Related Experiment Video
Updated: Apr 5, 2026
Mouse Model of Metabolic Dysfunction-Associated Steatotic Liver Disease with Fibrosis
Published on: July 18, 2025
Distinct Time Course of the Decrease in Hepatic AMP-Activated Protein Kinase and Akt Phosphorylation in Mice Fed a
Mami Shiwa1, Masayasu Yoneda1, Hirofumi Okubo1
1Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Hiroshima, Japan.
Abstract:
AMP-activated protein kinase (AMPK) plays an important role in insulin resistance, which is characterized by the impairment of the insulin-Akt signaling pathway. However, the time course of the decrease in AMPK and Akt phosphorylation in the liver during the development of obesity and insulin resistance caused by feeding a high fat diet (HFD) remains controversial. Moreover, it is unclear whether the impairment of AMPK and Akt signaling pathways is reversible when changing from a HFD to a standard diet (SD). Male ddY mice were fed the SD or HFD for 3 to 28 days, or fed the HFD for 14 days, followed by the SD for 14 days. We examined the time course of the expression and phosphorylation levels of AMPK and Akt in the liver by immunoblotting. After 3 days of feeding on the HFD, mice gained body weight, resulting in an increased oil red O staining, indicative of hepatic lipid accumulation, and significantly decreased AMPK phosphorylation, in comparison with mice fed the SD. After 14 days on the HFD, systemic insulin resistance occurred and Akt phosphorylation significantly decreased. Subsequently, a change from the HFD to SD for 3 days, after 14 days on the HFD, ameliorated the impairment of AMPK and Akt phosphorylation and systemic insulin resistance. Our findings indicate that AMPK phosphorylation decreases early upon feeding a HFD and emphasizes the importance of prompt lifestyle modification for decreasing the risk of developing diabetes.
Insights
AMP-activated protein kinase (AMPK) phosphorylation decreases early in high-fat diets, impacting insulin resistance. Reversing this requires prompt lifestyle changes to mitigate diabetes risk.
Area of Science:
- Metabolism
- Endocrinology
- Molecular Biology
Background:
- Insulin resistance is linked to impaired insulin-Akt signaling pathway.
- The precise timing of AMPK and Akt dephosphorylation during high-fat diet (HFD)-induced obesity and insulin resistance is debated.
- Reversibility of these pathway impairments upon switching from HFD to standard diet (SD) is not well understood.
Purpose of the Study:
- To investigate the time course of AMPK and Akt phosphorylation changes in the liver during HFD-induced obesity and insulin resistance.
- To determine if these impairments are reversible after transitioning from HFD to SD.
- To elucidate the early molecular events in HFD-induced metabolic dysfunction.
Main Methods:
- Male ddY mice were fed either a standard diet (SD) or a high-fat diet (HFD) for durations ranging from 3 to 28 days.
- A separate group was fed HFD for 14 days, followed by SD for 14 days.
- Liver tissue was analyzed for AMPK and Akt expression and phosphorylation levels using immunoblotting.
Main Results:
- HFD feeding for as early as 3 days led to weight gain, hepatic lipid accumulation, and significantly decreased AMPK phosphorylation compared to SD.
- After 14 days on HFD, systemic insulin resistance developed, accompanied by significantly decreased Akt phosphorylation.
- Switching from HFD to SD for 3 days reversed the impairments in AMPK and Akt phosphorylation and ameliorated systemic insulin resistance.
Conclusions:
- AMPK phosphorylation is an early indicator that decreases rapidly upon HFD consumption.
- Akt signaling impairment and insulin resistance manifest later but are reversible with dietary changes.
- Prompt lifestyle modifications are crucial for preventing or mitigating diabetes risk associated with HFD-induced metabolic changes.
Related Concept Videos
01:22PI3K/mTOR/AKT Signaling Pathway
01:25cAMP-dependent Protein Kinase Pathways