Fibroblast growth factor-2 acutely influences the impulse activity of rat dorsal horn neurones

The neurotrophic and neuroprotective actions of fibroblast growth factor-2 (FGF-2) are well-established. The signal cascade mediating these effects includes steps that are likely to influence also the electrical properties of neurones. However, the possibility that FGF-2 may acutely affect the processing of neuronal impulse activity is largely unexplored. In the present study the impulse activity of single dorsal horn neurones was recorded in the rat during ionophoretical administration of FGF-2 close to the neurones. Before and during FGF-2 ionophoresis the receptive field of each cell was tested with defined mechanical stimuli. At a concentration of 10 nM in the ionophoresis pipette, FGF-2 reduced the responses of the cells to mechanical stimulation. There was no preferential action of FGF-2 on a particular functional type of dorsal horn neurone; both non-nociceptive and nociceptive cells exhibited a reduced mechanical responsiveness. The background (ongoing) activity was also depressed in most neurones. The results of the study show that in addition to neurotrophic and neuroprotective actions FGF-2 has an acute inhibitory influence on the impulse activity of spinal sensory neurones. This depression of neuronal activity could add to the neuroprotective action of FGF-2 by counteracting glutamate excitotoxicity following a central nervous trauma.