title: Zingerone enhances glutamatergic spontaneous excitatory transmission by activating TRPA1 but not TRPV1 channels in the adult rat substantia gelatinosa.
abstract: Transient receptor potential (TRP) channels are thought to play a role in regulating nociceptive transmission to spinal substantia gelatinosa (SG) neurons. It remains to be unveiled whether the TRP channels in the central nervous system are different in property from those involved in receiving nociceptive stimuli in the peripheral nervous system. We examined the effect of the vanilloid compound zingerone, which activates TRPV1 channels in the cell body of a primary afferent neuron, on glutamatergic excitatory transmission in the SG neurons of adult rat spinal cord slices by using the whole cell patch-clamp technique. Bath-applied zingerone reversibly and concentration-dependently increased spontaneous excitatory postsynaptic current (EPSC) frequency. This effect was accompanied by an inward current at -70 mV that was resistant to glutamate receptor antagonists. These zingerone effects were repeated and persisted in Na(+)-channel blocker tetrodotoxin-, La(3+)-, or IP3-induced Ca(2+)-release inhibitor 2-aminoethoxydiphenyl borate-containing or Ca(2+)-free Krebs solution. Zingerone activity was resistant to the selective TRPV1 antagonist capsazepine but sensitive to the nonselective TRP antagonist ruthenium red, the TRPA1 antagonist HC-030031, and the Ca(2+)-induced Ca(2+)-release inhibitor dantrolene. TRPA1 agonist allyl isothiocyanate but not capsaicin inhibited the facilitatory effect of zingerone. On the other hand, zingerone reduced monosynaptically evoked EPSC amplitudes, as did TRPA1 agonists. Like allyl isothiocyanate, zingerone enhanced GABAergic spontaneous inhibitory transmission in a manner sensitive to tetrodotoxin. We conclude that zingerone presynaptically facilitates spontaneous excitatory transmission, probably through Ca(2+)-induced Ca(2+)-release mechanisms, and produces a membrane depolarization in SG neurons by activating TRPA1 but not TRPV1 channels.
authors: Department of Physiology, Saga Medical School, Saga, Japan.
authors: Hai-Yuan
authors: HY
authors: Yue
authors: Chang-Yu
authors: CY
authors: Jiang
authors: Tsugumi
authors: T
authors: Fujita
authors: Eiichi
authors: E
authors: Kumamoto
mesh_terms: D000818:Animals; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D018698:Glutamic Acid / Q000502:physiology; D006139:Guaiacol / Q000031:analogs & derivatives* / Q000494:pharmacology; D066298:In Vitro Techniques; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects; D008297:Male; D055369:Miniature Postsynaptic Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013376:Substantia Gelatinosa / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects*; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels / Q000819:agonists*; D050916:TRPV Cation Channels / Q000819:agonists*
chemical_list: D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels; D050916:TRPV Cation Channels; C480976:Trpa1 protein, rat; C493922:Trpv1 protein, rat; D018698:Glutamic Acid; C013738:zingerone; D006139:Guaiacol
keywords: TRPA1; excitatory transmission; patch clamp; spinal dorsal horn; zingerone