title: Morphological and histological adaptation of muscle and bone to loading induced by repetitive activation of muscle.
abstract: Muscular contraction plays a pivotal role in the mechanical environment of bone, but controlled muscular contractions are rarely used to study the response of bone to mechanical stimuli. Here, we use implantable stimulators to elicit programmed contractions of the rat tibialis anterior (TA) muscle. Miniature stimulators were implanted in Wistar rats (n = 9) to induce contraction of the left TA every 30 s for 28 days. The right limb was used as a contralateral control. Hindlimbs were imaged using microCT. Image data were used for bone measurements, and to construct a finite-element (FE) model simulation of TA forces propagating through the bone. This simulation was used to target subsequent bone histology and measurement of micromechanical properties to areas of high strain. FE mapping of simulated strains revealed peak values in the anterodistal region of the tibia (640 µε ± 30.4 µε). This region showed significant increases in cross-sectional area (28.61%, p < 0.05) and bone volume (30.29%, p < 0.05) in the stimulated limb. Histology revealed a large region of new bone, containing clusters of chondrocytes, indicative of endochondral ossification. The new bone region had a lower elastic modulus (8.8 ± 2.2 GPa) when compared with established bone (20 ± 1.4 GPa). Our study provides compelling new evidence of the interplay between muscle and bone.
authors: Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK.
authors: Paula
authors: P
authors: Vickerton
authors: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Merseyside, Liverpool L3 3AF, UK.
authors: Jonathan C
authors: JC
authors: Jarvis
authors: Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK.
authors: James A
authors: JA
authors: Gallagher
authors: Centre for Materials and Structures, School of Engineering, University of Liverpool, Merseyside, Liverpool L69 3GH, UK.
authors: Riaz
authors: R
authors: Akhtar
authors: Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Merseyside, Liverpool L3 3AF, UK.
authors: Hazel
authors: H
authors: Sutherland
authors: Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Sherrington Building, Ashton Street, Liverpool L69 3GE, UK njeffery@liverpool.ac.uk.
authors: Nathan
authors: N
authors: Jeffery
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D003198:Computer Simulation; D055119:Elastic Modulus; D004558:Electric Stimulation; D008297:Male; D008954:Models, Biological; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013977:Tibia / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D055114:X-Ray Microtomography
keywords: bone; loading; mechanotransduction; muscle electrical stimulation