title: TRPV1 agonist piperine but not olvanil enhances glutamatergic spontaneous excitatory transmission in rat spinal substantia gelatinosa neurons.
abstract: We examined the effects of TRPV1 agonists olvanil and piperine on glutamatergic spontaneous excitatory transmission in the substantia gelatinosa (SG) neurons of adult rat spinal cord slices with the whole-cell patch-clamp technique. Bath-applied olvanil did not affect the frequency and amplitude of spontaneous excitatory postsynaptic current (sEPSC), and unchanged holding currents at -70 mV. On the other hand, superfusing piperine reversibly and concentration-dependently increased sEPSC frequency (half-maximal effective concentration: 52.3 μM) with a minimal increase in its amplitude. This sEPSC frequency increase was almost repetitive at an interval of more than 20 min. Piperine at a high concentration produced an inward current in some neurons. The facilitatory effect of piperine was blocked by TRPV1 antagonist capsazepine. It is concluded that piperine but not olvanil activates TRPV1 channels in the central terminals of primary-afferent neurons, resulting in an increase in the spontaneous release of l-glutamate onto SG neurons.
authors.affiliation: Department of Physiology, Saga Medical School, 5-1-1 Nabeshima, Saga 849-8501, Japan.
authors.forename: Liu
authors.initials: L
authors.lastname: Yang
authors.forename: Tsugumi
authors.initials: T
authors.lastname: Fujita
authors.forename: Chang-Yu
authors.initials: CY
authors.lastname: Jiang
authors.forename: Lian-Hua
authors.initials: LH
authors.lastname: Piao
authors.forename: Hai-Yuan
authors.initials: HY
authors.lastname: Yue
authors.forename: Kotaro
authors.initials: K
authors.lastname: Mizuta
authors.forename: Eiichi
authors.initials: E
authors.lastname: Kumamoto
mesh_terms: D000470:Alkaloids / Q000494:pharmacology*; D000818:Animals; D052117:Benzodioxoles / Q000494:pharmacology*; D002211:Capsaicin / Q000031:analogs & derivatives / Q000494:pharmacology; D018683:Excitatory Amino Acid Agents; D005971:Glutamates / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology*; D053284:Polyunsaturated Alkamides / Q000494:pharmacology*; D051381:Rats; D013376:Substantia Gelatinosa / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission / Q000187:drug effects*; D050916:TRPV Cation Channels / Q000819:agonists*
chemical_list: D000470:Alkaloids; D052117:Benzodioxoles; D018683:Excitatory Amino Acid Agents; D005971:Glutamates; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D050916:TRPV Cation Channels; C493922:Trpv1 protein, rat; C054256:olvanil; C071423:capsazepine; D002211:Capsaicin; C008922:piperine