Long-term potentiation of glycinergic synapses triggered by interleukin 1β.
Long-term potentiation (LTP) is a persistent increase in synaptic strength required for many behavioral adaptations, including learning and memory, visual and somatosensory system functional development, and drug addiction. Recent work has suggested a role for LTP-like phenomena in the processing of nociceptive information in the dorsal horn and in the generation of central sensitization during chronic pain states. Whereas LTP of glutamatergic and GABAergic synapses has been characterized throughout the central nervous system, to our knowledge there have been no reports of LTP at mammalian glycinergic synapses. Glycine receptors (GlyRs) are structurally related to GABAA receptors and have a similar inhibitory role. Here we report that in the superficial dorsal horn of the spinal cord, glycinergic synapses on inhibitory GABAergic neurons exhibit LTP, occurring rapidly after exposure to the inflammatory cytokine interleukin-1 beta. This form of LTP (GlyR LTP) results from an increase in the number and/or change in biophysical properties of postsynaptic glycine receptors. Notably, formalin-induced peripheral inflammation in vivo potentiates glycinergic synapses on dorsal horn neurons, suggesting that GlyR LTP is triggered during inflammatory peripheral injury. Our results define a previously unidentified mechanism that could disinhibit neurons transmitting nociceptive information and may represent a useful therapeutic target for the treatment of pain.
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912.
Anda M
AM
Chirila
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912.
Travis E
TE
Brown
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912.
Rachel A
RA
Bishop
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912.
Nicholas W
NW
Bellono
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912.
Francesco G
FG
Pucci
Department of Molecular Pharmacology, Physiology and Biotechnology, Brown University, Providence, RI 02912 Julie_Kauer@brown.edu.
Julie A
JA
Kauer
D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D059330:GABAergic Neurons / Q000378:metabolism / Q000502:physiology; D005998:Glycine / Q000378:metabolism*; D006930:Hyperalgesia / Q000378:metabolism / Q000503:physiopathology; D053583:Interleukin-1beta / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D007395:Interneurons / Q000378:metabolism / Q000502:physiology; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009437:Neuralgia / Q000378:metabolism / Q000503:physiopathology*; D009443:Neuritis / Q000378:metabolism / Q000503:physiopathology; D009924:Organ Culture Techniques; D020671:Posterior Horn Cells / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D013116:Spinal Cord / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000502:physiology*
C587672:IL1B protein, mouse; D053583:Interleukin-1beta; D005998:Glycine