Sexual dimorphism in the dorsal root ganglia of neonatal mice identified by protein expression profiling with single-cell mass cytometry

Proper development of neuronal and glial populations in the dorsal root ganglia (DRG) is required for detection of touch, body position, temperature, and pain. While female-male differences in somatosensory perception have been previously reported, no study has examined global sex differences in the abundance of DRG cell types, and the developmental origin of these differences has not been characterized. To investigate whether sex-specific differences in neuronal and glial cell types arise in the DRG during development, we performed single-cell mass cytometry analysis on sex-separated DRGs from 4 separate litter replicates of postnatal day 0 (P0) mouse pups. In this analysis, we observed that females had a higher abundance of total neurons, as well as an increased abundance of TrkB+ and TrkC+ neurons responsible for mechanoreception and proprioception, respectively. Males had a higher abundance of TrkA+ neurons responsible for thermoreception and nociception. Pseudotime comparison of the female and male datasets indicates that male neurons are more mature and differentiated than female neurons at P0. These findings warrant further studies to better understand the origins and depth of sexual dimorphism in the DRG, develop protocols to conduct high dimensional proteomic analysis of adult DRG tissue, curate and develop more specialized antibody panels to better characterize distinct cell populations, and use additional tools to connect differences in molecular characterization to altered cellular function.