| References: |
Retigabine (D-23129) is a novel antiepileptic compound with broad spectrum and potent anticonvulsant properties, both in vitro and in vivo. The compound was shown to activate a K+ current in neuronal cells. The pharmacology of the induced current displays concordance with the published pharmacology of the M-channel, which recently was correlated to the KCNQ2/3 K+ channel heteromultimere. Retigabine is a novel anticonvulsant with an unknown mechanism of action. Application of 10 μM retigabine to oocytes expressing the KCNQ2/3 heteromeric channel shifted both the activation threshold and voltage for half-activation by approximately 20 mV in the hyperpolarizing direction, leading to an increase in current amplitude at test potentials between ?80 mV and +20 mV. Retigabine also had a marked effect on KCNQ current kinetics, increasing the rate of channel activation but slowing deactivation at a given test potential. Retigabine shifted the voltage dependence of channel activation with an EC50value of 1.6 ± 0.3 μM (slope factor was 1.2 ± 0.1,n = 4 to 5 cells per concentration). Retigabine (0.1 to 10 μM) also slowed the rate of channel deactivation, predominantly by increasing the contribution of a slowly deactivating tail current component. Administration of centrally acting M-channel opener retigabine (2.5 and 7.5 mg/kg) can dose-dependently raise the head withdrawal threshold of mechanical allodynia, and this analgesic effect can be reversed by the specific KCNQ channel blocker XE991 (3 mg/kg). Food intake was increased significantly by the administration of retigabine (2.5 and 7.5 mg/kg), and this effect was reversed by XE991 (3 mg/kg). Furthermore, intracerebralventricular injection of retigabine further confirmed the analgesic effect of central retigabine on inflammatory TMJ. Retigabine exerted both antiepileptogenic and antiictogenic effects under conditions of rapid kindling model. |
