Induction of Fos protein immunoreactivity by spinal cord contusion

• Published in: Brazilian journal of medical and biological research 2000-05, Vol.33 (5), p.521-528
• Main Authors: Del-Bel, E A, Borges, C A, Defino, H L, Guimarães, F S
• Format: Article
• Language: English
• Subjects: Animals; area postrema; BIOLOGY; Biomarkers; Brain Stem - chemistry; Brain Stem - injuries; Brain Stem - metabolism; Case-Control Studies; dorsal horn; Fos immunohistochemistry; Genes, fos - physiology; Immunohistochemistry; intermediolateral column neurons; Laminectomy; Male; MEDICINE, RESEARCH & EXPERIMENTAL; Neurons - physiology; Proto-Oncogene Proteins c-fos - analysis; Proto-Oncogene Proteins c-fos - biosynthesis; Rats; Rats, Wistar; reticular formation; Solitary Nucleus - chemistry; Solitary Nucleus - metabolism; solitary tract nuclei; Spinal Cord - chemistry; Spinal Cord - metabolism; Spinal Cord Injuries - metabolism; spinal cord injury
• ISSN: 0100-879X; 1414-431X; 0100-879X; 1414-431X
• DOI: 10.1590/S0100-879X2000000500006

The objective of the present study was to identify neurons in the central nervous system that respond to spinal contusion injury in the rat by monitoring the expression of the nuclear protein encoded by the c-fos gene, an activity-dependent gene, in spinal cord and brainstem regions. Rats were anesthetized with urethane and the injury was produced by dropping a 5-g weight from 20.0 cm onto the exposed dura at the T10-L1 vertebral level (contusion group). The spinal cord was exposed but not lesioned in anesthetized control animals (laminectomy group); intact animals were also subjected to anesthesia (intact control). Behavioral alterations were analyzed by Tarlov/Bohlman scores, 2 h after the procedures and the animals were then perfused for immunocytochemistry. The patterns of Fos-like immunoreactivity (FLI) which were site-specific, reproducible and correlated with spinal laminae that respond predominantly to noxious stimulation or injury: laminae I-II (outer substantia gelatinosa) and X and the nucleus of the intermediolateral cell column. At the brain stem level FLI was detected in the reticular formation, area postrema and solitary tract nucleus of lesioned animals. No Fos staining was detected by immunocytochemistry in the intact control group. However, detection of FLI in the group submitted to anesthesia and surgical procedures, although less intense than in the lesion group, indicated that microtraumas may occur which are not detected by the Tarlov/Bohlman scores. There is both a local and remote effect of a distal contusion on the spinal cord of rats, implicating sensory neurons and centers related to autonomic control in the reaction to this kind of injury.