title: C-fos can be induced in the neonatal rat spinal cord by both noxious and innocuous peripheral stimulation.
abstract: The development of spinal cord nociceptive pathways has been investigated in neonatal rat pups using the expression of Fos immunoreactivity in laminae I and II cells produced by high and low intensity skin stimulation. Noxious pinch of the hindpaw evoked a clear response in the newborn rat pup, which was not significantly different from that seen at postnatal day (P) 21. Low intensity touch stimulation also produced a significant fos response in laminae I and II cells at P3 which was 60% that of the pinch response. This was reduced to 27% of the pinch response by P10 and was gone by P21. Electrical stimulation through percutaneous electrodes showed that A beta fibre stimulation also produced a fos response at P3 that was not significantly different from that produced by C fibre stimulation. By P21 and P30 the response to C fibre stimulation was much greater and the response to A fibre stimulation was not significantly above background. The results suggest that in the neonatal spinal cord, low threshold A fibres are able to activate pathways in lamina I and II of the dorsal horn that in the adult are predominantly nociceptive.
authors.affiliation: Department of Anatomy & Developmental Biology, University College, London, UK.
authors.forename: E
authors.initials: E
authors.lastname: Jennings
authors.forename: M
authors.initials: M
authors.lastname: Fitzgerald
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D004558:Electric Stimulation; D005260:Female; D007124:Immunoenzyme Techniques; D008297:Male; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000294:innervation*; D013116:Spinal Cord / Q000378:metabolism*; D013314:Stress, Mechanical
chemical_list: D016760:Proto-Oncogene Proteins c-fos