Background & Aims

Chronic pain is associated with molecular, cellular, structural, and functional changes throughout the neuroaxis including in the prefrontal cortex (PFC). PFC plays a crucial role in the processing and modulation of pain sensation and in the integration of sensory, cognitive, and emotional information. We previously reported changes in gene expression in mouse PFC following spared nerve injury (SNI) that are associated with chronic pain1. However, the cell phenotypes driving these changes have not been studied. In this study, we aimed to identify cell type-specific gene expression changes in PFC using a single nuclei RNA sequencing approach in mouse models of transient vs persistent neuropathic pain.

Methods

Sciatic nerve crush (n=5) and SNI (n=5) models were induced in 10 to 12 week old C57BL6 male mice to model transient and persistent neuropathic pain, respectively. In brief, the common peroneal and tibial nerves were ligated for SNI or the left sciatic nerve was compressed by a hemostat for 15 seconds. Sham surgery (n=6) consisted of exposing the nerve. Mechanical and cold sensitivity on the ipsilateral hind paws were measured weekly via von Frey and Acetone, respectively. PFC was collected at 6 weeks post-surgery for single nuclei RNA sequencing and data was analyzed by the R package Seurat (v4.3). Pathway enrichment was assessed via GO database.

Results

Increased mechanical and cold sensitivity persisted in SNI but nerve crush mice showed progressive recovery over time. Multiple excitatory(Slc17a7+) and inhibitory(Gad 1, 2+) neuronal subpopulations and non-neuronal cell populations, including microglia, astrocytes, oligodendrocytes, oligodendrocyte precursor cells, and endothelial cells were identified. 80-90% of differentially expressed genes(>1000) were detected in neuronal populations following the SNI. GO pathway analysis revealed enrichment in pathways related to regulation of calcium ion transport in excitatory neurons, whereas macromolecule biosynthetic process and cytoplasmic translation pathways were enriched in inhibitory neurons. Crush nerve injury resulted in <700 genes differentially expressed in neurons. GO pathway analysis revealed enrichment in cell-cell adhesion and chemical synaptic transmission in excitatory populations, whereas axonogenesis and axon guidance pathway was enriched in inhibitory neurons.

Conclusions

Cell type-specific changes in gene expression in PFC following nerve injury could contribute to the establishment and persistence of chronic neuropathic pain. Identifying these genes and pathways may contribute to the identification of new therapeutic targets.

References

1.Alvarado S, Tajerian M, Millecamps M, Suderman M, Stone LS, Szyf M. Peripheral nerve injury is accompanied by chronic transcriptome-wide changes in the mouse prefrontal cortex. Mol Pain. 2013 Apr 18;9:21. doi: 10.1186/1744-8069-9-21. PMID: 23597049; PMCID: PMC3640958.

Presenting Author

Peter Lee

Poster Authors

Peter Lee

PhD

University of Minnesota

Lead Author

E-mail

Taylor Yeater

PhD

University of Minnesota

Lead Author

E-mail

Maureen S. Riedl PhD

University of Minnesota Twin Cities

Lead Author

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Lucy Vulchanova

PhD

University of Minnesota

Lead Author

E-mail

L. Stone

University of Minnesota Twin Cities

Lead Author

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Topics

  • Genetics