Vascular-Related and Mediated Alterations in Alzheimer’s Disease

Dietary high cholesterol and trace metals in the drinking water increase levels of ABCA1 in the rabbit hippocampus and temporal cortex

BACKGROUND

Cholesterol-fed rabbits have been documented to show increased amyloid-β (Aβ) deposits in the brain that can be exacerbated by the quality of drinking water especially if rabbits drink tap water or distilled water containing copper. One mechanism of cholesterol and Aβ clearance may be through the ATP-binding cassette transporter A1 (ABCA1).

OBJECTIVE AND METHODS

Using an ABCA1 antibody, we determined the number of ABCA1-immunopositive neurons in three areas of rabbit brain as a function of feeding 2% cholesterol and providing tap water, distilled water, or distilled water to which aluminum, copper, or zinc was added.

RESULTS

The number of neurons with ABCA1 immunoreactivity was increased significantly as a result of dietary cholesterol in the rabbit hippocampus and inferior and superior temporal cortex. The number of neurons with ABCA1 immunoreactivity was further increased in all three areas as a result of cholesterol-fed rabbits drinking tap water or distilled water with copper. Finally, cholesterol-fed rabbits that drank distilled water with aluminum also showed an increased number of ABCA1-immunopositive neurons in inferior and superior temporal cortex.

CONCLUSIONS

These data suggest that ABCA1 levels increase in parallel with previously documented increases in Aβ levels as a result of high dietary cholesterol and copper in the drinking water. Addition of aluminum to distilled water may have a similar effect in the temporal cortex. ABCA1 has been proposed as a means of clearing Aβ from the brain and manipulations that increase Aβ also result in an increase of clearance machinery.

Change in circulating C-reactive protein is not associated with atorvastatin treatment in Alzheimer's disease

Amyloid containing senile plaques (SP) and neurofibrillary tangles (NFT) are histologic hallmarks of Alzheimer's disease (AD). Interestingly the SP and NFT found in non-demented, age-matched individuals with ischemic heart disease and/or hypertension are morphologically and topographically identical to those in AD. Cholesterol plays a significant role in production and accumulation of amyloid beta (Abeta) and progression of AD. Cholesterol is also a major contributor in atherosclerotic changes and cardiovascular disease. Numerous studies acknowledged benefits of cholesterol-lowering statins in slowing down the progression of AD, improving cognitive status and significantly reducing risk of cardiovascular events. Accumulating evidence suggests that there is a chronic inflammatory reaction in the areas of the brain affected by AD and C-reactive protein (CRP) is identified as a key molecule of acute phase of inflammation. CRP is also a very sensitive marker for cardiovascular events and excellent prognostic tool in post-heart attack and post-coronary artery bypass surgery recovery. Here we report that cholesterol lowering with atorvastatin produces no significant change in CRP levels in treating AD patients who participated in ADCLT (AD cholesterol lowering trial).

Trace amounts of copper in water induce beta-amyloid plaques and learning deficits in a rabbit model of Alzheimer's disease

Despite the crucial role played by cholesterol and copper in nutrition and normal brain function, recent evidence indicates that they may both be important factors in the etiology of Alzheimer's disease (AD). Here we provide critical evidence for the role of cholesterol and copper in AD by showing that the addition of trace amounts of copper (0.12 ppm) to water given to cholesterol-fed rabbits can induce beta-amyloid (Abeta) accumulation, including senile plaque-like structures in the hippocampus and temporal lobe, and can significantly retard the ability of rabbits to learn a difficult trace conditioning task. The Abeta deposits do not affect the ability of rabbits to detect or respond to the training stimuli nor to learn a simpler delay conditioning task. Trace amounts of copper in drinking water may influence clearance of Abeta from the brain at the level of the interface between the blood and cerebrovasculature and combined with high cholesterol may be a key component to the accumulation of Abeta in the brain, having a significant impact on learning and memory. Cholesterol-fed rabbits have at least 12 pathological markers seen in AD, suggesting that the cholesterol-fed rabbit is a good animal model for studying AD.