Exercise Improves Insulin Sensitivity in the Absence of Changes in Cytokines
Number of pages
SourceMedicine and Science in Sports and Exercise, 48, 12, (2016), pp. 2378-2386
Article / Letter to editor
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Medicine and Science in Sports and Exercise
SubjectRadboudumc 0: Other Research RIHS: Radboud Institute for Health Sciences; Radboudumc 11: Renal disorders RIMLS: Radboud Institute for Molecular Life Sciences; Radboudumc 16: Vascular damage RIHS: Radboud Institute for Health Sciences; Radboudumc 6: Metabolic Disorders RIHS: Radboud Institute for Health Sciences
PURPOSE: The benefits of aerobic exercise training on insulin sensitivity in subjects with metabolic syndrome (MetS) are, at least in part, associated with changes in cytokines. Recent studies identified novel cytokines (e.g., fractalkine, omentin, and osteopontin) that are strongly involved in glucose homeostasis and therefore potentially contribute in the exercise-induced changes in insulin sensitivity. Therefore, we aim to examine changes in skeletal muscle RNA expression and plasma levels of novel cytokines after exercise training and correlate these changes to the exercise-induced changes in insulin sensitivity. METHODS: Women with metabolic syndrome (MetS, n = 11) and healthy women (n = 10) participated in a 6-month aerobic exercise training intervention (three times a week, 45 min per session at 65%-85% of individual heart rate reserve). Before and after training, we examined insulin sensitivity (M value during hyperinsulinemic euglycemic clamp) and circulating blood levels of cytokines (venous blood sample; leptin, adiponectin, omentin, fraktalkin, and osteopontin). The skeletal muscle RNA expression of these cytokines (muscle biopsy) was examined in two subgroups (MetS, n = 6; healthy women, n = 6). RESULTS: At baseline, plasma levels of omentin (85.8 +/- 26.2 ng.mL) and adiponectin (5.0 +/- 1.7 mug.mL) levels were significantly higher in controls compared with MetS (51.1 +/- 27.1; 3.6 +/- 1.1 respectively), and leptin levels were lower in controls (18.7 +/- 11.5 vs 53.0 +/- 23.5 ng.mL). M value was significantly higher in controls (8.1 +/- 1.9 mg.kg.min) than in MetS (4.0 +/- 1.7). Exercise training significantly improved M values in both groups (P < 0.01). Exercise training did not alter plasma and skeletal muscle RNA expression levels of cytokines, but no correlation was observed between changes in cytokine level/RNA expression and M values (P > 0.05). CONCLUSION: Although exercise training successfully improves insulin sensitivity in MetS and healthy women, we found no change in plasma and mRNA expression levels of novel cytokines.
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