Cluster analysis of mRNA expression levels identifies multiple sequential patterns following focal cerebral ischemia

The purpose of this study is to detect gene expression patterns following focal cerebral ischemia.

25 male Wistar rats were divided into control (n = 8) and ischemic (n = 17) groups. In the ischemic group, slowly progressing focal ischemia was simulated by two-vein occlusion with spreading depression (SD) a cortical microinjection of KCl induced. Ischemic tissue was removed at 2, 8, 24, or 72 h postischemia. Using semiquantitative reverse transcription polymerase chain reaction, we investigated mRNA expression levels of 13 representative genes related to cerebral ischemia. Cluster analysis of the gene expression levels was done.

In the ischemic group, the expression levels of c-fos, cyclin D1, and COX-2 were significantly higher at 2 h postischemia, and those of bcl-2, bcl-xL, and HO-1 at 72 h. Based on the cluster analysis, we statistically divided examined genes into three groups: group A, early expression (COX-2, c-fos, and bcl-2); group B, s expression (c-jun, SOD-1, bad, p53, SOD-2, bcl-xL, and bax); and group C, late expression (cyclin D1, c-myc, and HO-1).

We statistically classified the genes into three groups after focal ischemia. The genes of the early- and late-expression groups can be possible therapeutic targets for the treatment of cerebral ischemia.