INTRODUCTION: Nociception safeguards organisms from external injury and internal tissue damage by detecting and distinguishing harmful stimuli, and encoding their intensity and location, thereby driving adaptive behavioral and homeostatic responses.However, the relationship between specific function and molecular identity across nociceptors remains poorly understood.

AIM(S): Here,we mapped the peripheral architecture of nociceptive signaling by combining in vivo activity labeling of pelvic nerve afferents with single-cell RNA sequencing to understand how different classes of nociceptors encode interoceptive signals.

METHOD(S): To create a reference atlas,freshly dissociated cells in L5-S1 DRGs from adult C57BL/6Jrj mice were manually collected and sequenced using the Smart-Seq3 method.To label noxious stimuli-activated cells,we used animals that expressed the photoconvertible calcium reporter CaMPARI2A series of nociceptive stimuli was delivered,while DRGs were exposed to conversion-inducing UV-light,fluorescently labeling activated neurons.Labelled cells were sequenced and embedded in the control cell atlas.

RESULTS: We developed a cell atlas with 1037 manually sorted neurons and detected 10,000 genes per cell.Sequencing of 2.997 labelled cells revealed that while nociceptive stimuli activated multiple neuronal classes,some were specific to visceral nociceptive signals.For C- nociceptors, Adra2a cells were abundant among colon-innervating neurons but nearly absent among skin-innervating populations.A-nociceptors showed clear target-specific specialization with Adm cells preferentially responding to colorectal stroke and anorectal distension. Moreover,we identified a subpopulation of Adm neurons, marked by the Uts2b+ gene, that relates to physiological bladder stimulation specifically.

CONCLUSIONS: These findings reveal a hierarchical organization of peripheral mechanical pain encoding, in which increasingly specialized mechano-nociceptor populations are differentially engaged according to tissue domain and organ context.