Differential effects of whey protein concentrate and hydrolyzed whey/egg protein blends on post‐prandial markers of insulin signaling and skeletal muscle anabolism in rats (LB439)

We examined how gavage‐feeding the following dietary proteins (10 human eq. g dissolved in 1 ml of water) acutely affected skeletal muscle insulin signaling and anabolism markers 90‐ and 180‐min post‐feeding in male Wistar rats (~250 g) fasted overnight. Supplementation included: a) 80% whey protein concentrate (WPC, n = 15); b) 70% hydrolyzed whey + 30% hydrolyzed egg albumin (70W/30E, n = 15); c) 50W/50E (n = 15); d) 30W/70E (n = 15); and e) 1 ml of water with no protein (fasted, n = 14). Immunoblotting results from mixed gastrocnemius muscles revealed: 1) rats fed WPC, 70W/30E and 50W/50E typically presented an in phospho‐Akt (Thr308) compared to 30W/70E and fasting rats (p < 0.05); 2) markers of mTOR signaling (p‐mTOR Ser2481, p‐p70s6k Thr389, p‐rpS6 Ser235/236) were typically greater in rats fed 70W/30E and 50W/50E compared to WPC, 30W/70E and fasting rats (p < 0.05); and 3) 180‐min post‐feeding muscle protein synthesis (MPS) analysis demonstrated that, compared to fasted rats, WPC feeding increased MPS by 94% (p < 0.05), 70W/30E feeding increased MPS by 74% (p = 0.065) and 50W/50E and 30W/70E feedings non‐significantly increased MPS by 25% and 34%, respectively (p > 0.05). In summary, 70W/30E feeding elicits similar acute post‐feeding responses to that of WPC. However, replacing hydrolyzed whey with a higher percentage of hydrolyzed egg albumin attenuated these responses. Source of Research Support: 4LIFE Research, Inc.