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Myonuclear apoptosis occurs in regenerative process following eccentric contractions in rats
Author(s) -
Sudo Mizuki,
Kano Yutaka
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.962.6
Subject(s) - tunel assay , apoptosis , dapi , chemistry , regeneration (biology) , myofibril , inflammation , anatomy , pathology , microbiology and biotechnology , andrology , medicine , biology , biochemistry
Eccentric contractions (ECC) induce myofibrillar collapse, edema and inflammation. Although apoptosis of myonuclei following ECC are activated at inflammatory phase, the apoptosis response of regenerative phase remains to be elucidated. The aim of present study was to determine the inflammatory and regenerative phase of the apoptosis responses induced by ECC. In anesthetized rats, the tibialis anterior muscles were subjected to 40 times‐repeated ECC, which was evoked by surface electric stimulation (100Hz, 10V) with mechanical muscle stretch. The apoptosis was examined control, 1, 3, 7 and 14 d after ECC (n = 4). Identified TUNEL‐positive myonuclei were assessed by triple labeling with dystrophin staining, TUNEL assay and DAPI. At 1 and 3 d, focal edema and necrotic fibers invaded by mononuclear phagocytes were recognized. The regenerated fibers with central nucleus were detected at 7 and 14 d. TUNEL‐positive myonuclei were significantly increased at 7 and 14 d compared with control (7 d:7.0 ± 1.5%, 14 d:3.8 ± 1.1%, P < 0.05, respectively, % of total myonuclei, mean ± SE). Further we found that myonuclear apoptosis was located in subsarcolemma rather than central nucleus at 7 and 14 d. In conclusion, apoptosis responses in myocyte generate not only inflammatory phase but also regenerative process after ECC.