title: Induction of long-term potentiation and long-term depression is cell-type specific in the spinal cord.
abstract: The underlying mechanism of chronic pain is believed to be changes in excitability in spinal dorsal horn (DH) neurons that respond abnormally to peripheral input. Increased excitability in pain transmission neurons, and depression of inhibitory neurons, are widely recognized in the spinal cord of animal models of chronic pain. The possible occurrence of 2 parallel but opposing forms of synaptic plasticity, long-term potentiation (LTP) and long-term depression (LTD) was tested in 2 types of identified DH neurons using whole-cell patch-clamp recordings in mouse spinal cord slices. The test stimulus was applied to the sensory fibers to evoke excitatory postsynaptic currents in identified spinothalamic tract neurons (STTn) and GABAergic neurons (GABAn). Afferent conditioning stimulation (ACS) applied to primary afferent fibers with various stimulation parameters induced LTP in STTn but LTD in GABAn, regardless of stimulation parameters. These opposite responses were further confirmed by simultaneous dual patch-clamp recordings of STTn and GABAn from a single spinal cord slice. Both the LTP in STTn and the LTD in GABAn were blocked by an NMDA receptor antagonist, AP5, or an intracellular Ca chelator, BAPTA. Both the pattern and magnitude of intracellular Ca after ACS were almost identical between STTn and GABAn based on live-cell calcium imaging. The results suggest that the intense sensory input induces an NMDA receptor-dependent intracellular Ca increase in both STTn and GABAn, but produces opposing synaptic plasticity. This study shows that there is cell type-specific synaptic plasticity in the spinal DH.
authors.affiliation: Department of Neuroscience and Cell Biology, University of Texas Medical Branch, Galveston, TX, USA Department of Physiology, College of Korean Medicine, Daegu Haany University, Daegu, South Korea Department of Physiology, College of Medicine, Yonsei University, Seoul, South Korea.
authors.forename: Hee Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Jaebeom
authors.initials: J
authors.lastname: Jun
authors.forename: Jigong
authors.initials: J
authors.lastname: Wang
authors.forename: Alice
authors.initials: A
authors.lastname: Bittar
authors.forename: Kyungsoon
authors.initials: K
authors.lastname: Chung
authors.forename: Jin Mo
authors.initials: JM
authors.lastname: Chung
mesh_terms: D000818:Animals; D001703:Biophysics; D002118:Calcium / Q000378:metabolism; D002232:Carbocyanines / Q000378:metabolism; D004558:Electric Stimulation; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D036881:Long-Term Synaptic Depression / Q000187:drug effects / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D009415:Nerve Net / Q000502:physiology; D009474:Neurons / Q000145:classification* / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D013116:Spinal Cord / Q000166:cytology*; D014633:Valine / Q000031:analogs & derivatives / Q000494:pharmacology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: C582073:1,1'-dioleyl-3,3,3',3'-tetramethylindocarbocyanine; D002232:Carbocyanines; D018691:Excitatory Amino Acid Antagonists; D049452:Green Fluorescent Proteins; D005680:gamma-Aminobutyric Acid; C056639:2-amino-5-phosphopentanoic acid; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D014633:Valine; D002118:Calcium