trkC may be an inducible transcription factor target gene

Mechanical injury to hippocampus by needle insertion induces N-methyl-D-aspartate (NMDA) receptor-dependent expression of neurotrophin receptor mRNAs (trkB, trkC) and inducible transcription factors (ITFs, i.e. Fos, c-Jun, Krox-24) in dentate gyrus neurones. To examine the possibility that de novo synthesis of ITFs was necessary for increased expression of trk mRNA we prevented protein synthesis for 5 h using the protein synthesis inhibitor, cycloheximide (4 x 10 mg kg-1, i.p., 1 h before and 1, 2 and 3 h after injury). Cycloheximide abolished expression of ITFs 4 h after injury. Cycloheximide had no effect on trkB mRNA expression but attenuated the injury-induced increase in trkC mRNA expression in dentate gyrus at 4 h by 75%. These results suggest that trkC may be an ITF target gene in vivo.