Title: Expression profiles of microRNA and mRNA in the rat spinal cord under inflammatory pain

Ping Heng Tan

Chi Mei Medical Center, Taiwan


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Several recent studies demonstrated that microRNAs (miRNAs) are involved in pain processing pathways by using microarray-based approaches. However, a significant proportion of the computational predictions of miRNA targets are false-positive interactions. To increase the chance of identifying biologically relevant targets, an integrated analysis of both miRNA and mRNA expression profiles were done in the rat spinal cord under complete Freund's adjuvant (CFA)-induced inflammatory pain.


We analyzed miRNA and mRNA in the same spinal cord with microarrays on Days 5 and 14 after CFA injection. The rats were randomly assigned to different groups. CFA 5d group, Day 5 after CFA injection; CFA 14d group, Day 14 after CFA injection; Control group, without CFA injection. After behavioral tests, the ipsilateral lumbar (L4-L5) spinal cords were quickly dissected for microarray analysis of miRNA and mRNA (n = 3 each group).


Five miRNAs and 1096 mRNAs in the CFA 5d group and 16 miRNAs and 647 mRNAs in the CFA 14d group were differentially expressed filtered with at least a 1.5-fold change in either direction. The integrated analysis revealed 54 mRNA targets with an inverse correlation to the expression patterns of 3 miRNAs in the CFA 5d group. Seventy-five targets were inversely correlated to 6 miRNAs in the CFA 14d group. The miRNA-mRNA interaction networks revealed significant changes of miR-124, miR-149, miR-3584 and their target gene of IL6R, ADAM19, LAMC1 and CERS2 in the CFA 5d group. In the CFA 14d group, significant changes of miR-124, miR-29, miR-34, miR-30, miR-338 and their target gene of TIMP2, CREB5 and EFNB1 were noted. Interaction analysis between miR-124 and IL6R showed miR-124-3p could attenuate inflammatory pain and decrease IL6R expression in the spinal cord.


These specific miRNAs and their target genes provide novel biomarkers for the diagnosis and treatment of inflammatory pain.