VARIABLE RESPONSE OF THE MONGOLIAN GERBIL TO UNILATERAL CAROTID OCCLUSION - MAGNETIC-RESONANCE-IMAGING AND NEUROPATHOLOGICAL CHARACTERIZATION

In the present investigation, we estimated both the evolution and the severity of ischemic damage following unilateral carotid occlusion (UC O) in Mongolian gerbils by using conventional magnetic resonance imagi ng (MRI, i.e. T2 weighted imaging) and histological techniques. Immedi ately after UCO, the animals showed different clinical effects. The mo rtality (46%) detected within the first 48h was considered an ''stroke -sensitivity''; the ''stroke-resistant'' animals showed wide variabili ty in terms of both temporal evolution and the extent of ischemic dama ge. The signal hyperintensity and negative MRI observed during the fir st 30h after UCO did not always correlate with the cerebral damage pre sented after 14 days, although a close correlation was established bet ween the T2 weighted images taken move than 30h after UCO and neuropat hology: the gerbils negative to imaging showed no morphological change s, whereas an enhanced signal was always prognostic of ischemic injury , Moreover, late MRI documented ventricular dilatation. Histopathology showed that the ischemic damage differed among the stroke-resistant g erbils and was often bilateral, The present study confirms the differe nces in gerbil susceptibility to hemispheric infarction after permanen t UCO and suggests that conventional MRI may be a useful non-invasive method for i) identifying the stroke-resistant animals prone to mature ischemic injury and ii) monitoring the evolution of therapeutic effic acy without sacrificing animals.