The immunolocalization of cluster of differentiation 31, phalloidin and alpha smooth muscle actin on vascular network of normal and ischemic rat brain

Cluster of differentiation 31 (CD31), phalloidin and alpha smooth muscle actin (α-SMA) has been widely applied for labeling the cerebral blood vessels in the past years. CD31 is mainly used as endothelial marker in determining the cerebral capillaries in the past years. However, it seems likely that its labeling efficiency is closely correlated with the antibodies from the polyclonal or monoclonal one, as well as the conditions of blood vessels. In order to test this phenomenon, we firstly compare the labeling characteristics of goat polyclonal anti-CD31 (gP-CD31) and mouse monoclonal anti-CD31 (mM-CD31) on the rat brain in health and ischemic/reperfusion (I/R) with the middle cerebral artery occlusion. By multiple immunofluorescence staining and three-dimensional reconstruction techniques, it was found that gP-CD31 labeling expressed extensively on the cerebral capillaries in the normal and ischemic regions, but mM-CD31 labeling mainly presented on the capillaries in the ischemic region. In contrast to the vascular labeling with phalloidin andα-SMA, gP-CD31 labeling located on the lumen side of vascular wall and surrounded by phalloidin and α-SMA labeling. These results indicate that gP-CD31 is expressed more sensitively than mM-CD31 on the cerebral vasculature, and highly compatible with phalloidin and α-SMA for insight into the cerebral vascular network in a three-dimensional view under the physiological and pathological conditions.