Fig. 2

NGF sensitized muscle C-fiber afferents to mechanical stimulation. a, b Sample recording of muscle C-fibers with intramuscular injection of phosphate-buffered saline (PBS) (a) and NGF (b). Upper right insets in a, b show the location of the receptive field of the fiber. The 1st and 3rd traces are raw recordings of the fiber, and the 2nd and 4th traces show readouts of the mechanical force applied to the receptive field. c Summary of the change in the mechanical threshold. The threshold of the PBS group at each time point was set as 100 %. White circles, PBS group; filled black circles, NGF group. d Summary of the change in the magnitude of the response (number of discharges induced by mechanical stimulation). The magnitude of the response of the PBS group at each time point was set as 100 %. NGF was injected at time 0. *p < 0.05, **p < 0.01 compared with the PBS group at each time point in both c, d. From Murase et al. [64]