Effects of single ingestion of arginine on mTORC1 activation in rat fast- and slow-twitch muscles
- VernacularTitle:アルギニンの単回摂取がラット骨格筋におけるmTORC1活性化に及ぼす影響
- Author:
Keita KANZAKI
1
;
Yuki YAMASAKI
1
;
Masanobu WADA
2
Author Information
- Keywords: amino acid sensing; CASTOR1; leucine; Sestrin1; nitric oxide
- From:Japanese Journal of Physical Fitness and Sports Medicine 2022;71(2):213-225
- CountryJapan
- Language:Japanese
- Abstract: This study aimed to examine whether a single ingestion of arginine activates the mammalian target of rapamycin complex 1 (mTORC1) in rat fast- and slow-twitch skeletal muscles. In the first experiment, the rats were orally administered arginine (3 or 10 mmol/kg body weight) in water. The plantaris, gastrocnemius, and soleus muscles were excised 1 h after the administration. Immunoblot analysis showed that the administration with a higher dose (10 mmol/kg) resulted in increased phosphorylation of ribosomal S6 kinase (S6K) and ribosomal protein S6 only in the soleus muscles. The amounts of cellular arginine sensor for mTORC1 subunit 1 (CASTOR1) expressed were similar in these three muscles. In the second experiment, the plantaris and soleus muscles were excised 1 h after the administration of 10 mmol/kg of arginine. The binding of CASTOR1 to the GATOR2 complex was not detected in either muscle in co-immunoprecipitation and immunoblot analyses, irrespective of arginine administration. In the third experiment, a role of nitric oxide (NO) was elucidated. Treatment with an inhibitor of NO synthase blocked the arginine-induced increase in S6K phosphorylation. These results indicate that a single ingestion of arginine is capable of activating mTORC1 only in slow-twitch muscles and suggest that the activation may be mediated via NO, but not via the CASTOR1-GATOR2 complex pathway.
