Novel Binge Drinking Model Causes Perturbations in Muscle Metabolism with Refeeding

It is well known that acute alcohol intoxication impairs metabolic signaling within skeletal muscle including suppression of protein synthesis which is at least partially due to inhibition of mTOR activity as assessed by phosphorylation of its downstream substrates p70 ribosomal protein S6 Kinase 1 (S6K1), ribosomal protein S6 (rpS6) and eukaryotic initiation factor 4E (4E‐BP1). The current mouse model used to mimic binge drinking employs either oral gavage or intraperitoneal (IP) injection, both of which are stressful to the animal and in the case of the injection, lack physiological relevance as it bathes all organs in a high dose of alcohol while bypassing normal intestinal metabolism. Therefore, we wanted to determine if an acute ‘dose’ of alcohol incorporated into the food would be sufficient to mimic the binge drinking effects previously reported. Methods C57BL6 male (n=9) and female mice (n=10) were randomized to receive either control liquid diet food (# 710027, DYETS, Bethlehem, PA), or a calorie (kcal) matched liquid diet containing 32% kcal from alcohol (# 710260, DYETS, Bethlehem, PA). Following a 1 week acclimation period to the control liquid diet, mice were fasted for 16 hours during their light cycle and then, at the onset of the dark cycle, were provided with liquid diet (Con or EtOH) for 30 minutes. The gastrocnemius (GAS) and blood were collected 1.5 hour after the beginning of the refeeding period. Western blots were performed on GAS for protein expression. T‐tests (2 tailed, unpaired) for males (Con vs. EtOH), and females (Con vs. EtOH), or between sexes of the same dietary treatment group, were used for analysis (p<0.05). Results Despite the high concentration of alcohol in the liquid diet and its novel introduction to the EtOH group, male mice consumed the same volume of food regardless of treatment group. Control females though, consumed significantly more food than EtOH females (4.5 mL vs. 3.6 mL). Alcohol intake per kg body weight was higher in females than males; however, total alcohol intake (g), and blood alcohol levels (213 vs. 187 mg/dL), were not different between males and females. Alcohol intake decreased AKT S473 phosphorylation in GAS, along with phosphorylation of mTOR S2448 in males and females. Downstream substrates of mTOR were also suppressed by alcohol, including phosphorylation of S6K1 T389 and rpS6 S240/244. Conclusion Despite lower blood alcohol levels (compared to injection), alcohol reversed or prevented the increase in mTOR signaling typically induced by an anabolic stimulus (i.e. nutrient intake). Further, novel findings included the consumption of a high percentage of alcohol in liquid diet form without any prior exposure to a lower dose or acclimation period to alcohol. Future work will continue to characterize this model and lead to optimization of models of alcohol intoxication that best mimic human practice.