Ischaemic preconditioning in the rat brain: a longitudinal magnetic resonance imaging (MRI) study

Ischaemic preconditioning in rats was studied using MRI. Ischaemic precondi tioning was induced, using an intraluminal filament method, by 30 min middl e cerebral artery occlusion (MCAO), and imaged 24 h later. The secondary in sult of 100 min MCAO was induced 3 days following preconditioning and image d 24 and 72 h later. Twenty four hours following ischaemic preconditioning most rats showed small sub-cortical hyperintense regions not seen in sham-p reconditioned rats. Twenty-four hours and 72 h following the secondary insu lt preconditioned animals showed significantly smaller lesions (24 h = 112 +/- 31 mm(3), mean +/- standard error; 72 h = 80 +/- 35 mm(3)) which were c onfined to the striatum, than controls (24 h = 234 +/- 32 mm(3), p = 0.026; 72 h = 275 +/- 37 mm(3), p = 0.003). In addition during Lesion maturation from 24 to 72 h post-secondary MCAO, preconditioned rats displayed an avera ge reduction in lesion size as measured by MRI whereas sham-preconditioned rats displayed increases in lesion size; this is the first report of such d ifferential lesion volume evolution in cerebral ischaemic preconditioning. Copyright (C) 2001 John Wiley & Sons, Ltd.