DIFFERENTIAL RESPONSE OF 3 ASTROCYTE-SPECIFIC PROTEINS TO FIMBRIAL TRANSECTION OF THE RAT-BRAIN - IMMUNOHISTOCHEMICAL OBSERVATIONS WITH ANTIBODIES AGAINST GLIAL FIBRILLARY ACIDIC PROTEIN, GLUTAMINE-SYNTHETASE AND S-100 PROTEIN

Damages to selected pathways of the limbic system, such as the transection of the rat fimbria, result in some of the best characterized and robust sprouting responses in the central nervous system. We have studied astrocyte alteration after fimbrial transection of the rat septo-hippocampal pathway with immunohistochemical technique. Three markers were investigated with specific antibodies to glial fibrillary acidic protein (GFAP), glutamine synthetase (GS) and S-100 protein. When examined after 8-14 days post-lesion, GFAP immunostaining showed the most drastical response to fimbrial transection, whereas with S-100 protein-positive astrocytes, there was no conspicuous difference between the lesioned and control (corticotomized without fimbrial transection) animals. GFAP-positive or GS-positive astrocytes seemed to increase more in number in CA1 of the hippocampus than in CA3, but they did not localize in the same strate of the hippocampus. S-100 protein-positive astrocytes increased slightly in number similarly both in CA1 and CA3. In the septum areas, GFAP-positive astrocytes appeared to increase in number both in the lateral and medial septum nuclei, but GS-positive or S-100-positive astrocytes increased only in the lateral septum nucleus. These observations indicate that the three astrocyte-specific proteins respond differently to fimbrial transection with respect to the immunohistochemical localization and intensity and suggest that they may play different roles in the restoration of the CNS.