Plasma net cholesteryl ester (CE) transfer and optimum cholesteryl ester transfer protein (CETP) activity were determined in primary hypertriglyceridemic (a = 11) and normolipidemic (a = 15) individuals. The hypertriglyceridemic group demonstrated threefold greater net CE transfer leading to enhanced accumulation of CE in VLDL. This increased net transfer was not accompanied by a change in CETP activity. In normolipidemia, but not in hypertriglyceridemia, net CE transfer correlated with VLDL triglyceride (r = 0.92, P < 0.001). In contrast, net CE transfer in hypertriglyceridemia, but not in normolipidemia, correlated with CETP activity (r = 0.73, P < 0.01). Correction of hypertriglyceridemia with bezafibrate reduced net CE transfer towards normal and restored the correlation with VLDL triglyceride (r = 0.90, P < 0.005) while suppressing the correlation with CETP activity. That net CE transfer depends on VLDL concentration was confirmed by an increase ofnet CE transfer in normolipidemic plasma supplemented with purified VLDL. Supplementation of purified CETP to normolipidemic plasma did not stimulate net CE transfer. In contrast, net CE transfer was enhanced by addition of CETP to both plasma supplemented with VLDL and hypertriglyceridemic plasma.
Recent data have revealed that soluble oligomeric forms of amyloid peptide (Abeta) may be the proximate effectors of the neuronal injury and death occurring in Alzheimer's disease (AD). However, the molecular mechanisms associated with the neuronal cell death induced by the nonfibrillar Abeta remain to be elucidated. In this study, we investigated the role of the cytosolic Ca2+-dependent phospholipase A2 (cPLA2), and its associated metabolic pathway, i.e., the arachidonic acid (AA) cascade, in the apoptotic cell death induced by soluble oligomers of Abeta. The treatment of rat cortical neurons with low concentrations of soluble Abeta(1-40) or Abeta(1-42) peptide resulted in an early calcium-dependent release of AA associated with a transient relocalization of cPLA2. Both cPLA2 antisense oligonucleotides and a selective inhibitor of cPLA2 activity abolished the release of AA from neurons and also protected cells against apoptosis induced by Abeta. Furthermore, inhibitors of the PKC, p38, and MEK/ERK pathways that are involved in cPLA2 phosphorylation and activation reduced Abeta-induced cell death. Finally, we demonstrate that inhibitors of cyclooxygenase-2 reduced the Abeta-induced cell death by 55%. Our studies suggest a novel neuronal response of soluble oligomers of Abeta, which occurs through a cPLA2 signaling cascade and an AA-dependent death pathway. This may prove to be crucial in AD processes and could provide important targets for drug development.
Lipolysis-stimulated lipoprotein receptor, a component of the paracellular barrier at tricellular junctions, is necessary for proper blood–brain barrier sealing during embryogenesis.
Obesity is a multifactorial disease that occurs because of an imbalance between food intake and energy expenditure. Several molecular mechanisms acting on either neurological centres controlling eating behaviour or peripheral systems regulating energy expenditure have been identified as contributing to this imbalance [1,2]. The current view of the recent dramatic increase in the incidence of the obesity implicates the
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