[HTML][HTML] Transmitters and pathways mediating inhibition of spinal itch-signaling neurons by scratching and other counterstimuli

T Akiyama, M Iodi Carstens, E Carstens - PloS one, 2011 - journals.plos.org
T Akiyama, M Iodi Carstens, E Carstens
PloS one, 2011journals.plos.org
Scratching relieves itch, but the underlying neural mechanisms are poorly understood. We
presently investigated a role for the inhibitory neurotransmitters GABA and glycine in scratch-
evoked inhibition of spinal itch-signaling neurons in a mouse model of chronic dry skin itch.
Superficial dorsal horn neurons ipsilateral to hindpaw dry skin treatment exhibited a high
level of spontaneous firing that was significantly attenuated by cutaneous scratching, pinch
and noxious heat. Scratch-evoked inhibition was nearly abolished by spinal delivery of the …
Scratching relieves itch, but the underlying neural mechanisms are poorly understood. We presently investigated a role for the inhibitory neurotransmitters GABA and glycine in scratch-evoked inhibition of spinal itch-signaling neurons in a mouse model of chronic dry skin itch. Superficial dorsal horn neurons ipsilateral to hindpaw dry skin treatment exhibited a high level of spontaneous firing that was significantly attenuated by cutaneous scratching, pinch and noxious heat. Scratch-evoked inhibition was nearly abolished by spinal delivery of the glycine antagonist, strychnine, and was markedly attenuated by respective GABAA and GABAB antagonists bicuculline and saclofen. Scratch-evoked inhibition was also significantly attenuated (but not abolished) by interruption of the upper cervical spinal cord, indicating the involvement of both segmental and suprasegmental circuits that engage glycine- and GABA-mediated inhibition of spinal itch-signaling neurons by noxious counterstimuli.
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