Leaky Gate Model: Intensity-Dependent Coding of Pain and Itch in the Spinal Cord.

ABSTRACT: Coding of itch versus pain has been heatedly debated for decades. However, the current coding theories (labeled line, intensity, and selectivity theory) cannot accommodate all experimental observations. Here we identified a subset of spinal interneurons, labeled by gastrin-releasing peptide (Grp), that receive direct synaptic input from both pain and itch primary sensory neurons. When activated, these Grp⁺ neurons generated rarely seen, simultaneous robust pain and itch responses that were intensity dependent. Accordingly, we propose a "leaky gate" model in which Grp⁺ neurons transmit both itch and weak pain signals; however, upon strong painful stimuli, the recruitment of endogenous opioids works to close this gate, reducing overwhelming pain generated by parallel pa

SUBMITTER: Sun S 

PROVIDER: S-EPMC5324710 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature