DIFFERENTIAL EXPRESSION OF THE SMALL CHONDROITIN DERMATAN SULFATE PROTEOGLYCANS DECORIN AND BIGLYCAN AFTER INJURY OF THE ADULT-RAT BRAIN/

Chondroitin sulfate proteoglycans are widespread extracellular matrix proteins and are specifically upregulated after CNS injury at the lesi on site. Many proteoglycan core proteins have been described in the ra t brain, but detailed analysis of individual proteoglycans expressed a fter injury are missing. The present study represents an initial attem pt to assess the diversity and timing of lesion-induced expression of proteoglycans in order to elucidate their functional role in CNS injur y and repair. Using immunocytochemical methods we analysed the express ion of decorin and biglycan in the transected postcommissural fornix o f the adult rat. Transection of the fornix induced the upregulation of both decorin and biglycan. However, their expression differed with re spect to time course, regional extent and cellular localization. The r apid upregulation of decorin within a wide area around the lesion was followed by a massive appearance of biglycan that remained restricted to the transection site. Three months after lesion, differences of the area size of decorin- and biglycan-immunoreactivities were no longer detectable. Both proteoglycans were restricted to the lesion site and the fornix stumps. While decorin was primarily expressed by astrocytes , biglycan was deposited extracellularly in sheet-like structures. The upregulation of both proteoglycans persisted for at least up to 6 mon ths after lesion. These strong but divergent lesion-induced expression patterns indicate important but different roles of decorin and biglyc an in CNS injury.