Acute Exercise Improves Insulin‐Induced Glucose Uptake in Chow Fed and High Fat Fed Rats, with Differing Effects on Akt Phosphorylation

Multiple studies have shown that a single bout of exercise can increase insulin sensitivity in rats fed chow or a high fat diet (HFD). However, few studies have investigated signaling mechanisms for the improved insulin sensitivity following exercise in rats fed a HFD. Our purpose was to assess the effect of a physiologic insulin dose on skeletal muscle glucose uptake (GU) and Akt phosphorylation (pAkt) after acute exercise in rats fed either chow or HFD. Rats were randomly separated into 2 diet groups and either maintained on rat chow (low fat diet, LFD: 14% kcal fat) or provided HFD (60% kcal fat). After 2 wk of the diet, half of the rats from each group remained sedentary (LFD‐Sed & HFD‐Sed) or performed acute exercise (LFD‐Ex & HFD‐Ex; 4 × 30 min swim). At 3h post‐exercise (3hPEX), epitrochlearis muscles were isolated and incubated ex vivo (−/+ 100μU/mL insulin) for GU and pAkt measurements. Muscles from HFD‐Sed vs. LFD‐Sed rats had reduced insulin‐induced GU (~36%) and pAkt (~25%). At 3hPEX insulin‐induced GU and pAkt were restored in muscles from HFD‐Ex rats to LFD‐Sed levels. However, muscles from LFD‐Ex rats at 3hPEX vs LFD‐Sed rats had greater insulin‐induced GU (~65%) without increased pAkt. These results indicate that although exercise can enhance insulin‐induced GU in rats fed either LFD or HFD, greater insulin‐induced pAkt appears to be a potential mechanism for this benefit at 3hPEX only in HFD fed rats.