The expression profiling of the anterior cingulate cortex and hippocampus in chronic inflammatory pain mice

Chronic pain is a persistent unpleasant sensation that produces pathological synaptic plasticity in the central nervous system. Some of the studies demonstrate that the anterior cingulate cortex (ACC) is a critical area for nociceptive and chronic pain processing. Our previous study revealed that animal models of chronic pain alter excitatory and inhibitory synaptic transmission in the ACC. However, it is not clear what molecules are involved in the alterations of synaptic plasticity in the ACC of chronic pain models. To identify genes with altered expression in the ACC of a chronic pain model, whole transcriptome analysis were performed. In addition to the ACC, whole transcriptome analysis was also performed in the hippocampus, a brain region that has not been reported to be associated with chronic pain. Complete freund's adjuvant (CFA, Sigma-Aldrich, #F5881) into the left hind paw was used for induce chronic inflammatory pain in this study. Control or 50% of CFA were injected into the dorsal surface of the left hindpaw of mice (n=3, respectively). Two days after the injection, the mice were deeply anesthetized and transcardially perfused, then brains were quickly removed and punched out the ACC and hippocampus. The samples were subjected to whole transcriptome analysis or qRT-PCR.