Search

Garcinoic acid (GA or delta-T3-13'COOH), is a natural vitamin E metabolite that has preliminarily been identified as a modulator of nuclear receptors involved in beta-amyloid (Abeta) metabolism and progression of Alzheimer's disease (AD). In this study, we investigated GA's effects on Abeta oligomer formation and deposition. Specifically, we compared them with those of other vitamin E analogs and the soy isoflavone genistein, a natural agonist of peroxisome proliferator-activated receptor gamma (PPARgamma) that has therapeutic potential for managing AD. GA significantly reduced Abeta aggregation and accumulation in mouse cortical astrocytes. Similarly to genistein, GA up-regulated PPARgamma expression and apolipoprotein E (ApoE) efflux in these cells with an efficacy that was comparable to that of its metabolic precursor delta-tocotrienol and higher than those of alpha-tocopherol metabolites. Unlike for genistein and the other vitamin E compounds, the GA-induced restoration of ApoE efflux was not affected by pharmacological inhibition of PPARgamma activity, and specific activation of pregnane X receptor (PXR) was observed together with ApoE and multidrug resistance protein 1 (MDR1) membrane transporter up-regulation in both the mouse astrocytes and brain tissue. These effects of GA were associated with reduced Abeta deposition in the brain of TgCRND8 mice, a transgenic AD model. In conclusion, GA holds potential for preventing Abeta oligomerization and deposition in the brain. The mechanistic aspects of GA's properties appear to be distinct from those of other vitamin E metabolites and of genistein. Published under license by The American Society for Biochemistry and Molecular Biology, Inc.

Epidemiological studies indicate that long-term treatment with non-steroidal anti-inflammatory drugs reduces the risk of Alzheimer Disease and may delay its onset or slow its progression. Neuroinflammation occurs in vulnerable regions of the Alzheimer's disease (AD) brain where highly insoluble beta-amyloid (Abeta) peptide deposits and neurofibrillary tangles, as well as damaged neurons and neurites, provide stimuli for inflammation. To elucidate the complex role of inflammation in neurodegenerative processes and the efficacy of selective COX-2 inhibitors in AD, we examined whether the attenuation of brain inflammatory reaction by selective COX-2 inhibitors may protect neurons against neurodegeneration. The data reported in this review show that in in vivo models of brain inflammation and neurodegeneration, the administration of selective COX-2 inhibitors prevent not only the inflammatory reaction, but also the cholinergic hypofunction. Our data may help elucidate the epidemiological findings indicating that anti-inflammatory agents, in particular NSAIDs, reduce the risk of developing AD and may slow its progression.