Response of the Neuromuscular Unit to Spaceflight: What Has Been Learned from the Rat Model

  title={Response of the Neuromuscular Unit to Spaceflight: What Has Been Learned from the Rat Model},
  author={Roland R. Roy and Kenneth M. Baldwin and V. Reggie Edgerton},
  journal={Exercise and Sport Sciences Reviews},
Despite the inherent limitations placed on spaceflight investigations, much has been learned about the adaptations of the neuromuscular system to weightlessness from studies of rats flown for relatively short periods (approximately 4-22 days). Below is a summary of the major effects of spaceflight observed in muscles of rats that are not in their rapid growth stage: 1. Skeletal muscles atrophy rapidly during spaceflight; significant atrophy is observed as early as after 4 days of flight. 2. The… Expand
Survey of studies on how spaceflight affects rodent skeletal muscle.
These studies repeatedly confirm that exposure to spaceflight decreases the mass of limb muscles and leads to muscle atrophy, and substantial redundancy and inconsistencies are identified. Expand
Recovery of neuromuscular junction morphology following 16 days of spaceflight
The results suggest that the neuromuscular system possesses a robust capacity to recover from spaceflight‐induced perturbations upon return to normal gravitational influences. Expand
Neuromuscular adaptations to spaceflight are specific to postural muscles
The findings suggest that the deleterious effects of microgravity are most apparent among postural muscles, and are manifested both in myofibers and their synapses. Expand
Effects of spaceflight on murine skeletal muscle gene expression.
It is demonstrated that spaceflight induces significant changes in mRNA expression of genes associated with muscle growth and fiber type, as well as a significant decrease in levels of the microRNA miR-206. Expand
Effects of spaceflight on rhesus quadrupedal locomotion after return to 1G.
Adaptations in tendon force and EMG amplitude ratios indicate that the nervous system undergoes a reorganization of the recruitment patterns biased toward an increased recruitment of fast versus slow motor units and flexor versus extensor muscles. Expand
Comparison of soleus muscles from rats exposed to microgravity for 10 versus 14 days
Comparing the effects of two different duration spaceflights on the extent of atrophy, fiber type composition, and myosin heavy chain (MHC) content of rat soleus muscles were compared suggested fast-to-faster transformations continued during the longer spaceflight. Expand
Electrophysiological, histochemical, and hormonal adaptation of rat muscle after prolonged hindlimb suspension.
The data suggested that muscles atrophied, but they presented an adaptation pattern, while their endurance in fatigue was decreased, and there was a shift from oxidative to glycolytic metabolism during HLS. Expand
Metabolic and morphological stability of motoneurons in response to chronically elevated neuromuscular activity
It appears that the spinal motoneurons, unlike the muscle fibers, are highly stable over a wide range of levels of chronic neuromuscular activity. Expand
Effects of 14 days of microgravity on fast hindlimb and diaphragm muscles of the rat
Similar to data gathered following a 10-day spaceflight, the 14-day flight did not appear to cause significant slow-to-fast (I → IIA) or fast- to-faster (IIA →-IID →–IIB) transformations in hindlimb muscles containing predominantly fast-twitch fibers, however, the longer period of gravitational unloading did result in additional loss in muscle fiber cross-sectional area with involvement of more major fiber types. Expand
Comparison of knee motion on Earth and in space: an observational study
Overall knee-joint motion is reduced, and there is a transformation in the type of muscle action compared to that seen on Earth, with more isometric action at the expense of concentric and particularly eccentric action. Expand