The effects of huwentoxin-I on the voltage-gated sodium channels of rat hippocampal and cockroach dorsal unpaired median neurons

Huwentoxin-I (HWTX-I) is a 33-residue peptide isolated from the venom of Ornithoctonus huwena and could inhibit TTX-sensitive voltage-gated sodium channels and N-type calcium channels in mammalian dorsal root ganglion (DRG) neurons. However, the effects of HWTX-I on mammalian central neuronal and insect sodium channel subtypes remain unknown. In this study, we found that HWTX-I potently inhibited sodium channels in rat hippocampal and cockroach dorsal unpaired median (DUM) neurons with the IC50 values of 66.1 +/- 5.2 and 4.80 +/- 0.58 nM, respectively. Taken together with our previous work on DRG neurons (IC50 approximate to 55 nM), the order of sodium channel sensitivity to HWTX-I inhibition was insect central DUM >> mammalian peripheral > mammalian central neurons. HWTX-I exhibited no effect on the steady-state activation and inactivation of sodium channels in rat hippocampal and cockroach DUM neurons. (C) 2012 Elsevier Inc. All rights reserved.