Nerve growth factor stimulates synthesis of calcitonin gene-related peptide in dorsal root ganglion cells during sensory regeneration in capsaicin-treated rats.
Administration of human recombinant nerve growth factor (rhNGF) into one hindpaw of capsaicin-treated rats can locally facilitate the regeneration of calcitonin gene-related peptide (CGRP)-containing primary sensory neurons (Schicho, R., Skofitsch, G., Donnerer, J., 1999. Brain Res. 815, 60-69). In this study we used in situ hybridization histochemistry (ISH) to determine synthesis of CGRP mRNA in lumbar L4 dorsal root ganglion (DRG) cells during NGF-induced regeneration. Whereas 8 days after the capsaicin treatment alone (50 mg/kg s.c.) CGRP mRNA expression in DRG cells was reduced to 40-60% of control levels, the additional intraplantar injections of rhNGF (5 x 4 microg) during this time period were able to raise CGRP mRNA expression again. The increase in CGRP expression was seen ipsi- and contralaterally and it was more pronounced in small- and medium-sized (about 110% of control levels), than in large-sized CGRP-producing cells (70% of controls). The percentage of the CGRP-expressing neurons in capsaicinized and in capsaicin + NGF-treated animals stayed unaltered. In conclusion, the present results demonstrate that NGF-induced regeneration of capsaicin-lesioned sensory afferents is accompanied by an elevated production of CGRPmRNA mainly in small- and medium-sized DRG cells.
Schicho
R
R
Department of Experimental and Clinical Pharmacology, University of Graz, Austria.
Donnerer
J
J
D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D002211:Capsaicin / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D008297:Male; D020932:Nerve Growth Factor / Q000494:pharmacology*; D009416:Nerve Regeneration / Q000187:drug effects*; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017207:Rats, Sprague-Dawley
D012333:RNA, Messenger; D020932:Nerve Growth Factor; D015740:Calcitonin Gene-Related Peptide; D002211:Capsaicin