Ischemic tolerance was induced in spontaneously hypertensive rats (SHR) by injection of a single dose of lipopolysaccharide (LPS) (0.9 mg/kg, i.v.) 1–7 days prior to permanent middle cerebral artery occlusion (MCAO). Infarct volume, evaluated 24 h after MCAO, was significantly reduced by LPS administration 2, 3 or 4 days prior to MCAO (22.8, 25.9 and 20.5%, respectively). The beneficial effect of LPS pre-treatment was completely nullified by concurrent administration of TNFbp. On this basis, the tolerance to ischemia induced by LPS is likely to be mediated by TNF-α.
