Up-regulation of TNF-α in neurons of dorsal root ganglia and spinal cord during coronary artery occlusion in rats

Knowledge about the physiologic and pathophysiologic roles of tumor necrosis factor-α (TNF-α) in acute myocardial ischemia/infarction is still very limited. Evidence implies that TNF-α is involved in neural activity including nociception in peripheral and central nervous system. Current study was designed to examine the association of change in TNF-α and its mRNA in upper thoracic dorsal root ganglia and spinal cord (T1–T5) during acute myocardial ischemia/infarction induced by coronary artery occlusion (CAO) in rats. The experiment was performed using immunohistochemistry, enzyme immunoassay, in situ hybridization and real time reverse transcription-polymerase chain reaction techniques. At 0.5 h, 1 h, 3 h and 6 h of acute myocardial ischemia/infarction, TNF-α was mainly up-regulated in a sub-population of small and medium neurons and satellite cells in the dorsal root ganglia (DRG) and spinal neurons, mainly in laminae I, II and V, VI of the spinal dorsal horn of upper thoracic segments. The up-regulation of TNF-α mRNA was observed at 30 min of CAO, which was statistically significant, compared with the control and the sham surgery groups (P < 0.01). The TNF-α mRNA was located in the satellite cells and afferent neurons of the DRG and spinal neurons, located mainly in laminae II–VI. The findings indicate an association of up-regulation of TNF-α in DRG and spinal cord with acute myocardial ischemia/infarction, suggesting that TNF-α may be associated with the nociception initiated by acute myocardial ischemia/infarction, while the pathophysiological role needs to be studied.