Effects of dietary graded creatine nitrate (CrN) supplementation on the relative mRNA expression of LKB1, MO25α, STRADα, AMPKα1 and AMPKα2 in Pectoralis major muscle of broilers. The data are represented as the mean value ± SEM (n = 6). Means without a common letter (a or b) significantly differ (P < 0.05). Orthogonal polynomials were used to estimate the linear and quadratic effects of dietary CrN supplementation among the control, CrN300, CrN600, and CrN900 groups. Abbreviations: AMPKα1, adenosine 5′-monophosphate-activated protein kinase α1; AMPKα2, adenosine 5′-monophosphate-activated protein kinase α2; Control, basal diet; CrN300, CrN600, and CrN900, basal diets supplemented with 300, 600, and 900 mg/kg CrN, respectively; GAA600, basal diet supplemented with 600 mg/kg guanidinoacetic acid (GAA); LKB1, liver kinase B1; MO25α, mouse protein 25α; STRADα, STE20-related adaptor α.