title: Promotion of apoptosis and cytochrome c depletion by a low-temperature environment in hindlimb-unloading rats.
abstract: OBJECTIVE
  This study aimed to clarify the influence of a low-temperature environment on muscle atrophy and apoptosis.
  
  
  METHODS
  Wistar rats were divided into four groups: two groups of hindlimb-unloading rats maintained in a normal (25°C, HU) or low-temperature (10°C, HU+LT) environment for 3 weeks and two corresponding control groups (CON; normal temperature, CON+LT; low-temperature).
  
  
  RESULTS
  The soleus muscle wet weight and muscle-to-body mass ratio were lower in the experimental groups than in the control groups. The cross-sectional areas of myofibers in the HU+LT and HU groups were significantly decreased than those in the CON and CON+LT groups. Ubiquitin ladder levels from soleus muscle lysates were significantly increased in the HU+LT group. Caspase-3-activated myofibers were observed only in the HU+LT group. Decreased cytochrome c levels were present in these caspase-3-activated myofibers. Meanwhile, cytochrome c levels were increased significantly in CON+LT rats but unchanged in HU+LT rats.
  
  
  CONCLUSIONS
  Our results suggest that apoptosis caused by hindlimb unloading at low temperatures is associated with a lack of cytochrome c in myofibers. This indicates that long-term hindlimb unloading at low temperatures did not suppress muscle atrophy. We conclude that low-temperature stimulation should not be used as a long-term treatment for preventing disuse atrophy.
authors.affiliation: Department of Physical Therapy, Faculty of Rehabilitation, Fukui College of Health Sciences, Fukui, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Nagano
authors.forename: H
authors.initials: H
authors.lastname: Hori
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D003080:Cold Temperature; D045304:Cytochromes c / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D019417:Hindlimb Suspension / Q000502:physiology*; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000201:enzymology / Q000473:pathology; D018482:Muscle, Skeletal / Q000201:enzymology / Q000503:physiopathology; D009133:Muscular Atrophy / Q000201:enzymology / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D045304:Cytochromes c