Chronic aerobic exercise enhances components of the classical and novel insulin signalling cascades in Sprague–Dawley rat skeletal muscle

Abstract

Collectively, these findings suggest that chronic aerobic exercise enhances components of both the classical and novel insulin signalling cascades in normal rodent skeletal muscle, which may contribute to an increased insulin-stimulated plasma membrane GLUT4 protein concentration.

Exercise training increases components of the c-Cbl–associated protein/c-Cbl signaling cascade in muscle of obese Zucker rats

“…However, studies have demonstrated alterations of this pathway in rodent skeletal muscle in response to high-fat feeding [21], monosodium glutamate treatment [25], streptozotocin treatment [26], and exercise [4,16]. In the present investigation, we report no difference in the plasma membrane concentration of c-Cbl, CAP, or flotillin among sedentary lean and obese Zucker rats after insulin stimulation.…”

“…In contrast, insulin-stimulated TC10 protein concentration was not decreased in high-fat-fed Sprague-Dawley rats [16]. These differences could be attributed to the model of skeletal insulin resistance used.…”

“…Those that have studied this pathway under exercise conditions have done so after an acute bout of exercise in insulin-resistant tissue [4] or after training in healthy rodent skeletal muscle [16]. Thus, this appears to be the first study to measure components of the CAP/-c-Cbl pathway in the skeletal muscle of exercise-trained obese Zucker rats.…”

“…We were previously unable to detect protein concentrations of c-Cbl and CAP [16] as well as flotillin and TC10 (unpublished observations) in the crude fraction under both insulin-and non-insulin-stimulated conditions. In contrast, these proteins were readily detectable in the plasma membrane fractions, suggesting that components of the novel insulin signaling cascade are localized to the plasma membrane.…”

“…Bernard et al [16] found that plasma membrane-associated c-Cbl content was unchanged by 12 weeks of treadmill running in Sprague-Dawley skeletal muscle, but observed a significant increase in c-Cbl tyrosine phosphorylation. To the best of our knowledge, there has been no investigation of exercise training on the CAP/c-Cbl pathway in the muscle of insulinresistant obese Zucker rats, although Wadley et al [4] found no change in c-Cbl protein concentration or phosphorylation status with an acute bout of exercise.…”