Increases in mRNA and DREAM protein expression in the rat spinal cord after formalin induced pain.

Downstream Regulatory Element Antagonist Modulator (DREAM) protein modulates pain by regulating prodynorphin gene transcription. Therefore, we investigate the changes of mRNA and DREAM protein in relation to the mRNA and prodynorphin protein expression on the ipsilateral side of the rat spinal cord after formalin injection (acute pain model). DREAM like immunoreactivity (DLI) was not significantly different between C and F groups. However, we detected the upregulation of mean relative DREAM protein level in the nuclear but not in the cytoplasmic extract in the F group. These effects were consistent with the upregulation of the relative DREAM mRNA level. Prodynorphin like immunoreactivity (PLI) expression increased but the relative prodynorphin mRNA level remained unchanged. In conclusion, we suggest that upregulation of DREAM mRNA and protein expression in the nuclear compartment probably has functional consequences other than just the repression of prodynorphin gene. It is likely that these mechanisms are important in the modulation of pain.