Expression of heat shock protein 72 in atrophied rat skeletal muscles.
Changes in the expression of heat shock protein 72 (HSP72) in response to atrophic-inducing perturbations of muscle involving chronic mechanical unloading and denervation were determined. Adult male Wistar rats were assigned randomly to a sedentary cage control (CON), hind limb unloading (HU, via tail suspension), HU plus tenotomy (HU + TEN), HU plus denervation (HU + DEN), or HU + TEN + DEN group. Tenotomy and DEN involved cutting the Achilles tendon and removing a segment of the sciatic nerve, respectively. After 5 days, HSP72 levels in the soleus of the HU + DEN and HU + TEN + DEN groups were 42 (P < 0.05) and 53% (P < 0.01) less than CON, respectively. Soleus weight decreased in both groups. Heat shock protein 72 levels in the plantaris of the HU + TEN, HU + DEN, and HU + TEN + DEN groups were 31, 25, and 30% lower than CON, respectively (P < 0.05). Plantaris weight decreased in the HU + DEN and HU + TEN + DEN, but not in the HU + TEN group. Hind limb unloading alone had little effect on the HSP72 level in either muscle. Reduced levels of HSP72 were associated with a decreased soleus (r=0.62, P < 0.01) and plantaris (r=0.78, P < 0.001) weight. These results indicate that the levels of HSP72 in both a slow and a fast rat plantarflexor are responsive to a chronic decrease in the levels of loading and/or activation and suggest that the neuromuscular activity level and the presence of innervation of a muscle are important factors that induce HSP72 expression.
Oishi
Y
Y
Laboratory of Muscle Physiology, Faculty of Education, Kumamoto University, Japan. oishi@gpo.kumamoto-u.ac.jp
Ishihara
A
A
Talmadge
R J
RJ
Ohira
Y
Y
Taniguchi
K
K
Matsumoto
H
H
Roy
R R
RR
Edgerton
V R
VR
D000125:Achilles Tendon / Q000601:surgery; D000818:Animals; D001284:Atrophy / Q000378:metabolism* / Q000473:pathology; D015153:Blotting, Western; D001835:Body Weight; D003714:Denervation; D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000096:biosynthesis*; D019417:Hindlimb Suspension; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009929:Organ Size; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012584:Sciatic Nerve / Q000601:surgery; D016474:Weight-Bearing / Q000502:physiology
D050884:HSP72 Heat-Shock Proteins; D006360:Heat-Shock Proteins