Effects of physical exercise on myokines expression and brown adipose-like phenotype modulation in rats fed a high-fat diet

Abstract

Aims: Exercise-stimulated myokine secretion into circulation may be related with browning in white adipose tissue (WAT), representing a positive metabolic effect on whole-body fat mass. However, limited information is yet available regarding the impact of exercise on myokine-related modulation of adipocyte phenotype in WAT from obese rats. Main methods: Sprague-Dawley rats (n = 60) were divided into sedentary and voluntary physical activity (VPA) groups and fed with standard (35 kcal% fat) or high-fat (HFD, 71 kcal% fat)-isoenergetic diets. The VPA-groups had unrestricted access to wheel running throughout the protocol. After-9 weeks, half of sedentary standard (SS) and sedentary HFD (HS)-fed animals were exercised on treadmill (endurance training, ET) for 8-weeks while maintaining the dietary treatments. Key findings: The adipocyte hypertrophy induced by HFD were attenuated by VPA and ET. HFD decreased 5' AMPactivated protein kinase (AMPK) activity in muscle as well as peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) and uncoupling protein 1 (UCP1) proteins in eWAT, while not affecting circulating irisin. VPA increased eWAT Tmem26 mRNA levels in the standard diet-fed group, whereas ET increased AMPK, interleukin 6 (IL-6) and fibronectin type III domain-containing protein 5 (FNDC5) protein expression in muscle, but had no impact on circulating irisin protein content. In eWAT, ET increased bone morphogenetic protein 7 (Bmp7), Cidea and PGC-1 in both diet-fed animals, whereas BMP7, Prdm16, UCP1 and FNDC5 only in standard diet-fed group. Significance: Data suggest that ET-induced myokine production seems to contribute, at least in part, to the brown-like phenotype in WAT from rats fed a HFD.