Year-end Sale % OFF 
Abstract
High-frequency, low-magnitude vibration enhances bone formation ostensibly by mimicking normal postural muscle activity. We tested this hypothesis by examining whether daily exposure to low-magnitude vibration (VIB) would maintain bone in a muscle disuse model with botulinum toxin type A (BTX). Female 16–18 wk old BALB/c mice (N = 36) were assigned to BTX-VIB, BTX-SHAM, VIB, or SHAM. BTX mice were injected with BTX (20 µL; 1 U/100 g body mass) into the left hindlimb posterior musculature. All mice were anaesthetized for 20 min/d, 5 d/wk, for 3 wk, and the left leg mounted to a holder. Through the holder, VIB mice received 45 Hz, ±0.6 g sinusoidal acceleration without weight bearing. SHAM mice received no vibration. At baseline and 3 wk, muscle cross-sectional area (MCSA) and tibial bone properties (epiphysis, metaphysis and diaphysis) were assessed by in vivo micro-CT. Bone volume fraction in the metaphysis decreased 12±9% and 7±6% in BTX-VIB and BTX-SHAM, but increased in the VIB and SHAM. There were no differences in dynamic histomorphometry outcomes between BTX-VIB and BTX nor between VIB and SHAM. Thus, vibration did not prevent bone loss induced by a rapid decline in muscle activity nor produce an anabolic effect in normal mice. The daily loading duration was shorter than would be expected from postural muscle activity, and may have been insufficient to prevent bone loss. Based on the approach used in this study, vibration does not prevent bone loss in the absence of muscle activity induced by BTX.
Highlights
High strain magnitudes (.1000 me) and strain rates are well documented characteristics of an osteogenic mechanical stimulus [1,2]
Strain Measurement A sinusoidal, 45 Hz vibration signal with 60.6 g acceleration induced peak-to-peak strains of 5.860.3 me with a mean of zero on the proximal tibia recorded in several trials on two mice (Figure 3A)
We found that 20 minutes of daily exposure to high-frequency, low-magnitude vibration did not prevent muscle and bone loss associated with botulinum toxin type A (BTX) injection in BALB mice
Summary
High strain magnitudes (.1000 me) and strain rates are well documented characteristics of an osteogenic mechanical stimulus [1,2]. The application of low-magnitude vibratory stimuli to prevent bone loss was initiated, in part, due to the high prevalence of low strain magnitude events observed in bone during daily activities [5]. There is an inverse, nonlinear relation between the incidence of events and magnitude of strain that maintain bone mass, suggesting that loading regimes performed at a sufficiently large number of cycles per day, at lower strain magnitudes may elicit an osteogenic response [6]. These findings suggested that low-magnitude, rather than high-magnitude, strain events can drive osteogenesis and perhaps prevent bone loss
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
