RESUMO
Objective: To investigate the expression pattern of beta-amyloid (Aß) in rats after focal cerebral cortex infarction, and to identify whether the Aß expression in the ipsilateral thalamus was directly related to focal cerebral ischemia. Methods: The distal middle cerebral artery occlusion (MCAO) was performed by electrocoagulation in rats. The rats were divided randomly into sham group (n=18) and MCAO group (n=30) . We used 2, 3, 5-triphenyltetrazolium chloride (TTC) staining and immunohistochemical staining to detect the location of cerebral infarction and Aß expression, respectively. Results: TTC staining showed that the cerebral infarction was consistently restricted to the frontal and temporoparietal cortex. In the peri-infarct area of the MCAO group, Aß expression began at day 2, reached the maximum level at day 7, and disappeared almost completely at day 28 after MCAO. The Aß appeared as diffuse small dots, and was located in neurons and astrocytes at day 2 and day 28, respectively. Meanwhile, in the ipsilateral thalamus, Aß expression began at day 3, increased markedly at day 7, and remained until day 28 after MCAO. The Aß was located constantly in the extracellular region of the ipsilateral thalamus, and aggregated gradually from small dots to dense plaque-like deposits with the time of ischemia. Conclusions: There are dynamic changes of Aß expression in both the peri-infarct area and the ipsilateral thalamus following MCAO. The Aß expression in the ipsilateral thalamus is not directly related to focal cerebral ischemia.