RESUMO
The aim of our research was to study if cholesterol feeding might affect the ischemic changes in the vessels surrounding infarction foci in Sephadex G-75-induced cerebral ischemia model (SG-75). One hundred-twenty-four rabbits were divided as follows: group I was given standard food for 5 weeks; group II: as group I and then injected with SG-75; group III: standard food plus 1% cholesterol for 5 weeks; and group IV: as group III and then injected with SG-75. Rabbits were sacrificed 3 h, 6 h and 2, 5 and 7 days after ischemia had occurred. Vessels surrounding infarction foci (SIF) were identified by using a 6% carbon perfusion. Samples were examined by light microscopy and transmission electron microscopy (TEM). The occurrence of hemorrhagic infarction (HI) showed a clear time/course increase in group II whereas a decrease after 2 days in group IV was observed. The rate of HI was 40% and 20% in group II and IV, respectively. SIF vessels showed red blood cells leakage in group II, whereas multiple platelet thrombi appeared in group IV. This phenomenon caused a more extensive ischemic damage, when compared to group II. By making use of a widely employed model of high cholesterol diet and of a more physiological model of cerebral ischemia devised by us, we have provided the evidence that the hypercholesterolemia-induced changes in the SIF vessels strongly affect the pattern and progression of cerebral ischemia.
