Spinal c-fos expression is differentially induced by brief or persistent noxious stimulation.
The influence of stimulus duration on spinal induction of the c-fos proto-oncogene was analysed in the rat by pinching or heating the skin for periods varying from 20 s to 2 h. At stimulation periods shorter than 20 min, c-fos activation occurred in laminae I-IIi following mechanical stimulation and I-IIo following thermal stimulation. Mechanical stimulation produced delayed activation in laminae III-IV, V and VII at 30 min, 60 min and 2 h, respectively, and thermal stimulation in lamina IIi at 50 min. It is suggested that late c-fos activation signals inflammatory pain and is due to sensitization of primary afferent neurones.
Lima
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Institute of Histology and Embryology, Faculty of Medicine, University of Oporto, Porto, Portugal.
Avelino
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D000818:Animals; D015870:Gene Expression / Q000502:physiology*; D016762:Genes, fos; D006358:Hot Temperature; D008297:Male; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D013116:Spinal Cord / Q000166:cytology / Q000378:metabolism* / Q000502:physiology