Abstract
BackgroundWhole-body vibration has been suggested for the prevention of muscle mass loss and muscle wasting as an attractive measure for disuse atrophy. This study examined the effects of daily intermittent whole-body vibration and weight bearing during hindlimb suspension on capillary number and muscle atrophy in rat skeletal muscles.MethodsSixty male Wistar rats were randomly divided into four groups: control (CONT), hindlimb suspension (HS), HS + weight bearing (WB), and HS + whole-body vibration (VIB) (n = 15 each). Hindlimb suspension was applied for 2 weeks in HS, HS + WB, and HS + VIB groups. During suspension, rats in HS + VIB group were placed daily on a vibrating whole-body vibration platform for 20 min. In HS + WB group, suspension was interrupted for 20 min/day, allowing weight bearing. Untreated rats were used as controls.ResultsSoleus muscle wet weights and muscle fiber cross-sectional areas (CSA) significantly decreased in HS, HS + WB, and HS + VIB groups compared with CONT group. Both muscle weights and CSA were significantly greater in HS + WB and HS + VIB groups compared with HS group. Capillary numbers (represented by capillary-to-muscle fiber ratio) were significantly smaller in all hindlimb suspension-treated groups compared with CONT group. However, a reduction in capillary number by unloading hindlimbs was partially prevented by whole-body vibration. These findings were supported by examining mRNA for angiogenic-related factors. Expression levels of a pro-angiogenic factor, vascular endothelial growth factor-A mRNA, were significantly lower in all hindlimb suspension-treated groups compared with CONT group. There were no differences among hindlimb suspension-treated groups. Expression levels of an anti-angiogenic factor, CD36 (receptor for thrombospondin-1) mRNA, were significantly higher in all hindlimb suspension-treated groups compared with CONT group. Among the hindlimb suspension-treated groups, expression of CD36 mRNA in HS + VIB group tended to be suppressed (less than half the HS group).ConclusionsOur results suggest that weight bearing with or without vibration is effective for disuse-derived disturbance by preventing muscle atrophy, and whole-body vibration exercise has an additional benefit of maintaining microcirculation of skeletal muscle.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-315) contains supplementary material, which is available to authorized users.
Highlights
Whole-body vibration has been suggested for the prevention of muscle mass loss and muscle wasting as an attractive measure for disuse atrophy
Compared with the CONT group, the relative weights of soleus muscles in hindlimb suspension (HS), HS + weight bearing (WB), and HS + VIB groups were significantly reduced by 46%, 37%, and 37%, respectively
Protein at 14 days after the hindlimb suspension [33]. These results suggest that attenuation of vascular endothelial growth factor-A (VEGF-A)/vascular endothelial growth factorreceptor 2 (VEGF-R2) signaling contributed to the reduction in capillary number induced by hindlimb suspension in this study
Summary
Whole-body vibration has been suggested for the prevention of muscle mass loss and muscle wasting as an attractive measure for disuse atrophy. This study examined the effects of daily intermittent whole-body vibration and weight bearing during hindlimb suspension on capillary number and muscle atrophy in rat skeletal muscles. Avoiding excessive bed rest and maintaining appropriate amounts of daily activity during disuse conditions can suppress the development of muscle atrophy. Other interventions, such as medication [11,12], electrical stimulation [13], and static or repetitive stretching [14,15], have been tested to see whether they are capable of counteracting muscle atrophy, and have been shown to be effective to some extent [11,12,13,14,15]. Preventive effects of vibration against disuse muscle atrophy is still controversial: vibration on Achilles tendon partially prevented muscle atrophy of unloaded muscles [17], wholebody vibration alone was not as effective at suppressing muscle atrophy as weight bearing [18], or daily intermittent whole-body vibration for 6 weeks caused a reduction in capillary number in mouse soleus muscle [19]
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