NEUROPROTECTION AFTER FOCAL CEREBRAL-ISCHEMIA IN HYPERGLYCEMIC AND DIABETIC RATS

The effects of acute hyperglycaemia and streptozotocin-induced diabete s on infarct size were measured 48 h after middle cerebral artery occl usion (MCAO) in Fischer 344 rats, Both hyperglycaemia (+46%) and diabe tes (+68%) increased infarct volume when compared to normoglycaemic ra ts. Insulin-treated diabetic rats exhibited an infarct size similar to that observed in normoglycaemic rats. Neuroprotection has been diffic ult to demonstrate in pathological conditions that increase infarct vo lume such as chronic arterial hypertension, However, administration of the non-competitive NMDA antagonist, dizocilpine (MK-801), after MCAO , reduced the volume of ischaemic damage (by 33-48%) in all groups. Th e present findings indicate (a) that the detrimental effects of experi mental diabetes on infarct volume are largely attributed to hyperglyca emia; and (b) dizocilpine was as neuroprotective in hyperglycaemia and diabetic conditions as in normoglycaemic rats.