Plasma levels of 24S-hydroxycholesterol in patients with neurological diseases

The brain is the exclusive or almost exclusive site of formation of 24S-hyd roxycholesterol and we have shown that the circulating level of 24S-hydroxy cholesterol is dependent upon the relation between cerebral production and hepatic clearance. In the present work we determined plasma levels of 24S-h ydroxycholesterol in patients with various neurological diseases. Eleven su bjects with brain death occurring 6-10 h before collection of the plasma sa mples had markedly reduced circulating levels of 24S-hydroxycholesterol (-4 3%, P < 0.001). Patients with advanced Alzheimer's disease and cerebral inf lammatory diseases had slightly lower levels of 24S-hydroxycholesterol in p lasma when compared to matched controls. Patients with acute ischemic strok e, multiple sclerosis and primary brain tumors had levels not significantly different from those of controls. The conditions leading to reduced plasma levels of 24S-hydroxycholesterol had no significant effect on plasma level s of another side-chain oxidized oxysterol, 27-hydroxycholesterol. Except f or conditions characterized by very marked destruction of the central nervo us system, different severe neurological diseases seem to have relatively s mall effects on the flux of 24S-hydroxycholesterol from the brain, (C) 2000 Elsevier Science ireland Ltd. All rights reserved.