title: Differential activation of c-fos in spinal neurones by distinct classes of noxious stimuli.
abstract: The laminar distribution of spinal cord neurones expressing immunoreactivity to the Fos protein was evaluated in the rat following chemical, thermal or mechanical noxious stimulation of the skin for 2 h. After stimulation by 20% or 5% formalin, Fos-immunoreactive neurones prevailed in lamina I where they accounted for 64% and 59%, respectively, of the entire population of Fos-immunoreactive spinal cells. Values in the remaining laminae were low (2-10%). Following thermal stimulation by radiant heat at 65 degrees C or 58 degrees C, Fos cells were concentrated in laminae I and IIo, amounting to 57% and 62%, respectively, in lamina I, and to 26% and 29% in lamina IIo. Values were lower than 10% in the remaining laminae. Following mechanical stimulation by pinching or needle prick, Fos-positive cells were regularly distributed throughout laminae I-V amounting to 25-26% in lamina I, and 10-20% in each of the remaining laminae. These findings suggest that the spinal neuronal groups upon by prolonged noxious stimulation differ according to the nature of the stimulus.
authors.affiliation: Institute of Histology and Embryology, Faculty of Medicine, University of Oporto, Porto, Portugal.
authors.forename: D
authors.initials: D
authors.lastname: Lima
authors.forename: A
authors.initials: A
authors.lastname: Avelino
authors.forename: A
authors.initials: A
authors.lastname: Coimbra
mesh_terms: D000818:Animals; D016762:Genes, fos / Q000502:physiology*; D006358:Hot Temperature; D008297:Male; D009474:Neurons / Q000502:physiology*; D010146:Pain / Q000503:physiopathology*; D010812:Physical Stimulation; D051381:Rats; D017208:Rats, Wistar; D012879:Skin Physiological Phenomena; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D013268:Stimulation, Chemical