Exercise and adrenaline increase PGC-1{alpha} 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-1alpha, a master regulator of mitochondrial biogenesis, in rat abdominal adipose tissue. We hypothesized that (1) exercise training would increase PGC-1alpha mRNA expression in association with increases in mitochondrial marker enzymes, (2) adrenaline would increase PGC-1alpha mRNA expression and (3) the effect of exercise on PGC-1alpha mRNA expression in white adipose tissue would be attenuated by a beta-blocker. Two hours of daily swim training for 4 weeks led to increases in mitochondrial marker proteins and PGC-1alpha mRNA expression in epididymal and retroperitoneal fat depots. Additionally, a single 2 h bout of exercise led to increases in PGC-1alpha mRNA expression immediately following exercise cessation. Adrenaline treatment of adipose tissue organ cultures led to dose-dependent increases in PGC-1alpha mRNA expression. A supra-physiological concentration of adrenaline increased PGC-1alpha mRNA expression in epididymal but not retroperitoneal adipose tissue. beta-Blockade attenuated the effects of an acute bout of exercise on PGC-1alpha 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-1alpha 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-1alpha mRNA expression in rat abdominal adipose tissue.

Figure 1. The effects of exercise training on COXIV protein content (A), CORE1 protein content (B) and citrate synthase activity (C) in rat epididymal and retroperitoneal adipose tissue

Data are presented as means +s.e.m. for 10–14 samples per group. Representative western blots for CORE1, COXIV and β-actin are shown above the quantified data and results were normalized to actin protein content; *P < 0.05.

Figure 2. The effects of exercise training on the mRNA expression of PGC-1α (A), PGC-1β (B) and Tfam mRNA expression (C) in epididymal and retroperitoneal adipose tissue

Data are presented as means +s.e.m. for 10–14 samples per group, normalized to actin mRNA expression, and expressed as fold differences compared to sedentary controls; *P < 0.05.

Figure 3. The time course of exercise induced increases in PGC-1α and Tfam mRNA expression in epididymal (A) and retroperitoneal (B) adipose tissue

Data are presented as means +s.e.m. for 5–6 samples per group, normalized to actin mRNA expression, and expressed as fold differences compared to sedentary controls; *P < 0.05.

Figure 4. The dose–response relationship of adrenaline on PGC-1α mRNA expression in epididymal (A) and retroperitoneal (B) adipose tissue organ cultures

Data are presented as means +s.e.m. for 4–6 samples per group, normalized to actin mRNA expression, and expressed as fold differences compared to vehicle treated controls; *P < 0.05.

Figure 5. The time course of adrenaline (1 μm) induced increases in PGC-1α and Tfam mRNA expression in rat epididymal (A and C) and retroperitoneal (B and D) organ cultures

Data are presented as means +s.e.m. for 4–6 samples per group, normalized to actin mRNA expression, and expressed as fold differences compared to vehicle treated controls; *P < 0.05.

Figure 6. The effects of propranolol on the exercise induced increases in PGC-1α mRNA expression in rat epididymal (A) and retroperitoneal (B) adipose tissue

Data are presented as means +s.e.m. for 6–9 samples per group, normalized to actin mRNA expression, and are expressed as fold differences compared to non-exercised rats (*P < 0.05) or between the exercised groups with saline or propranolol treatment (#P < 0.05).