Repetitive stretch induces c-fos and myogenin mRNA within several hours in skeletal muscle removed from rats.
OBJECTIVE
To investigate what effect repetitive stretch has on gene transcription in muscle tissues removed from rats.


METHODS
Case-control study.


METHODS
University laboratory.


METHODS
Eight female 8-week-old Wistar rats.


METHODS
Rat anterior tibial and soleus muscles were removed and repetitively stretched about 20% of the muscle length by using the Magnus method in Krebs-Ringer solution. Stretch-relax cycles 15 times per minute were continued for 2 hours in 1 group and 4 hours in another group. Contralateral muscles removed from the same rat were incubated without stretch as the control.


METHODS
After repetitive stretch, total ribonucleic acid (RNA) was extracted from the muscles and Northern blotting was carried out using c-fos and myogenin oligonucleotide as probes.


RESULTS
Repetitive stretch during 2 hours significantly increased the expression of c-fos messenger RNA (mRNA) in both the tibialis anterior and soleus muscles. Increased expression of myogenin mRNA in both muscles was observed with repetitive stretch for 4 hours. Because of the initial increase of immediate early gene c-fos mRNA and the subsequent increase of myogenic transcription factor myogenin mRNA, it appears that repetitive muscle stretch induces sequential progression of gene transcription toward muscle hypertrophy.


CONCLUSIONS
Mechanical repetitive stretch for a few hours would be one of the stimulating factors for muscle growth and should be available for muscle training in clinical rehabilitation.
Ikeda
Satoshi
S
Department of Rehabilitation and Physical Medicine, Faculty of Medicine, Kagoshima University, Kagoshima, Japan. ikedas@m2.kufm.kagoshima-u.ac.jp
Yoshida
Akira
A
Matayoshi
Satoru
S
Tanaka
Nobuyuki
N
D000818:Animals; D001345:Autoradiography; D015152:Blotting, Northern; D005260:Female; D005786:Gene Expression Regulation / Q000502:physiology; D066298:In Vitro Techniques; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D018008:Myogenin / Q000096:biosynthesis / Q000235:genetics; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D013314:Stress, Mechanical; D013997:Time Factors; D014158:Transcription, Genetic
C503803:Myog protein, rat; D018008:Myogenin; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger