The effect of exercise on expression of myokine and angiogenesis mRNA in skeletal muscle of high fat diet induced obese rat

Abstract

The effect of exercise on expression of myokine and angiogenesis mRNA in skeletal muscle of high fat diet induced obese rat. JENB., Vol. 19, No. 2, pp.91-98, 2015 [Purpose] The purpose of this study was to investigate the effect of regular treadmill exercise on the mRNA expressions of myokines and angiogenesis factors in the skeletal muscle of obese rats.[Methods] Thirty two male Sprague-Dawley rats (4weeks old) were divided into the CO (control) and HF (high fat diet) groups. Obesity was induced in the HF group by consumption of 45% high-fat diet for 15 weeks. These groups were further subdivided into training groups (COT and HFT); the training groups conducted moderate intensity treadmill training for 8 weeks. Soleus muscles were excised and analyzed by real-time quantitative PCR.[Results] mRNA expression of myokines, such as PGC-1α, IL-6, and IL-15, in the COT and HFT groups (which conducted regular exercise), were higher as compared with the CO and HF groups (p < 0.05). Also, the levels in the HF group were significantly lower when compared with CO group (p < 0.05). Expression of angiogenesis mRNA, namely mTOR, VEGF, and FLT1, were significantly lower in the HF group, as compared to the CO group (p < 0.05). In addition, COT group had a higher expression of mTORC1, mTORC2, VEGF and FLT mRNA, than the CO group (p < 0.05); the HFT group also had higher expressions of mTOR, VEGF and FLT1 mRNA than the HF group (p < 0.05).[Conclusion] These results indicate that mRNA expression of myokines was increased through the activity of muscle contraction, and it also promoted the mRNA expression of angiogenesis due to activation of mTOR. Thus, we conclude that not only under normal health conditions, but in obesity and excess nutritional circumstances also, regular exercise seems to act positively on the glycemic control and insulin sensitivity through the angiogenesis signaling pathway.

Skeletal muscle inflammation and insulin resistance in obesity

“…Studies on the effects of obesity on myokine expression are limited and have had inconsistent results. For example, obesity in rats decreased IL-6 and IL-15 expression in SM (30). Similarly, cultured myocytes from SM of obese subjects with impaired glucose tolerance or T2D expressed lower IL-6 levels than those from healthy controls (31).…”

“…Differentiated cultured myocytes isolated from obese subjects with insulin resistance or T2D secrete more cytokines such as TNF-α and chemokines such as monocyte chemoattractant protein 1 (MCP-1) than myocytes from lean controls (31,34,38). Higher TNF-α levels were also observed in SM of rats fed a fructose-rich diet (39), and TNF-α can induce insulin resistance and mitochondrial dysfunc- promotes lipolysis and FA oxidation in myocytes, adipocytes, and whole body (19,20,(22)(23)(24)(25); inhibits inflammation (19, 26) Chronically: induces insulin resistance; promotes inflammation in skeletal muscle and liver (162,163) Increased with exercise (19,20), decreased in obesity and T2D (30,31), increased in obesity and T2D (32)(33)(34) IL-8 Induces angiogenesis and leukocyte recruitment (19,24) Upregulated with exercise (19,20), increased in obesity with T2D (34) IL-15…”

Magnetic fields modulate metabolism and gut microbiome in correlation with Pgc‐1α expression: Follow‐up to an in vitro magnetic mitohormetic study

“…11 VEGFA is an angiogenic myokine upregulated by PGC-1α and exercise. 60,61 Mef2c, Sirt1, and Vegf-a were all upregulated by PEMF treatment alone (-E/+P) in Solei ( Figures 2F, S3C,E, respectively), but not EDL ( Figures 2G, S3D,F, respectively). Therefore, 60 minutes of total PEMF exposure (distributed over 6 weeks) was sufficient to upregulate the expression of mitochondrial genes associated with PGC-1α (Mef2c and Sirt1), whereas genes related to muscle hypertrophy (Gasp1 and Trim55) or metabolic adaptations (Nampt, Cpt1β, and Fndc5) exhibited only nonsignificant elevations at 6 weeks in response to PEMF exposure, with or without exhaustive exercise.…”

Angiogenesis: focusing on the effects of exercise in aging and cancer

“…In this case, angiogenesis in the adipose tissue plays a role in inhibiting hypoxia and inflammation, mitigating cardiovascular disease 26 . In the case of 4-week-old Sprague-Dawley rats, mRNA expression levels of angiogenic factors that included VEGF, mammalian target of rapamycin (mTOR), and mTOR-C in the skeletal muscle increased after treadmill exercise 27 . To examine the effects of the resistance exercise, a clinical study was performed in which serum was collected and analyzed for 8 weeks after an exercise regimen.…”