Exercise and adrenaline increase PGC‐1α mRNA expression in rat adipose tissue

Abstract

The purpose of the present investigation was to explore the effects of exercise and adrenaline on the mRNA expression of PGC-1α, a master regulator of mitochondrial biogenesis, in rat abdominal adipose tissue. We hypothesized that (1) exercise training would increase PGC-1α mRNA expression in association with increases in mitochondrial marker enzymes, (2) adrenaline would increase PGC-1α mRNA expression and (3) the effect of exercise on PGC-1α mRNA expression in white adipose tissue would be attenuated by a β-blocker. Two hours of daily swim training for 4 weeks led to increases in mitochondrial marker proteins and PGC-1α mRNA expression in epididymal and retroperitoneal fat depots. Additionally, a single 2 h bout of exercise led to increases in PGC-1α mRNA expression immediately following exercise cessation. Adrenaline treatment of adipose tissue organ cultures led to dose-dependent increases in PGC-1α mRNA expression. A supra-physiological concentration of adrenaline increased PGC-1α mRNA expression in epididymal but not retroperitoneal adipose tissue. β-Blockade attenuated the effects of an acute bout of exercise on PGC-1α mRNA expression in epididymal but not retroperitoneal fat pads. In summary, this is the first investigation to demonstrate that exercise training, an acute bout of exercise and adrenaline all increase PGC-1α mRNA expression in rat white adipose tissue. Furthermore it would appear that increases in circulating catecholamine levels may be one potential mechanism mediating exercise induced increases in PGC-1α mRNA expression in rat abdominal adipose tissue.

Exercise regulation of adipose tissue

“…[19][20][21][22][23][24] Exercise training-induced decreases in adipocyte size and lipid content, and increases in GLUT4 and PGC1a expression have been observed in both scWAT 20,23 and vWAT. 19,20,[22][23][24] Importantly, many of these metabolic adaptations to adipose tissue can occur independently of significant weight loss 20 demonstrating that adipose tissue can be an important contributor to metabolic health, independent of changes in body weight. In addition, we have recently reported that transplantation of scWAT from exercise-trained mice into the visceral cavity of sedentary recipient mice results in improved glucose homeostasis in the recipient mice, 21 also demonstrating that training-induced changes in adipose tissue can have important metabolic effects on organism health.…”

“…21,23,[25][26][27] In rodent studies, 3-4 weeks of exposure to an enriched environment, which included the presence of a running wheel, resulted in the emergence of beige cells in scWAT. [25][26][27] These beige cells were identified by an increase in multilocular adipocytes and an increase in Ucp1, Prdm16 and other markers of BAT or beiging.…”

Exercise-induced adaptations to white and brown adipose tissue

“…There are also specific adaptations to each WAT depot, including adaptations to the structural lipidomic profile changes in scWAT (May et al, 2017) and the beiging of scWAT in rodents (Stanford et al, 2015a,b;Sutherland et al, 2009;Trevellin et al, 2014;Boström et al, 2012;Cao et al, 2011;Stanford and Goodyear, 2016) (Fig. 1).…”

“…Beige adipocytes are found intermixed within the WAT and appear morphologically similar to brown adipocytes with multilocular lipid droplets and an abundance of mitochondria (Hirshman et al, 1989;Enerbäck, 2009;Petrovic et al, 2010;Ishibashi and Seale, 2010). In rodents, beige cells can be induced by a variety of stimuli, including β3-selective adrenergic agonists (Ishibashi and Seale, 2010), cold-exposure (Petrovic et al, 2010), exercise (Stanford et al, 2015a,b;Sutherland et al, 2009;Trevellin et al, 2014;Boström et al, 2012;Cao et al, 2011) and an enriched environment (Cao et al, 2011). Upon stimulation, beige adipocytes express very high levels of Ucp1, show increased fuel oxidation and contribute to non-shivering thermogenesis Shabalina et al, 2013).…”

Lipid metabolism and exercise

“…Furthermore, Sutherland et al demonstrated that high-fat diet reduced mitochondrial proteins in adipose tissue thorough increases in plasma free fatty acid 28) . On the other hand, previous study demonstrated that exercise training increased mRNA of peroxisome proliferator-activated receptor (PPAR)-gamma coactivator 1alpha (PGC-1α), a master regulator of mitochondrial biogenesis, and mitochondrial proteins in rat adipose tissue, and suggested that exercise-induced increase in circulating catecholamine levels may be one potential mechanism of augmented mitochondrial biogenesis 29) . Because many studies have been focused on skeletal muscle mitochondrial biogenesis, it is reasonable to explore the molecular mechanisms underlying augmented mitochondrial biogenesis in adipocytes induced by exercise training based on the findings elucidated in skeletal muscles.…”