LIPOPOLYSACCHARIDE PRETREATMENT INDUCES RESISTANCE AGAINST SUBSEQUENTFOCAL CEREBRAL ISCHEMIC DAMAGE IN SPONTANEOUSLY HYPERTENSIVE RATS

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 re duced by LPS administration 2, 3 or 4 days prior to MCAO (22.8, 25.9 a nd 20.5%, respectively). The beneficial effect of LPS pre-treatment wa s completely nullified by concurrent administration of TNFbp. On this basis, the tolerance to ischemia induced by LPS is likely to be mediat ed by TNF-alpha.