The neuronal tyrosine kinase receptor ligand ALKAL2 mediates persistent pain

To identify putative genes that could contribute to the phenotypic plasticity of TRPV1 nociceptors in inflammation-induced sensitization, we used the Complete Freund’s Adjuvant (CFA) model of chronic inflammatory pain. Three days post intraplantar injection of CFA, ipsilateral and contralateral lumbar DRG neurons were separated, and TRPV1-pHluorin neurons were purified by FACS and analyzed through the GeneChip™ Mouse Gene 2.0 ST Array. The array analysis provided a complete expression profile of mRNA between contralateral and ipsilateral TRPV1 neurons following inflammatory insult. In inflammatory condition, we found >100 genes to be up or down regulated in TRPV1 neurons. 6 samples were analysed. Primary data analysis was carried out with the Affymetrix Expression Console 1.4.1.46 software including the Robust Multiarray Average module for normalization. Gene expression data were log-transformed. A change was considered significant when the FDR-corrected p-value/q-value thresholds met the criterion q < 0.01 at fold changes > 2 (expression increments or declines larger than two).