Mechanism of action of two insect toxins huwentoxin-III and hainantoxin-VI on voltage-gated sodium channels

作者：Wang, Rui-lan; Yi, Su; Liang, Song-ping^*

来源：Journal of Zhejiang University-Science B(Biomedicine & Biotechnology), 2010, 11(6): 451-457.

DOI：10.1631/jzus.B0900393

• Insect neurotoxin
• Dorsal unpaired median neurons
• Sodium channel
• Whole-cell patch clamp technique

Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China. Their venoms contain abundant peptide toxins. Two new neurotoxic peptides, huwentoxin-III (HWTX-III) and hainantoxin-VI (HNTX-VI), were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography (RP-HPLC). The mechanism of action of HWTX-III and HNTX-VI on insect neuronal voltage-gated sodium channels (VGSCs) was studied via whole-cell patch clamp techniques. In a fashion similar to delta-atracotoxins, HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median (DUM) neurons. Meanwhile, 10 mu mol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel. HWTX-III inhibited VGSCs on DUM neurons (concentration of toxin at half-maximal inhibition (IC50)a parts per thousand 1.106 mu mol/L) in a way much similar to tetrodotoxin (TTX). HWTX-III had no effect on the kinetics of activation and inactivation. The shift in the steady-state inactivation curve was distinct from other depressant spider toxins. The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides.

• 出版日期2010-6
• 单位湖南师范大学; 广东食品药品职业学院; 湖南科技大学