Regular aerobic exercises suppress pulmonary injury via angiogenesis in obese mice

Background Regular aerobic exercise training is essential for pulmonary function in obesity. This study aimed to investigate the effect of pulmonary injury and capillary angiogenesis by types of aerobic exercise training in high-fat diet-induced obese mice. Methods To achieve the purpose of the study, 5-week-old male C57BL/6 mice (n=40) were randomly divided into two groups: Chow diet and control (CH+CON, n=10) and high-fat diet (HF, n=30). After 8 weeks, the HF group was further randomly divided into three subgroups: high-fat diet control (HF+CON, n=10), moderate-intensity continuous training (MICT) with high-fat diet (HF+MICT, n=10), and high-intensity interval training (HIIT) with high-fat diet (HF+HIIT, n=10). The exercise program was as follows: MICT consisted of sessions at 19 m/min for 40 min (maximal running capacity; MCR) and HIIT consisted of 8 reps of high-intensity runs at 24 m/min for 2.5 min (90% MCR) with active rest at 14 m/min for 2.5 min (50% MCR) on the treadmill. Each session included a 5-min warm-up and cool-down respectively, and conducted for a total of 60 minutes, 5 days a week, for 12 weeks. Lung tissues were analyzed using H&E staining, immunohistochemistry (IHC), and Western blot. Ex vivo contractility of the diaphragm muscle was also measured. Results The results of the study showed that MICT and HIIT significantly reduced body weight, adipocyte size, and lung damage score in the lungs compared to HF+CON in obese mice. Additionally, the expression of VEGF, VEGFR2, REF-1, and CD31 in HF+MICT and HF+HIIT were increased compared to HF+CON in lung tissues. Both of MICT and HIIT significantly reduced TNF-α expression and increased the expression of SP-A and Catalase in lung tissues. Finally, Both of MICT and HIIT significantly increased diaphragm contractility in obese mice. Conclusions Our results suggest that both moderate-intensity continuous training and high-intensity interval training ameliorate pulmonary injury by enhancing angiogenesis and diaphragm function in high-fat diet-induced obese mice.