TRUNCATED AND CATALYTIC ISOFORMS OF TRKB ARE COEXPRESSED IN NEURONS OF RAT AND MOUSE CNS

Localization of mRNA encoding trkB indicates that two truncated isofor ms of trkB, T1trkB and T2trkB, are differentially distributed in the r odent nervous system, and that each of these transcripts is co-express ed with catalytic trkB (TK+trkB) in adult motor neurons. In contrast t o the prominent expression of T1trkB by nonneuronal cells, T2trkB expr ession appeared to be restricted to neurons and demonstrated significa nt overlap with the pattern of TK+trkB distribution. In developing spi nal cord ventral horn, an age-related increase in hybridization was ob served for truncated isoforms. These findings suggest that truncated t rkB may modulate neuronal responses to neurotrophins which act via trk B.