ABSTRACT
The deterioration of brain glucose metabolism predates the clinical onset of Alzheimer's disease (AD). Medium-chain triglycerides (MCTs) and docosahexaenoic acid (DHA) positively improve brain glucose metabolism and decrease the expression of AD-related proteins. However, the effects of the combined intervention are unclear. The present study explored the effects of the supplementation of MCTs combined with DHA in improving brain glucose metabolism and decreasing AD-related protein expression levels in APP/PS1 mice. The mice were assigned into four dietary treatment groups: the control group, MCTs group, DHA group, and MCTs + DHA group. The corresponding diet of the respective groups was fed to mice from the age of 3 to 11 months. The results showed that the supplementation of MCTs combined with DHA could increase serum octanoic acid (C8:0), decanoic acid (C10:0), DHA, and ß-hydroxybutyrate (ß-HB) levels; improve glucose metabolism; and reduce nerve cell apoptosis in the brain. Moreover, it also aided with decreasing the expression levels of amyloid beta protein (Aß), amyloid precursor protein (APP), ß-site APP cleaving enzyme-1 (BACE1), and presenilin-1 (PS1) in the brain. Furthermore, the supplementation of MCTs + DHA was significantly more beneficial than that of MCTs or DHA alone. In conclusion, the supplementation of MCTs combined with DHA could improve energy metabolism in the brain of APP/PS1 mice, thus decreasing nerve cell apoptosis and inhibiting the expression of Aß.
Subject(s)
Alzheimer Disease , Amyloid beta-Peptides , Mice , Animals , Amyloid beta-Peptides/metabolism , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Amyloid Precursor Protein Secretases/metabolism , Docosahexaenoic Acids/metabolism , Presenilin-1/genetics , Presenilin-1/metabolism , Mice, Transgenic , Aspartic Acid Endopeptidases/metabolism , Disease Models, Animal , Alzheimer Disease/drug therapy , Brain/metabolism , Dietary Supplements , Triglycerides/metabolismABSTRACT
The role of peroxisome proliferator-activated receptors (PPARs) as anti-inflammatory mediators has been established, and the fact that some isoflavones are dual agonists of PPARα/γ indicates the involvement of PPARα and/or PPARγ in the anti-inflammatory action of certain isoflavones. However, the dependency of isoflavones on PPARs in their anti-inflammatory action has not been demonstrated. Here, we report the dependency of an isoflavone biochanin A and the independency of another isoflavone genistein in relation to PPARγ to ameliorate the cytokine secretion profile of lipopolysaccharide (LPS)-stimulated mouse RAW264.7 macrophages. A total amount of 10 µmol/l of biochanin A or genistein significantly suppressed the secretion of tumor necrosis factor α (TNFα) and interleukin-6 (IL-6) in LPS-induced RAW264.7 cells, whereas another two isoflavones, formononectin and daidzein, only significantly suppressed the secretion of IL-6. Their anti-inflammatory efficiencies were not in correspondence with their PPARα/γ agonist activities. Inhibition of PPARγ activity by its antagonist GW9662 significantly reversed the anti-inflammatory effect of biochanin A but not genistein, which demonstrated the dependency of biochanin A and the independency of genistein on PPARγ in their anti-inflammatory actions. Meanwhile, the PPARγ-dependency of biochanin A was further confirmed by the result that the suppression of LPS-induced NF-κB activation by biochanin A was reversed following GW9662 co-treatment. Moreover, inhibition of PPARα activity by its antagonist MK886 did not significantly reverse the anti-inflammatory effects of biochanin A and genistein, indicating that their anti-inflammatory properties were PPARα-independent.