Expression of mRNAs for preprotachykinin and nerve growth factor receptors in the dorsal root-ganglion following peripheral inflammation.

Nerve growth factor (NGF) plays a dynamic role in the control of substance P (SP) levels and synthesis in the dorsal root ganglion (DRG). In the present study, in situ hybridization was used to examine the change of preprotachykinin (PTT), trkA and p75 mRNAs levels in the DRG after the injection of complete Freund's adjuvant into the hindpaws of rats. Peripheral tissue inflammation increased PTT and p75 mRNAs levels in the DRG, while trkA mRNA levels showed no change. These findings suggest that p75, in addition to trkA, also may be important in mediating the action of NGF on the synthesis of SP in the DRG following peripheral inflammation.