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.
The adipocyte hypertrophy induced by HFD were attenuated by VPA and ET. HFD decreased 5′ AMP-activated protein kinase (AMPK) activity in muscle as well as peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) 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-1α in both diet-fed animals, whereas BMP7, Prdm16, UCP1 and FNDC5 only in standard diet-fed group.
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.