Effects of (-)-gallocatechin-3-gallate on tetrodotoxin-resistant voltage-gated sodium channels in rat dorsal root ganglion neurons

Int J Mol Sci. 2013 May 7;14(5):9779-89. doi: 10.3390/ijms14059779.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Catechin / analogs & derivatives*
  • Catechin / pharmacology
  • Cells, Cultured
  • Drug Resistance
  • Ganglia, Spinal / cytology*
  • Ganglia, Spinal / drug effects*
  • Patch-Clamp Techniques
  • Rats
  • Rats, Sprague-Dawley
  • Sodium / metabolism
  • Sodium Channel Blockers / pharmacology*
  • Sodium Channels / metabolism*
  • Tetrodotoxin / pharmacology*

Substances

  • Sodium Channel Blockers
  • Sodium Channels
  • gallocatechin gallate
  • Tetrodotoxin
  • Catechin
  • Sodium