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Updated: Jun 20, 2026
Measurement of Insulin- and Contraction-Stimulated Glucose Uptake in Isolated and Incubated Mature Skeletal Muscle from Mice
Published on: May 16, 2021
Reduced AMP-activated protein kinase activity in mouse skeletal muscle does not exacerbate the development of insulin
S Beck Jørgensen1, H M O'Neill, K Hewitt
1St Vincent's Institute of Medical Research and Department of Medicine, University of Melbourne, Fitzroy, VIC, Australia. sbjorgensen@ifi.ku.dk
Aims/Hypothesis:
Obesity-related insulin resistance is associated with accumulation of bioactive lipids in skeletal muscle. The AMP-activated protein kinase (AMPK) regulates lipid oxidation in muscle by inhibiting acetyl-CoA carboxylase-2 (ACC2) and increasing mitochondrial biogenesis. We investigated whether reduced levels of muscle AMPK promote lipid accumulation and insulin resistance during high-fat feeding.
Methods:
Male C57/BL6 wild-type mice and transgenic littermates overexpressing an alpha2AMPK kinase-dead (KD) in muscle were fed control or high-fat diet. Whole-body glucose homeostasis was assessed by glucose and insulin tolerance tests, and by measuring fasting and fed serum insulin and glucose. Insulin action in muscle was determined by measuring 2-deoxy-[(3)H]glucose uptake and Akt phosphorylation in incubated soleus and extensor digitorum longus muscles. Muscle triacylglycerol, diacylglycerol and ceramide content was measured by thin-layer chromatography. Mitochondrial proteins were measured by immunoblotting.
Results:
KD mice had reduced skeletal muscle alpha2AMPK activity (50% in gastrocnemius and >80% in soleus and extensor digitorum longus) and ACC2 Ser228 phosphorylation (90% in gastrocnemius). High-fat feeding increased body mass and adiposity, and impaired insulin and glucose tolerance; however, there were no differences between wild-type and KD littermates. High-fat feeding impaired insulin-stimulated muscle glucose uptake and Akt-phosphorylation, while increasing muscle triacylglycerol, diacylglycerol (p = 0.07) and ceramide, but these effects were not exacerbated in KD mice. In response to high-fat feeding, mitochondrial proteins were increased to similar levels in wild-type and KD muscles.
Conclusions/Interpretation:
Obesity-induced lipid accumulation and insulin resistance were not exacerbated in AMPK KD mice, suggesting that reduced levels of muscle alpha2AMPK do not promote insulin resistance in the early phase of obesity-related diabetes.
Insights
Reduced muscle AMP-activated protein kinase (AMPK) did not worsen lipid accumulation or insulin resistance in mice on a high-fat diet. These findings suggest AMPK may not drive early-stage obesity-related insulin resistance.
Area of Science:
- Metabolic research
- Skeletal muscle physiology
- Obesity and diabetes research
Background:
- Obesity-related insulin resistance is linked to lipid buildup in skeletal muscle.
- AMP-activated protein kinase (AMPK) is crucial for regulating lipid oxidation and mitochondrial function in muscle.
Purpose of the Study:
- To investigate if reduced muscle AMPK levels exacerbate lipid accumulation and insulin resistance during high-fat feeding.
- To understand the role of AMPK in the early stages of obesity-induced insulin resistance.
Main Methods:
- Used wild-type and muscle-specific alpha2AMPK kinase-dead (KD) mice fed control or high-fat diets.
- Assessed glucose homeostasis, insulin action (glucose uptake, Akt phosphorylation), and muscle lipid content (triacylglycerol, diacylglycerol, ceramide).
- Measured mitochondrial protein levels via immunoblotting.
Main Results:
- KD mice exhibited significantly reduced muscle alpha2AMPK activity and ACC2 phosphorylation.
- High-fat feeding impaired glucose tolerance and insulin sensitivity in both wild-type and KD mice, with no significant differences between groups.
- Muscle lipid accumulation and mitochondrial adaptations to high-fat feeding were similar in both genotypes.
Conclusions:
- Reduced muscle alpha2AMPK does not exacerbate obesity-induced lipid accumulation or insulin resistance in the early phase.
- These findings suggest that muscle AMPK may not be a primary driver of early-stage insulin resistance in obesity.
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