Heart-Specific Spinal and Vagal Afferents: Transcriptomic Signatures and Optogenetically Modulated Functional...

Sensory neurons innervating the heart transmit chemical and mechanical cues to the central nervous system via the dorsal root ganglion (DRG) and nodose ganglion (NG). Despite their importance in cardiac pain and cardiovascular reflexes, the molecular and functional properties of heart-specific sensory (HS) neurons remain elusive. Here, DRG^HS and NG^HS neurons innervating the heart were FACS purified using a retrograde labeling strategy with Di-8-ANEPPQ, then characterized molecularly by bulk RNA sequencing or evaluated functionally in cocultures with neonatal cardiomyocytes. DRG^HS and NG^HS neurons formed functional connections with neonatal cardiomyocytes as demonstrated by immunolabeling, electron microscopy, and optogenetic manipulation. Functionally coupled DRG^HS neurons exhibited enhanced spontaneous and evoked Ca²⁺ activity in response to optogenetic and chemical stimulation, indicating dynamic neuro-cardiac communication. Global RNA sequencing analysis revealed that DRG^HS and NG^HS neurons exhibited distinct transcriptomic profiles, including enrichment of transcripts encoding ion channels and G protein-coupled receptors, compared with their respective total populations. In DRG^HS tissue, these included Scn10a, P2xr2, and Mrgprd, whereas NG^HS neurons preferentially expressed P2xr2, Ptgdr, and Cckar, collectively supporting a combination of molecular signatures including nociceptors. Collectively, these findings define molecularly distinct sensory pathways connecting the heart and the sensory nervous system, providing mechanistic insights and highlighting potential targets for modulation of cardiovascular reflexes and hemostasis.