title: Effects of (-)-gallocatechin-3-gallate on tetrodotoxin-resistant voltage-gated sodium channels in rat dorsal root ganglion neurons.
abstract: The (-)-gallocatechin-3-gallate (GCG) concentration in some tea beverages can account for as much as 50% of the total catechins. It has been shown that catechins have analgesic properties. Voltage-gated sodium channels (Nav) mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant compared to other isoforms and functionally linked to nociception. In this study, the effects of GCG on tetrodotoxin-resistant Na+ currents were investigated in rat primary cultures of dorsal root ganglion neurons via the whole-cell patch-clamp technique. We found that 1 μM GCG reduced the amplitudes of peak current density of tetrodotoxin-resistant Na+ currents significantly. Furthermore, the inhibition was accompanied by a depolarizing shift of the activation voltage and a hyperpolarizing shift of steady-state inactivation voltage. The percentage block of GCG (1 μM) on tetrodotoxin-resistant Na+ current was 45.1% ± 1.1% in 10 min. In addition, GCG did not produce frequency-dependent block of tetrodotoxin-resistant Na+ currents at stimulation frequencies of 1 Hz, 2 Hz and 5 Hz. On the basis of these findings, we propose that GCG may be a potential analgesic agent.
authors: Laboratory of Pharmacology and Toxicology, School of Pharmaceutical Sciences, Sun Yat-Sen University, Guangzhou 510006, China. lssjjm@mail.sysu.edu.cn.
authors: Yan
authors: Y
authors: Zhang
authors: Yan-Yan
authors: YY
authors: Jia
authors: Jin-Lei
authors: JL
authors: Guo
authors: Pei-Qing
authors: PQ
authors: Liu
authors: Jian-Min
authors: JM
authors: Jiang
mesh_terms: D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002478:Cells, Cultured; D004351:Drug Resistance; D005727:Ganglia, Spinal / Q000166:cytology* / Q000187:drug effects*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000378:metabolism; D026941:Sodium Channel Blockers / Q000494:pharmacology*; D015222:Sodium Channels / Q000378:metabolism*; D013779:Tetrodotoxin / Q000494:pharmacology*
chemical_list: D026941:Sodium Channel Blockers; D015222:Sodium Channels; C417940:gallocatechin gallate; D013779:Tetrodotoxin; D002392:Catechin; D012964:Sodium
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