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Increased Brain Glutathione Levels by Intranasal Insulin Administration
Taisuke Kawashima1, Wattanaporn Bhadhprasit1, Nobuko Matsumura1
1Department of Pharmacology, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi, Tokyo 173-8605, Japan.
Current Issues in Molecular Biology
|July 23, 2025
Summary
Intranasal insulin boosts brain glutathione (GSH) levels by upregulating EAAC1 and reducing AMPK activation. This suggests intranasal insulin may protect against neurodegeneration.
Area of Science:
- Neuroscience
- Biochemistry
- Pharmacology
Background:
- Oxidative stress contributes to neurodegeneration.
- Insulin's role in brain antioxidant defense is not fully understood.
- Glutathione (GSH) is a key endogenous antioxidant in the brain.
Purpose of the Study:
- To investigate the effect of intranasal insulin on brain GSH levels.
- To elucidate the mechanism by which insulin enhances brain antioxidant defenses.
Main Methods:
- C57BL/6J mice received daily intranasal insulin (2 IU/day) or saline for 7 days.
- Measured brain and liver GSH levels, blood glucose, and food intake.
- Assessed protein levels of EAAC1, GTRAP3-18, and activated AMPK in mouse brains.
Main Results:
- Intranasal insulin significantly increased hippocampal and midbrain GSH levels.
- Insulin treatment upregulated EAAC1 expression in mouse brains.
- Reduced interaction between EAAC1 and GTRAP3-18, and decreased activated AMPK levels were observed.
Conclusions:
- Intranasal insulin administration enhances brain GSH levels.
- The mechanism involves EAAC1 upregulation and reduced AMPK activation.
- Intranasal insulin shows promise for enhancing brain antioxidant defenses against neurodegeneration.
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