Induction of Macrophage Migration Inhibitory Factor Messenger Ribonucleic Acid in Rat Forebrain by Reperfusion

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Abstract
Macrophage migration inhibitory factor (MIF) is a cytokine that has the potential to immobilize and activate monocytes/macrophages. To examine whether MIF may potentially be involved in the pathogenesis of reperfusion injury of the brain, we investigated the expression of MIF in a rat model of reperfusion. A four-vessel occlusion procedure was performed for 30 minutes using male Wistar rats to obtain a moderate reperfusion in the forebrains. Semiquantitatively calibrated reverse-transcription polymerase chain reaction analysis was conducted to examine temporal profiles of messenger ribonucleic acid (mRNA) expression for MIF and macrophage chemoattractant protein 1. MIF protein expression was assessed with specific Western blot analysis. For anatomic mapping of MIF, an immunohistochemical study was performed. Reverse-transcription polymerase chain reaction demonstrated that the mRNA level of MIF increased depending on the duration of reperfusion (≤ 24 h) subsequent to global ischemia. The macrophage chemoattractant protein 1 mRNA was also observed to increase after reperfusional stress, but its maximum expression was reached earlier (1 h after the stress) than was MIF mRNA. Increase of MIF protein was also shown by Western blot. MIF-positive staining was observed in the neuronal processes (neuropil) in the cortex and basal ganglia of a rat forebrain. This protein is up-regulated and may modulate immunological reaction in secondary brain damage after ischemia and reperfusion stress.