Chonnam Med J.  2007 Dec;43(3):158-167.

The Effect of DA-5018, A Synthetic Capsaicin Derivative,on Voltage-Dependent Calcium Currents in TrigeminalGanglion Neurons of Neonatal Rats

• Kim JS

Abstract

Capsaicin is known to produce initial excitation followed by desensitization to various stimuli on the sensory neurons. The aim of this study was to investigate the electrophysiological characteristics of voltage-dependent calcium currents (ICa) in trigeminal ganglion (TG) neurons of neonatal rats, and the effect of DA-5018, a synthetic water-soluble capsaicin derivative, on the ICa in vitro using a whole cell patch-clamp technique. TG neurons were acutely isolated into single cells from Sprague-Dawley rats. Sixty two cells out of 68 cells displayed high-voltage activated (HVA) ICa, the rest of them did low-voltage activated (LVA or T-type) ICa. In most DA-5018-sensitive subpopulation of TG neurons (70%), the magnitude of HVA ICa was markedly inhibited by DA-5018 in a dose-dependent manner. The inhibition of DA-5018 on ICa was greater at basic pH than at physiological pH. DA-5018-induced inhibition of voltage-dependent ICa was reversibly blocked by pretreatment with ruthenium red, a non-competitive antagonist of vanilloid receptor. These results suggest that there are LVA and HVA Ca2+ channels including N and L type in small-sized TG neurons of neonatal rats, and that HVA ICa are more sensitive to DA-5018 than LVA ICa. DA-5018 inhibits voltage-dependent ICa in dose- and pH-dependent manner, possibly through the activation of vanilloid receptors.

Keyword

DA-5018; Capsaicin; Vanilloid receptor; Calcium channel; Trigeminal ganglion

MeSH Terms

Animals
Calcium Channels
Calcium*
Capsaicin*
Hydrogen-Ion Concentration
Neurons*
Patch-Clamp Techniques
Rats*
Rats, Sprague-Dawley
Ruthenium Red
Sensory Receptor Cells
Trigeminal Ganglion
TRPV Cation Channels
Calcium
Calcium Channels
Capsaicin
Ruthenium Red
TRPV Cation Channels