2023, Vol. 27 ›› Issue (8): 1237-1244

Effects of aerobic exercises with different load volumes on inflammatory response and insulin signaling pathway of skeletal muscle in obese rats

Zhang Yan1, He Ruibo2, Wang Qingbo1, Pi Yihua1, Lu Chunmin1, Xu Chuanyi1, Ma Gang2, Peng Peng2   

Abstract: BACKGROUND: Obesity is an important risk factor for elevated blood pressure, impaired glucose tolerance and dyslipidemia, in which imbalance in skeletal muscle renin-angiotensin system homeostasis may play a key role. Aerobic exercise is an important non-drug treatment for obesity, but the effects of aerobic exercises with different volumes are not been clarified.
OBJECTIVE: To compare the effects of different load volumes of aerobic exercises on inflammatory responses and insulin signaling pathways of the skeletal muscle in obese rats and to explore the possible mechanism of the renin-angiotensin system.
METHODS: Thirty Wistar-Kyoto rats were fed with high-fat diet. After 20 weeks, they were randomly divided into obese sedentary group, obese low-volume exercise group or obese high-volume exercise group. In the meantime, another 10 rats fed with standard chow were selected as the normal control group. Animals in the obese low- and high-volume exercise groups were subjected to aerobic exercise, 150 and 300 minutes per week, respectively; those in the normal control group and obese sedentary group were caged quietly. After 12 weeks, body mass, body composition, blood pressure, glucose and lipid metabolism, inflammatory factor levels, and the expression of insulin signaling, inflammatory pathway and renin-angiotensin system axis protein molecules in the skeletal muscle were detected.
RESULTS AND CONCLUSION: Body mass and body composition: compared with the obese sedentary group, body mass decreased significantly in the obese low- and high-volume exercise groups (P < 0.05). Compared with the obese low-volume exercise group, retroperitoneal and epididymal fat mass decreased significantly in the obese high-volume exercise group (P < 0.05). Blood pressure: compared with the obese sedentary group, systolic and diastolic blood pressure decreased significantly in the obese low- and high-volume exercise groups (P < 0.05). Glucose and lipid metabolism and inflammatory factors: compared with the obese sedentary group, contents of the above biochemical indexes decreased significantly in the obese low- and high-volume exercise groups (P < 0.05). Skeletal muscle insulin signal pathway: compared with the obese sedentary group, the protein expressions of phosphorylated protein kinase B and glucose transporter 4 increased significantly in the obese low- and high-volume exercise groups (P < 0.05), while the protein expression of protein tyrosine phosphatase 1B decreased significantly in the obese high-volume exercise group (P < 0.05). Skeletal muscle inflammation pathway: compared with the obese sedentary group, the protein expression of phosphorylated inhibitor α of nuclear factor κB decreased significantly in the obese low- and high-volume exercise groups (P < 0.05), and the protein expression of interleukin-6 decreased significantly in the obese high-volume exercise group (P < 0.05); compared with the obese low-volume exercise group, the protein expression of phosphorylated inhibitor α of nuclear factor κB decreased significantly in the obese high-volume exercise group (P < 0.05). Renin-angiotensin system axis of the skeletal muscle: compared with the obese sedentary group, the expression of angiotensin II type 1 receptor and Mas receptor proteins, as well as the ratio of angiotensin-converting enzyme/angiotensin-converting enzyme 2 and angiotensin II type 1 receptor/Mas receptor decreased significantly in the obese high-volume exercise group (P < 0.05). To conclude, aerobic exercise with different load volumes can improve body composition, glucose and lipid metabolism and blood pressure, ameliorate skeletal muscle insulin signaling pathway, and relieve inflammatory response in obese rats. However, the effect of high load volume protocol (300 minutes per week) is better than that of low load volume (150 minutes per week) and the mechanism may be related to the transition of skeletal muscle renin-angiotensin system balance from angiotensin-converting enzyme/angiotensin II type 1 receptor axis to angiotensin-converting enzyme 2/Mas receptor axis induced by high-volume aerobic exercises.
Key words: obesity, aerobic exercise, load volume, skeletal muscle, renin-angiotensin system, insulin resistance