MAP2 and neurogranin as markers for dendritic lesions in CNS injury. An immunohistochemical study in the rat

We compared two staining methods for the demonstration of dendrites under n ormal and pathological conditions of the rat central nervous system. MAP2- and neurogranin immunohistochemistry was applied to samples from normal tis sue, spinal cord subjected to graded compression trauma, cerebral cortex fo llowing contusion trauma, and brains with focal ischemic lesions induced by occlusion of the middle cerebral artery (MCAO). Normal rats showed MAP2 im munoreactivity in nerve cell bodies and dendrites of brain and spinal cord. However, neurogranin staining was present only in nerve cell bodies and de ndrites of the normal brain, and not in the spinal cord. Reduction of MAP2 immunoreactivity was seen in lesions of spinal cords subj ected to compression trauma. Neurogranin staining was of no value in this e xperimental condition since it was not present under normal conditions. The brain contusions showed loss of both MAP2- and neurogranin immunoreactivit y at the site of the lesion. MCAO resulted in an extensive loss of MAP2- an d neurogranin staining in the ipsilateral hemisphere. In conclusion, our study shows that MAP2 immunostaining is a sensitive meth od for identifying dendritic lesions of various CNS injuries in the rat. Ne urogranin immunostaining is an alternative method for investigations of den dritic pathology in the brain but not in the spinal cord.