SEIZURES INDUCE TENASCIN-C MESSENGER-RNA EXPRESSION IN NEURONS

Tenascin-C, an extracellular matrix glycoprotein that exhibits both gr owth-promoting and growth-inhibiting properties, is produced in the CN S mainly by astrocytes. In the present study we show that kainate-indu ced seizures result in an increased expression of tenascin-C in rat br ain. Tenascin-C mRNA was increased mainly in the granule cell layer of the hippocampal complex, but tenascin-C mRNA expression was also obse rved in the pyriform cortex and amygdalo-cortical nucleus. Double labe lling experiments using tenascin-C probes and MAP2 (a neuronal microtu bule associated protein) antibodies revealed many neurons in these lay ers that express tenascin-C mRNA. These results support our previous f indings of an increased tenascin-C immunoreactivity associated with th e axons of granule cells. Tenascin-C expression is rapidly induced by seizures (6 h), preceding any lesion and glial reaction. In this patho logical condition tenascin-C appears to be produced by both glia and n eurons. The functional repercussions on the scarring and remodelling p rocesses are also discussed.