King Grub
2014-12-06, 11:15
Increased plasma branched-chain amino acid concentrations are associated with insulin resistance and intravenous amino acid infusion blunts insulin-mediated glucose disposal. We tested the hypothesis that protein ingestion impairs insulin-mediated glucose disposal by leucine-mediated mTOR signaling, which can inhibit AKT. We measured glucose disposal and muscle p-mTORSer2448, p-AKTSer473 and p-AKTThr308 in 22 women during a hyperinsulinemic-euglycemic clamp procedure with and without concomitant ingestion of whey protein (0.6 g per kg fat-free mass; n=11) or leucine that matched the amount given with whey protein (n=11). Both whey protein and leucine ingestion raised plasma leucine concentration by ∼2-fold and muscle p-mTORSer2448 by ∼30% above the values observed in the control (no amino acid ingestion) studies; p-AKTSer473 and p-AKTThr308 were not affected by whey protein or leucine ingestion. Whey protein ingestion decreased insulin-mediated glucose disposal (38.8 [30.8, 61.8] vs 51.9 [41.0, 77.3] µmol glucose per µU insulin·ml-1·min-1; P<0.01; medians [quartiles]) whereas ingestion of leucine did not (52.3 [43.3, 65.4] vs 52.3 [43.9, 73.2]). These results indicate that: 1) protein ingestion causes insulin resistance and could be an important regulator of postprandial glucose homeostasis, and 2) the insulin-desensitizing effect of protein ingestion is not due to inhibition of AKT by leucine-mediated mTOR signaling.
Diabetes. 2014 Dec 4. Protein ingestion induces muscle insulin resistance independent of leucine-mediated mTOR activation.
Diabetes. 2014 Dec 4. Protein ingestion induces muscle insulin resistance independent of leucine-mediated mTOR activation.