Spontaneous L-glutamate release enhancement in rat substantia gelatinosa neurons by (-)-carvone and (+)-carvone which activate different types of TRP channel.
Transient receptor potential (TRP) channels in the spinal dorsal horn lamina II (substantia gelatinosa; SG), which are involved in the modulation of nociceptive transmission, have not yet been fully examined in property. Activation of the TRP channels by various plant-derived chemicals results in an increase in the spontaneous release of L-glutamate onto the SG neurons. We examined the effects of a monoterpene ketone (-)-carvone (contained in spearmint) and its stereoisomer (+)-carvone (in caraway) on glutamatergic spontaneous excitatory transmission in SG neurons of adult rat spinal cord slices by using the whole-cell patch-clamp technique. (-)-Carvone and (+)-carvone increased the frequency of spontaneous excitatory postsynaptic current (sEPSC) in a reversible and concentration-dependent manner with a small increase in its amplitude. Half-maximal effective concentrations of (-)-carvone and (+)-carvone in increasing sEPSC frequency were 0.70 mM and 0.72 mM, respectively. The (-)-carvone but not (+)-carvone activity was inhibited by a TRPV1 antagonist capsazepine. On the other hand, the (+)-carvone but not (-)-carvone activity was inhibited by a TRPA1 antagonist HC-030031. These results indicate that (-)-carvone and (+)-carvone activate TRPV1 and TRPA1 channels, respectively, resulting in an increase in spontaneous L-glutamate release onto SG neurons, with almost the same efficacy. Such a difference in TRP activation between the stereoisomers may serve to know the properties of TRP channels in the SG.
Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.
Qin
Q
Kang
Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.
Chang-Yu
CY
Jiang
Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.
Tsugumi
T
Fujita
Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan. Electronic address: kumamote@cc.saga-u.ac.jp.
Eiichi
E
Kumamoto
D000083:Acetanilides / Q000494:pharmacology; D000818:Animals; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D000081005:Cyclohexane Monoterpenes; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D018698:Glutamic Acid / Q000378:metabolism*; D008297:Male; D039821:Monoterpenes / Q000737:chemistry / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011687:Purines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013237:Stereoisomerism; D013376:Substantia Gelatinosa / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors; D050916:TRPV Cation Channels / Q000819:agonists / Q000037:antagonists & inhibitors; D050051:Transient Receptor Potential Channels / Q000819:agonists* / Q000037:antagonists & inhibitors
C552888:2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopropylphenyl)acetamide; D000083:Acetanilides; D000081005:Cyclohexane Monoterpenes; D039821:Monoterpenes; D011687:Purines; D000074025:TRPA1 Cation Channel; D050052:TRPC Cation Channels; D050916:TRPV Cation Channels; D050051:Transient Receptor Potential Channels; C480976:Trpa1 protein, rat; C493922:Trpv1 protein, rat; D018698:Glutamic Acid; C006923:carvone; C071423:capsazepine; D002211:Capsaicin
(+)-Carvone; (−)-Carvone; Glutamate release; Spinal substantia gelatinosa; TRPA1; TRPV1