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Seagriculture 2019

8th International Seaweed Conference

"Seaweed Success Stories"

25-26 September 2019, Ostend, Belgium

Monique T Mulder

Head of the laboratory Vascular Medicine

Erasmus MC University Medical Center, NL

"Dietary Sargassum fusiforme improves memory and reduces amyloid plaque load in an Alzheimer’s disease mouse model"

WEDNESDAY

25-09-'19

10.40

Our laboratory focuses on lipid metabolism in the context of cardiometabolic diseases, type 2 diabetes and Alzheimer’s disease. We are interested in diagnostics, monitoring effects of treatment and in unraveling the underlying mechanisms.  We are interested in applying seaweed or its products as natural liver x receptor agonists in the treatment of Alzheimer’s disease and potentially cardiometabolic diseases and type 2 diabetes.

Presentation:

Activation of liver X receptors (LXRs) by synthetic agonists was found to improve cognition in Alzheimer’s disease (AD) mice. However, these LXR agonists induce hypertriglyceridemia and hepaticsteatosis, hampering their use in the clinic. We hypothesized that phytosterols as LXR agonists enhance cognition in AD without affecting plasma and hepatic triglycerides. Phytosterols previously reported to activate LXRs were tested in a luciferase-based LXR reporter assay. Using this assay, we found that phytosterols commonly present in a Western type diet in physiological concentrations do not activate LXRs. However, a lipid extract of the 24(S)-Saringosterol-containing seaweed Sargassum fusiforme did potently activate LXRβ. Dietary supplementation of crude Sargassum fusiforme or a Sargassum fusiforme-derived lipid extract to AD mice significantly improved short-term memory and reduced hippocampal Aβ plaque load by 81%. Notably, none of the side effects typically induced by full synthetic LXR agonists were observed. In contrast, administration of the synthetic LXRα activator, AZ876, did not improve cognition and resulted in the accumulation of lipid droplets in the liver. Administration of Sargassum fusiforme-derived 24(S)-Saringosterol to cultured neurons reduced the secretion of Aβ42. Moreover, conditioned medium from 24(S)-Saringosterol-treated astrocytes added to microglia increased phagocytosis of Aβ. Our data show that Sargassum fusiforme improves cognition and alleviates AD pathology. This may be explained at least partly by 24(S)-Saringosterol-mediated LXRβ activation.


Keywords: Alzheimer’s disease, liver x receptor, Sargassum fusiforme, 24(S)-Saringosterol, cognition  

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