Expression of receptors for complement anaphylatoxins C3a and C5a following permanent focal cerebral ischemia in the mouse

In the present study, we have examined the expression of anaphylatoxin C3a and C5a receptors (C3aR and C5aR) at the mRNA and protein levels in ischemi c brain tissues following permanent middle cerebral artery (MCA) occlusion in the mouse. C3aR and C5aR mRNAs were both detected by semiquantitative re verse transcription and polymerase chain reaction (RT-PCR) and the cellular distribution of each receptor was analyzed by immunohistochemistry. Signif icant increases in the expression of C3aR and C5aR mRNAs in the ischemic co rtex were observed; the expression of both reached a peak at 2 days after M CA occlusion (4.3- and 3.4-fold increases, respectively, compared with nono perated control cortical samples; P < 0.00625 with Bonferroni's correction, n = 3), C3aR and C5aR stainings were found constitutively on neurons and a strocytes, In ischemic tissues, we observed that C3aR and C5aR were express ed de novo on endothelial cells of blood vessels, at 6 h and 2 days after M CA occlusion, respectively. C3aR and C5aR immunostaining was increased in m acrophage-like cells and reactive astrocytes 7 days postocclusion, C3a and C5a may play an important role in promoting inflammatory and/or repair proc esses in the ischemic brain by regulating glial cell activation and chemota xis, (C) 2000 Academic Press.