Effect of chronic AICAR treatment on muscle fiber composition and enzyme activity in skeletal muscle of rats

ABSTRACT

Muscle fiber is the basic unit of skeletal muscle. Muscle fiber types play a crucial role in improving meat quality. In the current study, Wistar rats were chronic injected with 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) for four weeks in order to define the 5′-AMP-activated protein kinase (AMPK) protein activity on muscle fiber composition, enzyme activity and the mRNA expression of muscle fiber type-related genes in gastrocnemius (GS) muscle. Food intake and body weight did not show a significant difference after AICAR treatment (P > .05). The AICAR treatment caused a significantly increased number and area proportion of type I muscle fiber and expression level MyHC I mRNA (P < .05), succinic dehydrogenase (SDH) and malate dehydrogenase (MDH) activities (P < .05), but decrease in the number proportion of type IIB muscle fiber and MyHC IIb and MyHC IIx mRNA level (P < .05). The Peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) mRNA level (P < .05) was increased and glucose transporter 4 (GLUT-4) mRNA level tended to be higher (P = .052) in the AICAR group. These results demonstrated that chronic AICRA treatment induces oxidative muscle fiber switching, enhances oxidative enzyme activity and GLUT4 mRNA level, mediated by PGC-1α.

KEYWORDS:

• AMPK
• AICAR
• muscle fiber characteristics
• MyHC
• PGC-1α
• enzyme activity

Disclosure statement

No potential conflict of interest was reported by the author(s).

Ethics statement

All experimental procedures were strictly conducted in accordance with the Inner Mongolia Agricultural University guidelines for the Care and Use of Laboratory Animals and were approved by the University Animal Experiment Committee.

Additional information

Funding

This work was supported by the Major Special Projects of Natural Science Foundation in Inner Mongolia Autonomous Region: [Grant Number 2020ZD11] the Special Project of Scientific and Technological Achievements Transformation in Inner Mongolia Autonomous Region: [Grant Number 2019CG066]; the National Nature Science Foundation of China: [Grant Number 32060519].