Fig. 1.

Effect of superfusion of BDNF, NGF, and NT-3 on afferent-evoked spinal reflex activity recorded in vitro. c, e, C-fiber-evoked responses. d, f, A-fiber-evoked responses. All responses were evoked in preparations from naïve animals. Compounds were superfused in the bathing medium for the periods indicated by filledand open bars. a, Example VRP responses showing a significant increase in the C-fiber-mediated component of the reflex response after BDNF (arrow). The short latency A-fiber-evoked component is also indicated by the dashed arrow. c, Summarized data. BDNF (200 ng/ml) was superfused either alone for 30 min (filled bar) or together with trkB-IgG (500 ng/ml) (open bar). BDNF superfusion alone was followed by a significant increase in the size of the C-fiber-evoked VRP. Pre- and co-administration of trkB-IgG along with BDNF prevented the BDNF-induced response. d, BDNF superfusion alone induced a nonsignificant and transient rise in the size of the A-fiber-evoked response. Pre- and co-administration of trkB-IgG along with BDNF prevented the small increase in amplitude. The effect of BDNF on afferent-evoked responses was dose-dependent (b); however, the maximal response was not established. NGF (200 ng/ml; e, f) or NT-3 (600 ng/ml; e, f) did not have any effect on either C- or A-fiber-evoked VRP responses.