EN
Membrane receptor sortilin is involved in sorting and processing of proteins. In complex with p75 receptor binds proneurotrophins what can lead to apoptosis and remodeling of neuronal network. To study sortilin involvement in spinal cord (SC) remodeling after injury, we characterized its distribution patterns, levels and relation to p75 expression in L3/L4 segments, 6 weeks after SC transection at low thoracic level. In intact rats sortilin immunoreactivity (IR) was widely distributed in white and grey matter. The strongest IR was observed in glial cells of lateral and ventral funiculi. In the grey matter sortilin IR appeared in number of neurons and glial cells, except for the lamina 2, where it rarely occurred. In contrast, p75 was limited to the bundle of strongly IR fi bers in dorso-lateral lamina 2. Sortilin and p75 did not colocalise there and overlapped in isolated large neurons of lamina 9. Spinalization caused a 5% decrease of sortilin IR in the white matter not accompanied by p75 IR changes. In the grey matter sortilin IR level was not changed but frequency of p75/sortilin IR overlapping increased in lamina 9 neurons. This result indicates postlesion increase of p75/sortilin complexing in motoneurons which may refl ect activation of proneurotrophin-mediated dysfunction. Our data show lack of such interaction in primary sensory afferents. Sortilin IR in numerous cells devoid of p75 labeling confi rms that it plays also other roles. Supported by MSE P-N/029/2006 grant.