Cholesterol-enriched diet causes age-related macular degeneration-like pathology in rabbit retina.

Background: Alzheimer's disease (AD) and age-related macular degeneration (AMD) share several pathological hallmarks including β-amyloid (Aβ) accumulation, oxidative stress, and apoptotic cell death. The causes of AD and AMD are likely multi-factorial with several factors such as diet, environment, and genetic susceptibility participating in the pathogenesis of these diseases. Epidemiological studies correlated high plasma cholesterol levels with high incidence of AD, and feeding rabbits with a diet rich in cholesterol has been shown to induce AD-like pathology in rabbit brain.

Molecular interplay between leptin, insulin-like growth factor-1, and β-amyloid in organotypic slices from rabbit hippocampus.

Background: Evidence shows that the insulin-like growth factor-1 (IGF-1) and leptin reduce β-amyloid (Aβ) production and tau phosphorylation, two major hallmarks of Alzheimer's disease (AD). IGF-1 expression involves the JAK/STAT pathway and the expression of leptin is regulated by the mammalian target of rapamycin complex 1 (mTORC1). We have previously shown that Aβ reduces leptin by inhibiting the mTORC1 pathway and Aβ was also suggested to inhibit the JAK/STAT pathway, potentially attenuating IGF-1 expression.

Differential effects of 24-hydroxycholesterol and 27-hydroxycholesterol on beta-amyloid precursor protein levels and processing in human neuroblastoma SH-SY5Y cells.

Background: Activation of the liver x receptors (LXRs) by exogenous ligands stimulates the degradation of beta-amyloid 1-42 (Abeta42), a peptide that plays a central role in the pathogenesis of Alzheimer's disease (AD). The oxidized cholesterol products (oxysterols), 24-hydroxycholesterol (24-OHC) and 27-hydroxycholesterol (27-OHC), are endogenous activators of LXRs. However, the mechanisms by which these oxysterols may modulate Abeta42 levels are not well known.