Influence of locomotor training on the structure and myosin heavy chains of the denervated rat soleus muscle.
OBJECTIVE
Mechanism of denervation atrophy remains poorly understood. In particular, the question about irreversibility of the late atrophy is still open. Therefore, in the present study, we investigated whether and how a passive movement can affect a progress of atrophy in rat soleus muscle. To address this issue, a locomotor training on a treadmill was applied to rats with their right hindlimb muscles denervated.


METHODS
The hindlimb muscles were denervated by cutting the sciatic nerve. Starting either 7 days or 1 month after the surgery, the animals were trained on a treadmill. Two months after denervation, the soleus muscle was investigated using light and electron microscopy and biochemical methods. Control soleus muscles were obtained from non-trained animals: the untreated and the 2-month denervated.


RESULTS
Locomotor training caused slight increase in denervated rat soleus muscle weight and significant increase in its fiber diameter. The training positively affected some of the factors that were believed to be the reasons of atrophy irreversibility, because of significant increase in the number of capillary blood vessels and muscle fiber nuclei with the concomitant decrease in the number of severely damaged muscle fibers and amount of collagen. Morphology of the contractile apparatus was also improved as more regular organization of sarcomeres and the hexagonal arrangement of myosin filaments was evident. Moreover, the amount of myosin heavy chains (MHC) significantly increased after training. The effects were more evident in the animals with longer training.


CONCLUSIONS
Passive movement seems to attenuate some of the pathologic processes within the denervated muscle.
Jakubiec-Puka
Anna
A
Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland. annajakubiec@o2.pl
Sławińska
Urszula
U
Redowicz
Maria J
MJ
Biral
Donatella
D
Łapińska
Irena
I
Chomontowska
Hanna
H
Karczewska
Emilia
E
Krawczyk
Kazimierz
K
Bilski
Henryk
H
Pliszka
Barbara
B
D000818:Animals; D002452:Cell Count; D005260:Female; D008124:Locomotion / Q000502:physiology*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009121:Muscle Denervation; D018482:Muscle, Skeletal / Q000737:chemistry / Q000294:innervation* / Q000378:metabolism* / Q000648:ultrastructure; D009210:Myofibrils / Q000473:pathology; D018995:Myosin Heavy Chains / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors
D018995:Myosin Heavy Chains