Dietary cholesterol and estrogen administration elevate brain apolipoprotein E in mice by different mechanisms.

Apolipoprotein (apo) E plays an important role in the whole body cholesterol homeostasis. Recent studies suggest that it may also be involved in the local cholesterol transport in the brain, and influence the pathogenesis of Alzheimer's disease (AD) by interacting with the beta-amyloid protein and brain lipoprotein receptors. Since apoE expression is highest in the brain, next only to the liver and associated with the pathogenesis of AD, we hypothesized that dietary and hormonal intervention, known to regulate hepatic apoE expression may also regulate brain apoE and thereby influence local cholesterol transport. To test this hypothesis, groups of male C57BL mice were fed either regular rode…

Estrogen increases hepatic lipase levels in inbred strains of mice: A possible mechanism for estrogen-dependent lowering of high density lipoprotein

We have shown mouse to be an useful animal model for studies on the estrogen-mediated synthesis and secretion of lipoproteins since, unlike in rats, low density lipoprotein receptors are not upregulated in mice [3]. This results into the elevation of plasma levels of apolipoprotein (apo) B and apoE, and lowering of apoA-I-containing particles. The mechanisms of apoB and apoE elevation by estrogen have been elucidated [6], but the mechanism of lowering of plasma levels of HDL is still not known. Among other factors, apoA-I, cholesterol ester transfer protein (CEPT), scavenger receptor B1 (SR-B1), and hepatic lipase are potential candidates that modulate plasma levels of HDL. Since estrogen t…

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