Time-course of changes in the myonuclear domain during denervation in young-adult and old rat gastrocnemius muscle.
If myonuclear loss initiates muscle wasting, it should precede the loss of muscle mass. As aging affects muscle plasticity, the time-course of muscle atrophy during disuse may differ between young and old animals. To investigate this, gastrocnemius muscles of 5- and 25-month-old rats were exposed to 1, 2, or 4 weeks of denervation, whereas the contralateral gastrocnemius muscles served as controls. Muscle fibers of each type responded similarly to 4 weeks of denervation. For both ages most of the atrophy (36%; P < 0.001) occurred in the first 2 weeks. In young-adult muscles, the myonuclear number remained constant, but in old muscles it decreased to below control level after 4 weeks of denervation (P < 0.05). Despite this differential response, myonuclear domain size decreased similarly at both ages (P < 0.001). In both young-adult and old rats, denervation-induced atrophy was not preceded by a loss of myonuclei.
Institute for Biomedical Research into Human Movement and Health, Manchester Metropolitan University, Manchester M1 5GD, UK. sander.vandermeer@dlr.de
Sander F T
SF
van der Meer
Richard T
RT
Jaspers
David A
DA
Jones
Hans
H
Degens
D000375:Aging; D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D002467:Cell Nucleus / Q000502:physiology* / Q000648:ultrastructure; D005786:Gene Expression Regulation; D007211:Indoles; D008297:Male; D009121:Muscle Denervation; D018485:Muscle Fibers, Skeletal / Q000473:pathology / Q000648:ultrastructure*; D018482:Muscle, Skeletal / Q000294:innervation* / Q000378:metabolism; D009218:Myosins / Q000378:metabolism; D009929:Organ Size / Q000502:physiology; D051761:Paired Box Transcription Factors / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D032496:Satellite Cells, Skeletal Muscle / Q000473:pathology / Q000648:ultrastructure; D013997:Time Factors; D014909:Wheat Germ Agglutinins / Q000378:metabolism
D007211:Indoles; C530821:PAX7 protein, rat; D051761:Paired Box Transcription Factors; D014909:Wheat Germ Agglutinins; C007293:DAPI; D009218:Myosins