Magnolol inhibits sodium currents in freshly isolated mouse dorsal root ganglion neurons. - GreenMedInfo Summary
Magnolol inhibits sodium currents in freshly isolated mouse dorsal root ganglion neurons.
Clin Exp Pharmacol Physiol. 2020 Oct 16. Epub 2020 Oct 16. PMID: 33064853
The voltage gated sodium channel (VGSC) currents in dorsal root ganglion (DRG) neurons contain mainly TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) Nacurrents. Magnolol (Mag), a hydroxylated biphenyl compound isolated from the bark of Magnolia officinalis, has been well documented to exhibit analgesic effects, but its mechanism is not yet fully understood. The aim of the present study was to investigate whether the antinociceptive effects of Mag is through inhibition of Nacurrents. Nacurrents in freshly isolated mouse DRG neurons were recorded with the whole-cell patch clamp technique. Results showed that Mag inhibited TTX-S and TTX-R Nacurrents in a concentration-dependent manner. The ICvalues for block of TTX-S and TTX-R Nacurrents were 9.4μM and 7.0 μM, respectively. Therefore, TTX-R Nacurrent was more susceptible to Mag than TTX-S Nacurrent. For TTX-S Nachannel, 10μM Mag shifted the steady-state inactivation curve toward more negative by 9.8 mV, without affecting the activation curve. For TTX-R Nachannel, 7μM Mag shifted the steady-state activation and inactivation curves toward more positive and negative potentials by 6.5 mV and 11.7 mV, respectively. In addition, Mag significantly postponed recovery of TTX-S and TTX-R Nacurrents from inactivation, and produced frequency dependent blocks of both subtypes of Nacurrents. These results suggest that the inhibitory effects of Mag on Nachannels may contribute to its analgesic effect.