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.
Keywords: catechins; (−)-gallocatechin-3-gallate; Na+ channel; dorsal root ganglion; tetrodotoxin-resistant
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Zhang, Y.; Jia, Y.-Y.; Guo, J.-L.; Liu, P.-Q.; Jiang, J.-M. Effects of (−)-Gallocatechin-3-Gallate on Tetrodotoxin-Resistant Voltage-Gated Sodium Channels in Rat Dorsal Root Ganglion Neurons. Int. J. Mol. Sci. 2013, 14, 9779-9789.
Zhang Y, Jia Y-Y, Guo J-L, Liu P-Q, Jiang J-M. Effects of (−)-Gallocatechin-3-Gallate on Tetrodotoxin-Resistant Voltage-Gated Sodium Channels in Rat Dorsal Root Ganglion Neurons. International Journal of Molecular Sciences. 2013; 14(5):9779-9789.
Zhang, Yan; Jia, Yan-Yan; Guo, Jin-Lei; Liu, Pei-Qing; Jiang, Jian-Min. 2013. "Effects of (−)-Gallocatechin-3-Gallate on Tetrodotoxin-Resistant Voltage-Gated Sodium Channels in Rat Dorsal Root Ganglion Neurons." Int. J. Mol. Sci. 14, no. 5: 9779-9789.