Axotomy induces preprotachykinin gene expression in a subpopulation of dorsal root ganglion neurons.
The distribution of dorsal root ganglion (DRG) cell sizes that show changes in preprotachykinin (PPT) gene expression and substance P (SP) levels following axotomy was examined using RNA blot analysis, in situ hybridization histochemistry, and immunocytochemistry. PPT mRNA was induced in medium-sized (1,000-2,000 microns 2) and large-sized (> 2,000 microns 2) cells in the DRG after axotomy. There was a 165% increase in the number of labeled cells after sciatic transection and a 260% increase after spinal nerve transection which results in axotomy of all the cells in the ganglion. The further increase after spinal nerve transection suggests that the induction occurred in axotomized neurons. PPT mRNA label was also present in a reduced number of small (< 1,000 microns 2) cells after axotomy. SP immunoreactivity was also induced in medium- and large-sized cells and reduced in small-sized cells. Our findings suggest that the expression of the PPT gene and SP is differentially regulated in different subpopulations of DRG neurons after axotomy and is consistent with the hypothesis that tachykinins may be important in both sensory transmission and regeneration.
Noguchi
K
K
Neurobiology and Anesthesiology Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Dubner
R
R
De Leon
M
M
Senba
E
E
Ruda
M A
MA
D000818:Animals; D001369:Axons; D005727:Ganglia, Spinal / Q000166:cytology* / Q000378:metabolism; D005786:Gene Expression Regulation; D017403:In Situ Hybridization; D008297:Male; D009416:Nerve Regeneration; D009474:Neurons / Q000378:metabolism*; D011498:Protein Precursors / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley; D012584:Sciatic Nerve / Q000293:injuries / Q000502:physiology*; D013127:Spinal Nerves / Q000293:injuries / Q000502:physiology*; D013373:Substance P / Q000096:biosynthesis*; D015320:Tachykinins / Q000096:biosynthesis*
D011498:Protein Precursors; D012333:RNA, Messenger; D015320:Tachykinins; C044206:preprotachykinin; D013373:Substance P