Comparative Ion Channel Transcriptomes of NK1R and Somatostatin Neurons in the preBötzinger Complex of the...

The preBötzinger Complex is among the few neural circuits where selective elimination of defined neuronal subpopulation is sufficient to destabilize a core autonomic function and can fatally impair breathing. Within this circuitry, neurons expressing the neurokinin-1 receptor (Tacr1/NK1R) and somatostatin (Sst) are critical subpopulations; Tacr1 ⁺ neurons respond to the neuropeptide substance P and are necessary for maintaining inspiratory rhythms, and ablation of Sst ⁺ neurons results in apneas. To further dissect and analyze the specific roles for Tacr1 ⁺ and Sst ⁺ cell types, we conducted a comprehensive transcriptomic analysis using single-nucleus RNA sequencing of enriched preBötC from neonatal C57BL/6J mice. Because respiratory rhythmogenesis is an inherently electrophysiological process, we focused on the ion channel transcriptomes of Tacr1 + and Sst+ populations to resolve the molecular underpinnings of their distinct contributions to breathing. A balanced Random Forest classifier distinguished Tacr1⁺ from Sst⁺ neurons with higher accuracy, indicating a distinct and relatively homogeneous ion channel identity in Tacr1⁺ neurons. Differential expression analyses identified coordinated upregulation of Trpc5, Kcnc2 and Cacna2d2 genes in Tacr1⁺ neurons. Tacr1⁺ neurons further exhibited elevated expression of the NALCN channelosome subunits and selective enrichment genes of Htr2c and Adra1a neuromodulatory receptor genes. Together, these findings define a molecularly distinct ion channel composition of Tacr1⁺ neurons and imply convergent substance P linked mechanisms: TRPC5-mediated I_CAN and NALCN-mediated sodium leak conductance supporting rhythmic inspiratory activity, providing a molecular framework for targeted interrogation of respiratory circuit function.