) and COL4A6 (p=0.03; R2=0.97). In addition the reflex activity was significantly correlated to mRNA expressions of HSPG2 (p=0.02; R2=0.67), LAMc1 (p=0.04; R2=0.69) and COL4A6 (p=0.05; R2=0.96). Furthermore, the sarcomere length was significantly increased in children with CP when compared with TD (p=0.04). Subsequently children with CP showed more pathogenic variants in the mitochondria compared to TD children (variants shown as variants in total) , especially in COII (CP=11; TD=4), COIII (CP=11; TD=6) and ATPase6 (CP=10; TD=5). Conclusion: The present study shows that some of the investigated targets potentially might be associated to the severity of passive stiffness and reflex activity in cerebral palsy. Perspectives: The cause and effect between the expression of certain genes and muscle stiffness still has to be proven in order to create a better treatment for muscle contractures. Funding This project was funded by the Danish research Council (DFF-1333-00197), and the Elsass Foundation.

Where applicable, experiments conform with Society ethical requirements