What is it about?

Cognitive impairment may result from neuronal apoptosis in specific regions of the brain, a process that involves mitochondrial dysfunction. Population studies have shown that people with higher blood levels of lutein and zeaxanthin (oxocarotenoids enriched in vegetables) are less likely to have cognitive impairment. We wanted to understand whether oxocarotenoids protect neuronal mitochondria under stress. We used an n oxidised phospholipid, POVPC, that we had shown previously to be increased in the blood of people with Alzheimer’s disease, to stress SHSY-5Y neurones sin vitro. We determined concentrations of POVPC that did not cause neuronal death but did cause mitochondrial dysfunction. WE then looked at whether carotenoids could protect brain cell metabolism. Co-treatment of neurones with oxo carotenoids preserved mitochondrial function only when POVPC concentrations were low. At higher POVPC concentrations, oxo carotenoids did not protect mitochondrial ATP production. We showed for the first time that the oxo carotenoids lutein and zeaxanthin are taken up by neuronal cells and protect neuronal mitochondria from loss of function induced by low concentrations of POVPC.

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Why is it important?

We have shown that low level mitochondrial dysfunction, without neuronal cell death, is reversible by oxocarotenoids. Our work has identified mitochondrial function in neurones as a new avenue to explore in our understanding about the correlation previously reported between oxocarotenoid concentration and cognition in epidemiological studies.

Perspectives

The association between carotenoids and cognitive function has been reported for almost twenty years. Whether any mechanistic link exists between the protective association of elevated blood levels of oxocarotenoids and cognitive function is unknown. This intrigued us and when we uncovered work showing that a specific carotenoid cleavage enzymes, BCO 2, which metabolises lutein and zeaxanthin, is compartmentalised in mitchondria, we speculated that mitochondria may be an important target for neuronal protection by oxocarotenoids, This raises an interesting question of whether measurement of mitochondrial dysfunction may be an antecedent marker of neuronal cell death. If so, oxocarotenoids may be effective in preserving metabolic function during a prodromal stage of neurodegeneration

Helen Griffiths
University of Surrey

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This page is a summary of: Partial Mitigation of Oxidized Phospholipid-Mediated Mitochondrial Dysfunction in Neuronal Cells by Oxocarotenoids, Journal of Alzheimer s Disease, March 2020, IOS Press,
DOI: 10.3233/jad-190923.
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