CHANGES OF CYTOSKELETAL PROTEIN IMMUNOSTAINING IN MYELINATED FIBER TRACTS AFTER FOCAL CEREBRAL-ISCHEMIA IN THE RAT

Breakdown of the cytoskeleton has been proposed to be a central event in the evolution of ischaemic brain damage. Alterations in the immunos taining of cytoskeletal proteins, particularly microtubule-associated protein (MAP) 2, have been suggested to be sensitive markers of ischae mic damage in the somatodendritic compartment. However, axons are also subjected to the adverse conditions created by an ischaemic challenge , but MAP2 is not located in the axonal compartment. The purpose of th e present study was to examine immunostaining of beta-tubulin, MAP1a a nd MAP5, all of which are located in axons as well as perikarya, speci fically in myelinated fibre tracts in rats subjected to unilateral mid dle cerebral artery (MCA) occlusion. In sham-operated control rats imm unostaining of all three antibodies in myelinated fibre tracts had a s mooth, regular appearance. Two hours after MCA occlusion there were st riking changes in the patterns of immunostaining of all three antibodi es in myelinated fibre tracts within the MCA territory. These were par ticularly noticeable in beta-tubulin- and MAP5-stained sections where the pattern in white matter had a rough, globular appearance. This pat tern was accentuated at 6 h after MCA occlusion and the presence of '' bulb-like'' profiles in white matter tracts was notable particularly i n the MAPS-stained sections. Thus, the changes in the patterns of stai ning at 2 h after MCA occlusion may represent the early stages of axon al disconnection, and immunostaining of microtubular proteins may repr esent a sensitive method to assess ischaemically induced damage to mye linated fibre tracts.