Abstract
Aims: Glucocorticoids bindtothe glucocorticoid receptor (GR) and increase catabolismof muscle proteins via the ubiquitin-proteasome pathway. Activation of β 2-adrenergic receptor (β 2-AR) in skeletal muscle has been shown to induce muscle hypertrophy by promoting muscle protein synthesis and/or attenuating protein degradation. The aim of this study was to investigate the correlation between disuse-induced muscle atrophy, and expression of GR and β 2-AR. Methods: Rats were subjected to casted-immobilization (knee and foot arthrodesis), a model for muscle disuse, for 10 days. Fast-twitch (extensor digitorum longus: EDL) and slow-twitch (soleus: SOL) muscles were isolated and subsequently used for analysis. The expression of GR and β 2-AR was analyzed by real-time RT-PCR and western blotting. In addition, we analyzed plasma catecholamine and corticosterone concentrations by ELISA. Key findings: Casted-immobilization- induced muscle atrophy was much greater in the SOL muscle than in the EDL muscle. Casted-immobilization decreased the expression of GR mRNA and protein in the SOL muscle but not in the EDL muscle. Although the expression of β 2-AR protein in the cytosol and membrane-rich fractions was not changed by casted-immobilization in either muscle, casted-immobilization decreased the expression of β 2-AR mRNA in the SOL muscle. Plasma catecholamine and corticosterone concentrations, however, were largely unaffected by casted-immobilization during the experimental period. Significance: This study provides evidence that casted-immobilization-induced muscle disuse downregulates GR expression in slow-twitch muscle. These results suggest that muscle disuse suppresses glucocorticoid signals, such as muscle protein breakdown and transcription of the β 2-AR gene, via downregulation of GR expression in slow-twitch muscle.
| Original language | English |
|---|---|
| Pages (from-to) | 962-967 |
| Number of pages | 6 |
| Journal | Life Sciences |
| Volume | 89 |
| Issue number | 25-26 |
| DOIs | |
| Publication status | Published - 2011 Dec 19 |
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Keywords
- Glucocorticoid receptor β - adrenergic receptor
- Immobilization
- Muscle atrophy
ASJC Scopus subject areas
- Pharmacology, Toxicology and Pharmaceutics(all)
- Biochemistry, Genetics and Molecular Biology(all)
Cite this
Casted-immobilization downregulates glucocorticoid receptor expression in rat slow-twitch soleus muscle. / Sato, Shogo; Suzuki, Hideki; Tsujimoto, Hisaya; Shirato, Ken; Tachiyashiki, Kaoru; Imaizumi, Kazuhiko.
In: Life Sciences, Vol. 89, No. 25-26, 19.12.2011, p. 962-967.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Casted-immobilization downregulates glucocorticoid receptor expression in rat slow-twitch soleus muscle
AU - Sato, Shogo
AU - Suzuki, Hideki
AU - Tsujimoto, Hisaya
AU - Shirato, Ken
AU - Tachiyashiki, Kaoru
AU - Imaizumi, Kazuhiko
PY - 2011/12/19
Y1 - 2011/12/19
N2 - Aims: Glucocorticoids bindtothe glucocorticoid receptor (GR) and increase catabolismof muscle proteins via the ubiquitin-proteasome pathway. Activation of β 2-adrenergic receptor (β 2-AR) in skeletal muscle has been shown to induce muscle hypertrophy by promoting muscle protein synthesis and/or attenuating protein degradation. The aim of this study was to investigate the correlation between disuse-induced muscle atrophy, and expression of GR and β 2-AR. Methods: Rats were subjected to casted-immobilization (knee and foot arthrodesis), a model for muscle disuse, for 10 days. Fast-twitch (extensor digitorum longus: EDL) and slow-twitch (soleus: SOL) muscles were isolated and subsequently used for analysis. The expression of GR and β 2-AR was analyzed by real-time RT-PCR and western blotting. In addition, we analyzed plasma catecholamine and corticosterone concentrations by ELISA. Key findings: Casted-immobilization- induced muscle atrophy was much greater in the SOL muscle than in the EDL muscle. Casted-immobilization decreased the expression of GR mRNA and protein in the SOL muscle but not in the EDL muscle. Although the expression of β 2-AR protein in the cytosol and membrane-rich fractions was not changed by casted-immobilization in either muscle, casted-immobilization decreased the expression of β 2-AR mRNA in the SOL muscle. Plasma catecholamine and corticosterone concentrations, however, were largely unaffected by casted-immobilization during the experimental period. Significance: This study provides evidence that casted-immobilization-induced muscle disuse downregulates GR expression in slow-twitch muscle. These results suggest that muscle disuse suppresses glucocorticoid signals, such as muscle protein breakdown and transcription of the β 2-AR gene, via downregulation of GR expression in slow-twitch muscle.
AB - Aims: Glucocorticoids bindtothe glucocorticoid receptor (GR) and increase catabolismof muscle proteins via the ubiquitin-proteasome pathway. Activation of β 2-adrenergic receptor (β 2-AR) in skeletal muscle has been shown to induce muscle hypertrophy by promoting muscle protein synthesis and/or attenuating protein degradation. The aim of this study was to investigate the correlation between disuse-induced muscle atrophy, and expression of GR and β 2-AR. Methods: Rats were subjected to casted-immobilization (knee and foot arthrodesis), a model for muscle disuse, for 10 days. Fast-twitch (extensor digitorum longus: EDL) and slow-twitch (soleus: SOL) muscles were isolated and subsequently used for analysis. The expression of GR and β 2-AR was analyzed by real-time RT-PCR and western blotting. In addition, we analyzed plasma catecholamine and corticosterone concentrations by ELISA. Key findings: Casted-immobilization- induced muscle atrophy was much greater in the SOL muscle than in the EDL muscle. Casted-immobilization decreased the expression of GR mRNA and protein in the SOL muscle but not in the EDL muscle. Although the expression of β 2-AR protein in the cytosol and membrane-rich fractions was not changed by casted-immobilization in either muscle, casted-immobilization decreased the expression of β 2-AR mRNA in the SOL muscle. Plasma catecholamine and corticosterone concentrations, however, were largely unaffected by casted-immobilization during the experimental period. Significance: This study provides evidence that casted-immobilization-induced muscle disuse downregulates GR expression in slow-twitch muscle. These results suggest that muscle disuse suppresses glucocorticoid signals, such as muscle protein breakdown and transcription of the β 2-AR gene, via downregulation of GR expression in slow-twitch muscle.
KW - Glucocorticoid receptor β - adrenergic receptor
KW - Immobilization
KW - Muscle atrophy
UR - http://www.scopus.com/inward/record.url?scp=84865718012&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84865718012&partnerID=8YFLogxK
U2 - 10.1016/j.lfs.2011.10.008
DO - 10.1016/j.lfs.2011.10.008
M3 - Article
C2 - 22036623
AN - SCOPUS:84865718012
VL - 89
SP - 962
EP - 967
JO - Life Sciences
JF - Life Sciences
SN - 0024-3205
IS - 25-26
ER -