S-myotrophin promotes the hypertrophy of skeletal muscle of mice in vivo.
S-myotrophin is a newly discovered muscle growth factor. Effects of crude S-myotrophin injection on the growth and morphology of skeletal muscle of normal, ScN and mdx mice were investigated in the present study. Total dose of crude S-myotrophin was 100 microg (100 microg protein/ml x 50 microl x 20 times). In the case of normal mice (Sea:ddY), body weight and the weight of M. gluteus major of crude S-myotrophin injected mice was significantly heavier than that of control (PBS-injected) mice after 5 weeks' feeding. Antibody staining of laminin and dystrophin showed clear sarcolemmal and basement membrane structure surrounding each muscle fibre. The numbers of muscle fibres per 100 microm(2) was less in crude S-myotrophin-injected normal mice than in PBS-injected mice. Quite similar observations as in the case of normal mice were obtained in the case of ScN mice having heterogeneous gene of dystrophin. In the case of mdx mice, body weight and the weight of M. gluteus major of crude S-myotrophin injected mdx mice was significantly heavier than that of PBS-injected mdx mice. Antibody staining of laminin showed almost intact structure of the basement membrane containing laminin even in skeletal muscle of mdx mice subjected to crude S-myotrophin injection, while irregular and incompletely developed structure of muscle fibres or necrosis were observed in muscle fibres of PBS-injected mdx mice. In spite of crudeness of the preparation, the present animal experiments indicate that S-myotrophin has a strong growth promoting activity of muscle cells of normal and dystrophic mice.
Laboratory of Chemistry and Technology of Animal Products, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-Ward, Fukuoka 812-8581, Japan.
Shohei
S
Shiraishi
Yoshi-Nori
YN
Nakamura
Hisao
H
Iwamoto
Atsushi
A
Haruno
Yusuke
Y
Sato
Sunao
S
Mori
Yoshihide
Y
Ikeuchi
Jiro
J
Chikushi
Toshiya
T
Hayashi
Masamichi
M
Sato
Robert G
RG
Cassens
Tatsumi
T
Ito
D000818:Animals; D001835:Body Weight / Q000187:drug effects; D016189:Dystrophin / Q000235:genetics / Q000378:metabolism; D006984:Hypertrophy / Q000139:chemically induced; D036341:Intercellular Signaling Peptides and Proteins / Q000302:isolation & purification / Q000378:metabolism* / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D018482:Muscle, Skeletal / Q000187:drug effects / Q000254:growth & development* / Q000473:pathology*; D009137:Muscular Dystrophy, Animal / Q000235:genetics / Q000378:metabolism
D016189:Dystrophin; D036341:Intercellular Signaling Peptides and Proteins; C065700:myotrophin