GSE202111
Major differences in transcriptional alterations in dorsal root ganglia between spinal cord injury and peripheral neuropathic pain models
Chronic, often intractable pain is caused by neuropathic conditions such as peripheral nerve injury (PNI) and spinal cord injury (SCI). These conditions are associated with alterations in gene and protein expression correlated with functional changes in somatosensory neurons having cell bodies in dorsal root ganglia (DRGs). Most studies of DRG transcriptional alterations have utilized PNI models where axotomy-induced changes important for regeneration may overshadow changes that drive neuropathic pain. Both PNI and SCI produce DRG neuron hyperexcitability linked to pain, but contusive SCI produces little peripheral axotomy or peripheral nerve inflammation. Thus, comparison of transcriptional signatures of DRGs across PNI and SCI models may highlight pain-associated transcriptional alterations that don't depend on peripheral axotomy and associated effects such as peripheral Wallerian degeneration. Data from our rat thoracic SCI experiments were combined with meta-analysis of whole-DRG RNA-seq datasets from prominent rat PNI models. Striking differences were found between transcriptional responses to PNI and SCI, especially in regeneration-associated genes and long noncoding RNAs. Many transcriptomic changes after SCI were also found after corresponding sham surgery, indicating they were caused by injury to surrounding tissue rather than to the spinal cord itself. Another unexpected finding was of few transcriptomic similarities between any rat neuropathic pain model and the only reported transcriptional analysis of human DRGs linked to neuropathic pain. These findings show that DRGs exhibit complex transcriptional responses to central and peripheral neural and tissue injury. Although few genes in DRG cells show similar changes in gene expression across all these painful conditions, the few widely shared transcriptional alterations promise novel insights into fundamental mechanisms within DRGs that can drive neuropathic pain. Overall design: Comparative gene expression profiling analysis of RNA-seq data generated from lumbar and thoracic dorsal root ganglia (DRG) samples excised bilaterally below spinal level T11 under three conditions: Naïve, Sham, and spinal cord injury (SCI). We used three biological replicates of each experimental group.