Expression of tenascin R and Jl mRNA in motoneurons after a traumatic lesion in the spinal cord

We demonstrate, using in situ hybridization, that mRNA for the anti-adhesiv e molecules tenascin R and J1 in the adult rat spinal motoneurons are down- regulated rapidly as a reaction after a ventral funiculus lesion. Tenascin- R was significantly down-regulated at day 1 and normalized after 3 weeks. T enascin-J1 declined to its lowest value at day 3 and returned to the initia l level after 3 weeks. In adjacent sections, the distribution of macrophage s was studied with immunohistochemistry. The density of macrophages reached a maximum 3 days after the injury. Thus, the density of macrophages appear ed to be inversely related to the level of tenascin mRNA. These data are co mpatible with the notion that neuronal tenascins may modulate the adhesion of perincurial inflammatory cells. (C) 2001 Lippincott Williams & Wilkins.