TABLE 1.
Study characteristics (including classifications from naive and nerve-injured DRGs).
| References | Species | Sex | Age | Sample number | Location | Techniques | Gene numbers per neuron | Clusters number | Functional aspects |
| Usoskin et al., 2015 | C57BL/6 mice | Male and female | 6–8 weeks old | 6 | L4-L6 | Single-cell RNA-seq | 3,574 ± 2,010 | 11 | 3 LTMRs (NF1, NF2, NF3), 2 proprioceptive (NF4, NF5), and 6 types of thermosensitive (PEP1), itch sensitive (NP1, NP2, NP3), type C-LTMRs (TH) and nociceptive neurons (PEP2) |
| Li et al., 2016 | C57BL/6 mice | Male | 8–10 weeks old | 5 | L5 | Single-cell RNA-seq | 10,950 ± 1,218 | 10 | 6 small neurons types: 1 C-LTMR and 5 MHNs; 4 large neurons types: neurexophilin 1-expressing MHNs and MNs expressing Baiap2l1 |
| Wang et al., 2021 | C57BL/6 mice | Male | 7–8 weeks old | 6 | L4-L5 | Single-cell RNA-seq | 6,407 | 19 | 6 PEP clusters, 5 NP clusters, 5 myelinated neurons types and 3 SNIICs |
| Renthal et al., 2020 | C57BL/6 mice | Male and female | 8–12 weeks old | 5 male, 2 female | L3-L5 | Single-nucleus RNA-seq | 1,284 | 10 | PEP1, PEP2, NPs, SST, Aβ-LTMRs, NF1, NF2, NF3, cLTMR, p_cLTMR2 |
| Hu et al., 2016 | C57BL/6 mice | Male and female | 2 months old | NA | L3-L5 | Single-cell RNA-seq | 7,569 ± 1,456 | 5 | NP, C-LTMR, PEP, LTMRs, proprioceptors |
| Zhang et al., 2022 | C57BL/6 mice | Male and female | 7–8 weeks old | 5 | L4-L5 | Single-cell RNA-seq | NA | 16 | NF1-2, NP1-3, PEP1-6, cLTMR, CCI-ind1-4 |
| Zhou et al., 2022 | Sprague-Dawley rats | Male | Adult | 24 | L5 | Single-cell RNA-seq | NA | 11 | NP, PEP, SST, C-LTMR, and TRPM8 |
| Nguyen et al., 2021 | Human donors | Male and female | 34–55 years old | 1 male, 4 female | L4-L5 | Single-nucleus RNA seq | 2,839 ± 1,917 | 15 | NA |
| Tavares-Ferreira et al., 2022 | Human donors | Male and female | 24–65 years old | 4 male, 4 female | Lumbar | Spatial transcriptomics | 24,000 genes per section | 12 | 5 C nociceptors, 1 C-LTMR, 1 Aβ nociceptor, 1 Aδ HTMR, 2 Aβ LTMRs, 1 Aδ LTMR and 1 proprioceptor subtypes |
| Yu et al., 2023 | Human donors | Male and female | 23–61 years old | 1 male, 2 female | Thoracic (T11-T12) and L2-L5 | Single-soma RNA-seq | 9,486 | 16 | hTRPM8, hC.LTMR, hNP1, hNP2, hPEP.SST, hPEP.TRPV1/A1.1, hPEP.TRPV1/A1.2, hPEP.PIEZOh, hPEP.KIT, hPEP.CHRNA7, hPEP.NTRK3, hPEP.0, hAδ.LTMR, hAβ.LTMR, hPropr, hATF3 |
| Kupari et al., 2021 | Rhesus macaques | Male and female | 5–14 years old | 1 male, 2 female | Lumbar | Single-cell RNA-seq | 5,687 | 9 | NP1, NP2, NP3, PEP1, PEP2, PEP3, C-LTMRs, TrpM8high, and A-LTMRs |
| Jung et al., 2023 | C57BL/6J mice, guinea pigs, cynomolgus monkeys, and human donors | Male and female for humans and mice; only female for guinea pigs and monkeys | Mice: 6–17 weeks old; Humans: 21–48 years old; Guinea pigs: 5.5–6 months old; Monkeys: 8–9 years old |
5 mice, 2 guinea pigs, 3 monkeys, and 7 humans (5 male and 2 female) | Lumbar | Single-nucleus RNA-seq | NA | 11 | Proprioceptor & Aβ SA-LTMR, Aβ SA-LTMR Ntrk3, Aδ-LTMR Ntrk2, C-LTMR P2ry1, NP1 Gfra1 Gfra2, NP2 Gfra1, NP3 Sst, PEP1 Adcyap1, PEP2 Ntrk1, PEP2 Fam19a1, cold Trpm8. |
LTMRs, low-threshold mechanoreceptors; C-LTMRs, C-fiber low-threshold mechanoreceptors; MHNs, mechanoheat nociceptors; MNs, mechanical nociceptors; PEP, peptidergic; NP, non-peptidergic; SNIICs, spared nerve injury-induced neuron clusters; SST, somatostatin+ pruriceptors; NF, neurofilament; Aβ-LTMRs, Aβ low-threshold mechanoreceptors; cLTMR1, C-fiber LTMRs; p_cLTMR2, putative cLTMR2; Baiap2l1, BAI1-associated protein 2-like 1; TRPM8, transient receptor potential cation channel subfamily M member 8; NA, not available.