Pain signal transmission pathways

Pain signal transmission pathways encompass the neural circuits from peripheral nociceptors to the spinal cord dorsal horn and higher brain centers, involving Aδ and C fibers that detect noxious stimuli like heat, mechanical damage, or chemicals. These pathways process signals through laminae I-II in the dorsal horn, where peptidergic (releasing substance P, CGRP) and non-peptidergic fibers synapse with projection neurons forming the spinothalamic tract, which relays to thalamic nuclei and cortex for localization, intensity, and emotional aspects of pain.[1][3][4] Key molecular players include voltage-gated sodium channels (e.g., Nav1.7), TRP channels (TRPV1), and receptors for prostaglandins, bradykinin, and glutamate, which sensitize during inflammation via second messengers like cAMP/PKA and PKC.[2] Dysregulation contributes to chronic pain in inflammation, neuropathy, and nociplastic conditions, making components like Nav1.7 promising for non-opioid analgesics, though complete blockade risks injury insensitivity.[1][3][6] Drugs target specific nodes, such as CGRP monoclonal antibodies for migraine or opioids for broad inhibition, but challenges include tolerance and side effects.[2][3]

Other names

Nociceptive pathwaysPain pathwaysNociception signalingSomatosensory pain pathways

Voltage-gated sodium channel blockade (Nav1.7); TRP channel desensitization (TRPV1); Neurokinin receptor antagonism (NK1); Opioid receptor agonism (mu, delta, kappa); CGRP receptor blockade; GABAergic inhibition