Exercise retards ongoing adipose tissue fibrosis in diet-induced obese mice

Figures

• 

  Figure 1. Exercise reduces body weight in high-fat diet-induced obese mice. Male C57BL/6J mice (n = 36) were randomly divided into normal diet group (ND group, n = 14) and high-fat diet group (HFD group, n = 22). After 12-week obesity-induction period, the body weight of all mice was measured and six mice from the ND group and six mice from the HFD group were sacrificed. The remaining mice received 12 weeks of diet and exercise intervention (diet and exercise intervention period): the mice in the ND group (n = 8) were continuously fed the normal diet; the high-fat diet-fed mice were divided into the high-fat diet group (HFD group, n = 8) and the high-fat diet plus exercise group (HFD+EXE group, n = 8). (A) Initial body weight, body weight at the end of obesity-induction period and body weight at the end of diet and exercise intervention period. (B) Body weight measured weekly during the diet and exercise intervention period. Data are presented as the mean ± s.d. For panel A, *P < 0.05; for panel B, *P < 0.05 HFD+EXE vs HFD.

• 

  Figure 2. Exercise improves glucose metabolism in high-fat diet-induced obese mice. Glucose metabolism-related parameters were measured after the diet and exercise intervention period (n = 8). (A) Fasting blood glucose levels. (B) Serum levels of insulin in fasted state. (C) mRNA levels of Glut4 in adipose tissue. (D) OGTT was performed in mice fasted overnight, with glucose (1 mg/g) administrated intragastrically. (E) AUC analysis during OGTT. (F) For the ITT, mice were fasted for 3 h and insulin (0.75 IU/kg) injected intraperitoneally. (G) AUC analysis during ITT. (H) Western blot analysis of IRS1 and phosphorylation of IRS-1 (p-IRS1-S307). (I) mRNA levels of IRS1 in adipose tissue. Data are presented as the mean ± s.d., *P < 0.05.

• 

  Figure 3. Exercise reverses existing collagen deposition in high-fat diet-induced obese mice. Masson’s trichrome staining and hydroxyproline content measurement were performed after the obesity-induction period (n = 6) and after the diet and exercise intervention period (n = 8). (A) Representative images (20× objective) of adipose tissue sections stained with Masson’s trichrome dye (collagen appears blue as arrows pointed out). The Masson-positive area was quantified using ImageJ Software. (B) Hydroxyproline content in adipose tissue. Data are presented as the mean ± s.d., *P < 0.05.

• 

  Figure 4. Exercise reduces fibrosis-related genes expression in adipose tissue. We detected adipose tissue fibrosis-related genes expression after the obesity-induction period (n = 6) and after the diet and exercise intervention period (n = 8). (A) mRNA levels of Col1α1, (B) mRNA levels of Col3α1, (C) mRNA levels of Col6α1, (D) mRNA levels of LOX, (E) mRNA levels of fibronectin. Data are presented as the mean ± s.d., *P < 0.05.

• 

  Figure 5. Exercise enhances PPARγ levels and down-regulates HIF-1α expression in adipose tissue. PPARγ and HIF-1α levels in adipose tissue were examined after the obesity-induction period (n = 6) and after the diet and exercise intervention period (n = 8). (A) Western blot analysis of PPARγ. (B) Western blot analysis of HIF-1α. (C) mRNA levels of PPARγ, (D) mRNA levels of HIF-1α. Data are presented as the mean ± s.d., *P < 0.05.

• 

  Figure 6. Exercise attenuates adipose tissue inflammation in high-fat diet-induced obese mice. We detected the effect of exercise on adipose tissue inflammation after the diet and exercise intervention period (n = 8). (A) The H&E staining images of adipose tissue were observed using a 20× objective (the arrows point to the crown-like structures formed by immune cell aggregation). (B) The average adipocyte area was estimated using Leica Application Suite V3. (C) Images of F4/80 stained adipose tissue sections were taken using a 20× objective (the arrows point to the crown-like structures formed by macrophage aggregation). (D) mRNA levels of F4/80 in adipose tissue. (E) mRNA expression of inflammation-related genes in adipose tissue. Data are presented as the mean ± s.d., *P < 0.05.