Muscle IGF-I Ea, MGF, and myostatin mRNA expressions after compensatory overload in hypophysectomized rats.
To determine whether IGF-I Ea, MGF, and myostatin mRNAs are related to GH-independent overload-induced muscle growth, we examined the expressions of IGF-I Ea and MGF mRNAs in the plantaris muscle after compensatory overload in hypophysectomized rats. The muscles were divided into four groups: normal-control, normal-overloaded, hypophysectomized-control, and hypophysectomized-overloaded. The weights of the plantaris muscle in the normal-overloaded were significantly higher than those of the normal-control. The weights of the hypophysectomized-overloaded were also significantly higher than those of the hypophysectomized-control. IGF-I Ea and MGF mRNAs in normal-overloaded and hypophysectomized-overloaded 3 days after overload were significantly higher than those of normal-control and hypophysectomized-control, respectively. Myostatin mRNAs in normal-overloaded and hypophysectomized-overloaded 3 days after the overload were significantly lower than those of normal-control and hypophysectomized-control, respectively. Thus, it was shown that IGF-I Ea, MGF, and myostatin mRNAs were expressed in association with muscle enlargement after compensatory overload independently of pituitary state. These observations suggest that the expression of IGF-I Ea, MGF, and myostatin mRNAs due to compensatory overload would be associated in a growth-hormone-independent manner.
Yamaguchi
Akihiko
A
School of Dentistry, Health Sciences University of Hokkaido, Kanazawa, Ishikari-Tobetsu, Hokkaido, Japan. yama@hoku-iryo-u.ac.jp
Fujikawa
Takahiko
T
Shimada
Seita
S
Kanbayashi
Isao
I
Tateoka
Masaru
M
Soya
Hideaki
H
Takeda
Hidekatsu
H
Morita
Isao
I
Matsubara
Kunio
K
Hirai
Toshihiro
T
D000818:Animals; D015870:Gene Expression; D007016:Hypophysectomy; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D024510:Muscle Development / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism*; D055435:Myostatin; D051381:Rats; D017208:Rats, Wistar; D016212:Transforming Growth Factor beta / Q000378:metabolism*
C525913:Mstn protein, rat; D055435:Myostatin; D016212:Transforming Growth Factor beta; C519382:mechano-growth factor, rat; D007334:Insulin-Like Growth Factor I