Figure 2.

Exogenous BDNF enhances postsynaptic activity in the spinal cord and endogenous BDNF contributes to reflex excitability. (a) Spinal reflex excitability was assessed from the VRP evoked after electrical stimulation of C fibers in the dorsal root of an isolated hemisected rat spinal-cord preparation. Under normal circumstances, the VRP evoked by C fiber activation is characterized by a prolonged, slowly decaying potential, and this potential remains stable from trial to trial. (b) After a 30-min superfusion with BDNF (200 ng/ml), the amplitude and duration of the C fiber-evoked VRP increased significantly relative to pretreatment activity (arrow, control trace; arrowhead, trace after BDNF superfusion). (c) The contribution of endogenous BDNF to reflex excitability was assessed after a 30-min superfusion of spinal-cord preparations with trkB-IgG (500 ng/ml). Under these circumstances C fiber-evoked activity was reduced significantly compared with pretreatment control responses (arrow, control response; arrowhead, response after trkB-IgG superfusion). (b and c; bars = 0.5 mV and 5.0 s.)