| 18824159 |
Cho JS, Kim TH, Lim JM, Song JH: Effects of eugenol on Na+ currents in rat dorsal root ganglion neurons. . Brain Res. 2008 Dec 3;1243:53-62. Epub 2008 Sep 19.
Eugenol is an aromatic molecule found in several plants and widely used in dentistry for analgesic and antiseptic purposes. It inhibits pro-inflammatory mediators including nitric oxide synthase, cyclooxygenase and lipoxygenase. It also regulates ion channels involved in pain signaling, such as TRPV1 receptor, high-voltage-activated Ca (2+) channels, NMDA receptor and GABA (A) receptor. The expression and functional properties of voltage-gated Na (+) channels in primary sensory neurons are altered following inflammation or nerve injury. To elucidate an involvement of Na (+) channels in the eugenol-induced analgesia we investigated the effects of eugenol on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na (+) currents in acutely dissociated rat dorsal root ganglion neurons. Eugenol inhibited TTX-S and TTX-R Na (+) currents in a concentration-dependent manner. The K (d) values were 308 muM and 543 muM, respectively. Eugenol did not influence the activation voltage of either type of Na (+) current. However, eugenol moved the steady-state inactivation curves of both Na (+) currents to a hyperpolarizing direction and reduced the maximal Na (+) current. Thus eugenol appears to inhibit Na (+) currents through its interaction with both resting and inactivated Na (+) channels. The recovery from inactivation of both Na (+) currents was slowed by eugenol. The eugenol inhibition of Na (+) currents was not dependent on the stimulus frequency. The inhibition of Na (+) currents is considered as one of the mechanisms by which eugenol exerts analgesia. |
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