Immunohistochemical detection of laminin and vimentin in the thalamic VB nucleus after ablation of somatosensory cortex in the rat.

The ventrobasal (VB) nucleus has been studied after ablation of somatosensory cortex in 62 adult rats by the application of both vimentin and laminin immunoreactivity. Both vimentin- and laminin-immunoreactivity are confirmed in reactive astrocytes (GFAP-positive cells) in the affected VB area and its surroundings. The vimentin immunoreactivity first gives rise in the affected VB at seven days postlesion and appears more active in its surrounding area at fourteen day postlesion. At the twenty-eight days, vimentin-positive astrocytes are reduced in cell volume and their processes become thin. The laminin immunoreactivity is also first detected in the affected area at seven days postlesion and spread in its surrounding area at fourteen days postlesion. At the twenty-eight days, laminin-positive astrocytes are reduced in cell volume and their processes become thin. The time course of both vimentin and laminin immunoreactivity correlates with the degree of astrocytic hypertrophy. Acquisition of vimentin is one of the typical astroglial reactions by brain injury (5). The laminin in the reactive astrocyte contributes to the temporal activation for the regeneration. But the neurons in the affected VB area mostly die. And reactive domain in its surrounding area, will support the repair of affected BV area and form glial scar. The induction of laminin might be involved in scar formation (8).