Elsevier

Sleep Medicine

Volume 14, Supplement 1, December 2013, Page e262
Sleep Medicine

Sleep deprivation impairs functional muscle recovery following injury

https://doi.org/10.1016/j.sleep.2013.11.638Get rights and content

Introduction

Skeletal muscles possess the ability to completely regenerate following muscular injury. Sleep is believed to play an important role in this regenerative process; however, the nature of this role has not been previously tested. Our aim was to investigate the effects of sleep deprivation on molecular, histological and functional indices of muscle repair following myotoxic injury.

Materials and methods

Male rats were injected with 1.5% bupivacaine into the masseter muscle to induce myotoxic damage. Subjects were either sleep deprived for 8 h during the light period using a forced locomotion activity wheel, or served as activity controls. They were subsequently sacrificed at 2, 7 or 14 days post-injection. Western Blot analysis was used to assay for protein expression of positive (MyoD, myogenin) and negative (myostatin) molecular repair markers. Evans Blue Dye staining for damaged muscle fibres was used to examine histopathology. Functional muscle repair was evaluated after 2 weeks using in situ contractility testing to measure the force–frequency relationship during isometric contractions.

Results

Sleep deprivation suppressed MyoD protein levels in the masseter at 2 and 7 days, and myogenin at 2 days post-injection, compared to activity controls. Myostatin levels were unaffected. Histopathology revealed no effect of sleep deprivation on the extent of muscle fibre degeneration following injury. The force-frequency curve tended to shift downward and to the right in response to sleep loss, indicating compromised contractile force at moderate to high stimulation frequencies.

Conclusion

We demonstrate that sleep loss impairs functional recovery of the masseter muscle following myotoxic injury. Specifically, 8 h of sleep deprivation acutely downregulated molecular markers of muscle repair and resulted in contractile function deficits during recovery. Together, these findings suggest that sleep normally plays a permissive role in the regeneration of damaged muscle tissue.

Acknowledgements

PS thanks the National Sciences and Engineering Research Council of Canada (NSERC) for his Ph.D. funding. This research is supported by funds from Canadian Institutes of Health Research (CIHR) and NSERC.

References (0)

Cited by (0)

View full text