Expression of Fos protein in the rat central nervous system in response to noxious stimulation: effects of chronic inflammation of the superior cervical ganglion.
The aim of this study was to investigate the possible interactions between the nociceptive system, the sympathetic system and the inflammatory process. Thus, the superior cervical ganglion of rats was submitted to chronic inflammation and Fos expression was used as a marker for neuronal activity throughout central neurons following painful peripheral stimulation. The painful stimulus consisted of subcutaneously injected formalin applied to the supra-ocular region. Fos-positive neurons were identified by conventional immunohistochemical techniques, and analyzed from the obex through the cervical levels of the spinal cord. In the caudal sub-nucleus of the spinal trigeminal nuclear complex, the number of Fos-positive neurons was much higher in rats with inflammation of the superior cervical ganglion than in control rats, either sham-operated or with saline applied to the ganglion. There was a highly significant difference in the density of Fos-positive neurons between the inflamed and control groups. No significant difference was found between control groups. These results suggest that the inflammation of the superior cervical ganglion generated an increased responsiveness to painful stimuli, which may have been due to a diminished sympathetic influence upon the sensory peripheral innervation.
Departamento de Fisiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Brasil. adrilaud@usp.br
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A
Laudanna
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MI
Nogueira
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M
Mariano
D000818:Animals; D001341:Autonomic Nervous System / Q000503:physiopathology; D015415:Biomarkers; D002490:Central Nervous System / Q000503:physiopathology*; D002908:Chronic Disease; D007249:Inflammation; D008297:Male; D009474:Neurons / Q000378:metabolism; D010146:Pain / Q000503:physiopathology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D017208:Rats, Wistar; D013268:Stimulation, Chemical; D017783:Superior Cervical Ganglion; D013564:Sympathetic Nervous System / Q000503:physiopathology; D014279:Trigeminal Nucleus, Spinal
D015415:Biomarkers; D016760:Proto-Oncogene Proteins c-fos