A novel aspect of thrombin in the tissue reaction following central nervous system injury.

Thrombin and two different types of control solutions (buffer and albumin) were continuously infused into the rat caudoputamen by an osmotic minipump. Routine histological studies with immunohistochemistry using antibodies for BrdU, GFAP, vimentin and laminin were carried out to assess infiltration of inflammatory cells, formation of edema, cell proliferation, and reactivity of astrocytes and mesenchymal cells. The number of inflammatory cells, number of BrdU positive cells, area and number of vimentin positive astrocytes, and the area of GFAP-positive reactive astrocytes were quantitatively analyzed. In the thrombin group, pale tissue foci due to spongiosis were observed together with infiltration of inflammatory cells, proliferation of mesenchymal cells, and increase of vimentin positive astrocytes which was significantly different from the control groups. The results suggest that thrombin plays an important role in inflammation, brain edema and reactive gliosis following CNS injury.