amyloid-beta-peptides and Hyperlipidemias

Amyloid beta (Abeta) peptide is closely related to the onset of Alzheimer's disease (AD). A high-cholesterol or high-energy diet was demonstrated to stimulate Abeta formation and deposition in the amyloid precursor protein (APP) pathway and, oppositely, downregulate the secretion of the neuroprotective soluble APP alpha-fragment (sAPPalpha). Monascus-fermented red mold rice (RMR) including multiple cholesterol-lowering agents, antioxidants, and anti-inflammatory agents has been proven to ameliorate Abeta40 infusion-induced memory deficit in our previous study. In this study, the ethanol extract of RMR (RE) and natural RMR were respectively tested for their effect on the mediation of the proteolytic process of APP in cholesterol-treated human neuroblastoma IMR32 cell, as well as their effect on memory and learning ability and the expression of AD risk factors in intracerebroventricular Abeta40-infused hyperlipidemic rats. In the results, RE suppressed cholesterol-raised beta-secretase activity and further resulted in the increase of sAPPalpha secretion in the IMR32 cell. In the animal test, RMR potently reversed the memory deficit in the water maze and passive avoidance tasks. RMR administration could prevent against Abeta40 infusion plus the great damage caused by a high energy diet in hippocampus and cortex involved in the raise of thiobarbituric acid reactive substances and reactive oxygen species. The neuroprotection provided by RMR downregulates Abeta40 formation and deposition by suppressing the cholesterol-raised beta-secretase activity and apolipoprotein E expression, as well as mediates the proteolytic process of APP toward neuroprotective sAPPalpha secretion in hippocampus.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Amyloid Precursor Protein Secretases; Animals; Brain; Cerebral Ventricles; Cholesterol; Fungi; Humans; Hyperlipidemias; Infusions, Intravenous; Learning Disabilities; Lovastatin; Male; Maze Learning; Memory Disorders; Monascus; Oryza; Peptide Fragments; Rats; Rats, Wistar; Reactive Oxygen Species; Thiobarbituric Acid Reactive Substances

The circulation constitutes a potential source of the beta-amyloid (A beta) protein deposited cerebrally in Alzheimer's disease (AD). Cardiovascular risk factors, including hyperlipidaemia, may be involved in the pathogenesis of AD. Plasma A beta 40 was measured by radioimmunoassay in normal and hyperlipidaemic subjects with the aim of determining if plasma lipid content and/or age correlated with circulating A beta 40 concentration. Plasma A beta 40 levels in hyperlipidaemics were elevated by 20.3% compared to normal subjects. A beta 40 did not correlate with plasma lipids in normal subjects. Age, however, correlated positively with A beta 40 in these individuals and with total cholesterol, low-density lipoprotein (LDL) and triglycerides. No correlations were observed in hyperlipidaemic patients or when the data for the two groups were combined. These data are consistent with ageing, the primary risk factor for AD, but not hyperlipidaemia influencing circulating A beta 40 levels.

Topics: Adult; Aged; Aging; Amyloid beta-Peptides; Female; Humans; Hyperlipidemias; Male; Middle Aged; Peptide Fragments; Radioimmunoassay; Statistics as Topic