| First Author | Kido K | Year | 2017 |
| Journal | Am J Physiol Regul Integr Comp Physiol | Volume | 313 |
| Issue | 2 | Pages | R110-R119 |
| PubMed ID | 28515080 | Mgi Jnum | J:245140 |
| Mgi Id | MGI:5916091 | Doi | 10.1152/ajpregu.00063.2017 |
| Citation | Kido K, et al. (2017) Effect of resistance exercise under conditions of reduced blood insulin on AMPKalpha Ser485/491 inhibitory phosphorylation and AMPK pathway activation. Am J Physiol Regul Integr Comp Physiol 313(2):R110-R119 |
| abstractText | Insulin stimulates skeletal muscle glucose uptake via activation of the protein kinase B/Akt (Akt) pathway. Recent studies suggest that insulin downregulates AMP-activated protein kinase (AMPK) activity via Ser485/491 phosphorylation of the AMPK alpha-subunit. Thus lower blood insulin concentrations may induce AMPK signal activation. Acute exercise is one method to stimulate AMPK activation; however, no study has examined the relationship between blood insulin levels and acute resistance exercise-induced AMPK pathway activation. Based on previous findings, we hypothesized that the acute resistance exercise-induced AMPK pathway activation would be augmented by disruptions in insulin secretion through a decrease in AMPKalpha Ser485/491 inhibitory phosphorylation. To test the hypothesis, 10-wk-old male Sprague-Dawley rats were administered the toxin streptozotocin (STZ; 55 mg/kg) to destroy the insulin secreting beta-cells. Three days postinjection, the right gastrocnemius muscle from STZ and control rats was subjected to resistance exercise by percutaneous electrical stimulation. Animals were killed 0, 1, or 3 h later; activation of the Akt/AMPK and downstream pathways in the muscle tissue was analyzed by Western blotting and real-time PCR. Notably, STZ rats showed a significant decrease in basal Akt and AMPKalpha Ser485/491 phosphorylation, but substantial exercise-induced increases in both AMPKalpha Thr172 and acetyl-CoA carboxylase (ACC) Ser79 phosphorylation were observed. Although no significant impact on resistance exercise-induced Akt pathway activation or glucose uptake was found, resistance exercise-induced peroxisome proliferator-activated receptor (PPAR)-gamma coactivator-1 alpha (PGC-1alpha) gene expression was augmented by STZ treatment. Collectively, these data suggest that circulating insulin levels may regulate acute resistance exercise-induced AMPK pathway activation and AMPK-dependent gene expression relating to basal AMPKalpha Ser485/491 phosphorylation. |
