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