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Updated: May 14, 2026
Measurement of Fatty Acid β-Oxidation in a Suspension of Freshly Isolated Mouse Hepatocytes
Published on: September 9, 2021
NADPH oxidase inhibition prevents beta cell dysfunction induced by prolonged elevation of oleate in rodents
K Koulajian1, T Desai, G C Liu
1Department of Physiology, University of Toronto, Medical Sciences Building, Room 3336-1 King's College Circle, Toronto, ON M5S 1A8, Canada.
Aims/Hypothesis:
The activation of NADPH oxidase has been implicated in NEFA-induced beta cell dysfunction. However, the causal role of this activation in vivo remains unclear. Here, using rodents, we investigated whether pharmacological or genetic inhibition of NADPH oxidase could prevent NEFA-induced beta cell dysfunction in vivo.
Methods:
Normal rats were infused for 48 h with saline or oleate with or without the NADPH oxidase inhibitor apocynin. In addition, NADPH oxidase subunit p47(phox)-null mice and wild-type littermate controls were infused with saline or oleate for 48 h. This was followed by measurement of NADPH oxidase activity, reactive oxygen species (ROS) and superoxide imaging and assessment of beta cell function in isolated islets and hyperglycaemic clamps.
Results:
Oleate infusion in rats increased NADPH oxidase activity, consistent with increased total but not mitochondrial superoxide in islets and impaired beta cell function in isolated islets and during hyperglycaemic clamps. Co-infusion of apocynin with oleate normalised NADPH oxidase activity and total superoxide levels and prevented beta cell dysfunction. Similarly, 48 h NEFA elevation in wild-type mice increased total but not mitochondrial superoxide and impaired beta cell function in isolated islets. p47(phox)-null mice were protected against these effects when subjected to 48 h oleate infusion. Finally, oleate increased the levels of total ROS, in both models, whereas inhibition of NADPH oxidase prevented this increase, suggesting that NADPH oxidase is the main source of ROS in this model.
Conclusions/Interpretation:
These data show that NADPH-oxidase-derived cytosolic superoxide is increased in islets upon oleate infusion in vivo; and whole-body NADPH-oxidase inhibition decreases superoxide in concert with restoration of islet function.
Insights
Inhibition of NADPH oxidase prevents non-esterified fatty acid-induced beta cell dysfunction by reducing superoxide levels in islets. This finding highlights NADPH oxidase as a therapeutic target for metabolic disorders.
Area of Science:
- Metabolic research
- Oxidative stress biology
- Endocrinology
Background:
- Non-esterified fatty acids (NEFA) are linked to beta cell dysfunction.
- NADPH oxidase activation is suspected but not proven to cause NEFA-induced beta cell dysfunction in vivo.
Purpose of the Study:
- To investigate if inhibiting NADPH oxidase prevents NEFA-induced beta cell dysfunction in vivo.
- To determine the role of NADPH oxidase in NEFA-induced reactive oxygen species (ROS) production.
Main Methods:
- Rats and mice were infused with oleate (a NEFA) with or without the NADPH oxidase inhibitor apocynin.
- Genetic knockout of NADPH oxidase subunit p47(phox) was used in mice.
- NADPH oxidase activity, ROS, superoxide, and beta cell function were assessed.
Main Results:
- Oleate infusion increased NADPH oxidase activity, cytosolic superoxide, and ROS in islets, impairing beta cell function.
- Apocynin treatment or genetic knockout of p47(phox) prevented oleate-induced beta cell dysfunction.
- NADPH oxidase inhibition normalized superoxide and ROS levels, indicating it is the primary ROS source.
Conclusions:
- NADPH oxidase-derived cytosolic superoxide contributes to NEFA-induced beta cell dysfunction in vivo.
- Inhibiting NADPH oxidase restores islet function by reducing oxidative stress.
